Handbook of Pediatric Neurosurgery

The dura is not opened until the peritoneal phase
is complete and the distal catheter has been passed
completely. The dura is identified and cauterized
with bipolar forceps before it is incised in a cruci-
ate fashion. The pia is also cauterized and incised
with the tip of the bipolar forceps.
37.5.5 Peritoneal Phase
A transverse 2- to 3-cm long linear incision, located
on the ipsilateral abdominal quadrant, centered
over the lateral border of the anterior rectus muscle,
approximately 2 to 3 cm lateral and 1 to 2 cm above
the umbilicus. Immediately after dissecting the sub-
cutaneous fat, the anterior rectus sheath is identi-
fied and incised. The fibers of the rectus muscle are
split following the direction of the fibers until the
posterior rectus sheath is unveiled and incised. The
peritoneum is identified and carefully grabbed with
the tips of two mosquito forceps in a tent-like fash-
ion, with great care to avoid any accidental lesion to
the peritoneal cavity content. A purse-string suture
is placed, either 3.0 Vicryl or 4.0 silk before the inci-
sion is done.
37.5.6 Shunt Tunneling Phase
A shunt passer is bent and advanced through the
subcutaneous fat layer, from the abdominal
incision all the way up to the scalp incision. Try to
avoid a superficial tunnel trajectory. We usually do
additional incisions where the passer stops, before
traumatizing the skin when trying to force our dis-
sector. A retroauricular incision over the tip of the
mastoid is usually necessary. A subcutaneous
pocket for the valve is dissected over the trajectory
of the passer. The distal catheter is passed from
the cephalic to the abdominal incision. We usually
open the package containing the shunt compo-
nents only after the incisions and dissection of the
cephalic and distal wounds are complete. We
manipulate the components with blunt or rubber-
protected instruments.
37.5.7 Catheter Placement
Frontal Approach
● Relocate the head to neutral position.
● Use external cranial marks to define the
trajectory of the ventricular catheter. This should
end up being located at the ipsilateral foramen
of Monro. On the coronal plane, the trajectory of
the catheter is directed posteriorly towards the
Fig. 37.1 Schematic drawing of the precoronal Kocher’s
point location. CS, coronal suture; MPL, mid-pupillary
line; N, nasion; PK, point of Kocher. (Courtesy of
Gutiérrez-Oliva K.)
Fig. 37.2 Schematic drawing of the posterior parietal
Frazier’s point location. IN, inion; PF, point of Frazier; SS,
sagittal suture. (Courtesy of Gutiérrez-Oliva K.)
Developmental and Congenital Cranial Disorders
308

outer ear, while the tip of the catheter, in the
sagittal anteroposterior (AP) plane, is in line
with the ipsilateral medial canthus.
● Should feel entering the frontal horn 3 to 5 cm
deep. The catheter is advanced 1 cm further
before the stylet is w ithdrawn. The rest of the
catheter is advanced without the inner
stylet at a depth of 5 to 6 cm from the cranial
vault.
Posterior Parietal Approach
● Direct a parallel trajectory aiming for the
ipsilateral medial canthus.
● Should feel entering the occipital horn by 3 to
4 cm from the cranial vault.
● The catheter is advanced 2 cm further before the
stylet is withdrawn and the rest of the catheter
is advanced to a depth of 6 cm, according to the
preoperative measures.
The spontaneous flow of CSF is the commonest
sign of a successful catheter location. The gentle
aspiration of CSF without resistance trough a blunt
needle connected to the catheter might be needed
in cases when cerebral parenchyma or a blood clot
blocks the catheter.
The most common devices come with a 90
degrees angle fixing attachment at the outer bor-
der of the burr hole, to stitch it to pericranium and
to protect the catheter from the overbending. The
proximal catheter is assembled with the reservoir
shunt which has been previously attached the dis-
tal catheter. An arrow or arrowhead is usually
drawn on the valve reservoir pointing at the direc-
tion of the flow, from cephalic to distal. The distal
catheter is cut in a length that permits to locate
the valve 2 to 3 cm distal from the burr hole, close
to the incision and not far back in the neck. This
will facilitate a revision procedure through only
one incision when needed.
A final assessment of the catheter placement and
of the correct assembly of the shunt, components
should be done before placing the distal catheter
inside the peritoneal cavity. CSF is aspirated from
the distal catheter with a blunt needle through one
of the distal catheter slits. There should be no
resistance to gentle aspiration. Any di culty sug-
gests that the ventricular catheter has been
retracted out of the ventricle, or cerebral paren-
chyma or a blood clot blocks the catheter, usually at
the connections of the system, or that the assembly
of the components have been erroneous.
The immediate postoperative care demands the
continuous use of antibiotics for 24 hours, mobili-
zation to be delayed for 6 to 12 hours, and dis-
charge to home after 24 to 48 hours.
37.6 Complications
37.6.1 Transoperative
Cranial Complications
Erroneous Location of the Ventricular
Catheter
● Too deep
● Misdirected trajectory
No spontaneous CSF flow through the catheter
once inserted, or any resistance to gentle aspira-
tion suggest blockade by a blood clot, brain
parenchyma, or choroid plexus. Gently inject 2 cm
of saline solution to unblock the flow. If there is no
CSF flow and the resistance persists, parenchymal
or cisternal location is suspected. The catheter has
to be relocated.
Intracerebral or Intraventricular
Hemorrhage
It is noticed when blood flows along with CSF
through the catheter. It is especially common
among patients with coagulopathies, which is a
frequent complication of severe infectious
disorders.
Usually, stops spontaneously or with saline solu-
tion instillation through the catheter. An immedi-
ate postoperative CT is mandatory to define the
extent of the hemorrhage and decide whether
to keep the shunt in place or change it for an
external drainage. Rarely, an open craniotomy is
required to explore and directly coagulate the
injured vessel.
Abdominal Complications
Misplacement of the Distal Catheter
Preperitoneal location. Identified with resistance
to pass the catheter into the abdominal cavity or
the presence of CSF leaking through the abdominal
wound.
Relocate the catheter.
Treatment of Hydrocephalus in the Developing World
309

Injury to Abdominal Viscera
Identified with the presence of intestinal fluid or
hemorrhage from the injured wall.
Usually required assistance of a general pediatric
surgeon. The peritoneal cavity might no longer be
the option for CSF drainage. Select to either trans-
form for an external drainage or modify the distal
location of the catheter.
37.7 Postoperative
37.7.1 Shunt Malfunction
A mechanical obstruction is a common delayed
complication. The overall failure rate during the
first year of implantation is 35 to 40%.14,15 Could
be detected at the proximal catheter due to protru-
sion of the choroid plexus, infiltration from tumor,
collapse of the ventricular walls, glial tissue from
astrocyte proliferation, debris, or blood.16 When
the distal catheter is the site of the obstruction,
consider preperitoneal migration or displacement
and omentum obstruction.
37.7.2 Infections
Incidence of shunt infections ranges from 8 to
12%.14,15,17,18,19 Shunt insertion at younger age,
prematurity, and CSF leak are recognized risk fac-
tors.20
Several bacterial pathogens have been
described: Staphylococcus epidermidis, Staphylo-
coccus aureus, Klebsiella pneumoniae, Pseudomonas
aeruginosa, and Candida albicans.19,20 The use of
antibiotic-impregnated shunts lowers, but not
abolishes, the infection rates. The infection rate in
these shunts is 5%.21 Great care should be taken
during the preoperative phase to reduce the infec-
tion and contamination risks.
Shunt Erosion through Skin
To prevent this in malnourished and premature
patients:
● Select the smallest shunt system available.
● Draw a larger scalp flap with extensive skin
dissection.
● Avoid suture lines over any of the shunt
components.
Catheter Migration
● Intestinal migration
● Rare migration sites
Identify the location and patency of the connec-
tions of the system by X-ray films.
Remove the system. Disarticulate the compo-
nents and pull out the distal catheter from the
exposed migration site. Never try to pull it out
through the cephalic incision or along the subcuta-
neous trajectory.
Complication of Previous Abdominal
Conditions Such as Hydrocele,
Defects of the Abdominal Wall, or
Ascites
Peritoneal Pseudocyst
Rare but recognized com plication. Related to the
presence of inflam m atory cells and fibrous tis-
sue lining on the surface of the distal catheter.
Previous shunt infection or repetitive revisions
are probable risk factors.22 The rem oval of the
w hole system is advised, since it seem s to be
related to bacterial colonization of the distal
catheter.
Seizures
The incidence of seizures in shunted children is
reported to be quite high, ranging from 20% to
approxim ately 50%.23 Early shunting in patients
younger than 2 years, history of shunt com plica-
tions, shunt infection, and revisions are signifi-
cant risk factors for developing post-shunt
seizures.24
37.8 Common Clinical
Questions
1. Which management strategy represents the
optimal approach in Chiari I malformation with
hydrocephalus?
2. Which is the best treatment for an infant with
congenital hydrocephalus secondary to cerebral
aqueduct stenosis?
3. Describe the management strategy that should
be followed in order to reduce the risk of shunt
infections.
4. Are the programmable valves more suitable
than the set pressure valves in the developing
world scenario?
Developmental and Congenital Cranial Disorders
310

37.9 Answers to Common
Clinical Questions
1. In patients with Chiari I malformations and
hydrocephalus, shunting or ETV is used to
resolve hydrocephalus. It is recommended
before trying foramen magnum decompression
(FMD). Only if the symptoms and signs persist
after the CSF shunt, a FMD should be
considered.8
2. The overall success rates of ETV are 23 to 94%,
with a m ean of 68%. The success rate is
hom ogeneous above 60% at any age in cases of
obstructive hydrocephalus confined to the
third and lateral ventricles. There is a trend in
lower success rates in infants younger than 6
m onths of age.25 In these patients, a low-
pressure valve shunt is recom m ended. In a
retrospective study, low-pressure shunts were
e ective in m ore than 80% of children under 2
years of age.26
3. Incidence of shunt infections ranges from 8 to
12%.14,15,17,18,19 The use of antibiotic-
impregnated shunts mildly lowers the infection
rates. The infection rate in these shunts is 5%.21
The most important preoperative issues are
directed toward the reduction of infection and
contamination risks especially in patients at
higher risk such as young infants or premature
newborns. We recommend to schedule as the
first case at the neurosurgery operating room,
limit the number of medical and paramedical
personnel inside the OR, and avoid in and out
tra c from the OR. Manipulate the components
of the shunt as minimum required, with
instruments rather than with your hands. We
usually do additional incisions where the passer
stops, before traumatizing the skin when trying
to force our dissector. Since CSF leak is one of
the recognized risk factors,20 we avoid the
incisions over the burr hole in order to reduce
the risk of CSF fistula or the exposure of the
catheter entry.
4. Several authors described safety and e cacy of
programmable shunts as comparable with set
pressure valves.14,15 The main advantage of
programmable shunts is reduced risk of overall
shunt revision and proximal obstruction.13
These arguments are in favor of programmable
valves in developing countries, especially in
areas with scarce distribution of neurosurgical
services in large territories with poor means of
transportation that demand long and complex
journeys from their homes. The main obstacle is
the cost-e ectiveness relation when comparing
to set pressure valves.
References
[1] Rekate HL. Hydrocephalus in children. In: Winn HR, ed.
Youmans Neurological Surgery. 5th ed. New York, NY:
Saunders Elsevier; 2004:3387–3404
[2] Bondurant CP, Jiménez DF. Epidemiology of cerebrospinal
fluid shunting. Pediatr Neurosurg. 1995; 23(5):254–258,
discussion 259
[3] Melo JRT, de Melo EN, de Vasconcellos AG, Pacheco P.
Congenital hydrocephalus in the northeast of Brazil:
epidemiological aspects, prenatal diagnosis, and treatment.
Childs Nerv Syst. 2013; 29(10):1899–1903
[4] Warf BC. Hydrocephalus associated with neural tube defects:
characteristics, management, and outcome in sub-Saharan
Africa. Childs Nerv Syst. 2011; 27(10):1589–1594
[5] Tamburrini G, Frassanito P, Iakovaki K, et al.
Myelomeningocele: the management of the associated
hydrocephalus. Childs Nerv Syst. 2013; 29(9):1569–1579
[6] Robinson S. Neonatal posthemorrhagic hydrocephalus from
prematurity: pathophysiology and current treatment
concepts. J Neurosurg Pediatr. 2012; 9(3):242–258
[7] Behjati S, Emami-Naeini P, Nejat F, El Khashab M. Incidence
of hydrocephalus and the need to ventriculoperitoneal
shunting in premature infants with intraventricular
hemorrhage: risk factors and outcome. Childs Nerv Syst.
2011; 27(6):985–989
[8] Lee S, Wang K-C, Cheon J-E, et al. Surgical outcome of Chiari I
malformation in children: clinico-radiological factors and
technical aspects. Childs Nerv Syst. 2014; 30(4):613–623
[9] Cho YH, Ho TS, Wang SM, Shen CF, Chuang PK, Liu CC.
Childhood tuberculosis in southern Taiwan, with emphasis
on central nervous system complications. J Microbiol
Immunol Infect. 2014; 47(6):503–511
[10] Vinchon M, Rekate H, Kulkarni AV. Pediatric hydrocephalus
outcomes: a review. Fluids Barriers CNS. 2012; 9(1):18
[11] Anderson RCE, Garton HJL, Kestle JRW. Treatment of
hydrocephalus with shunts. In: Albright AL, Pollack IF, Adelson
PD, eds. Operative Techniques in Pediatric Neurosurgery. New
York, NY: Thieme; 2001
[12] Jain H, Sgouros S, Walsh AR, Hockley AD. The treatment of
infantile hydrocephalus: “di erential-pressure” or “flow-
control” valves. A pilot study. Childs Nerv Syst. 2000; 16(4):
242–246
[13] McGirt MJ, Buck DW, II, Sciubba D, et al. Adjustable vs set-
pressure valves decrease the risk of proximal shunt
obstruction in the treatment of pediatric hydrocephalus.
Childs Nerv Syst. 2007; 23(3):289–295
[14] Drake JM, Kestle JR, Milner R, et al. Randomized trial of
cerebrospinal fluid shunt valve design in pediatric
hydrocephalus. Neurosurgery. 1998; 43(2):294–303, discussion
303–305
[15] Pollack IF, Albright AL, Adelson PD, Hakim-Medos
Investigator Group. A randomized, controlled study of a
programmable shunt valve versus a conventional valve for
patients with hydrocephalus. Neurosurgery. 1999; 45(6):
1399–1408, discussion 1408–1411
[16] Singh I, Rohilla S, Kumawat M, Goel M. Comparison of total
versus partial revision of primary ventriculoperitoneal shunt
failures. Surg Neurol Int. 2013; 4:100
Treatment of Hydrocephalus in the Developing World
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[17] Eymann R, Steudel WI, Kiefer M. Pediatric gravitational
shunts: initial results from a prospective study. J Neurosurg.
2007; 106 suppl 3:179–184
[18] Simon TD, Hall M, Riva-Cambrin J, et al. Hydrocephalus
Clinical Research Network. Infection rates following initial
cerebrospinal fluid shunt placement across pediatric
hospitals in the United States. Clinical article. J Neurosurg
Pediatr. 2009; 4(2):156–165
[19] Ahn ES, Bookland M, Carson BS, Weingart JD, Jallo GI. The strata
programmable valve for shunt-dependent hydrocephalus: the
pediatric experience at a single institution. Childs Nerv Syst.
2007; 23(3):297–303
[20] Lee JK, Seok JY, Lee JH, et al. Incidence and risk factors of
ventriculoperitoneal shunt infections in children: a study of
333 consecutive shunts in 6 years. J Korean Med Sci. 2012; 27
(12):1563–1568
[21] Kan P, Kestle J. Lack of e cacy of antibiotic-impregnated
shunt systems in preventing shunt infections in children.
Childs Nerv Syst. 2007; 23(7):773–777
[22] Yuh SJ, Vassilyadi M. Management of abdominal pseudocyst in
shunt-dependent hydrocephalus. Surg Neurol Int. 2012; 3:146
[23] Sato O, Yamguchi T, Kittaka M, Toyama H. Hydrocephalus and
epilepsy. Childs Nerv Syst. 2001; 17(1–2):76–86
[24] Majed M, Andrabi Y, Nejat F, El Khashab M. Seizure risk
factors in shunted hydrocephalic patients. Pediatr Neurosurg.
2012; 48(5):286–290
[25] Spennato P, Tazi S, Bekaert O, Cinalli G, Decq P. Endoscopic
third ventriculostomy for idiopathic aqueductal stenosis.
World Neurosurg. 2013; 79 suppl 2:21.e13–21.e20
[26] Breimer GE, Sival DA, Hoving EW. Low-pressure valves in
hydrocephalic children: a retrospective analysis. Childs Nerv
Syst. 2012; 28(3):469–473
Developmental and Congenital Cranial Disorders
312

VII
Section VII
Developmental and
Congenital Spinal Disorders
38 Abnormalities of the
Craniocervical Junction and
Cervical Spine

314
39 Spina Bifida: Classification and
Management

321
40 Pathophysiology and
Management of Tethered
Cord (Including
Myelomeningocele)

