Atlas-of-Neurosurgical-Techniques-Spine-and-Peripheral-Nerves

840
MinimallyInvasiveSpine Procedures: Lumbar
Figure 114-5
Initial anatomy.

,
114
Retroperitoneal Exposure
841
andthe neural foramen. This minimizes the risk of com-
promisingarterial blood supply to the neural foramen.
Afterligating the segmental vessels, expose the anterior
surfaceof the vertebral body by bluntly dissecting between
theanterior longitudinal ligament and the vertebral body
witha Cobbelevator. The disk spaces are identified and the
appropriatedecompression, reconstruction, and stabiliza-
tionare performed depending on the goalsof the opera-
tion.lfupper lumbar (L1-L2) exposure is needed, curve the
skinincision proximally to the end of the eleventh or
twelfthrib. After entering the retroperitoneum, upper lum-
barexposureis achieved by retracting the lower pole of the
kidneymedially and superiorly. After mobilizing the ureter,
theleft diaphragmatic crus, which extends to the second
vertebralbody,is taken down.
. Decompressive Techniques
Diskectomy
Thedisk space is incised with a knife blade or osteotome
andremovedanterior to the posterior longitudinal ligament
usinglargecurettesandrongeurs(Fig.114-6).Ahigh-speed
drillisthen used to widen the disk space posteriorly until a
thincortical"eggshell"remains,thus creatinga troughan-
teriorto the spinal canal. This allows the surgeon to remove
thediskand the thin rim of remaining cortical bone anteri-
orlyawayfrom the thecal sac.
--"'"
Figure 114-6
Diskectomy.
The posterior longitudinal ligament should be resected
using small Kerrison rongeurs along the entire width of the
spinal canal to ensure adequate decompression.
Vertebrectomy
The segmental vessels of the vertebral body to be resected
as well as those of the vertebral bodies directly above and
below are then identified and controlled as already de-
scribed. The boundaries of the vertebral canal must be
clearly delineated before continuing with vertebrectomy
(Fig. 114-7). This avoids entry into the canal and facilitates
ideal placement of instrumentation if necessary. The end
plates and disk spaces above and below the level of interest
must be clearly identified. The disk spaces above and below
the level of interest are incised with a knife blade or os-
teotome and removed using large curettes and rongeurs.
The vertebrectomy is performed using rongeurs and a high-
speed cutting bur.The drill is used to thin the posterior and
far lateral cortex to an "eggshell" width (Fig. 114-8).
Curettes and Kerrisonrongeurs are then used to remove the
thinned posterior cortex and posterior longitudinal liga-
ment anteriorly off the thecal sac. Toensure complete de-
compression, the pedicle on the deep side of the vertebral
body should be palpated. Bleeding during the vertebrec-
tomy is controlled using bone wax, Gelfoam, and resection
of the cancellous bone back to the relatively avascular corti-
cal bone. Epidural bleeding is controlled with Gelfoam and
bipolar cautery. Keepthe anterior longitudinal ligament and

842
Minimally InvasiveSpineProcedures:'Lumbar
Figure114-7
Complete vertebral body ex-
posure.
Figure 114-8
Removalof the vertebral body usinga
high-speed drill.

,
114
Retroperitoneal Exposure
843
C
Figure114-9
Completed
vertebrectomy.
(A) Vertebrectomy
cavity. (8) Placement of reconstruction
screws and staple. (e) Cross section of verte-
bral body
screws.
thefar lateral cortex intact as much as possible to avoid
damageto the anterior
and deep lateral vascular and
visceralstructures during the reconstruction
procedure
(Fig.114-9).