325
41 Intraspinal Lipomas

332
42 Scoliosis

335
43 Achondroplasia

342

38 Abnormalities of the Craniocervical Junction and
Cervical Spine
Jared S. Fridley, Christina Sayama, Andrew Jea
38.1 Introduction
Abnormalities of the craniocervical junction (CCJ)
and cervical spine (CS) can be seen in both adults
and children. There is a wide spectrum of disor-
ders that can a ect the CCJ and CS. Their etiology
may be developmental, congenital, or acquired. In
the pediatric population, these abnormalities are
often associated with a syndrome, such as Down’s
syndrome or Morquio’s syndrome. Understanding
the disease entities that underlie CCJ and CS
abnormalities can help with identification of the
underlying abnormal pathophysiology. Early iden-
tification and treatment of these patients may help
prevent progression to more severe problems,
such as basilar invagination or spinal cord injury/
compression.
● Basilar invagination is a developmental anomaly
of the CCJ in which the odontoid prolapses into
the foramen magnum.1
● Atlantoaxial instability is present in 14 to 20%
patients with Down’s syndrome, due to
ligamentous laxity.2
● Foramen magnum stenosis is seen in patients
with achondroplasia, sometimes with
cervicomedullary compression, which can lead
to respiratory compromise.
● Odontoid anom alies include aplasia,
hypoplasia, and os odontoideum , and are
com m only seen in Morquio’s syndrom e
(30–50% with com bination of os odontoideum ,
atlantoaxial instability (AAI), and
cervicothoracic abnorm alities).3
● Klippel–Feil syndrome comprises a spectrum of
CS osseous disorders often with congenital
cervical fusion, limitation of cervical motion, and
scoliosis in up to 50% of patients.4
● Majority of cervical spine injuries occur in
children due to ongoing development of CS
ossification centers, weak neck muscles with a
relatively large head, ligamentous laxity, and
angled facet joints.
● Patients with occipital–cervical synostosis have
congenital fusion of the occiput to C1, which can
lead to C1–C2 instability.
● Unilateral C1 absence can cause torticollis, and is
associated with tracheoesophageal fistula.
38.2 Anatomy
● CCJ extends from the occipital bone to C2.
● Atlas develops from three ossification centers,
the first of which (the body) appears at 1 year of
age, completely fused and visible by 7 years of
age.5
● Axis develops from five ossification centers;
body fused to the dens by age 6.5
● Fifty percent of cervical spine rotation occurs at
C1–C2.
● C2 is the first bifid process of the cervical
spine.
● The superior and inferior obliques, levator
scapulae, and rectus capitis muscles make up the
musculature of the CCJ (Fig. 38.1).
● Ligamentous structures of the CCJ include the
anterior longitudinal ligament, the cruciate
ligament (composed of the transverse and
longitudinal ligaments), and the tectorial
membrane (Fig. 38.2).
● The hypoglossal nerve can be found exiting
anterior and superior to the occipital condyle.
● The vertebral artery usually enters the
transverse foramen of C6, ascends to the
transverse foramen of C2, then travels through
the C1 transverse foramen, and enters the sulcus
arteriosus along the superior aspect of the C1
lamina, prior to piercing the dura.
● Borders of the suboccipital triangle include (1)
obliquus capitis superior, (2) obliquus capitis
inferior, and the (3) rectus capitis posterior
major ( Fig. 38.3).
● The vertebral artery above C1 can be found
within the suboccipital triangle.
38.3 Examination
Initial examination of the pediatric patient with a
CCJ or CS abnormality must be comprehensive.
This includes a thorough history of neurological
and nonneurological systemic symptoms/signs.
Physical examination should look for signs of an
associated syndrome, looking for facial, neck,
extremity, chest, back, and visceral abnormalities.
Family history should be obtained in every patient.
314

Fig. 38.1 The superior and inferior obliques, levator scapulae, and rectus capitis muscles make the musculature of the
CCJ. (Courtesy of Katherine Relyea.)
Fig. 38.2 Ligamentous structures of
the CCJ include the anterior longitudi-
nal ligament, the cruciate ligament
(composed of the transverse and
longitudinal ligaments), and the
tectorial membrane. (Courtesy of
Katherine Relyea.)
Abnormalities of the Craniocervical Junction and Cervical Spine
315

Questions regarding developmental delay should
be asked, especially with regard to motor function.
38.3.1 Physical Examination
● Up to 85% children with CCJ abnormality present
with neck or occipital head pain.3
● Torticollis may be an important clinical sign of a
CCJ abnormality in an infant or toddler.
● Cocking of the head to one side (“cock robin”
deformity) in children can indicate atlantoaxial
rotatory subluxation (AARS).
● Klippel–Feil syndrome classic clinical triad: (1)
decreased neck range of motion, (2) short neck,
(3) low posterior hairline.
● Myelopathy is the most common neurological
deficit encountered in CCJ abnorm alities.3
● In patient’s suspected of Klippel–Feil syndrome,
evaluate for associated renal abnormalities,
congenital heart disease, and hearing impairment.
● “Basilar migraine” can be seen in 25% of patients
with basilar invagination with compression of
the vertebrobasilar arterial tree and/or medulla
resulting in pain and neurological deficit.6
38.3.2 Radiographic Examination
● Flexion/extension lateral cervical X-rays can help
screen for cervical instability.
● Computed tomography (CT) and magnetic
resonance imaging (MRI) are useful to define
bony anatomy/epiphyseal growth plates and
ligamentous abnormalities prior to surgical
intervention.
● The atlanto-dens interval (ADI) is normally less
than or equal to 5 mm in children younger than
8 years; increased ADI can indicate atlantoaxial
instability.
● Pseudosubluxation of the cervical spine at
C2–C3 or C3–C4 occurs in 20 to 46% of children
younger than 8 years.7,8
● Up to 6 mm of C1 lateral mass overhang on C2
can be seen in patients up to 8 years old, and is a
normal variant.9
● If the tip of the dens is above a line
(McRae’s line) extending from the basion
to opisthion, basilar invagination is
present.
● Norm al atlanto-occipital interval (AOI) is less
than 2 m m in children and is strongly
sym m etric on the left and right sides10; an AOI
greater than or equal to 4 m m has high
sensitivity and specificity for atlanto-occipital
dislocation.11
● Normal posterior interspinous distance should
be less than or equal to 1.5 times the
interspinous distance above or below the level
being examined.7
Fig. 38.3 Borders of the suboccipital
triangle include obliquus capitis
superior, obliquus capitis inferior,
and the rectus capitis posterior major.
(Courtesy of Katherine Relyea.)
Developmental and Congenital Spinal Disorders
316

38.4 Nonsurgical Management
● Mobile AARS man be treated conservatively with
anti-inflammatory medications in patients
where the cause is due to a post-inflammatory
reaction, usually due to infection.12
● In AARS patients who undergo closed cervical
reduction, collar immobilization may be
considered.
● In neurologically intact patients with mild
basilar invagination, clinical and radiographic
follow-up may be tried.
● In children with Down’s syndrome and
radiographic concern for AAI, it is reasonable to
manage them conservatively if there is no
evidence of spinal cord injury.
38.5 Surgical Indications
A neurological deficit in a pediatric patient with
either a CCJ or CS abnormality is an absolute indi-
cation for surgical intervention. Other indications
for surgery include (1) AAI secondary to either
acquired or congenital etiologies, (2) severe basilar
invagination, (3) unilateral occipitocervical synos-
tosis, (4) occipitocervical dislocation, (5) type II
odontoid fractures, (6) occipitocervical instability
secondary to acquired or congenital etiologies, and
(7) iatrogenic kyphotic postoperative deformities.
Prior to surgical intervention, preoperative
imaging must be obtained and reviewed. A thin-
slice CT scan from occiput to lower cervical spine
is useful to examine the bony anatomy of the path-
ology in general, but also for instrumentation
planning.13 The location of the vertebral artery
must be identified as it courses from the cervical
spine into the cranium. Patients with an abnormal
course of the vertebral artery may preclude
pedicle/pars or transarticular screws at C2. A CT
sagittal view of the C2 pars is essential to identify
the feasibility of a C2 pars screw. Screw lengths
and widths should be discerned prior to entering
the operating room. MRI examination is also useful
to look for the extant of ligamentous instability
and to identify any sites of neural compression.
38.6 Surgical Technique
The type of surgical approach chosen for patients
with CS and CCJ pathologies is based on multiple
factors including (1) level of the pathology, (2)
whether neural compression is present and, if so,
whether it is anterior or posterior, (3) site(s) of
instability, (4) patient’s age, weight, and comorbid-
ities, and (5) bone quality. To access the anterior
CCJ, a transnasal- or transoral–transpalatophar-
yngeal approach may be used. This allows access
to the clivus, atlas, and axis. Posterior approaches
will often involve posterior occipital and/or cervi-
cal decompression of neural elements followed by
stabilization with instrumentation using various
techniques.
● The anterior approach to the CCJ is useful for
lesions causing cervicomedullary compression,
especially nonreducible lesions, such as in cases
of basilar invagination.
● The transoral–transpalatopharyngeal approach
can be combined with palatal and/or mandibular
splitting for further rostral or caudal exposure.
● The incision for the transoral approach is made
in the midline posterior pharynx from the
rostral clivus to the C2–C3 disc space to expose
the prevertebral fascia and longus colli.
● Anatomical landmarks for the placement of
occipital screws include (1) posterior rim of the
foramen magnum, (2) superior nuchal line, (3)
inferior nuchal line, and (4) external occipital
protuberance (Fig. 38.4).
● Drilling for occipital screws should be done in a
stepwise fashion, in 2-mm increments, until the
occipital bone inner cortex is penetrated to allow
bicortical screw placement.
● When placing C1 lateral mass screws, the medial
and lateral borders of the lateral masses should
be palpated.
● Significant bleeding may be encountered due to
the C1–C2 venous plexus, which can be avoided
with careful subperiosteal dissection and bipolar
cautery.
● The C2 nerve root can be transected if it is
unable to be retracted for screw placement; this
results in posterior scalp numbness.
● The entry point is in the center of the lateral
mass, aiming toward the anterior arch of C1, 0 to
5 degrees medially.
● Placement of C1–C2 transarticular screws
requires a steep insertion angle utilizing a
posterior stab incision around T1, aiming for the
medial border of the C2 pars.
● C2 pars screws are placed along a line running
from the inferior articular process to the
superior articular process, using a vertical
trajectory.
● C2 pedicle screws utilize a more medial,
horizontal trajectory, starting beneath the
superior articular process, along the C2 superior
laminar ridge.
Abnormalities of the Craniocervical Junction and Cervical Spine
317

● C2 translaminar screws have a high fusion rate, a
low risk of vertebral artery injury, and are nearly
always anatomically feasible.14
● The entry point for translaminar screw
placement is made at the junction of the C2
spinous process and lamina.
● Subaxial cervical spine (C3–C7) lateral mass
screw entry point is 1 mm medial and 1 mm
inferior to the midpoint of the lateral mass, the
trajectory is directed approximately 20 degrees
cranial and 20 degrees lateral.
● Endoscopic endonasal approaches to the CCJ and
upper cervical spine may o er improved
visualization and decreased morbidity compared
to the open transoral approach.15
38.7 Complications
● Complications associated with the transoral
approach include posterior pharyngeal wound
dehiscence, pharyngeal wound infection,
velopharyngeal incompetence, dysphagia,
odynophagia, and meningitis.16,17
● Anterior cervical approach dural tears should be
primarily repaired or patched with a synthetic or
fascial graft.
● There is an approximately 2.2% risk, per
transarticular screw, of injuring the vertebral
artery.18
38.8 Postoperative Care
All patients undergoing cervical spine surgery
should be placed on analgesics and muscle relaxants
postoperatively. Early mobilization and chemopro-
phylaxis to prevent deep venous thrombosis is insti-
tuted early after surgery. Posterior cervical patients
have their diet advanced as tolerated, while special
consideration is given to those patient’s undergoing
an anterior cervical approach, especially when sig-
nificant laryngeal edema or dysphagia is present.
Patients undergoing a transoral approach have a
nasogastric tube and endotracheal tube left in place
after surgery for one to several days to (1) protect
airway and allow tracheal/airway edema to
decrease, (2) provide nutrition, and (3) prevent gas-
tric reflux into wound.19
38.9 Outcomes
● Pediatric patients undergoing a transoral
approach usually experience neurological
improvement and have an overall good
neurological outcome despite a small but
significant risk of morbidity/mortality.17,20
● Cervical spine instrumentation in the pediatric
population has a high fusion rate (95–99%) with
wiring constructs having higher morbidity than
screw constructs.13,21
● Preoperative planning and review of patient’s
bony, neural, and vascular anatomy are critical to
ensure the success of instrumentation constructs
and avoidance of complications.13
● Bicortical occipital screw placement in children
results in a higher fusion rate in occipitocervical
constructs, but carries a small risk of dural
venous sinus injury, and cerebrospinal fluid
(CSF) leak.22
(Tendon) of the occipitalis
(Tendon) of the trapezius
Semispinalis capitis
Sternocleidomastoid
Splenius capitis
Hypoglossal
canal
Rectus capitis posterior major
Rectus capitis posterior minor
Obliquus capitis superior
Rectus capitis lateralis
Foramen
magnum
M
e
d
i
a
n

n
u
c
h
a
l

l
i
n
e
Basilar
plat e
Jugular
process
Rectus capitis anterior
Longus capitis
H
ig
h
es
t
nu
ch
al l
in
e
S
u
p
e
ri
o
r
n
u
c
h
a
l
li
n
e
E
xt
.
o
cc
ip
.
p
r
o
t
u
b
e
r-


a
n
c
e
I
n
f
e
r
i
o
r
n
u
c
h
al
li
ne
C
o
n
d
yl
oi
d
c
a
n
al
O
c
c
i
p
it
a
l
c
o
n
d
y
l
e
Fig. 38.4 Anatomical landmarks for
the placement of occipital screws
include (1) posterior rim of the fora-
men magnum, (2) superior nuchal line,
(3) inferior nuchal line, and (4) external
occipital protuberance. (Courtesy of
Katherine Relyea.)
Developmental and Congenital Spinal Disorders
318

● Sectioning of the C2 nerve root for occipital mass
screw placement in children enhances visibility
of the C1 lateral mass, minimizes intraoperative
complications, and does not lead to significant
functional deficits.23
38.10 Surgical Pearls
● Always have a contingency plan determined
preoperatively for placement of instrumentation
if your first plan fails or is not feasible.
● Always look at the course of the vertebral artery,
which may be anomalous in children with
underlying disorders. Obtain preoperative
vascular imaging if T2 flow void imaging is not
su cient.
38.11 Common Clinical
Questions
1. What is the youngest age that a child has
undergone craniocervical stabilization surgery?
2. How often should you image a child you are
following conservatively for craniocervical
instability?
3. Is there any utility in external cervical orthosis
after fusion in the pediatric population?
4. What types of adjuvants are used to help aid in
fusion?
38.12 Answers to Common
Clinical Questions
1. 18 months. The surgeon must consider the
individual child’s anatomy, feasibility of
hardware placement, bone maturity, and
pathophysiology before committing the child to
a fusion procedure.
2. Six- to twelve-month interval imaging with
flexion and extension radiographs is su cient
unless the patient becomes symptomatic with
neurological decline.
3. In special cases, there is a role for a rigid
cervical collar after internal fixation, however,
the senior author does not routinely use rigid
cervical orthoses after cervical fusion.
4. Autograft when available, allograft based bone
graft substitutes, rBMP-2, demineralized bone
matrix, transforming growth factor-β (TGF-β),
platelet-derived growth factor (PDGF),
fibroblast growth factor (FGF). The senior
author routinely uses the first three and has
had an excellent fusion rates with no untoward
complications.
References
[1] Klimo P, Jr, Rao G, Brockmeyer D. Congenital anomalies of the
cervical spine. Neurosurg Clin N Am. 2007; 18(3):463–478
[2] Menezes AH. Specific entities a ecting the craniocervical region:
Down’s syndrome. Childs Nerv Syst. 2008; 24(10):1165–1168
[3] Menezes AH. Craniovertebral junction database analysis:
incidence, classification, presentation, and treatment
algorithms. Childs Nerv Syst. 2008; 24(10):1101–1108
[4] Herman MJ, Pizzutillo PD. Cervical spine disorders in
children. Orthop Clin North Am. 1999; 30(3):457–466, ix
[5] O’Connor JF, Cranley WR, McCarten KM. Imaging of
musculoskeletal disorders in children. Curr Opin Radiol.
1991; 3(5):727–736
[6] Menezes AH. Craniovertebral junction anomalies: diagnosis
and management. Semin Pediatr Neurol. 1997; 4(3):209–223
[7] Lustrin ES, Karakas SP, Ortiz AO, et al. Pediatric cervical
spine: normal anatomy, variants, and trauma. Radiographics.
2003; 23(3):539–560
[8] Cattell HS, Filtzer DL. Pseudosubluxation and other normal
variations in the cervical spine in children. A study of one
hundred and sixty children. J Bone Joint Surg Am. 1965; 47
(7):1295–1309
[9] Suss RA, Zimmerman RD, Leeds NE. Pseudospread of the
atlas: false sign of Je erson fracture in young children. AJR
Am J Roentgenol. 1983; 140(6):1079–1082
[10] Pang D, Nemzek WR, Zovickian J. Atlanto-occipital dislocation:
part 1—normal occipital condyle-C1 interval in 89 children.
Neurosurgery. 2007; 61(3):514–521, discussion 521
[11] Pang D, Nemzek WR, Zovickian J. Atlanto-occipital
dislocation—part 2: the clinical use of (occipital) condyle-C1
interval, comparison with other diagnostic methods, and the
manifestation, management, and outcome of atlanto-
occipital dislocation in children. Neurosurgery. 2007; 61(5):
995–1015, discussion 1015
[12] Copley LA, Dormans JP. Cervical spine disorders in infants
and children. J Am Acad Orthop Surg. 1998; 6(4):204–214
[13] Menezes AH. Craniocervical fusions in children. J Neurosurg
Pediatr. 2012; 9(6):573–585
[14] Dorward IG, Wright NM. Seven years of experience with C2
translaminar screw fixation: clinical series and review of the
literature. Neurosurgery. 2011; 68(6):1491–1499, discussion
1499
[15] Kassam AB, Snyderman C, Gardner P, Carrau R, Spiro R.
The expanded endonasal approach: a fully endoscopic
transnasal approach and resection of the odontoid process:
technical case report. Neurosurgery. 2005; 57(1) Suppl:
E213–, discussion E213
[16] Menezes AH. Surgical approaches: postoperative care and
complications “transoral-transpalatopharyngeal approach to
the craniocervical junction”. Childs Nerv Syst. 2008; 24(10):
1187–1193
[17] Hadley MN, Spetzler RF, Sonntag VK. The transoral approach
to the superior cervical spine. A review of 53 cases of
extradural cervicomedullary compression. J Neurosurg.
1989; 71(1):16–23
[18] Wright NM, Lauryssen C, American Association of Neurological
Surgeons/Congress of Neurological Surgeons. Vertebral artery
injury in C1–2 transarticular screw fixation: results of a survey
of the AANS/CNS section on disorders of the spine and
peripheral nerves. J Neurosurg. 1998; 88(4):634–640
Abnormalities of the Craniocervical Junction and Cervical Spine
319

[19] Cheung KM, Mak KC, Luk KD. Anterior approach to cervical
spine. Spine. 2012; 37(5):E297–E302
[20] Yang SY, Gao YZ. Clinical results of the transoral operation for
lesions of the craniovertebral junction and its abnormalities.
Surg Neurol. 1999; 51(1):16–20
[21] Hwang SW, Gressot LV, Rangel-Castilla L, et al. Outcomes of
instrumented fusion in the pediatric cervical spine. J
Neurosurg Spine. 2012; 17(5):397–409
[22] Hwang SW, Gressot LV, Chern JJ, Relyea K, Jea A. Complications
of occipital screw placement for occipitocervical fusion in
children. J Neurosurg Pediatr. 2012; 9(6):586–593
[23] Patel AJ, Gressot LV, Boatey J, Hwang SW, Brayton A, Jea
A. Routine sectioning of the C2 nerve root and ganglion
for C1 lateral m ass screw placement in children: surgical
and functional outcom es. Childs Nerv Syst. 2013; 29(1):
93–97
Developmental and Congenital Spinal Disorders
320

39 Spina Bifida: Classification and Management
Lorelay Gutierrez, Luis A. Arredondo, Rodrigo Mercado
39.1 Introduction
Spinal dysraphism represents a constellation of
clinical entities. The term covers a wide range of
developmental conditions of the spinal cord and
its surrounding structures. It is often referred as
spina bifida (SB) or neural tube defects. Spinal dys-
raphism includes two conditions that may be
present at birth or during linear growth:
● Spina bifida aperta (SBA), always evident at birth.
● Spina bifida occulta (SBO), or occult dysraphism.
The congenital absence of the posterior
vertebrae arches with no visible exposure of
meninges or neural tissue.1
In recent years the prevalence of SB evident at
birth appears to be reducing, due to better prena-
tal screening and nutrition programs. The causes
of SB are multifactorial, with a significant genetic
component. Familial tendency is probably due to a
polygenic mechanism. Nutritional factors still play
an important etiological role and is reflected in the
higher incidence among the socioeconomical vul-
nerable segments of the population in developing
countries. Low folate intake during preconception
is the most common nutritional factor implicated
in the etiology of SB. Several common medications
such as anticonvulsants have also been implicated
in animal models as teratogens.2,3
39.2 Spina Bifida Occulta
The prevalence in North America is 5 to 10%. In
early ages, the most common finding is the pres-
ence of a cutaneous marker or stigmata. In older
children, the symptomatology is often associated
with tethered spinal cord syndrome (TSCS) and
becomes more evident during linear growth.
Lesions associated with SBO:
● Lipomyelomeningocele.
● Conus medullaris lipoma.
● Dermal sinus.
● Split cord malformation.
● Filum terminale lipomas.
● Rare conditions include myelocystocele and
neurenteric cyst, usually accompanied by
genitourinary malformations.4,5,6
39.3 Spina Bifida Aperta
SBA encloses two main abnormalities (Fig. 39.1):
● Meningocele. Congenital defect of vertebral arch
with posterior distension of meninges with no
Fig. 39.1 Schematic drawings of the anatomical features of common dysraphisms. (Courtesy of Gutiérrez-Oliva K.)
321

neural tissue included. About 30% could be
associated to tethered spinal cord.
● Myelomeningocele. Congenital defect of
vertebral arch with a cystic dilation of meninges
including neural tissue and a placode.
39.4 Embryology
Three phases of the development of the embryonic
spinal cord are described. This process begins
around day 18 of gestation (Table 39.1).
39.5 Clinical Presentation
The severity of the clinical presentation varies
according to the type of dysraphism.
Myelom eningocele. The most severe defect is
evident at birth. Characterized by:
● Presence of a midline cutaneous defect, more
often lumbosacral.
● Protrusion of meninges and neural tissue
enclosed in a cystic malformation.
● Neurological deficit is commonly associated with
variable severity. Paraplegia with severe urinary
dysfunction is the worst scenario.
● Associated nervous system developmental
anomalies.
● Hydrocephalus.
● Chiari II malformation.
● Symptomatology related to SBO, such as
urological, orthopedic, or neurological
impairments, may be present at birth, but
eventually will get worst or evident as the child
grows.4,6,7
39.6 Prenatal Assessment
Prenatal assessment includes maternal ultrasonog-
raphy, and biochemical markers such as high levels
of alpha-feto protein in amniotic fluid at weeks 13
to 16, and amniotic acetycholinesterase levels
greater than 500 ng/ml.
39.7 Postnatal Assessment
39.7.1 Imaging
● Magnetic resonance imaging (MRI) is the most
reliable image study to determine the
compromise of the neural structures. MRI is not
mandatory in myelomeningocele cases, whereas
it represents the gold standard when studying
SBO cases.
● Plain X-ray and CTscan with 3D reconstruction
are useful to evaluate the precise site of the
dysraphism bone defect and to precise other
orthopedic anomalies.
39.7.2 Electrophysiology
● Electromyography and motor- and sensory-
evoked potentials are useful to evaluate the
extent of neurological damage, especially in
older children SBO cases.
39.7.3 Urodynamic Studies
● Serial urine test must be performed regularly in
search of repetitive urinary tract infections.
Retrograde cystourethrography to assess bladder
function and to rule out the presence of cysto
ureteral reflux. Urodynamic studies are of great
value to select surgical candidates.8
39.7.4 Surgical Goals
Keep in mind that we are facing a malformation,
so the primary goal is to achieve an anatomical
environment as normal as possible.
● Myelomeningocele. Thoroughful reconstruction
of the anatomical planes leads to a normal
neural tube environment.
● SBO. Identify the anatomical features with
attention to tethered cord.
● Spinal lipoma s are complex lesions and its
management remains controversial in the
absence of symptoms.9 Refer to Chapter 41
Table 39.1 Embryology of the spinal cord and closing failures
Spinal cord embryology

Main feature

Common failure
Primary neurulation

Closure of neural tube at day 21

Myelomeningocele
Secondary neurulation

Closure of the tail bud or posterior neuropore Lipomas of the filum terminale
Regression of the caudal cell mass Formation of sacral bone

Sacrum agenesis
Myelocystocele
Developmental and Congenital Spinal Disorders
322

The dura is present in the majority of the malfor-
mations. Great care shall be observed when dis-
secting the dural layer. Watertight closure must be
achieved in order to avoid cerebrospinal fluid
(CSF) leaks.
39.7.5 Postoperative Care and
Follow-up
Surgical repair does not represent the end of the
treatment. A multidisciplinary team must be
involved to evaluate and follow every case, opti-
mizing functional recovery and looking for delayed
complications and hidden associated anomalies.10
39.8 Common Clinical
Questions
1. Which is the best timing for myelomeningocele
repair?
2. Describe the best management strategy in
patients with myelomeningocele and
hydrocephalus.
3. Define the concept of occult tethered cord
syndrome (OTCS).
4. Is surgery indicated for occult tethered
cord?
39.9 Answers to Common
Clinical Questions
1. Corrective surgery should be done as soon as
possible. A retrospective study demonstrate
that surgical intervention within the first 5 days
was associated with a shorter duration of
hospital stay, antibiotic therapy, and a lower
complication rate.11 Even more important are
the results of a study on postoperative
urological function, that showed an increased
incidence of febrile urinary tract infections,
vesicoureteral reflux, hydronephrosis, and
secondary tethering of the spinal cord in
children operated 72 hours after birth.12
2. Only one out six infants with
myelomeningocele presents signs of intracranial
pressure at birth. Hydrocephalus is commonly
noticed at 2 to 3 weeks of age.13 There is
controversy over whether simultaneous CSF
shunt insertion and repair of myelomeningocele
increase shunt-related complications. One study
concludes that there was no statistically
significant di erence between complication
rates in patients in whom the two procedures
were performed concurrently and those who
underwent separate operations.14 A larger and
more recent study described that patients
shunted prior to, simultaneously, or within the
first 4 days after SB closure had a fivefold higher
shunt infection rate than those shunted 5 to
10 days following SB closure. Shunt
malfunctions were also significantly higher in
the group shunted prior to myelomeningocele
closure.15 We prefer to wait at least 5 days after
the dysraphism is repaired, before placing a
ventricular shunt.
3. In this condition, symptoms consistent with TCS
are present and are thought to be related to
tethering of the spinal cord by the filum,
although the conus is in a normal position.
Symptoms are classified into four main
categories: neurological, motor or sensory
dysfunction, urological, neurocutaneous, and
neuro-orthopedic. The most common is urinary
dysfunction, which is seen in 68 to 100% of the
patients.16
4. The natural history of OTCS remains
controversial. Some authors have suggested that
neurological progression and deterioration
occur in over 50% of patients with clinical
tethered cord syndrome. A retrospective study
compared OTCS patients undergoing surgery
versus conservative treatment, found that 88%
of patients improved with surgery and 29% of
patients managed conservatively also had
improvement in their symptoms.17 The main
surgical goal when operating OTCS is to
disconnect the filum.
References
[1] Kumar R, Singhal N. Outcome of meningomyelocele/
lipomeningomyelocele in children of northern India. Pediatr
Neurosurg. 2007; 43(1):7–14
[2] MRC Vitamin Study Research Group. Prevention of neural
tube defects: results of the Medical Research Council Vitamin
Study. Lancet. 1991; 338(8760):131–137
[3] Laurence KM. A declining incidence of neural tube defects in
the U.K. Z Kinderchir. 1989; 44 suppl 1:51
[4] Bui CJ, Tubbs RS, Oakes WJ. Tethered cord syndrome in
children: a review. Neurosurg Focus. 2007; 23(2):E2
[5] McLone DG, La Marca F. The tethered cord: diagnosis,
significance and management. Seminars in Pediatric
Neurology. 1997; 4(3):192-208
[6] Huang SL, Shi W, Zhang LG. Surgical treatment for
lipomyelomeningocele in children. World J Pediatr. 2010; 6
(4):361–365
[7] Blount JP, Elton S. Spinal lipomas. Neurosurg Focus. 2001; 10
(1):e3
Spina Bifida: Classification and Management
323

[8] Nogueira M, Greenfield SP, Wan J, Santana A, Li V. Tethered
cord in children: a clinical classification with urodynamic
correlation. J Urol. 2004; 172(4 pt 2):1677–1680, discussion
1680
[9] Finn MA, Walker ML. Spinal lipomas: clinical spectrum,
embryology, and treatment. Neurosurg Focus. 2007; 23(2):E10
[10] Wai EK, Owen J, Fehlings D, Wright JG. Assessing physical
disability in children with spina bifida and scoliosis. J Pediatr
Orthop. 2000; 20(6):765–770
[11] Oncel MY, Ozdemir R, Kahilogulları G, Yurttutan S, Erdeve O,
Dilmen U. The e ect of surgery tim e on prognosis in
newborns with meningomyelocele. J Korean Neurosurg Soc.
2012; 51(6):359–362
[12] Tarcan T, Onol FF, Ilker Y, Alpay H, Simşek F, Ozek M. The timing
of primary neurosurgical repair significantly a ects neurogenic
bladder prognosis in children with myelomeningocele. J Urol.
2006; 176(3):1161–1165
[13] Tamburrini G, Frassanito P, Iakovaki K, et al.
Myelomeningocele: the management of the associated
hydrocephalus. Childs Nerv Syst. 2013; 29(9):1569–1579
[14] Radmanesh F, Nejat F, El Khashab M, Ghodsi SM, Ardebili HE.
Shunt complications in children with myelomeningocele:
e ect of timing of shunt placement. Clinical article. J
Neurosurg Pediatr. 2009; 3(6):516–520
[15] Margaron FC, Poenaru D, Bransford R, Albright AL. Timing of
ventriculoperitoneal shunt insertion following spina bifida
closure in Kenya. Childs Nerv Syst. 2010; 26(11):1523–1528
[16] Tu A, Steinbok P. Occult tethered cord syndrome: a review.
Childs Nerv Syst. 2013; 29(9):1635–1640
[17] Steinbok P, Kariyattil R, MacNeily AE. Comparison of section
of filum terminale and non-neurosurgical management for
urinary incontinence in patients with normal conus position
and possible occult tethered cord syndrome. Neurosurgery.
2007; 61(3):550–555, discussion 555–556
Developmental and Congenital Spinal Disorders
324

40 Pathophysiology and Management of Tethered
Cord (Including Myelomeningocele)
Eelco W. Hoving
40.1 Definitions
The word tether means to fasten, and it is used in
the context of fastening an animal with a rope. The
term tethered spinal cord was first used by Ho -
man et al describing 31 patients with a thickened
terminal filum.1 The symptomatology of these
patients resolved after sectioning the filum.
Tethered spinal cord is strongly associated with
the morphology of spinal dysraphism. A distinc-
tion can be made between spina bifida aperta
(SBA) and spina bifida occulta (SBO).
● In SBA, the cord is open (aperta) which means
that the neural folds have not closed to a tube,
and subsequently the lesion cannot be covered
with skin. This is called a primary neurulation
defect, and it results in a myelomeningocele
(MMC).
● SBO refers to a variety of congenital anomalies
that are all covered with skin (occult), but due to
di erent pathophysiological disturbances during
embryology. Premature disjunction between
neuroectoderm (cord) and surface ectoderm
(skin) may result in lipomyelomeningocele,
while incomplete disjunction between these
layers may lead to a dermal sinus fistula/cyst
or limited dorsal myeloschisis (LDM) lesions.2
SBOs of the most distal part of the cord, fatty
terminal filum and terminal spinal lipomas, are
associated with disturbances in secondary
neurulation.3
The anatomy of spinal dysraphism will create a
tethered cord (TC). As soon as clinical symptoma-
tology arises, one speaks of tethered cord syndro-
me (TCS). These symptoms can be neurological,
urological, orthopedic, and pain or a combination.
The pathophysiology of TCS is widely studied by
Yamada et al, and it is considered to be a stretch-
induced injury to the caudal end of the spinal cord
up to the level of the dentate ligaments.4 However,
the symptomatology in TCS patients does not
always resolve after surgical detethering and may
even follow a progressive course. In this respect,
myelodysplasia is considered to play an additional
role in combination with TCS. In order to define
clinical indications for surgical detethering in TCS
patients, three di erent categories were proposed
by Yamada and Won.5
● Category 1 represents TC patients with
symptoms typically related to stretch-induced
injury to the caudal spinal cord (inelastic
terminal filum and caudal
lipomyelomeningocele [LMMC]).
● Category 2 represents TC patients with similar
symptoms, but due to additional local
compression and subsequent ischemia to dorsal
neural structures (MMC and dorsal or
transitional LMMC).
● Category 3 represents patients with extensive
and irreversible neurological and urological
deficits due to myelodysplasia (large
thoracolumbar MMC).
Based on these categories, a distinction can be
made between true TCS (category 1) and relative
TCS (category 2). Category 3 does not represent
TCS patients. Only patients from categories 1 and 2
will benefit from surgical detethering.
40.2 Pathophysiology of TCS
TCS is a stretch-induced functional disorder of the
spinal cord with its caudal portion anchored by an
inelastic structure according to Yamada et al.4 Exten-
sive experimental work on TCS has been published
by Yamada and his coworkers, and the following
basic questions have been addressed on this topic:
● Experimental work in cats has shown that
isotonic traction of the spinal cord results in
di erent elongation of various cord segments.
The viscoelasticity of the filum has the largest
potential to elongate, and this protects the spinal
cord from overstretching.
● The mechanism of TC dysfunction is related to
electrical and metabolic changes in the
interneurons of the cord that are located in gray
matter. These changes could be recorded by
measuring the redox shifts of cytochrome a,a3 as
the final step of oxidative phosphorylation of
adenosine diphosphate (ADP) to provide
adenosine triphosphate (ATP) within the
mitochondrion during traction of the distal cord.
325

Diminished spinal cord blood flow and altered
glucose metabolism may play an additional role.
● These metabolic changes appeared to be
reversible depending on the traction force and
its duration. Excessive traction force of long
duration will result in permanent neuronal
damage within the caudal spinal cord.
● Permanent neuronal damage may also result
from sudden stretching of the chronically
tethered cord.
● Timing of detethering should preferably take
place during the reversible phase of metabolic
changes within the cord. Irreversible neuronal
damage should be prevented.
● Early untethering, when only mild symptoms
are present, warrants best results in TCS
patients.
40.3 Pathophysiology of
Recurrent Tethered Cord
Secondary deterioration of symptoms has been
noticed in about one-third of MMC patients and
about 10% of LMMC patients.6
In MMC patients, adhesions of the placode
within a narrow spinal canal can hardly be pre-
vented during primary surgical closure of the
defect. Surgical aspects that may contribute to
diminish the risk of secondary tethering are the
remodeling of the neural placode into a neural
tube and trying to create a dural sac as spacious as
possible. The limited dimensions of the spinal
canal at the site of the MMC cannot be changed,
and most closed MMC will show the morphology
of a TC.
The treatment of prophylactic LMMC patients
has been controversial for many years because of
the interpretation of secondary TCS. Some believed
that the natural history would be responsible for
secondary deterioration in 40% of patients during
follow-up.7,8 Others considered recurrent tether-
ing to be the cause of progression of symptoms.9
Pang et al have published extensively on these
matters.10,11 According to his data prophylactic
detethering can be extremely e ective in LMMC
patients if one tries to resect the lipoma totally.
The postoperative cord-sac ratio was found to be
the most important prognostic factor in prevent-
ing secondary symptoms due to recurrent
tethering. This finding was most apparent in the
asymptomatic young LMMC patients.
The excellent lasting outcome after surgical
detethering with complete resection of the lipoma
corroborates the pathophysiological aspect of rete-
thering in recurrent TCS.
40.4 Assessment of TCS
In MMC patients, any progression of neurological,
urological, or orthopedic symptoms should be
considered possibly due to TCS. The morphology of
a surgically closed MMC is almost synonymous
with a TC, and this may create additional damage
to the cord. Most MMC patients will be followed in
multidisciplinary spina bifida teams, and most
changes of symptoms will be diagnosed. Since the
majority of MMC patients belong to category 2
with relative TCS, the decision to propose surgical
detethering should be judged per individual pa-
tient. A percentage between 10 and 30% of MMC
patients is described to become symptomatic of a
TCS.6
SBO patients are often diagnosed in a newborn
when characteristic stigmata along the dorsal mid-
line are present. These cutaneous manifestations
are diagnosed in approximately 40% of patients,
and they can be recognized as a tuft of hair, a lip-
omatous mass, a dimple or an abnormal coloring
of the skin. The presence of musculoskeletal
deformities such as a clubfoot may also indicate
the presence of a TCS. Urological symptoms are
prominent features of TCS, but they are not always
recognized in young children. A history of a poor
urinary stream or dribbling should be explored.
Neurological symptoms may become apparent by
an alteration of gait or motor strength in the legs.
Sensory loss in the lower extremities is more sel-
dom in a child.
The typical presentation of symptoms of TCS
varies with age.12
● Children under 10 years often present with gait
weakness, incontinence of reemergence of
enuresis, or mild foot deformities.
● Teenagers tend to develop scoliosis or
incontinence.
● In adults, pain is the most prominent symptom.
The localization may be nonspecific but often
within the perineal area.
Physical examination should include both a neuro-
logical and an orthopedic evaluation. Urological
judgement often requires additional urodynamic
tests by the urologist.
Developmental and Congenital Spinal Disorders
326