VertebralReconstruction
Thegoalof spinal reconstruction
is to restore alignment.
lordosis,and the load-bearing and biomechanical proper-
tiesofthe reconstructed spinal segment so that it performs
adequatelyunder physiological loads. Anterior lumbar ver-
tebralreconstruction methods vary depending upon the
pathologybeing treated. Vertebral reconstruction can be
performedusing structural bone graft (auto- or allograft).
titaniumcages. biological plastics, or Steinmann pins and
methylmethacrylate. In general, reconstruction for trau-
maticfracture, degenerative disease. or infection should be
performedwith auto- or allograft bone. either structural or
placedintoa titanium cage(Fig.114-10),to achievebony
fusionof the affected lumbar vertebral levels.13.14Recon-
structionfor pathological fracture secondary to metastatic
cancercan be performed with Steinmann pins and methyl
methacrylate.titanium cages, or biological plastics.IS.16
Anterior Instrumentation
After anterior reconstruction, anterior spinal fixation is per-
formed using a fixed rigid plate or screw-rod system, which
allows for immediate stability, increased fusion rates. and
maintenance
of disk height and interpedicular
distance
while awaiting development
of a physiological
fusion
massY-19The instrumentation is anchored in the vertebral
bodies directly adjacent to the margins of the vertebrec-
tomy cavity (Figs.114-9 and 114-11).
Closure
Wound closure is straightforward. All peritoneal violations
are repaired. The wound is copiously irrigated with antibi-
otic solution and inspected for any bleeding or chylous leak-
age. Amultilayered closure is performed. Each layer of the
abdominal wall musculature
is identified and carefully
reapproximated
taking care to obliterate potential dead
spaces between layers. The superficial soft tissues are
closed in a standard multilayered anatomical fashion. The
skin is closed with a running subcuticular stitch. Dry sterile
dressings are placed. The patient should receive continuous
neurovascular monitoring in the intensive care unit.

844
,
Minimally Invasive Spine Procedures: Lumbar
Figure114-10
Vertebral body reconstruction with tita.
nium cageorstructuralallograft.
Figure 114-11
Screw and rod anterior lumbar instrumentation
system.

,
. Complications
Vascular.bowel. and ureteral injuries are all possible with
theretroperitoneal approach. Furthermore, because one or
moremajoranterior abdominalwall musclesare divided,
woundehiscence,herniation, and hematoma can also
occur.20-22
Thesurgeon should
be prepared
for vascular
anomaly,
andvascular instruments
should always be available when
performingretroperitoneal
approaches.
If injury to one of
thegreat vessels occurs, compression
above and below the
injuryor placing temporary
vascular clamps will reduce he-
morrhagewhile the defect is being repaired.11.23
Perforation of the peritoneum
during retroperitoneal
ap-
proachesis not uncommon,
and peritoneal
tears should be
immediatelyrepaired. All bowel perforations
must be over-
sewn.usually with the help of a general surgeon.24
Ureteral injury
or delayed
ureteral
fibrosis
may occur
frommanipulation or traction. For this reason, if ureteral
mobilizationis necessary,
include a generous
portion of the
periureterictissue to avoid compromising
blood supply.25-27
Ifa cerebrospinal
fluid (CSF) leak occurs, direct closure
shouldbe attempted.
If direct closure is not possible,
Gelfoamshould be placed
over the defect and fibrin glue
References
1. LesoinF.Bouasakao N. Lozes G. et al. Anterointernal
approach to the
lumbarspine: technical note. Neurosurgery 1985;17:80-83
2. McCormack B. Maher D. Fessler R.Anterior approaches to the lumbar
spine.In: Sonntag V. ed. Principles of Spinal Surgery. New York: Mc-
Graw-Hill:1996:1293-1306
3. WestfallSH,Akbarnia BA,Merenda JT.et al. Exposure of the anterior
spine: technique.
complications.
and results
in 85 patients.
Am J Surg
1987:154:700-704
4. Bianchi C. Ballard JL. Abou-Zamzam AM. et al. Anterior retroperi-
toneallumbosacral
spine exposure:
operative
technique
and results.
AnnVasc Surg 2003:17:137-142
5. BaroneGW,Pait TG. Eidt JF, et al. "General surgical pearls" for the
anteriorexposure of vertebral fractures. Am Surg 2001 ;67:939-942
6. BirchBD.Desai RD.McCormick Pc. Surgical approaches to the thora-
columbarspine. Neurosurg Clin N Am 1997;8:471-485
7. CauchoixJ. Binetj.
Anterior
surgical
approaches
to the spine. Ann R
CoilSurg Eng11957;21 :234-243
8. HovorkaI, de Peretti F.Damon F.et al. Fiveyears' experience of the
retroperitoneal
lumbar
and
thoracolumbar
surgery.