40.5 Imaging of TC
Magnetic resonance imaging (MRI) is essential in
order to visualize TC. The morphology of TC can be
clearly visualized on MRI in most cases of spinal
dysraphism, but the degree of tension along the
cord can only be postulated. In case of suspected
tight filum terminale, sometimes only circumstan-
tial evidence is present to support the diagnosis of
TC. Therefore, the MRI should be examined sys-
tematically.13
● The position of the cord: A normal position of
the conus is at the level of the L1–L2 disc. An
abnormal caudal position of the conus may
indicate a TC.
● The filum terminale may be thickened (wider
than 2 mm) or fatty. The latter can be recognized
by bright attenuation on T1-weighted MRI
sequences.
● The position of the filum terminale may be
posteriorly located within the dural sac because
of covering the shortest distance between the
dentate ligament and the tethering site.
● The presence of a syrinx within the distal cord.
● The presence of occult defects in the posterior
elements of the spinal column (bifid lamina).
● The presence of additional congenital anomalies
along the spine.
Dysraphic anomalies with a classical appearance
on MRI and that may cause a TC are as follows:
● Dermoid cyst/fistula that can often be visualized
with a subcutaneous midline descending course
and an intraspinal ascending course sometimes
up to the level of the conus.
● Split cord malformations (SCMs) should be
distinguished in type 1 (two hemicords within
separate dural sheaths and a midline bony spur)
and type 2 (two hemicords within one dural
sac).14 Type 1 is typically associated with TCS.
SCM is often accompanied with vertebral
anomalies (block or hemivertebrae).
● LMMCs can be subdivided in caudal, dorsal, or
transitional lipomas.
● Limited dorsal myeloschisis may present with a
subtle morphology of cord tethering along the
dorsal midline in cervical, thoracic, or lumbar
region.2
Ultrasonography can be used as a first evaluation
of TC, but additional MRI will be indicated in case
of its suspected presence.15 The presence of pulsa-
tions of the cord may be useful in the evaluation of
recurrent tethering in repaired MMC/LMMC
patients.
40.6 Treatment of Tethered
Cord
40.6.1 Myelomeningocele
Primary Closure
● Prenatal primary closure of the MMC has been
developed in order to prevent secondary
damage to the placode during gestation. The
neural tube closes during the third and fourth
gestational week. In MMC patients, the failure of
closure creates a persistent neural placode with
concomitant primary neurological damage. The
exposure of the placode to the amniotic fluid
during pregnancy has been found to lead to
secondary neurological damage.16,17
● Intrauterine repair was also found to reduce the
shunt insertion rate and to diminish hindbrain
hernation.18,19 These potential benefits must be
considered in relation to the risk of surgery in a
fetus and the maternal risks of hysterotomy. The
Management of Myelomeningoceles Study
(MOMS) has been designed to investigate in a
randomized controlled fashion the benefit of
reduction in shunt insertion and the
neurological functional level after prenatal
surgery.20 The results showed a significant
decrease in shunt-insertion rate in the prenatal
group to 40% in relation to the postnatal group
with 82% at 12 months. Improvements of mental
developmental and motor function at 30 months
were also significantly shown in the prenatal
group. Hindbrain herniation and other
secondary outcomes were also improved after
prenatal repair. Only experienced surgical teams
were involved in this trial, and the long-term
risks for the development of a secondary TCS
after prenatal repair have not been settled.
Extensive prenatal counseling is required in
order to discuss an individual benefit/risk
profile.
● Postnatal primary closure of the MMC is meant
to cover the unprotected neural placode and to
prevent an infection of the central nervous
system (CNS). The surgical aim is to create a
watertight closure of dura, to provide a good
skin cover, and to prevent secondary tethering.21
● Subsequent surgical steps can be distinguished:
identification of the placode, resection of the
surrounding thin epithelium; removal of
cutaneous elements from the edges of the
placode; transformation of the placode into a
neural tube by approximation of the lateral
Pathophysiology and Management of Tethered Cord (Including Myelomeningocele)
327

edges; mobilization of the underlying dura from
the underlying fascial layer; creating a dural sac
surrounding the neural cord as spacious as
possible; an additional fascial layer to cover the
dura is optional; closure of the skin (skin or
musculocutaneous flap techniques may be used
in case of large defects).
● Hydrocephalus is associated with most MMC
patients (90%). Ventriculoperitoneal (VP) shunt
insertion can be combined with closure of the
MMC, if hydrocephalus is present at
presentation. Most patients develop
hydrocephalus after the defect has been closed,
and a second surgery for shunt insertion will be
needed.
● Chiari II is strongly associated with MMC, but
only 10% of patients become symptomatic.
● Secondary TCS in MMC patients is present in 10
to 30% of patients.6
40.6.2 Spina Bifida Occulta
Tight Filum Terminale
● The viscoelasticity of the filum terminale is
considered to protect the distal cord from
stretch-induced injury. A loss of this
viscoelasticity either due to a filum lipoma or to
its shortness of length may result in a true TCS
(category 1).5 The tightness itself cannot be
visualized. In case of a normal anatomy on MRI
in conjunction with suspected symptoms, one
may speak of an occult tethered cord
syndrome.22 Urological problems appear to be
the most prominent initial symptoms in these
patients.23 The indication to treat these patients
is questionable.23,24 The surgical technique of
cutting a tight filum is straightforward. After
exposure of the caudal nerve roots intradurally
at the level of the tight filum, one needs to
identify the filum. The filum should be isolated
from the caudal nerve roots, coagulated, and
subsequently cut. Direct stimulation can be used
to confirm the nonfunctional status of the
filum.25,26 The risks for surgical morbidity and
for recurrent tethering are very low.
Limited Dorsal Myeloschisis
● LDM has been identified by Pang et al as a
distinct form of spinal dysraphism with two
distinct features: the presence of a fibroneural
stalk connecting the skin and the cord
underneath an intact skin along the dorsal
midline.2 Awide variety of lesions have been
described that can occur along dorsal spinal
cord, and a classification is proposed in
nonsaccular and saccular types. Surgical
detethering is aimed at disconnection of the
cord from the fibroneural stalk and
reconstruction of the cord and/or dura in order
to prevent recurrent tethering.
40.6.3 Lipomyelomeningocele
Split Cord Malformation
● SCM is strongly associated with concomitant
congenital anomalies of the spine, and
preoperative imaging of the complete spine with
MRI is essential.14 The presence of an additional
filum terminale lipoma should be ruled out. The
indication to treat is aimed at relieving
symptoms of TCS and to prevent progression of
symptoms. The exploration of the spinal canal
may be complicated by the abnormal shape of
the vertebrae and its posterior bony parts. In
case of SCM type 1, the midline bony spur
should be resected. After opening of the dural
sacks, the cords can be detethered by dissecting
the nonfunctional medial nerve roots that end
blindly in the diastema. Subsequently, the
medial parts of the dura at the site of the
diastema can be resected, and one dural sac
should be created containing both hemicords.21
In SCM type 2, intradural detethering of both
hemicords will su ce.
Spinal Inclusion Cysts
● Spinal inclusion cysts refer to dermoid fistulas/
cysts, and should be treated to prevent
accumulation of dermis within the spinal canal
and secondary infection.27 The close relationship
of the dermis fistula/cyst with the cord may also
result in a TCS. Radical excision is indicated, and
a preoperative MRI is mandatory. The
intradermal extension of the fistula is situated
within the midline and may run in a
rostrocaudal direction. The intradural extension
is often present in a caudorostral direction up to
the level of the conus. Total resection might
require extensive multilevel intradural exposure
of the fistula, and laminotomy with
repositioning of the laminae is advised in
children.
Developmental and Congenital Spinal Disorders
328

40.6.4 Miscellaneous
● Caudal spinal cord malformations may be
associated with anorectal or urogenital
anomalies like the caudal regression syndrome
or the Currarino triad. These combinations of
congenital disturbances might result in a TCS,
but they always require an extensive diagnostic
work-up and a multidisciplinary treatment
strategy.21
40.7 Intraoperative
Neuromonitoring in TCS
Intraoperative neuromonitoring (IONM) is meant
to improve safety in TCS surgery by minimizing
neurological morbidity.25,26,28,29
The distinction
between functional nerve roots and nonfunctional
atretic nerve roots or fibrous bands may be di -
cult in various types of spina bifida. IONM has
been used e ectively in detethering of LMMC,
LDM, tight filum terminale, and in recurrent TCS in
MMC.
Three modalities of IONM are most widely used:
direct nerve root stimulation (DNRS), transcranial
electrical motor-evoked potentials (MEP) and bul-
bocavernosus reflex (BCR).29
● DNRS is used to discriminate between functional
nerve roots and nonfunctional tethering
structures. Multichannel electromyography
(EMG) recording can be applied.
● MEP is utilized to identify the integrity of the
motor pathways in the individual patient and to
provide feedback on this during surgical
detethering.
● BCR provides continuous feedback on the
integrity of the sensory sacral nerve roots and
the S2–S4 cord segments.
● IONM in small children is feasible, but
preconditioning techniques might be
required.25,30
40.8 Outcome in TCS
Considering the outcome in TCS surgery, one
should realize that true TCS patients (category 1)
represent the most reliable population concerning
the evaluation of results of surgical detethering.
Patients belonging to relative TCS (category 2) may
also be symptomatic by other reasons than tether-
ing like myelodysplasia or local compression.
Most TCS patient can be treated e ectively and
safely with the use of IONM.2,10,25,29
● True TCS in tight filum terminale is associated
with excellent outcome and no surgical
morbidity. The indication for treatment of occult
TCS remains controversial, hence this a ects
evaluation of outcome.23
● LMMC can e ectively be treated for TCS by
radical excision of the lipoma creating an
optimal cord-sack ratio with a low risk of
recurrent TCS.10,11,31
● Prophylactic total resection appears to be the
best option for the young child (<2 years) with
asymptomatic LMMC.31
● TCS surgery in adult patients can be quite
e ective, especially concerning improvement of
pain.32
● Recurrent TCS in MMC patients can e ectively
be treated with improvement of symptoms in a
majority of cases.6
40.9 Complications
● The use of IONM may contribute to minimize the
chance of neurological morbidity especially in
TCS patients with LMMC or in recurrent TCS
patients with MMC.21,26,28
● Reversible surgical morbidity in TCS surgery is
associated to disturbed wound healing,
cerebrospinal fluid (CSF) leakage,
pseudomeningocele, and infection.
● Recurrent TCS may occur after closure of MMC
and after partial resection of LMMC.6,7,10
40.10 Surgical Pearls
● The primary goal of TCS surgery is to free the
cord from its tethering structures and to create a
spacious environment (dural sack) in order to
prevent retethering.10
● IONM may contribute to the safety and e cacy
of TCS surgery.25,29
● Timing of TCS surgery should take place before
irreversible ischemic damage has occurred.4
● True TCS (category 1) includes tight filum
terminale and caudal LMMC.2
40.11 Common Clinical
Questions
1. Describe the pathophysiology in TCS.
2. Explain why the morphology of tight filum
terminale and caudal LMMC are associated with
true TCS.
Pathophysiology and Management of Tethered Cord (Including Myelomeningocele)
329

3. What are the potential benefits of prenatal
treatment of MMC?
4. Which surgical techniques can be used to
potentially decrease the chance of recurrent TCS
in MMC and LMMC treatment?
40.12 Answers to Common
Clinical Questions
1. TCS is a stretch-induced functional disorder of
the caudal portion of the cord due to anchoring
by inelastic structures.4 Repetitive strain to the
cord will eventually lead to ischemic and
metabolic injury to neurons located within the
gray matter of the cord. The normal
viscoelasticity of the terminal filum and the
dentate ligaments protect the cord from
repetitive strain injury.
2. A decreased viscoelasticity of the terminal filum
or a caudal LMMC create repetitive stretch-
induced injuries to the cord up to the level of
the dentate ligaments.4 The part of the cord
distal to the dentate ligaments is most
vulnerable to these forces. Since tight filum
terminale and caudal LMMC are limited to the
most caudal part of the cord as secondary
neurulation disorders, additional aspects as an
abnormal morphology of the cord due to
primary neurulation or compression of the cord
by the lipoma do not contribute to the
symptomatology in these patients. In this
respect, the symptomatology of these patients
can be truly explained by tethering of the cord.
3. The MOMS trial has shown that a significant
reduction in shunt insertion for hydrocephalus
(40% instead of 80%), and a significant
improvement of mental and motor score at 30
months had been achieved in the prenatally
treated group of patients.20 A reduction in
hindbrain herniation as a result of prenatal
treatment of MMC could also be confirmed.19,20
4. In order to prevent recurrent tethering, one
should try to create a maximal cord-sack ratio.
This means that in primary closure of MMC, it is
advisable to reshape the placode into a cord and
to make the dural sack as spacious as possible.21
Because of the limited dimensions of the spinal
canal at the site of the MMC, the morphology of
a tethered cord can hardly be prevented in
MMC patients. Only 10 to 30% of MMC patients
become symptomatic and develop a TCS.6
LMMC patients should be detethered by
resecting the lipoma as radical as possible in
order to create a maximal cord-sack ratio.10,31
Reshaping the cord after resection of the lipoma
(surgical neurulation) may also contribute to
the prevention of recurrent tethering.31
References
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41 Intraspinal Lipomas
Rodrigo Mercado, Luis A. Arrendondo, Lorelay Gutierrez, Jesus A. Villagómez
41.1 Introduction
Spinal lipomas are the most common presentation
of occult spinal dysraphism, term used to describe
those malformations of the neural tube covered by
skin. Represent a complex condition involving ana-
tomical and clinical features and treatment deci-
sions. The treatment options are controversial and
the vast majority of neurosurgeons advocate for
early treatment to avoid further complications
during axial growth.
The neurosurgeon must keep in mind the fact
that no lipoma is equal, and every case represents
a new challenge. These lesions have similar embry-
ology and can cause eventually, during aging, a
wide spectrum of neurological, urological, or
orthopedical deficits related to the tethered cord
syndrome. Tethered cord syndrome develops dur-
ing child growth, and the symptoms are mainly
related to the e ects of traction applied to the spi-
nal cord from the anatomical location of the lip-
oma. Lipomas cause a fixed position of the spinal
cord, and as the child grows, the spinal cord is
stretched and su ers ischemic damage. This dam-
age is more deleterious at the level of the conus
medullaris.
41.2 Classification
The most accepted classification of the lesions
divides the spinal lipomas into three major catego-
ries:
● Lipomas of the conus medullaris.
● Lipomas of the filum terminale.
● “Subpial” lipomas.
41.2.1 Lipomas of the Conus
Medullaris
The most important group of malformations are
the lipomas of the conus medullaris comprising
more than 70% of cases among the lipomatous
lumbosacral lesions. They are classified as dorsal,
caudal, or transitional. This system is useful to
define surgical extent and the main anatomical
features. The variants are based on the situation of
the lipoma related to the conus.
● Dorsal conus medullaris is attached to the dorsal
aspect of the conus medullaris including the
cord, the dura, and the fat. It might include an
associated thickened filum.
● Caudal conus medullaris describes a lipoma
attached to the inferior aspect of the conus,
extends to the central canal, and includes nerve
roots within the lipoma.
● Transitional conus medullaris lipomas represent a
combination of the two previous variants. The
lipoma attaches to the dorsal aspect of the cord
and extends into the central canal. It is
commonly associated with a large placode–
lipoma interface.
McLane and Naidich have proposed an interesting
theory to explain the surgical anatomy of conus
medullaris lipomas in which the anterior anatomy
represents normal tissue and anatomical struc-
tures, whilst the posterior aspect represents the
lipoma. They referred to a disjunction of the neural
tube from the surrounding ectoderm leading to an
opening of the neural plate posteriorly, while
allowing mesenchymal cells to enter the cleft and
being induced to form fatty tissue by the primitive
ependymal. This is important to consider at the
moment of the surgery because the dural border,
the lipoma, and the nervous tissue coincide at the
lateral edges of the placode.
Regarding the development of filum lipomas,
most of the speculative theories center on the lack
of retrogressive di erentiation leading to a di er-
entiation of pluripotent mass cells into adipocytes.
Lipomyelomeningocele is used often to describe
all lumbosacral lipomas, however, it refers to a
malformation including a neural placode lying out-
side the spinal canal attached to a fatty mass
which extends to the subcutaneous tissue. This le-
sion should be considered as an open myelome-
ningocele due to the anatomical organization of
the roots. The tethering site is often asymmetrical
and leads to rotation of the cord. In a few cases,
the sacral roots course inside the lipoma.
41.3 Clinical Presentation
There are two main findings:
1. Presence of cutaneous marker, which is evident
early in life.
2. Neurological deficits that develop gradually
related to the tethered cord.
332