Eur Spine
J
2000:9(SuppI1
):530-534
9. WatkinsRG.Surgical Approaches to the Spine. New York: Springer-
Verlag;1983
10. HarmonPH.Anterior extraperitoneallumbar
disk excision and verte-
bralbody fusion. ClinOrthop 1960;169-184
11. BakerJK, Reardon
PR, Reardon
MJ, et al. Vascular
injury
in anterior
lumbar surgery. Spine 1993;18:2227-2230
12. RoccoAG. Palombi D.Raeke D.Anatomy of the lumbar sympathetic
chain. Reg Anesth
1995;20:13-19
13. Wetzel FT.Hoffman MA. Arcieri RR.Freeze-dried fibular allograft in
anterior spinal surgery:
cervical
and lumbar
applications.
Yale J Bioi
Med 1993:66:263-275
14.WolflaCEoMaiman DJ,Coufal FJ.et al. Retroperitoneal lateral lumbar
interbody fusion with titanium threaded fusion cages. J Neurosurg
2002;96:50-55
15. Cooper PR, Errico TJ. Martin
R, et al. A systematic
approach
to spinal
reconstruction
after anterior
decompression
for neoplastic
disease of
the thoracic and lumbar
spine. Neurosurgery
1993;32:1-8
16. LozesG,FawazA. Devos P, et al. Operative
treatment
of thoraco-Ium-
barmetastases. using methylmetacrylate and Kempfs rods for verte-
bral replacement and stabilization. Report of 15cases. Acta Neurochir
(Wien)1987;84:118-123
114
Retroperitoneal Exposure
845
should be instilled over the Gelfoam. Consideration should
be given to spinal drainage in the case of a significant CSF
leak or with an irreparable durotomy.28.29
Injury to the thoracic duct can also occur with retroperi-
toneal approches. Prior to closure the resection cavity should
be inspected for chylous leakage. If found, primary closure
should be attempted.3o.3!If not possible, it can be treated
with drainage and intralesional sclerosis.Occasionally.explo-
ration and ligationofthe thoracic duct are required.
. Conclusions
Appropriate surgical therapy for lesions of the lumbar spine
is determined by the vertebral segment involved and by the
site and type of pathology. These factors govern the choice
of surgical approach and the method of postdecompression
reconstruction and stabilization used. The retroperitoneal
approach provides excellent anterior exposure of the mid-
to lower lumbar spine (L2-L5). This allows for successful
neural decompression and spinal reconstruction in patients
with pathological processes involving the anterior lumbar
spine while minimizing potential morbidity.
17.
Bozkus H. Chamberlain RH.PerezGarza LE,et al. Biomechanical com-
parison of anterolateral
plate, lateral plate. and pedicle screws-rods
for enhancing
anterolateral
lumbar
interbody
cage stabilization.
Spine 2004:29:635-641
18.
Brodke DS,Gollogly 5, Bachus KN, et al. Anterior
thoracolumbar
in-
strumentation:
stiffness and load sharing characteristics of plate and
rod systems. Spine 2003;28:1794-1801
19. FaroFD.White KK,Ahn JS,et al. Biomechanical analysis of anterior in-
strumentation
for lumbar corpectomy. Spine 2003:28:E468-E471
20.
Honig MP,Mason RA,Giron F.Wound complications of the retroperi-
toneal approach to the aorta and iliacvessels.JVascSurg 1992;15:28-34
21.
McDonnell
MF. Glassman SD. Dimar JR II. et al. Perioperative
compli-
cations of anterior procedures on the spine. J Bone Joint Surg Am
1996:78:839-847
22. Smith MD.Bressler EL,LonsteinJE,et al. Deep venous thrombosis and
pulmonary
embolism
after major reconstructive
operations
on the
spine:
a prospective
analysis
of three
hundred
and
seventeen
pa-
tients. J BoneJoint Surg Am 1994:76:980-985
23. Woolsey RM.Aortic laceration after anterior spinal fusion. Surg Neu-
roI1986:25:267-268
24.
Rajaraman
V. Vingan R, Roth P, et al. Visceral and vascular
complica-
tions resulting from anterior lumbar interbody fusion. J Neurosurg
Spine 1999:91 :60-64
25.
FarajM. WebbJK,LembergerRj.Urinary bladder dysfunction follow-
ing anterior lumbosacral spine fusion: case report and review of the
literature.
Eur Spine J 1996:5:121-124
26.
Isiklar ZU. Lindsey RW. Coburn M. Ureteral
injury
after anterior
lum-
bar interbody
fusion: a case report. Spine 1996:21 :2379-2382
27.
Johnson
RM, McGuire
EJ. Urogenital
complications
of anterior
ap-
proaches
to the lumbar spine. Clin Orthop
1981 :114-118
28.
NairusJG,
RichmanJD.
Douglas RA. Retroperitoneal
pseudomeningo-
cele complicated
by meningitis
following
a lumbar
burst
fracture:
a case report. Spine 1996:21 :1090-1093
29.
Gurgo RD.Turkiewicz
DB. Guazzo EP. et al. A cerebrospinal
fluid col-
lection presenting
as an abdominal
mass following
lumbar
vertebrec-
tomy for trauma. Aust N ZJ Surg 2000;70:
140-141
30.
Levi AD. Treatment
of a retroperitoneal
lymphocele
after
lumbar
fusion
surgery
with
intralesional
povidone
iodine:
technical
case
report. Neurosurgery
1999;45:658-661
31.
Nagai H, Shimizu
K, Shikata J. et al. Chylous leakage
after circumfer-
ential thoracolumbar
fusion for correction
of kyphosis
resulting
from
fracture: report of three cases. Spine 1997;22:2766-2769

,
115
Microendoscopic Diskectomy
Robert E.Isaacs, Richard G. Fessler, and Lacey Bresnahan
.
Indications
.
Contraindications
. Advantages
. Disadvantages
.
Surgical Technique
Anesthesia
Positioning and Setup
Incision and Localization
Serial Dilation
Anatomical Localization
Laminectomy
Closure
Classicsurgical approaches were developed with the goal of
safely visualizing the required tissues while facilitating the
surgeon's ability to perform the case. Over the past decade,
led by the adoption of the endoscope into surgery, a major
shift in emphasis has taken place from the primary concern
for the surgeon to that of the patient. Issues such as patient
satisfaction with the surgical procedure have come to the
forefront. Economic factors such as decreasing length of
hospital stay have compounded this change. From this has
arisen the proliferation of endoscopic techniques in abdom-
inal, thoracic, and arthroscopic procedures. Spine surgery
has been slower to follow this movement, largely due to the
fact that no large spaces or potential spaces exist in which
to work. Improvements in camera technology and the adop-
tion of muscle-splitting techniques, coupled with this trend
in health care,have led to the acceptance of minimally inva-
sive approaches to spinal surgery.
The lumbar microendoscopic diskectomy (MED),as weIl
as its derivatives, which wiII be covered in subsequent
chapters, stands as a means to address pathology of the
dorsal spine while minimizing coIlateral injury to overlying
structures. It helps to preserve the adjacent bone and liga-
ments, thereby aIlowing for improved postoperative mus-
cle reattachment and function. It is particularly attractive
for its smaIl skin incision, gentle tissue dissection, and ex-
ceIlent visualization.
FinaIly, this endoscopic technique
gives the surgeon the ability to achieve equivalent results
to open techniques while minimizing postoperative pain,
846
perioperative
narcotic analgesic use, length of hospital
stay, and blood loss. In this manner,
lumbar MEDtrulyful.
fiIls the requirements
of an effective minimally invasive
technique.
.
Indications
.
MedicaIly refractory
lumbar radiculopathy
secondaryto
disk herniation
or foraminal stenosis
.
Contraindications
.
Segmental instability
.
Advantages
. Lessperioperative morbidity (pain, blood loss)
.
Preservation of uninvolved structures
.
ExceIlentvisualization of the offending pathology
.
Possiblydecreased risk of infection as well as other
potential delayed postoperative morbidity
.
Small skin incision

,
. Disadvantages
. Requireslearning endoscopic techniques
. Typicallynot as quick an operative
procedure
as an open
laminectomy
. Limitedvisual field
. SurgicalTechnique
Anesthesia
Thepatient is typically placed under general anesthesia. It
ispossibleto perform the procedure under intravenous
sedationwith local, epidural, or spinal anesthesia as well.