Six di erent forms of cutaneous markers have
been described:
1. Fatty lumbosacral mass in the midline or
parasagittal plane
2. Hirsutism
3. Dermal sinus
4. Hemangiomas
5. Rudimentary tail
6. Atretic meningocele
Some patients present a coccygeal pit within the
gluteal fold and the association with lipomas is
considered to be rare. Patients having a cutaneous
marker should be included in a tethered cord
study protocol.
Neurological deficits are present in 70% of
patients. Most of the lipomas are asymmetrical
and the neurological deficit is related to the lipom-
atous attachment. Tethering of spinal cord leads to
urological, orthopedical, and neurological dysfunc-
tions. Infants at birth are often asymptomatic and
the neurological sequelae may persist occult dur-
ing infancy, whereas patient’s symptomatology
becomes evident throughout the years of growth.
Urological manifestations a ect 50% of patients
including recurrent urinary tract infections, abnor-
mal voiding, hyperactive bladder, and sphincter
dysfunction. Urological signs can be reversible if
detected early in infants, but prognosis in older chil-
dren and adults is poor. Motor and orthopedic signs
a ect 33% of patients and may include progressive
scoliosis, toes and lower limbs malformations, such
as clubfoot and equinovarus. Sensitive symptoms
may present as ulcerations and pain. Pain is a com-
mon symptom in older children and adults.
Patients with spinal lipomas will develop teth-
ered cord syndrome eventually during aging. The
most important factor to consider is the presence
of tension and traction to the spinal cord. Mechan-
ical stress represents the major risk during physi-
cal activity and leads to ischemic changes. Several
studies have demonstrated an improvement in
function after untethering, however, the results of
the surgery are variable and the goal is to stabilize
the symptoms.
41.4 Imaging
Magnetic resonance imaging (MRI) is mandatory
in every patient with cutaneous markers or
symptoms related to tethered cord syndrome is
useful when planning the surgery to identify asso-
ciated malformations and to evaluate the presence
of syrinx. The position of the conus medullaris is
often distal. An apparent “normal conus position” is
not completely safe for patients who complaint of
symptoms such as incontinence, gait disturbances,
and scoliosis. Postoperative MR will always look
tethered and must be interpreted with caution.
41.5 Surgical Treatment
The main goals are to preserve neurological func-
tion and to avoid delayed neurological decline. To
achieve these goals, it is important to follow four
important principles:
1. Untether the spinal cord
2. Preserve neurological tissue
3. Debulk the lipoma
4. Reconstruct neural tube and anatomical planes
The vast majority of studies advocate for surgical
treatment in order to avoid potential deterioration
during grow th. The decision to operate in asymp-
tomatic patients is still controversial.
41.5.1 Surgical Technique
● Patient in prone position.
● Intraoperative monitoring for continuous
electromyography (EMG) and motor-evoked
potentials. Avoid the use of muscular relaxants if
possible during the procedure.
● A midline incision is centered from one or two
normal spinous process rostral to the lipoma and
extended caudal to the lesion.
● Debulking of the lipoma is done with monopolar
electrocautery and the amount of lipoma excised
must be planned to allow an adequate and
cosmetic closure at the end of surgery.
● Dissection of the lipoma begins one level rostral
and continues in a circumferential fashion until
the pedicle of lipoma is apparent. The dissection
must follow the bone plane to avoid dural
damage.
● Dural opening starts after the removal of the
lipoma. Rostral in the first upper normal level
and continues caudally until the lipoma unites to
the neural tissue.
● Disrupt any adhesion under continuous
electrophysiological monitoring to preserve the
normal neurological tissue.
Intraspinal Lipomas
333

● Remove the majority of fatty tissue attached
to the neural tissue and reconstruct the
placode when present with 5.0 nylon sutures to
the pia.
● Finally, a thick filum terminal must be cut.
It is important to notice that the liberation of trac-
tion mechanisms interfere with the pathogenesis
of tethering. Treatment of syringomyelia is contro-
versial. Reoperation is considered when symptoms
of tethered spinal cord reappear.
Developmental and Congenital Spinal Disorders
334

42 Scoliosis
Anthony J. Herzog, Paul D. Sponseller
42.1 Introduction
Scoliosis is defined as spinal curvature in the
coronal plane greater than 10 degrees by Cobb’s
angle measurement. It can be caused by multiple
etiologies, each with a di erent natural history of
disease (Table 42.1).
● Idiopathic scoliosis:
– Infantile: Occurs in 0 to 3 years of age. Can
rapidly progress and compromise
cardiopulmonary function by adulthood. It is
associated with a high risk of neural axis
abnormalities. Left apex thoracic curves are
more common in this form. There is a
decreased risk of progression if the patient
presents before the age of 1. Because of high
risk of rapid progression and 20% risk of neural
axis abnormality with curves greater than 20
degrees, obtain magnetic resonance imaging
(MRI) during work-up.1
– Juvenile: Occurs in 4 to 9 years of age. More
commonly occurs in females. Right apex curves
are more common, left apex curves warrant
concern for neural axis abnormalities. There is
a high rate of rapid curve progression and
21.7% risk of neural axis abnormality with
curve greater than 20 degrees. Obtain MRI as
part of work-up.1
– Adolescent: Occurs in ages 10 and over. Larger
curves over 40 degrees are nine times more
frequent in girls. There is also an increased
incidence with a positive family history,
polygenic interaction is theorized. The risk of
progression is based on size of curve and
skeletal maturity (tanner stage, menarche,
Risser’s score, bone age).2
● Congenital: Scoliosis is caused by primary bony
malformations of the vertebrae. There is no
specific inheritance pattern but is associated
with multiple syndromes. It occurs in 1% of the
population. The greatest risk of progression is
during rapid growth from 0 to 2 years of age or
during the adolescent growth spurt.
– Failure of segmentation: Bars present between
vertebrae. Can be unilateral or bilateral bars
(block vertebrae, best prognosis).
– Failure of formation: May be in the form of
hemivertebra or wedge-shaped vertebrae.
These malformations can be segmented (open
growth plates around malformed vertebrae),
semisegmented, or unsegmented
(nonprogressive with best prognosis).
– Combinations: There may be di erent
compositions of segmentation and formation
defects. Hemivertebra with contralateral bar
has worst prognosis and is rapidly progressive.
● Neuromuscular: Any disorder that disturbs
balance of trunk can potentially cause scoliosis.
Often presents as the rapid development of a
large curve or with neurological symptoms.
Table 42.1 Etiological causes of scoliosis
Type

Etiology

Treatment
Congenital

Failure of segmentation (bars)
Failure of formation (hemivertebra,
wedges)
Bracing not effective. Can fuse in situ or excision
with rod instrumentation over curve
Neuromuscular/syndromic Syringomyelia, meningomyelocele,
cord injury before puberty, Rett’s, CP,
CMTD, FA, MD, NF1, MS, LDS, EDS, OI
Bracing not effective. Curves often rapidly pro-
gressive. Likely need extended PSF
Idiopathic

Infantile
Juvenile
Adolescent
Can observe curves less than 20–25 degrees
Curves 25–50 degrees, consider bracing
Curves greater than 50 degrees, consider surgery
Casting is an option in infantile for curves 30–50
degrees
Infantile curves before 1 year or less than
30 degrees can be observed
Abbreviations: CMTD, Charcot–Marie–Tooth disease; CP, cerebral palsy; EDS, Ehlers–Danlos syndrome; FA, fractional
anisotropy; LDS, Loeys–Dietz syndrome; MD, muscular dystrophy; MS, Marfan’s syndrome; NF1, neurofibromatosis type
1; OI, osteogenesis imperfecta; PSF, posterior spinal fusion.
335

– Cerebral palsy (CP): Quadriplegic and totally
involved CP have the highest incidence of
scoliosis with over 50% of children developing
it. Bracing is ine ective in preventing curve
progression with CP, and often these curves
will continue to progress even after skeletal
maturity. Close follow-up is warranted.
– Rett’s syndrome: Characterized by poor
coordination and imbalance of muscles around
spine. Scoliosis is more likely to develop in
severe forms of the disease and less common
in girls who continue to ambulate.
– Myelomeningocele: Often associated with
multiple defects including scoliosis, tethered
cord, and syringomyelia. Can be classified
according to location, thoracic/high lumbar,
low lumbar, or sacral involvement.
– Spinal cord injury before puberty: This often
results in paralysis causing scoliosis of the
growing spinal cord. Most of these children
develop a progressive scoliosis that requires
surgical correction.
– Friedreich’s ataxia: Involves a genetic mutation
resulting in progressive neurological damage,
including poor muscle control often leading to
scoliosis. Other findings include pes cavus,
incoordination, speech problems, and diabetes.
– Charcot–Marie–Tooth disease: A progressive
disease resulting from peripheral nervous
system damage leading to loss of motor
function. Cannot perform neuromonitoring
during surgical repair of scoliosis in these
patients due to damage to peripheral nervous
system.
– Syringomyelia: Dilation of the canal of the
spinal cord. The syrinx can disturb anterior
horn cells a ecting motor function and
crossing fibers of the spinothalamic tract
resulting in sensory deficits. Warning signs are
rapidly progressive curve, asymmetrical
abdominal reflexes, or left thoracic curve. It is
detected with a MRI of the spinal cord.
● Syndromic: Disorders that disturb ligament
integrity, growth, and balance are often
associated with scoliosis.
– Neurofibromatosis type 1: Mutation in
neurofibromin 1 gene involved in the RAS cell
signaling pathway. This mutation results in
multiple benign tumors neural in origin. It is
unknown how this disorder results in scoliosis.
The curve seen can be a dystrophic type curve
(sharply angulated) or nondystrophic curve.
– Marfan’s syndrome: Defect in connective
tissue protein fibrillin resulting in ligamentous
laxity and thin pedicles. Scoliosis occurs in 60%
of these patients and if there is growth
potential left there is a very high likelihood of
curve progression even with bracing. Obtain
MRI prior to surgery (dural ectasia may be
seen which is important for surgical planning).
– Loeys–Dietz syndrom e: Transforming growth
factor-β (TGF-β) mutation resulting in
connective tissue disorder with many similar
features to Marfan’s syndrome, including
progressive scoliosis.
– Ehlers–Danlos syndrome: Multiple types of the
syndrome classified according to collagen
defect. Ehlers–Danlos type VI with a defect in
lysyl hydroxylase commonly results in a
progressive scoliosis. These patients often need
longer fusions due to potential junctional
complications.
– Osteogenesis imperfecta: Defect in type 1
collagen resulting in weak bone with frequent
breaks. Often have progressive scoliosis treated
with extended posterior spinal fusion (PSF).
● Evaluation of scoliosis:
– Family history: Positive in about 10% of
scoliosis patients. Twin studies also suggest a
polygenetic autosomal or sex-linked
inheritance pattern. Scoliosis is three times
more likely if a parent is a ected and seven
times more likely if sibling is a ected.2
– Growth history: Growth should be evaluated
at every visit when following scoliosis. There is
greatest risk for curve progression during
growth spurts. The risk of progression
decreases when growth slows to less than
1 cm in 6 months’ time.
– Motor evaluation: Evaluate for symmetric
strength and reflexes. Asymmetry can indicate
neural axis problem. Abdominal reflex
asymmetry can indicate the level of a neural
axis abnormality.
– Balance/symmetry: Check for shoulder
asymmetry which can indicate a rotational
deformity of the spinal cord. If there is no
shoulder asymmetry present but a thoracic
curve is corrected, shoulder imbalance can
result. Planning of more cephalad fusion levels
is warranted in this case.2,3 Plumb line can
estimate head deviation from midline.
Performed by drawing a vertical line from C7
to the gluteal cleft and visualizing distance
from midline. Adams’ forward bend test
screens for thoracic and lumbar rotational
deformity. Performed by evaluating the patient
from behind with the patient bent at waist
Developmental and Congenital Spinal Disorders
336

attempting to touch toes. Can determine
degree of rotation with scoliometer (5–7-
degree scoliometer correlates roughly with
20–25 Cobb’s measurement).
– Kyphosis: Often occurs with scoliosis. Can
assess clinically by viewing the patient
laterally with Adam’s forward bend test or
radiographically by measuring the curvature.
– Lower extremities/gait: Evaluate for symmetric
gait, strength, coordination, and inspect feet
for cavovarus deformity.
● Radiographs:
– Cobb’s measurement: This is the angle
between superior and inferior end plate
vertebrae of the curve. To measure, draw lines
parallel to the superior and inferior end plates.
Can be measured directly with the di erence
between these lines, or geometrically by
measuring the di erence between lines
perpendicular to the horizontal end plate lines.
– Risser’s scale: Estimate of skeletal maturity
that is measured radiographically on a scale of
0 to 5 based on the amount of calcification
over the Ilium (Table 42.2). Risser 0 indicates
skeletal immaturity, 5 indicates skeletal
maturity. Risser 0 has no ossification over the
Ilium. Risser 1 is 25% ossification beginning
with the lateral aspect of the Ilium, Risser 2 is
25%-50%, Risser 3 is 50%-75%, Risser 4 is 100%
and Risser 5 is 100% ossification with closure
of the apophysis.
– Triradiate cartilage: Y-shaped ossification
center on the floor of the acetabulum. Closes
prior to calcification of ilium and just after
period of peak growth velocity.
– MRI: Indicated for early-onset, congenital,
significant pain, left main thoracic curves, or
curves associated with neuromuscular
conditions.
● Behavior and health e ects of scoliosis:
– Progression rates: Idiopathic curve progression
rate is related to the magnitude of the curve
and skeletal maturity. Risser 0–1 with curve
less than 20 degrees has less than a 25% risk of
progression. Risser 0–1 with a curve greater
than 20 degrees has a risk of progression of
about 70%. Risser 2–4 with less than 20
degrees of curvature have less than 2% risk of
progression. Patients who are Risser 2–4 with
greater than 20 degrees of curvature have 23%
risk of progression.4 Congenital curve
progression related to the type of
malformation. Unsegmented bars with
contralateral hemivertebra have the highest
risk of being rapidly progressive. Unilateral
unsegmented bar is rapidly progressive. Fully
segmented hemivertebra is progressive at a
constant rate. Partially segmented
hemivertebra is less rapidly progressive.
Incarcerated or unsegmented hemivertebra
have little progression if any.
– Pulmonary function test (PFT): Thoracic curves
approaching 90 degrees can compromise
pulmonary function. Forced vital capacity and
forced expiratory volume in one second
decrease linearly when curves are greater than
100 degrees.
– Back pain: Increased incidence of back pain in
scoliosis, but most of the back pain is rated as
minimal and does not cause disability.5
– Appearance concerns: Cosmetic concerns
regarding scoliosis are a legitimate reason to
consider surgical options. Must balance
appearance versus surgical risks and known
consequences of surgery (decreased motion in
fused segment of back).
– The majority of scoliosis cases are non–life
threatening. In early-onset scoliosis, certain
congenital scoliosis and scoliosis associated
with neuromuscular conditions, the curve can
be rapidly progressive with cardiopulmonary
compromise when curve is greater than 100
degrees.
Table 42.2 Risser’s scoring index
Risser 0

No calcification on iliac crest
Risser I

Lateral 25% of iliac crest ossified
Risser II

Lateral 25–50% of iliac crest ossified
Risser III

Lateral 50–75% of iliac crest ossified
Risser IV

Iliac crest 75–100% ossified
Risser V

Iliac crest 100% ossified with closure
of the apophysis
Scoliosis
337

42.2 Nonsurgical Treatment
There are multiple modes of treatment of scoliosis,
ranging from observation to surgery. Di erent
treatment options are considered in di erent
curves. The best treatment is individualized to the
patient and the curve.
● Physical therapy (PT): Very good for overall
health and bone health. PT has not been shown
to prevent curve progression.
● Observation: Initially indicated for most curves.
It is important to determine rate of curve
progression and overall growth rate. Curves less
than 25 degrees should be monitored every 4 to
12 months with radiographic assessment. The
curves should be monitored more frequently
during periods of rapid growth rate. Curves
greater than 30 degrees should continue to be
monitored even after skeletal maturity.
● Mehta’s casting: Indicated for infantile idiopathic
scoliosis (IIS). The casting is not well tolerated in
older children. If rib vertebra angle di erence is
greater than 20 degrees or curve is greater than
35 degrees in IIS, consider casting followed by
bracing when the child becomes more mobile. If
the curve is under 25 degrees or the child is
under 1, there is a high probability that curve
will spontaneously resolve. Follow-up in 4
months is acceptable.
● Brace treatment: Indicated for idiopathic
scoliosis with 25 to 40 degrees of curvature. May
also be used but with less success for
nonidiopathic cases. Bracing does not correct the
deformity; rather it slows the rate of curve
progression. For adolescent idiopathic scoliosis
(AIS), it has been shown that the more hours in
the day you wear the brace, the better the
results. For best results, the patient should wear
the brace for 23 hours every day. The patient can
stop wearing the brace at skeletal maturity,
assessed by Risser’s score and grow th rate
among other parameters. Bracing can be 65 to
75% e ective with proper indications and
compliance.2,4
42.3 Surgical Treatment
● Lenke’s classification for AIS (Table 42.3). Used
for planning surgical treatment in AIS.2,3,6,7
– Classifies curves into six major curve types
with modifiers for the deviation of the apical
vertebra and amount of kyphosis. The major
curves are the largest curved vertebrae
measured by the Cobb angle. They are
classified as structural or nonstructural based
on flexibility in lateral flexion. Structural
curves do not bend out to less than 25 degrees
in lateral flexion. The structural curves are
classified according to location. Type 1 is main
thoracic with a structural thoracic curve.
Type 2 is double thoracic with two structural
thoracic curves. Type 3 is double major with a
structural thoracic and lumbar curve. Type 4 is
a triple major with two structural thoracic
curves and one structural lumbar curve. Type 5
is thoracolumbar/lumbar with a structural
curve in the lumbar or thoracolumbar region.
Type 6 is thoracolumbar/lumbar and thoracic
with a structural thoracolumbar/lumbar and
thoracic curves.
– Lumbar modifiers are determined by the
intersection of the stable vertebra with a line
drawn vertically from the sacrum, the center
sacral vertical line (CSVL). A modifier, the CSVL
intersects between the pedicles of the stable
vertebra. B modifier, the CSVL touches the
pedicles of the stable vertebra. C modifier, the
CSVL does not touch the pedicles of the stable
vertebra.
– Sagittal profile is modified according to the
degree of kyphosis. Hypokyphotic is less than
10 degrees. Normal is between 10 and 40
degrees. Hyperkyphotic is greater than 40
degrees.
● PSF is the gold standard treatment. It is normally
o ered for curves greater than 50 degrees. The
PSF varies according to the curve. Perform
selective PSF of the structural curves in
idiopathic scoliosis. Typically fuse from the
neutral vertebra above to 1 to 2 levels below the
stable vertebra.2 Fuse selectively with congenital
curves, modify according to the defect. Fuse
more segments in neuromuscular and
syndromic causes, often requiring pelvic
fixation.
● Osteotomies: Ponte’s osteotomy involves
removal of facet joints which typically limit
extension of the spine. This allows for correction
of kyphosis. Indicated in rigid curves. Vertebral
column resection (VCR) allows for the largest
correction of kyphosis. Indicated for very large
focal curves.
● Anterior spinal fusion (ASF): Indicated for
skeletally immature patients and extreme
lordosis. Skeletally immature patients, Risser 0
with triradiate cartilage open, are at greater risk
for crankshaft phenomenon if PSF is performed.
ASF can prevent this. ASF is also indicated for
Developmental and Congenital Spinal Disorders
338

lordosis as this approach allows direct access to
the vertebra in the thoracolumbar and lumbar
region. This approach can get similar correction
with fusion of less vertebral levels. However, the
surgery can increase thoracic kyphosis, and is a
more di cult surgery that requires more time in
the operating room.7
● Growing rod instrumentation: Indicated for
young children with grow th potential left with
progressive curves that do not respond to
bracing. Fuse proximally and distally to spinal
curve with rods that distract across the curve.
Perform growing rod distraction every 6 to 12
months until the patient is done growing.
Eventually, the patient will need PSF. Another
option is the vertical expandable prosthetic
titanium rib (VEPTR). This device is attached to
the ribs and distracted periodically in a spine-
sparing approach. It is indicated in early-onset
scoliosis and thoracic insu ciency.
● Innovative ideas: Anterior stapling/tethering
involves attaching pedicle screws to the
convexity of the curve connected by a cable that
corrects the deformity. This method corrects
deformity without fusion allowing the spine to
grow and remain flexible. There is also no
growing rod distraction periodically required
with this technique. There is potential for
overcorrection and no long-term follow-up with
this technique.
Table 42.3 Lenke’s classification of adolescent idiopathic scoliosis
Type Lenke I

Lenke II

Lenke III

Lenke IV

Lenke V

Lenke VI
Curve
type
Main thoracic
curve
Double thoracic
curve
Double Major
curve
Triple major
curve
Thoracolumbar/
lumbar curve
Thoracolumbar/
lumbar thoracic curve
Lumbar modifiers

A. CSVL intersects between
pedicles of stable vertebra
B. CSVL touches stable
vertebra
C. CSVL does not intersect
stable vertebra
Sagittal modifiers

Hypokyphotic (−)
<10 degrees kyphosis
Normal kyphosis (N)
10–40 degrees kyphosis
Hyperkyphotic (+)
>40 degrees of kyphosis
Scoliosis
339

● Neuromonitoring: Monitor both motor and
sensory pathways during surgical correction of
curves. Somatosensory-evoked potentials and
motor-evoked potentials are generated by
stimulating the torso and legs distally and
measuring response in brainstem. Allows for
rapid detection of any central nervous system
(CNS) insult associated with correction of
deformity. Many factors can interfere with
neuromonitoring: inhalational anesthetics,
hypothermia, hypotension, and technical
malfunction. With a real deficit detected on
neuromonitoring, a wake-up test should be
performed. If a change in neuro status is real,
steps to correct the deficit should be taken
immediately including increase BP to a mean
arterial pressure (MAP) greater than 90,
decrease correction of spinal cord deformity,
keep hematocrit above 30 (transfuse if necessary),
administer high-dose intravenous (IV) steroids,
and remove hardware if all else fails.
42.4 Complications
● Progression: Potential for failure of implants
from fracture or dislodgement of implants
leading to progression of the curve.
Pseudoarthorosis formation can eventually lead
to rod fracture. If spinal fusion is too short, it can
lead to junctional problems at ends of the fused
spinal segment, such as fracture or degenerative
change, as these regions are subject to increased
mechanical forces.
● Deep infection: Risk factors that are associated
with increased rate of delayed infection include
receiving blood transfusion, fusion into the
lumbar region, significant medical history, and
not using a drain postoperatively. Occurs roughly
in 1 to 2% of patients. Requires instrument
removal and antibiotic therapy. Early infection
had the highest rate in neuromuscular curves at
9% and lowest in idiopathic scoliosis at 1.6%.
Infection rate also varies according to the
procedure performed being lowest for
distraction procedures. Gram-negative bacteria
are more commonly involved in infection in
nonidiopathic curves, targeted antibiotics should
be given in the perioperative period.8,9
● Neurological injury: Risk is less than 1% with
typical AIS. The rate is higher with congenital or
severe curves. Causes of neurological injury
include correction of curvature leading to
traction on the cord, o set at osteotomies,
hypotension, and direct contact with root or
cord causing contusion (risk with hooks,
screws).
42.5 Conclusion
Scoliosis may arise from any disturbance of the
structure or regulation of spinal balance. It pro-
gresses most rapidly during growth but may
slowly worsen at any time. It a ects pulmonary
function when the curve becomes substantial
leading to cardiopulmonary compromise. There is
an increased incidence of back pain associated
with scoliosis. Bracing during growth, and surgery
are the only methods proven to a ect the natural
history. Bracing prevents progression while sur-
gery can correct the defect. The role of surgery
depends on multiple factors. It must be performed
with the utmost safety to maintain and improve
quality of life.
42.6 Common Clinical
Questions
1. When is it indicated to order an MRI in
scoliosis?
2. Why is bracing the recommended treatment for
scoliosis?
3. When is surgery the recommended treatment
for scoliosis?
4. What are the steps to take if intraoperative
neuromuscular monitoring changes during
surgery?
42.7 Answers to Common
Clinical Questions
1. MRI is indicated in congenital, infantile, and
juvenile curves to rule out intraspinal
pathology. These curves are at higher risk and
warrant an MRI to rule out abnormalities such
as tethered cord, syringomyelia, and spinal cord
tumor. Specific curves that are alarming are left
apex thoracic curve, short angular curves,
patients less than 10 with a curve greater than
20 degrees, any neurological abnormality
associated with a curve, excessive pain, or rapid
progression of the curve.
2. Bracing is indicated in patients with idiopathic
curves 25 to 40degrees. In IIS, bracing or casting
is started when the curve is greater than 30
degrees. Many curves less than this in infantile
Developmental and Congenital Spinal Disorders
340

will spontaneously resolve. In juvenile and
adolescent, bracing is considered when curves
become greater than 20 to 25 degrees. The
more the patient wears the brace, the more
likely it is to be e ective. Ideal treatment
involves wearing the brace for 23 hours per day.
Bracing should be continued until the patient is
skeletally mature or until the curve progresses
beyond 45 to 50 degrees.4
3. Surgery is indicated in idiopathic scoliosis when
curve reaches 50 degrees. The curve is likely to
continue progressing at this point and will not
improve with bracing. It is indicated in
congenital scoliosis when there is a curve
known to be at high risk of progression (such as
a unilateral bar with contralateral
hemivertebra) or associated with severe pain,
neurological defect, or pulmonary
compromise.2,7
4. When intraoperative neurophysiological
monitoring (IONM) changes first assess that it is
a true neurological defect? Neuromonitoring
changes can also be caused by hypotension,
hypothermia, inhaled anesthetics, or technical
errors such as monitor detachment. When a
true neurological change is detected on IONM,
perform a wake-up test, increase BP to a MAP
greater than 90, keep hematocrit above 30
(transfuse if necessary), administer high-dose
corticosteroids, reverse correction of spinal cord
defect, and remove hardware as a last resort.
References
[1] Dobbs MB, Lenke LG, Szymanski DA, et al. Prevalence of
neural axis abnormalities in patients with infantile
idiopathic scoliosis. J Bone Joint Surg Am. 2002; 84-A(12):
2230–2234
[2] Rose PS, Lenke LG. Classification of operative adolescent
idiopathic scoliosis: treatment guidelines. Orthop Clin North
Am. 2007; 38(4):521–529, vi
[3] Lenke LG, Betz RR, Harm s J, et al. Adolescent idiopathic
scoliosis: a new classification to determ ine extent of
spinal arthrodesis. J Bone Joint Surg Am . 2001; 83-A(8):
1169–1181
[4] Nachemson AL, Peterson LE. E ectiveness of treatment with
a brace in girls who have adolescent idiopathic scoliosis. A
prospective, controlled study based on data from the Brace
Study of the Scoliosis Research Society. J Bone Joint Surg Am.
1995; 77(6):815–822
[5] Weinstein SL, Dolan LA, Spratt KF, Peterson KK, Spoonamore
MJ, Ponseti IV. Health and function of patients with
untreated idiopathic scoliosis: a 50-year natural history
study. JAMA. 2003; 289(5):559–567
[6] Lenke LG. The Lenke classification system of operative
adolescent idiopathic scoliosis. Neurosurg Clin N Am. 2007;
18(2):199–206
[7] Newton PO, Marks MC, Bastrom TP, et al. Harms Study Group.
Surgical treatment of Lenke 1 main thoracic idiopathic
scoliosis: results of a prospective, multicenter study. Spine.
2013; 38(4):328–338
[8] Ho C, Sucato DJ, Richards BS. Risk factors for the development
of delayed infections following posterior spinal fusion and
instrumentation in adolescent idiopathic scoliosis patients.
Spine. 2007; 32(20):2272–2277
[9] Mackenzie WG, Matsumoto H, Williams BA, et al. Surgical
site infection following spinal instrumentation for scoliosis: a
multicenter analysis of rates, risk factors, and pathogens. J
Bone Joint Surg Am. 2013; 95(9):800–806, S1–S2
Scoliosis
341

43 Achondroplasia
Debraj Mukherjee, Moise Danielpur
43.1 Introduction
Achondroplasia is the most common of the skeletal
dysplasia, occurring in approximately one of every
15,000 to 40,000 live births.1 It is an autosomal
dominant condition, with most cases due to new
activating mutations in the FGFR3 gene. The molec-
ular defect in achondroplasia causes a quantitative
decrease in the rate of endochondral bone forma-
tion, resulting in short and squat long bones, short
stature, large calvarium, midface hypoplasia, short
basicranium with narrowed foramen magnum and
vascular channels, and small vertebral bodies with
shortened pedicles and narrow spinal canals
(Fig. 43.1).1,2,3 The most concerning neurological
sequelae of achondroplasia that are important to
the neurosurgeon include cervicomedullary com-
pression, spinal stenosis, and hydrocephalus.
43.2 Cervicomedullary
Compression
The most serious neurological complication in
patients with achondroplasia is cervicomedullary
junction (CMJ) compression caused by a tight
deformed foramen magnum.2 Compression at the
foramen magnum can result in cervical myelopathy
manifested as clonus and hyperreflexia, hypotonia,
sleep apnea, and even sudden death.2,3,4,5,6 Because
of the potentially lethal complication associated
with symptomatic disease, neurosurgical decom-
pression has been used to widen the foramen
magnum and relieve the pressure on the emerging
cervical cord. Fortunately, most children with
achondroplasia do not su er neurological symp-
toms and achieve normal motor and intellectual
development without surgical intervention.6,7
Criteria for decompression have been previously
described in large surgical series, generally con-
sisting of imaging and clinical findings consistent
with symptomatic cervicomedullary stenosis.3,8
Unfortunately, there has never been a study which
provided a fail-safe method for prospectively iden-
tifying patients who are likely to die or experience
severe neurological complications if decompres-
sion surgery was not performed. At our institution,
we have used complete obliteration of cerebrospi-
nal fluid (CSF) flow anterior to the spinal cord as
an indication for decompression in symptomatic
patients. Based on findings of our recent series,
there may be a role for the use of dynamic cervical
flexion/extension magnetic resonance imaging
(MRI) and CSF flow studies in the evaluation of
cervicomedullary compression among sympto-
matic patients with achondroplasia.
Fig. 43.1 Activating mutations in FGFR3 within chondrocytes can lead to cervicomedullary compression, spinal stenosis,
or hydrocephalus by decreasing the relative rate of endochondral bone formation.
342

43.3 Spinal Stenosis
Patients with achondroplasia are predisposed to
spinal stenosis as a result of pedicles shortened in
anteroposterior length and decreased interpedicu-
lar distance, leading to narrowed spinal canals.9,10
The series of Jeong et al found that while the inter-
pedicular distance widens from L1 to L5 in patients
without achondroplasia, the interpedicular dis-
tance progressively decreases from L1 to L5 in
patients with anchondroplasia.11 Such patients
often become symptomatic in young adulthood,
when degenerative changes lead to thickening of
the ligamentum flavum, limiting an already nar-
rowed canal and causing symptomatic stenosis. It
has been postulated that this stenosis is height-
ened by thoracolumbar kyphosis and compensa-
tory lumbar hyperlordosis.10,12 By the sixth decade
of life, approximately 80% of patients will develop
spinal stenosis, with approximately 10 to 20%
requiring surgical intervention.10,13
Indications for surgery within their cohort
remain broadly defined, but the largest series to
date included the following operative criteria14:
● The presence of signs or symptoms of chronic
spinal cord compression (weakness, bowel or
bladder dysfunction, hyperreflexia or
hypertonia, spastic gait, or clonus) or chronic
nerve root compression (neurogenic
claudication, weakness or sensory disturbance in
a radicular pattern, or hyporeflexia).
● Neuroimaging evidence of spinal stenosis.
Once the decision has been made to pursue surgical
intervention, the neurosurgeon must be aware of
possible complications specific to this patient
cohort.15 Patients with achondroplasia are prone to
have thinned dura, increasing the relative odds of an
intraoperative durotomy. Additionally, the presence
of scoliosis and thoracolumbar kyphosis is higher
within this patient population and may require the
use of either interspinolaminar decompression with-
out laminectomy or use of concurrent or delayed
instrumentation to prevent postoperative instability.
43.4 Hydrocephalus
Infants with achondroplasia commonly have an
enlarged head; however, not all such patients require
surgical intervention. All infants with achondroplasia
should have head growth monitored at regular inter-
vals using head circumference charts for achondro-
plasia, not charts for the general population.16 The
majority of patients with achondroplasia and macro-
cephaly with mild to moderately enlarged ventricles
have spontaneous stabilization of ventricular size.
Patients with enlarging head circumference as well
as signs or symptoms of increased intracranial
pressure, such as a full fontanelle or dilated facial
veins should be investigated with intracranial imag-
ing, either ultrasonography or MR imaging. While
cranial ultrasonography is thought to be an ad-
equate screening test, MRI imaging allows for both
assessment of ventricular size as well as evidence
of transependymal flow. Ventriculoperitoneal
shunting should be reserved for severely sympto-
matic patients with enlarging ventricles.17 Although
a specific mechanism has not been fully elucidated
to explain the possible relationship between achon-
droplasia and hydrocephalus, previous authors
have postulated that intracranial venous sinus
hypertension secondary to jugular foramen steno-
sis, and in some cases jugular vein stenosis at the
thoracic inlet within this patient population.18,19
References
[1] Rimoin DL. The chondrodystrophies. Adv Hum Genet. 1975;
5:1–118
[2] Hecht JT, Francomano CA, Horton WA, Annegers JF. Mortality
in achondroplasia. Am J Hum Genet. 1987; 41(3):454–464
[3] Pauli RM, Horton VK, Glinski LP, Reiser CA. Prospective
assessment of risks for cervicomedullary-junction
compression in infants with achondroplasia. Am J Hum
Genet. 1995; 56(3):732–744
[4] Bagley CA, Pindrik JA, Bookland MJ, Camara-Quintana JQ,
Carson BS. Cervicomedullary decompression for foramen
magnum stenosis in achondroplasia. J Neurosurg. 2006; 104
suppl 3:166–172
[5] Bland JD, Emery JL. Unexpected death of children with
achondroplasia after the perinatal period. Dev Med Child
Neurol. 1982; 24(4):489–492
[6] Francomano CA, Carson B, Seidler A, et al. Morbidity and
mortality in achondroplasia: e cacy of prospective evaluation
and surgical intervention. Am J Hum Genet. 1993; 53 3:112
[7] Reid CS, Pyeritz RE, Kopits SE, et al. Cervicomedullary
compression in young patients with achondroplasia: value of
comprehensive neurologic and respiratory evaluation. J
Pediatr. 1987; 110(4):522–530
[8] Rimoin DL. Cervicomedullary junction compression in
infants with achondroplasia: when to perform neurosurgical
decompression. Am J Hum Genet. 1995; 56(4):824–827
[9] Dubosset J. Cervical abnormalities in osteochondroplasia. In:
Nicoletti B, Kopits S, Ascani E, McKusick VA, eds. Human
Achondroplasia: A Multidisciplinary Approach. New York,
NY: Plenum Press; 1988:215–218
[10] Kopits SE. Orthopedic aspects of achondroplasia in children.
Basic Life Sci. 1988; 48:189–197
[11] Jeong ST, Song HR, Keny SM, Telang SS, Suh SW, Hong SJ. MRI
study of the lumbar spine in achondroplasia. A
morphometric analysis for the evaluation of stenosis of the
canal. J Bone Joint Surg Br. 2006; 88(9):1192–1196
[12] Lutter LD, Langer LO. Neurological symptoms in achondroplastic
dwarfs—surgical treatment. J Bone Joint Surg Am. 1977; 59(1):
87–92
Achondroplasia
343