Thechoiceisdetermined primarily by surgeon comfort.
Positioningand Setup
Thepatient is turned into the prone position. Care is made to
insureadequate padding of all pressure
points and extremi-
ties.Oncethe patient is prepped, the surgeon generally stands
onthe same side as the patient's
pathology. All other equip-
ment-the arm that holds the working channel, the base and
monitorfor the fluoroscopy, and the surgeon's
video moni-
tor-istypicallyon the opposite side. Thisallows the surgeon
tofaceforwardthroughout the procedure (Fig.115-1).
Incisionand Localization
Thelumbar level to be approached
is confirmed using lateral
fluoroscopy.For this, a 20 gauge spinal needle
is inserted
115
Microendoscopic Diskectomy
847
into the paraspinal musculature one fingerbreadth (1.5em)
lateral to the midline. The needle is repositioned until it is
directly over the disk space. Marcaine (0.25-0.5%)is injected
into the muscle as the needle iswithdrawn. This is repeated
along the intended skin incision (Fig.115-2).
The spinal needle is removed and a vertical puncture is
made with a no. 11 blade knife. ASteinmann pin is placed
perpendicularly through the puncture site and directed to-
ward the inferior aspect of the superior lamina under lateral
fluoroscopy. Once confirmed (Fig. 115-3A), the incision is
lengthened symmetrically and should match the diameter
ofthe respective tubular retractor. For example, the 16 mm
tubular retractor will require a 16 mm incision.
Serial Dilation
Utilizing a twisting motion, sequential soft tissue dilators
are inserted.
Once the initial dilator is safely docked
onto the laminofacet junction of the superior lamina, the
Steinmann pin is removed (Fig. 115-38). A slight medial
angulation is desirable at this point to ensure optimal visu-
alization of the interlaminar space and lateral recess during
the procedure. Confirmatory radiographs are taken. Some
surgeons favor using the initial dilator to palpate the lam-
ina in both the coronal and the sagittal planes. This maneu-
ver helps to feel the anatomy and also sweeps
the
paraspinal musculature off the laminar edge facilitating
soft tissue removal. Caremust be taken if this is attempted
because this technique runs the risk of injuring adjacent
neural structures.
Subsequent dilators are sequentially placed over the
initial dilator down to the lamina. X-rays are taken after
each passage to confirm that the dilators remain in position
(Fig.115-3(,D). Finally,once the desired working dimension
Figure 115-1
An example of the operating
room
setup for
a lumbar
microendoscopic
diskectomy. The surgeon stands ipsilateral to the
patient's pathology with the endoscopic monitor
acrossthe table.

848
MinimallyInvasiveSpine Procedures: Lumbar
A
-
B
C
.ar...fIJffl1!1.--uan
,--" ='-
IUMCII
~""-:t'
~~.~
~~~"'-'_.,'.
, D
Figure 115-2A-D
The METRxendoscopic system (Medtronic-Sofamor
Danek; Memphis, TN) includes (A) a set of metal sequential soft tissuedila.
tors, (8) an 18 mm working channel, (C) a 3D-degree endoscope, and (D) a flexible bed rail-mounted retractor arm.
is obtained, the working channel/tubular retractor is placed
over the dilators and confirmed with fluoroscopy. The flexi-
ble arm (Fig. 115-2D), which is secured to the table, is at-
tached to the tubular retractor to hold it firmly in place. The
dilators are removed, establishing an operative corridor to
the lamina and interlaminar space. Positioning is finalized
with fluoroscopy.
The endoscope is then inserted into the tubular retractor
(Fig. 115-4). The locking arm on the ring attachment
secures the endoscope to the tubular retractor. Initial
placement of the endoscope should be in its most retracted
position to avoid contact of the endoscope with soft tissue
and subsequent smudging. When this occurs, remove the
endoscope from the tubular retractor and clean the lens us-
ing antifog solution and gauze. The endoscope should be
focused and orientated to the standard position (on the
video screen, up is medial). AV-shaped indicator has been
placed on the video image to represent the position of the
endoscope within the tubular retractor. The V-shaped indi-
cator on the video screen should mirror the endoscope's
position with respect to the tubular retractor. Whenever
the endoscope is turned, the orientation should be cor-
rected.