[13] Hall JG. The natural history of achondroplasia. Basic Life Sci.
1988; 48:3–9
[14] Sciubba DM, Noggle JC, Marupudi NI, et al. Spinal stenosis
surgery in pediatric patients with achondroplasia. J
Neurosurg. 2007; 106 suppl 5:372–378
[15] King JA, Vachhrajani S, Drake JM, Rutka JT. Neurosurgical
implications of achondroplasia. J Neurosurg Pediatr. 2009; 4
(4):297–306
[16] Horton WA, Rotter JI, Rimoin DL, Scott CI, Hall JG. Standard
growth curves for achondroplasia. J Pediatr. 1978; 93(3):
435–438
[17] Pierre-Kahn A, Hirsch JF, Renier D, Metzger J, Maroteaux P.
Hydrocephalus and achondroplasia. A study of 25
observations. Childs Brain. 1980; 7(4):205–219
[18] Yamada H, Nakamura S, Tajima M, Kageyama N. Neurological
manifestations of pediatric achondroplasia. J Neurosurg.
1981; 54(1):49–57
[19] Mukherjee D, Pressman BD, Krakow D, Rimoin DL,
Danielpour M. Dynamic cervicomedullary cord compression
and alterations in cerebrospinal fluid dynamics in children
with achondroplasia: review of an 11-year surgical case
series. J Neurosurg Pediatr. 2014; 14(3):238–244
Developmental and Congenital Spinal Disorders
344

VIII
Section VIII
Functional Disorders
44 The Evaluation and
Classification of Epilepsy

346
45 Surgical Management of
Childhood Epilepsy: Temporal
and Extratemporal
Pathologies

351
46 Surgical Management of
Childhood Epilepsy: Corpus
Callosotomy and Vagal Nerve
Stimulation

358
47 Surgical Management of
Pediatric Spasticity

368

44 The Evaluation and Classification of Epilepsy
Sarah A. Kelley, Adam L. Hartman
44.1 Introduction
This chapter outlines epilepsy related definitions
and classifications as put forth by the International
League Against Epilepsy. Acquired forms of epi-
lepsy and epileptic syndromes are then reviewed
followed by a discussion of the evaluation of a
patient with epilepsy.
44.2 Definitions
Recent updates to the International League Against
Epilepsy classification scheme in 2017 are
reflected here.1
A seizure is abnormal electrical activity in the
brain that results in clinical signs and symptoms.
These symptoms can range from motor or sensory
symptoms to alternation in consciousness, and
autonomic symptoms.
Epilepsy is two or more unprovoked (i.e., not
provoked by fever, electrolyte abnormalities, drug
withdrawal) seizures or one unprovoked seizure
plus an electroencephalography (EEG) abnormal-
ity suggesting that the patient is at high risk for
another seizure.
Incidence: About 10% of the population will
have a single seizure at some point in life. The inci-
dence of actively treated epilepsy is about 1% in
the general population.2
Status epilepticu s: Continuous seizure activity
lasting 30 minutes or longer or more than one seiz-
ure without return to baseline cognition in
between. Some have proposed using a shorter
time frame because the vast majority of seizures
last less than 5 to 10 minutes.
44.3 Classification of Epilepsy
44.3.1 Definitions
Generalized onset seizure: A seizure appearing to
involve simultaneous abnormal firing of the whole
brain and subsequent full body involvement and/
or loss of awareness.
Focal Onset seizure: A seizure that involves
abnormal neuronal firing of one part of the brain,
which may or may not spread to involve the whole
brain (focal to bilateral tonic-clonic—previously
called secondary generalization) and subsequent
localized symptoms as described below. If there is
loss of awareness with these seizures, they are
described as focal with impaired awareness (previ-
ously complex partial seizure). If there is no loss of
awareness, they are termed focal aware seizures
(previously simple partial seizures).
Any patient with a focal seizure should get brain
imaging (preferably magnetic resonance imaging
[MRI]) unless the history and EEG are consistent
with a benign epilepsy syndrome (see below).
44.3.2 Structural Abnormalities
Tumors: Common developmental tumors seen in
pediatric patients include dysembryoplastic neu-
roepithelial tumors (DNET) and gangliogliomas.
These may cause seizures while impinging on
cortical tissue and are frequently associated with
malformations of cortical development. MRI will
identify these lesions as they may need to be
resected if medication does not control seizures.
Cortical dysgenesis: Abnormalities in the forma-
tion of the cortex during development. In some
cases, these may be easily demonstrated on MRI
(lissencephaly, polymicrogyria) or less easily seen
(such as in some syndromes where abnormal for-
mation of the cell layers of the cortex may not be
seen). These lesions may also be amenable to sur-
gical resection.
● Mesial tem poral sclerosis occurs when there is
scarring of the temporal lobe for any number of
reasons from infection to trauma. There is
continuing debate as to whether it may be
caused by febrile seizures. This, too, is often
amenable to surgical resection with a temporal
lobectomy and amygdalohippocampectomy.
● Vascular m alform ations: The most likely
vascular malformations to lead to seizure are
arteriovenous malformations and cavernous
angiomas. They lead to epilepsy due to
hemorrhage or surrounding brain tissue injury.
Both are associated with focal epilepsy.
44.3.3 Posttraumatic Epilepsy
Posttraumatic epilepsy is a very common form
of acquired epilepsy and is defined as recurrent
seizures after a traumatic brain injury. These are
divided into three main categories: immediate
seizures, which occur within 24 hours of injury,
early seizures, which occur within 1 week of injury
346

and late seizures, which occur more than week
after injury. An increased risk of developing epi-
lepsy after head injury is noted if there is a
depressed skull fracture, penetrating injury, intra-
cranial hematoma, or early seizures.3 Prophylaxis
has been demonstrated to prevent early but not
late posttraumatic seizures.4 Posttraumatic seiz-
ures may be di cult to treat surgically due to
coup–contrecoup injuries that may create multiple
epileptogenic foci.
44.3.4 Epilepsy Syndromes
The diagnosis of epilepsy syndromes gives infor-
mation as to how to best treat the patient as well
as the likely prognosis.5
Neonatal
Neonatal seizures may be caused by all of the same
etiologies as described above. In addition, there
are a number of syndromes that are specific to the
neonatal age group.
● Benign syndromes: Children most often
grow out of these seizures. Benign idiopathic
neonatal seizures and benign familial neonatal
seizures both often occur within the first week
of life.
● Other syndromes that occur early in the
neonatal period including early infantile
epileptic encephalopathy (Ohtahara’s syndrome)
and early myoclonic encephalopathy are
refractory to treatment and the patients have
poor outcomes. Both are characterized by a burst
suppression pattern on the EEG.
Infant/Childhood
● Febrile seizures are the most common type of
seizure in this age group, occurring in up to 5%
of children between the ages of 6 months and 6
years in the US (this varies by country). These
are typically developing children who have a
fever over 38 °C without evidence of a central
nervous system (CNS) infection. Febrile seizures
are divided into two categories: simple and
complex. Simple febrile seizures are relatively
short (<15 minutes), are generalized, and do not
recur within a 24-hour period. Complex febrile
seizures are longer (>15 minutes), focal, or recur
within 24 hours. Those with simple febrile
seizures do not have an increased risk of later-
developing epilepsy. The risk doubles for those
who had complex febrile seizures. Those who
have simple febrile seizures do not require any
additional work-up including EEG, brain
imaging, or lumbar puncture. The source of the
fever should be investigated and treated. Seizure
prophylaxis is typically not recommended in
these patients and studies have demonstrated
that fever control does not reduce the risk of a
subsequent febrile seizure.6
● Infantile spasm s generally occur around 4 to 8
months of age. The triad of infantile spasms
(flexor or extensor spasms often occurring in
clusters often around sleep–wake transitions), a
high voltage, chaotic, multifocal EEG
(hypsarrhythmia), and developmental delay
constitute West’s syndrome. The vast majority of
these patients (80–90%) have underlying brain
pathology. Most have developmental delay and
many go on to have other seizure types later in
life.
● Absence seizures are divided into two types,
childhood and juvenile, depending on the age
of onset and associated seizure types. They
develop between 4 and 14 years of age and
are characterized by staring and behavior
arrest lasting on average 10 to 12 seconds,
sometim es associated w ith automatism s and
often occurring very frequently throughout
the day. These patients can also develop
generalized tonic–clonic seizures and
myoclonic jerks. Their seizures m ay be
induced by hyperventilation and their EEG
dem onstrates generalized 3-Hz spike and
slow-wave activity.
● Benign epilepsy with centrotem poral spikes
(previously called benign rolandic epilepsy) is
the most common focal epilepsy of childhood
occurring between 3 and 13 years of age. These
seizures often occur just after falling asleep and
often involve one side of the face and tongue
with inability to talk. They will often evolve into
generalized tonic–clonic seizures. The EEG
shows a classic centrotemporal spike
distribution which may be unilateral.
Children often grow out of these seizures around
puberty.
● Lennox–Gastaut syndrom e (LGS) is
characterized by multiple seizure types
including tonic, atonic, and absence seizures as
well as focal and generalized tonic–clonic
seizures. These children have very abnormal
EEGs (slow spike wave and paroxysmal fast) and
most have developmental delay. Children who
have infantile spasms often go on to develop
LGS.
The Evaluation and Classification of Epilepsy
347

Adolescent
● Juvenile m yoclonic epilepsy is the most
common generalized epilepsy in adolescents and
often emerges in the teenage years. Usually,
patients will experience early morning
myoclonic jerks (although they can occur any
time of day) prior to developing a generalized
tonic–clonic seizure. Absence seizures may also
be seen and the EEG typically shows a 4- to 5-Hz
generalized spike and wave pattern. Most
patients require lifelong treatment for this
disorder.
44.4 Evaluation of Epilepsy
44.4.1 History
What happened to the patient during the seizure?
This will vary depending on which part of the
brain is involved. The initial clinical finding at the
beginning of the seizure is often the most helpful
in localizing the onset of the seizure within a spe-
cific anatomical location.
● Generalized onset seizure: Behavior arrest,
staring, myoclonus, tonic posturing, tonic–clonic
seizures
● Focal onset seizure: Localized motor, sensory or
autonomic function, behavior arrest, or staring
(the latter two can be seen with either
generalized or focal seizures). Examples include
left arm shaking, numbness on the side of the
face, eye deviation, automatisms (chewing, lip
smacking, picking behaviors). Auras also fall into
this category. Auras consist of altered sensory
function that start just before more obvious
seizure activity. This can include an unusual
feeling, sense of fear, unpleasant taste, or smell,
among other symptoms.
After the Seizure (Postictal Signs
and Symptoms)
● Lethargy or confusion: Unilateral weakness
(Todd’s paralysis) may indicate that a seizure
was focal in nature.
Subtle Findings
Asking about more subtle clinical findings may
help to determine how frequently the patient is
having seizures. For example, asking about staring
spells, myoclonic jerks, loss of time, unexplained
nocturnal tongue biting, or enuresis.
Risk Factors
● Brain trauma, meningitis, encephalitis, febrile
seizures as a child, or a complicated prenatal
course are most likely to place a person at risk
for future epilepsy.
● Other risk factors include a history of stroke,
vascular malformations (if impinging on the
cortex), cortical or developmental
malformations, intracranial hemorrhage, and
metabolic abnormalities.
44.4.2 Physical Examination
● Neurological deficits on physical examination
may give clues as to an underlying lesion which
could be the cause of the patient’s seizures.
● A thorough skin examination may identify
neurophokomatoses such as tuberous sclerosis,
Sturge–Weber syndrome, or neurofibromatosis.
44.4.3 Diagnostic Studies
Characterization and Localization
1. Electroencephalogram (EEG): A routine (20–
30 minutes) study will detect abnormalities
even if no seizures are captured in about 90% of
those with generalized epilepsy and half of
those with focal epilepsy. Therefore, a normal
routine EEG does not rule out the diagnosis of
epilepsy. The interictal (between seizure) EEG
may demonstrate a specific pattern which is
diagnostic of a certain epilepsy syndrome (see
below). Provocative tests such as
hyperventilation and intermittent photic
stimulation may bring out epileptiform
discharges in certain types of epilepsy.
● When to get an EEG?
– After a new onset, unprovoked seizure
– If there is a change in seizure characteristics
from the patient’s baseline seizures
– Concern for status epilepticus (clinical or
subclinical)
2. Epilepsy m onitoring unit (EMU): Extended
monitoring of the EEG is often needed to
further characterize seizure type to guide future
treatment or localize a seizure focus for possible
surgical resection. This also can be used to
determine whether events are epileptic or
nonepileptic in nature.
3. Intracranial electrode m onitoring: Placing
grids or strips of electrodes on the surface of the
brain or depth wires with electrodes into the
Functional Disorders
348

brain parenchyma can better localize a seizure
focus in preparation for surgical resection of
this focus. These electrodes also allow
functional mapping of potentially eloquent
areas of cortex (via direct current stimulation
during various motor, language, and sensory
paradigms), which in turn allows for improved
tailoring of resections.
4. Magnetic resonance im aging: MRI is helpful in
identifying a lesion that may be the cause for
focal epilepsy. This may be due to any number
of lesions including tumors, strokes, cortical
malformations, or vascular malformations.
Obtaining a “seizure protocol” MRI that
specifically acquires coronal slices along the
long axis through the hippocampus is more
sensitive in finding volumetric di erences
between mesial temporal structures than
conventional MRI.
5. Positron em ission tom ography (PET) scan:
This radioisotope study (typically using 18F-
deoxyglucose) evaluates metabolic activity
within the brain. Regions with decreased
metabolism may be abnormal and therefore
have the potential to lead to seizures.
Conversely, seizure activity may increase focal
metabolism (an EEG should be recorded during
PETstudies to monitor for this potential
confounder).
6. Single-photon em ission tom ography (SPECT):
This radionuclide study may identify the region
where seizures originate. It requires an
injection of the isotope immediately after the
onset of a seizure, followed by rapidly obtained
nuclear medicine studies.
7. Magnetoencephalography (MEG): This type of
study localizes magnetic dipoles, which, in
combination with MRI (magnetic source
imaging), can be useful in finding areas of
cortical irritability. MEG is considered to be
complementary to EEG.
Studies to Aid in the Determination
of Risk of Surgical Resection
● Neuropsychological testing: Typically
administered by a neuropsychologist, this
testing may identify possible areas of
dysfunction as well as the likelihood that the
patient will have additional deficits if certain
portions of the brain are resected.
● Functional MRI (fMRI): Performed using
specific motor and language paradigms, fMRI
may show specific regions of the brain that are
activated during a task.
● Wada test: Using intracarotid amobarbital or
methohexital, this study can lateralize language
and memory function by anesthetizing half the
brain and then testing with a neuropsychology
battery of tests.
● MEG: This modality also can be used to localize
neurological function.
Careful evaluation via history, physical examina-
tion, ancillary testing, and subsequent correct clas-
sification of seizure type and seizure syndrome is
important to determine the correct treatment and
likely outcome for a patient with epilepsy.
44.5 Common Clinical
Questions
1. What criteria would you use to diagnose a
patient with epilepsy?
2. What are the studies of choice for a patient who
presents with right arm twitching that then
spreads to entire body tonic–clonic activity
with loss of consciousness?
3. Should a patient with a traumatic brain injury,
who has not had a seizure, be treated
prophylactically with anticonvulsant
medications?
4. When would you refer a patient to the epilepsy
monitoring unit for prolonged EEG monitoring?
44.6 Answers to Common
Clinical Questions
1. Diagnose a patient with epilepsy if the patient
has had two or more unprovoked seizures (i.e.,
not due to fever, metabolic abnormality, etc.) or
has had one seizure and has epileptiform
activity on the EEG that suggests they are likely
to have another seizure.
2. This is a focal to bilateral tonic-clonic seizure
(focal seizure with secondary generalization).
An EEG and MRI of the brain would be
appropriate studies to obtain at this time. Both
of these studies will help to localize the
epileptogenic zone and the MRI of the brain will
help to determine if there is an underlying
The Evaluation and Classification of Epilepsy
349

structural pathology that is leading to the
seizure.
3. Data demonstrate that prophylaxis does
prevent early posttraumatic seizures (within
the first 7 days of injury) but not late
posttraumatic seizures (after 7 days). Therefore,
the patient may be treated prophylactically for
7 days; however, treatment should be stopped if
s/he has not developed seizures within the first
week.
4. Refer to the epilepsy m onitoring unit to
further characterize seizure type, to guide
future treatment, or localize a seizure focus
for possible surgical resection. The
m onitoring m ay also be used to determ ine
w hether events are epileptic or nonepileptic
in nature.
References
[1] Berg AT, Berkovic SF, Brodie MJ, et al. Revised terminology
and concepts for organization of seizures and epilepsies:
report of the ILAE Commission on Classification and
Terminology, 2005–2009. Epilepsia. 2010; 51(4):676–685
[2] Hauser WA, Annegers JF, Kurland LT. Prevalence of epilepsy in
Rochester, Minnesota: 1940–1980. Epilepsia. 1991; 32(4):429–445
[3] Lowenstein DH. Epilepsy after head injury: an overview.
Epilepsia. 2009; 50 suppl 2:4–9
[4] Temkin NR, Dikmen SS, Wilensky AJ, Keihm J, Chabal S, Winn
HR. A randomized, double-blind study of phenytoin for the
prevention of post-traumatic seizures. N Engl J Med. 1990;
323(8):497–502
[5] Muthugovindan D, Hartman AL. Pediatric epilepsy syndromes.
Neurologist. 2010; 16(4):223–237
[6] Rosenbloom E, Finkelstein Y, Adams-Webber T, Kozer E. Do
antipyretics prevent the recurrence of febrile seizures in
children? A systematic review of randomized controlled trials
and meta-analysis. Eur J Paediatr Neurol. 2013; 17(6):585–588
Functional Disorders
350

45 Surgical Management of Childhood Epilepsy:
Temporal and Extratemporal Pathologies
Aurelia Peraud
45.1 Introduction
In most patients, seizures can be well controlled
with appropiate medication, but 20 to 30% of the
patients are refractory to all forms of medical ther-
apy. There has been increasing consensus on the e -
cacy of surgery to treat drug-resistant focal epilepsy
in children. In addition to the control of disabling
seizures, surgery may improve developmental, psy-
chosocial, and behavioral impairment in children
with early-onset epilepsy and those with long-
standing antiepileptic medication. Brain maturation
in infancy and early childhood leads to a complex
evolution of seizure semiology, electroencephalo-
graphy (EEG), and neuroimaging findings. Not
surprisingly, developmental delay or progressive dis-
turbances in cognition, behavior, and psychiatric
state are common in pediatric epilepsy. Therefore,
early surgical intervention is crucial in infants with
catastrophic epilepsy to prevent such a developmen-
tal delay. Moreover, surgery in early childhood may
take advantage of brain plasticity with chances for
recovery from seizure-related damage and possible
postsurgical neurological deficits. However, the clini-
cal presentation and the etiology of medically refrac-
tory localized seizures can be rather heterogeneous.
45.2 Epilepsy Disorders in
Childhood Epilepsy
45.2.1 Cortical Dysplasia
Cortical dysplasia is the most common neuropa-
thological entity found in pediatric epilepsy and
may be focal or multilobar. Neuroradiological
alterations can be subtle or even absent, and if
visible on MR images, the lesion may only be a
small part of larger di use structural abnormality.
Exact presurgical evaluation and surgical planning
are of utmost importance to delineate the entire
abnormal cortical area for complete resection
yields the best seizure control.
45.2.2 Tuberous Sclerosis
Complex
The evaluation of the epileptogenic focus in this
patient groups can be challenging. These children
may have a single epileptogenic region suitable for
resection despite having multiple other tubers or a
multifocal, rather di use, seizure onset.
45.2.3 Polymicrogyria
The clinical and eletrophysiological spectrum in
this entity can be widespread and seizures may
spontaneously remit. Polymicrogyria is commonly
found in both hemispheres predominantely in the
perirolandic or perisylvian region.
45.2.4 Hypothalamic Hamartoma
Seizures orginating from hypothalamic hamarto-
mas are often pharmacoresistant and develop-
mental and, behavioral problems as well as
endocrinological disturbances are not uncommon.
Several surgical approaches have been described
including stereotactic, endoscopic, and radiosurgi-
cal procedures.
45.2.5 Hemispheric Syndroms
Congenital abnormalities a ecting an entire
hemisphere such as hemispheric dysplasia or hem-
imegalencephaly are summarized under this title.
Surgical techniques include hemispherectomy or
hemispherotomy procedures.
45.2.6 Sturge–Weber Syndrome
When seizures occur early in infancy or are associ-
ated with significant developmental delay or pro-
gressive focal deficits such as hemiparesis, urgent
surgical intervention might be necessary. Depend-
ing on the seizure-onset zone, focal resection or
hemispheric procedures are required. Operative
risks are not only related to the size of resection
but to the hemodynamic e ects, which can com-
promise also the contralateral hemisphere.
45.2.7 Rasmussen’s Syndrome
The etiology of Rasmussen’s syndrome is still not
understood (viral vs. autoimmune), but the severity
of disabling seizures resistant to antiepileptic drugs
makes surgical intervention necessary as early as
351

possible to prevent other comorbidities. Hemispher-
otomies and other disconnection procedures are
the treatment of choice. The risk–benefit assess-
ment requires considerable clinical experience and
these children should be evaluated in experienced
pediatric epilepsy centers providing the whole
armamentarium of medical and surgical manage-
ment of this disease.
45.2.8 Tumors and
Cerebrovascular Disorders
Seizures are a common initial presenting symptom
of pediatric brain tumors especially of the cerebral
hemispheres. However, brain tumors are a rare
cause of childhood epilepsy and account for seiz-
ures in only 0.2 to 0.3% of the cases. However, in
vascular problems, seizures can occur either as a
presenting symptom or as a complication. Best
examples are caveromas with sourrounding
epileptogenic hemosiderin rims and large middle
cerebral artery (MCA) aneurysms provoking
temporal lobe epilepsy.1,2
45.3 Presurgical Evaluation
Surgical outcome in pediatric epilepsy is signifi-
cantly correlated with correct patient selection (Is
the patient truely refractory to medical treat-
ment?) and presurgical assessment. This includes
thorough neurological examination (clinical his-
tory and physical examination) by pediatric neu-
rologists, electrophysiological assessment by
pediatric epileptologists, cognitive evaluation by
neuropsychiatrists, and finally the collaborative
decision about the candidate and appropriate sur-
gical procedure together with pediatric neurosur-
geons. The presurgical evaluation should clarify
whether the seizures are focal or generalized, and
if focal, whether the origin is temporal or extra-
temporal. Is there a lesion visible on MR images
that could be linked to the seizures? Are there
functional important areas involved or close by the
possible area of resection?
If the results of this noninvasive phase remain
inconclusive, more invasive examinations are war-
ranted.
45.4 Neuroimaging
In search for focal lesions, MR is the imaging
modility of choice. Routine epilepsy protocols with
additional special sequences (fluid-attenuated
inversion recovery [FLAIR], magnetization-pre-
pared rapid acquisition gradient echo [MP-RAGE],
inversion recovery, di usion tensor imaging [DTI])
in thin cuts and 3D reconstruction to existing MR
protocols are capable to detect even small lesions
such as focal cortical dysplasia (FCD), hamartomas,
polymicrogyria, hippocampal sclerosis, and glial
tumors.3,4 Special MR sequences may be required
in the first 2 years of life because of immature
myelination, and serial scans may be necessary to
identify abnormalities during early postnatal brain
development.5
Other options are ictal and interictal single-pho-
ton emission computed tomography (SPECT) and
positron emission tomography (PET) investiga-
tions and these analyses can be very helpful in
nonlesional seizure foci especially in extratempo-
ral epilepsy to identify the area of further invasive
investigations.6,7,8,9,10,11,12,13
Via substraction of
ictal and interictal SPECT signal and by coregistra-
tion with MR images (SISCOM), the exact anatomi-
cal localization of the ictal seizure-onset zone can
be highlighted. To determine hemispheric domi-
nance for language, functional MR has been estab-
lished in some centers to estimate the possible
benefits of surgery against the risk of postoperati-
ve language deficits. Intracarotid amobarbital test
(Wada’s test) have been abandonned even in adult
epilepsy surgical centers because of the risk of
stroke and the more invasive nature of the proce-
dure.14,15
45.5 EEG Investigations
The mainstay of presurgical evaluation is still the
analysis of EEG activity between events (interictal)
or of specific activity during events (ictal) which
provides evidence of focal electrical dysfunction.
Interictal EEG alterations such as spikes and slow-
wave complexes can be of localizing value. Serial
EEG studies may be necessary to document consis-
tency or progression of epileptic area especially in
infants and young children. Video EEG recordings
are of utmost importance to simultaneously ana-
lyse seizure semiology during an epileptogenic
event. Patients are hospitalized for video EEG
monitoring and the antiepileptic medication is
reduced or even withdrawn to provoke seizures.
Patients’ behavior during a seizure (semiology)
allows an experienced epileptologist to gain an
idea about the seizure origin in parallel to the EEG
findings. Invasive electrode recordings are being
performed more selectively and are indicated
Functional Disorders
352

primarily to localize the epileptogenic region
when alternative methods are nonconclusive.
45.6 Surgical Options
Surgical methods applied in epilepsy treatment
can be roughly divided into diagnostic and thera-
peutic procedures.
45.6.1 Diagnostic Surgical
Procedures
In case of nonconclusive results with regard to the
seizure-onset zone obtained from noninvasive
evaluations, further invasive EEG monitoring
investigations have to be considered. Subdural
strip electrodes are used to distinguish between
cerebral lobes and can be very helpful in frontal
interhemispheric ictal onset zones.16 In recent
years, stereotactically placed depth electrodes are
more and more used because they can be precisely
placed and allow recordings even from deep-
seated locations such as the insula and the white
matter.17,18 When the area of seizure onset is
known and the zone has to be further evaluated,
subdural grid electrodes with EEG recordings
directly from the cortex come into play.16,19 In this
way, the epileptogenic zone and the area of seizure
propagation can be clearly discerned. The main
goals of epilepsy surgery are to precisely localize
the epileptogenic region and to resect the focus as
completely as possible without causing further
neurological or cognitive deficits. The proximity to
functionally important, for example, eloquent
areas may increase the risk of surgery and the
resection has to be tailored accordingly. Although
functionally important areas may be approximated
with the help of anatomical landmarks, individual
variations and distortion of these landmarks by
the local pathology have to be taken into account.
Therefore, mapping for functional important areas
such as speech or motor function is crucial during
invasive EEG monitoring prior to surgcial resec-
tion. During the resective procedure, these func-
tional areas will be reidentified by direct cortical
stimulation.20,21,22
45.6.2 Therapeutic Surgical
Procedures
When the presurgical planning is finalized, the
microsurgical resection can be accomplished in a
subpial fashion. Cortical gray and white matter are
carefully removed by suction and/or cavitron
thereby leaving the adjacent gyri untouched. The
vasculature and especially the large draining veins
remain intact. The amount of scar tissue formation
is minimal. Di erent types of surgical resections
can be discerned such as lesionectomy, temporal
lobe resection with selective amygdalohippocam-
pectomy, extratemporal resections, and hemisper-
otomy or hemispherectomy. Other disconnective
procedures include corpus callosotomy and multi-
ple subpial transsections.
Lesionectomy
Lesions that are clearly identified as the cause of
seizures can be of diverse histology. Cavernomas
should be removed whenever safely possible
including the hemosiderin-stained surrounding
brain tissue.23,24,25 Areas of focal atrophy or corti-
cal dysplasia should be widely resected and the
extent of cortical and subcortical resection is best
determined by invasive monitoring for the epilep-
togenic area of these lesions tend to be larger than
the morphological changes on preoperative MR
images.26,27,28,29 A recent retrospective study of
Rowland and coworkers summarizing 37 studies
with 2014 pediatric patients with FCD found that
partial seizures, a temporal location, positive find-
ings on MR images, complete margins of resection,
and histological FCD type II were significantly
associated with a seizure-free outcome, whereas
age at surgery and the possibility to localize the
epileptogenic region on EEG did not a ect seizure
freedom.30 Brain tumors present in about 16% with
seizures and as shown in a large series by the
group of Constantini partial seizures were found in
85% of the cases. The tumors in this series of 48
children were all supratentorial mainly temporal
in location and almost all gliomas frequently of
low grade. A recent study suggests that glutamate
secretion from gliomas may induce seizures.31
Approximately, 92% of children in their study were
seizure free for at least 2 years and significant ped-
ictors were gross total tumor resection, seizure
duration of less than 1 year, and temporal location.
The same is true for dysembryoplastic neuroepi-
thelial tumors with a predominant temporal loca-
tion and good seizure control rates.32 However,
DNETs tend to be associated with focal cortical
dysplasia with its own epileptogenic potential.
Complete tumor resection along with the epilepto-
genic zone of cortical dysplasia is therefore impor-
tant and intraoperative electrocorticography can
be of immense value in this context.33 Tuberous
Surgical Management of Childhood Epilepsy: Temporal and Extratemporal Pathologies
353

sclerosis is another well-known etiological entity
leading to epilepsy in children. A recent paper
from the Hospital of Sick Children in Toronto sum-
marizes the results of 20 studies with 181 patients
and determined that there was a nonsignificant
trend on multivariate analysis for improved seiz-
ure outcomes over the last 15 years following
resective surgery. The most likely reasons are
advanced imaging and localization modalities
introduced over the last years which help to dis-
cern between tubers responsible for epileptic
discharges and those who are silent.34,35 Most chil-
dren do have multiple tubers and the challenge in
epilepsy surgery is to identify those from which
seizure originates. The resection of this lesion may
have favourable outcome with regard to seizure
control and only the concerted results from MR
sequences, nuclear medicine studies, and electro-
corticography are able to precisely define the epi-
leptogenic tuber.
Temporal Resections
Hippocampal sclerosis is the most common path-
ology in adults undergoing surgery for temporal
lobe epilepsy. In contrast, the majority of children
receiving temporal lobe resection are found to
have focal cortical dysplasia or low-grade gliomas
as the primary underlying pathology. Hippocam-
pal sclerosis prevails in 13 to 40% in children suf-
fering from medically intractable epilepsy which is
in contrast to 73% in adults. Seizure freedom after
surgery is comparable and ranges between 66 and
80%.4,36 While the sensitivity of MR images for the
detection of hippocampal sclerosis in adults is
high, this remains uncertain in children. Several
studies agreed that the most reliable MR criteria
for correct diagnosis are increased signal on T2-
weighted MR images and reduced hippocampal
volume. The presence of a dual pathology (hippo-
campal sclerosis and FCD) has been estimated to
range between 12 and 79%.37,38,39
Selective Amygdalohippocampectomy/
Mesial Temporal Resection
Temporal lobectomies for mesial temporal sclero-
sis have been abandonned because of the inherent
risk of injury to the optic radiation with quadran-
tanopsia. Several surgical approaches to the mesial
temporal structures have been described via the
temporal pole, transventricular subtemporal, or
transylvian. Important in preoperative assessment
is age-adapted neuropsychological testing because
of the risk of verbal memory deficits after resec-
tion in the dominant hemisphere. The younger the
child’s age, the less like is any neuropsychological
deficit and it is speculated that these patients have
poor verbal memory at baseline. Children appear
to recover more quickly and completely than
adults. Verbal memory deterioration in adults after
left temporal resection prevails even 1 year after
surgery, while the initial deterioration in children
is recovered within 1 year.40 Others even report
on long-term follow-up (>5 years) a significant
increase in intelligence quotient (IQ), psychosocial
outcome, and quality of life in surgically treated
children compared to those with only medical
treatment for temporal lobe epilepsy.39,41
More extensive temporal resections may be
useful in young children with epileptic encephal-
opathy and di use or multifocal epileptiform
discharges on EEG but predominance for the tem-
poral lobe. Recent date provide encouraging
results in this catastrophic cases of epileptic ence-
phalopathy. Seizures show an early onset during
the first 3 months of life and are accompanied by
an enormous developmental delay.42
Extratemporal Resection
More challenging than temporal epilepsy is the
localization of a seizure focus in the frontal, fronto-
parietal of occipital lobe. Surgical outcome in gen-
eral is by far better when a single seizure focus can
be discerned than in cases with a more wide-
spread epileptogenic zone requiring multilobar
resections. A meta-analysis performed by Ansari
and coworkers of 15 case series and two case
reports confirmed that seizure type (complex par-
tial seizures appear to have better outcomes) and
pathological findings (patients with cortical dys-
plasia do better than those with other pathologies)
are factors significantly associated with postopera-
tive seizure outcome. Older children seem to bene-
fit more most likely due to the greater di culty in
localizing the epiletogenic region in very young
children.43
Hemispherectomy
Patients with Rasmussen’s encephalitis or Sturge–
Weber syndrome are the typical candidates for this
type of procedure. The propagation of epilepto-
genic discharges from the pathological hemisphere
to the opposite hemisphere should be impaired.
The continuous seizure activity is provoking uni-
lateral motor seizures and causing hemiparesis.
Functional Disorders
354

Also, patients with hemimegalencephaly and large
areas of infarction or trauma or cerebral dysgene-
sis may benefit from this procedure. Functional
hemispherectomy is very e ective in seizure
control with a success rate of more than 80% and
in behavioral performance as well as cognitive
function.44,45,46,47
Disconnective Surgical Procedures
Corpus Callosotomy
It is an option to alleviate seizure activity in chil-
dren with di erent types of seizure, mainly in
drop attacks or those in whom a single focus could
not be identified or more than one focus seem to
be present. Initially, the anterior two-thirds of the
corpus callosum are sectioned and only when seiz-
ures persist, the remaining connective fibers are
sacrificed in a second procedure. Apraxia and di -
culties in bimanual tasks may be present following
complete callosotomy but well compensated by
improved seizure control.48,49
Multiple Subpial Transections
Rarely applied and thought to be e ective in seiz-
ures originating from functional important areas.
The vertical columnar arrangement of the cortex
remains intact thereby preserving function.
Stereotactic Ablation
Stereotactic ablation has been described as an op-
tion for hypothalamic hamartomas. Stereotactic
brachytherapy with radioactive seeds is a well
estabilshed method in the treatment of low-grade
gliomas even in children thereby possibly control-
ling seizures.
Neuroaugmentative Surgery
Vagus Nerve Stimulation
The vagus nerve stimulation (VNS) device consists
of pliable, spiral-shaped electrodes that wrap
around the vagal nerve and a generator implanted
subcutaneously above the pectoral muscle. Typi-
cally, the left side is used to prevent disturbance of
the cardiac electric current system. The e ciacy of
this treatment modality has been tested in two tri-
als and a reduction in seizure frequencey as well
as intensity after an interval of 3 to 6 months. Seiz-
ure reduction has been described to be around
50%, complete seizure freedom is rare. Hoarseness
and dyspnea during stimulation and voice altera-
tions can occur and are transient.50,51 Fortunately,
VNS has also a positive e ect on depression and
mood which might not be as important in infants
but in older children.
Deep Brain Stimulation
More recently, deep brain stimulation (DBS) to the
anterior thalamic nuclei has been attempted in
order to ameliorate seizure activity in otherwise
refractory patients. The success rate of 54% in seiz-
ure reduction is in the range of VNS.51
Radiosurgery
Gamma Knife radiosurgery is an e ective tool in
the treatment of refractory gelastic seizures due to
hypothalamic hamartoma. A recent report with
robotic-arm stereotactic radiosurgery in a teen-
ager is very promising with complete absence of
seizures after 12 months’ posttreatment with a
dose of 30 Gy in five fractions.52
45.7 Summary
In conclusion, the ultimate goal of epilepsy surgery
would be a seizure-free state without significant
neurological impairment. Once a child failed to
respond to three antiepileptic drugs, surgical eval-
uation and intervention has to be considered.
Proper selection and investigation of children is of
utmost importance. With recent advances in neu-
roimaging, functional analysis, and video EEG
monitoring in precisely localizing the seizure
focus, the overall surgical results can be improved.
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