Anatomical Localization
A Bovieelectrocautery can be used to dissect anysoft
tissue present in the operativefield.It is best to beginthis
dissection laterally where the bone is clearly felt. Remain.
ing tissue is removed with a pituitary rongeur. It isessen.
tial to remove all residual soft tissue in the operativecorri.
dor to maximize the working space within the tubular
retractor. Soft tissue removal helps to identify the edgeof
the lamina and interlaminar space, and the position ofthe
retractor with reference to the facet (Fig. 115-5). Itisthis
anatomy that aids in correctly performing the laminotomy.
The working channel should be repositioned, if necessary,
so that the medial facet,lateral lamina,and smallamount
of interlaminar
space are present within the surgeon's
view.
Laminectomy
The ligamentum flavum is then detached from the under.
surface
of the
lamina
with
a small
curved curette
(Fig. 115-6). Endoscopic Kerrison rongeurs are used toreo
move the lamina and medial aspect of the facet (Fig.tt5-7~

..
115
Microendoscopic Diskectomy
849
(
Figure115-3
A series of lateral fluoroscopic images demonstrating (A) placement of the initial Steinmann pin down to the operative level and
(H,C)the sequential passage of the tubular soft tissue dilators, which gently spread the posterior
musculature.
(D) The serial dilators in position.
D
Attimes,the facet mayrequiredrillingto thin the bone for
saferemovalwith a rongeur.Apartfromthe limitationsof
workingthrough a tubular retractor, the bony removal is
fairlysimilarto a microscopicdiskectomy.In this fashion,
thehemilaminotomy, facetectomy, and foraminotomy over
thenerve root are completed. The ligamentum fIavum is
openedwith an up-angled curette worked into the epidural
spaceutilizinga twistingmotion.Theligamentis liftedand
resectedwith a Kerrison punch. In doing so, the lateral
thecalsacand rootare exposed.Utilizinga Penfielddissec-
tor,the lateral aspect of the thecal sac can be identified. The
freednerve root and thecal sac are then retracted medially
usinga suction retractor (Fig. 115-8). Epidural veins may
becauterized with bipolar cautery and divided with mi-
croscissors.A no. 10 blade is used to open the disk space.
Small pituitary rongeurs aid in evacuating the disk material
(Fig.115-9).
Closure
Periosteal and bone bleeding are addressed with bone wax
and cautery. Soft tissue hemostasis is obtained by bipolar
cautery
and gentle tamponade
with
thrombin-soaked
Gelfoam.The area is then copiously irrigated with lactated
Ringer's impregnated with bacitracin antibiotics prior to
closure. The fascia is closed with interrupted absorbable su-
tures.
Inverted
subcutaneous
interrupted
sutures
are
placed, and a running subcuticular is used to close the skin.
Steri-Strips (3M Health Care, St. Paul, MN) and a dressing
are applied to the wound.
.-- B
- -
A
"
:J
,..."
-,
-;

850
Minimally Invasive Spine Procedures: Lumbar
Figure 115-4
The working channel once the serial dilators have
been removedand the endoscopeis placed.
Figure 115-5
The correct visualization
inside the tubular
retractor.
Confirming
this anatomy facilitates
the case substantially.
B
Figure 115-6
(A) A drawing and (8) an x-ray view of the curette beginning
the initial dissection
of the ligament.

11IIIII'
,
115
MicroendoscopicDiskectomy
851
Figure115-7
The Kerrison rongeur removing the superior lamina.
A
Figure 115-8
The root is retracted medially to expose the disk.
B
c
Figure115-9
(A) A drawing,
(8) the intraoperative
monitor,
and (C) x-ray views of the pituitary
rongeur removing
the offending
disk material.

,
116
Microendoscopic Decompression
for LumbarStenosis
Robert E.Isaacs, Richard G. Fessler, and Lacey Bresnahan
.
Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
SurgicalTechnique
PositioningandSetup
Lumbar spinal stenosis with concomitant neurogenic clau-
dication is an unfortunate condition that affects many in
the elderly population. Given the current demographic
shift, treatment of this disorder will continue to take up an
increasing amount of time of many spine surgeons. Novel
treatment options for this disorder have been limited. The
adaptations to the classic decompressive lumbar laminec-
tomy that have been accepted have sought ways to preserve
the uninvolved superficial structures. This can be accom-
plished by angling the dissection of the lateral recess un-
derneath the facetjoint (preserving an increased amount of
the facet complex) or by performing bilateral laminotomies
(preserving the midline structures).
Originally described in 1988, the microscopic lamino-
tomy allowed for a unilateral takedown. thus preserving
both the midline as well as the contralateral muscular and
ligamentous attachments. Working from within the lamina
gives the surgeon the ability to decompress the opposite
side, removing the neural compression while limiting the
disruption of the normal. adjacent anatomical structures.
Expanding upon this idea, our endoscopic approach af-
fords an increased visualization of the contralateral lateral
recess while preserving the ipsilateral muscular attach-
ments to the remaining bone. An equivalent decompres-
sion can be performed while limiting the amount of blood
loss and postoperative pain as well as the need for hospi-
talization.
.
Indications
. Medically refractory lumbar spinal stenosis secondary to
ligamentum flavumredundancy and/or bony hypertrophy
852
Incision and Localization
Serial Dilation
Anatomical Localization
Laminectomy
Diskectomy
Contralateral
Decompression
Closure
.
Contraindications
.
Segmental instability
.
Advantages
.
Lessperioperative morbidity (pain. blood loss)
.
Preservation of uninvolved structures
.
Excellent visualization of the offending pathology
.
Possiblydecreased risk of infection as well as other
potential delayed postoperative morbidity
. Asmall skin incision
.
Disadvantages
. Requires learning endoscopic techniques
. Typicallynot as quickan operativeprocedureas anopen
laminectomy
.
Limitedvisual field
.
Surgical Technique
Positioningand
Setup
Thepatient isturned intothe prone position.Careismade
to insure adequate
padding of all pressure points and
extremities.
Once the patient
is prepped,
the surgeon

T
I
\
116
Microendoscopic Decompression for Lumbar Stenosis
853
generallystands on the same side as the patient's worst
pathology-the patient's most symptomatic side. In cases
wherethere is essentially equivalent disease bilaterally,
mostright-handed surgeons prefer standing on the left
side,facilitating the removal of the lamina. Allother equip-
ment-the arm that holds the working channel, the base
andmonitor for the fluoroscopy, and the surgeon's video
monitor-is typically on the opposite side of the patient.
Thisallowsthe surgeon to face forward throughout the case
(Fig.116-1).
Incisionand Localization
Thelumbar level to be approached is confirmed using lat-
eralfluoroscopy.For this, it is useful to use a 20 gauge
spinalneedle inserted into the paraspinal musculature one
fingerbreadth(1.5 cm) lateral to the midline. The needle is
repositioned until
it is directly over the disk space.
Marcaine(0.25-0.5%)is injected into the muscle as the nee-
dleiswithdrawn. This is repeated along the intended skin
incision.
Thespinal needle is removed and a vertical puncture is
madewith a no. 11blade knife.ASteinmannpin is placed
perpendicularlythrough the puncture site and directed to-
wardthe 'inferior aspect of the superior lamina under lateral
fluoroscopy.Once confirmed (Fig. 116-2A), the incision is
lengthenedsymmetrically and should match the diameter
ofthe respective tubular retractor. Forexample, the 16 mm
tubularretractor will require a 16 mm incision.
In the case of multilevel pathology, the initial Stein-
mann pin placement
is equidistant
between
the disk
spaces.Serial dilation takes place while docked slightly
inferiorto the pedicle of the caudal vertebral body. Once
fullydilated, the endoscope is wanded (angled) toward
theinferior disk space, beginning the procedure docked in
Figure 116-1
An example of the operating
room
setup for a lumbar microendoscopic
decompres-
sion forstenosis. The surgeon stands ipsilateral to
the
patient's
worst
pathology
with
the
endo-
scopic monitor
across the table.
the same relative position as with single-level
disease
(Fig.116-3).
Serial Dilation
Utilizing a twisting motion, sequential soft tissue dilators
are inserted. Once the initial dilator is safely docked onto
the laminofacet junction of the superior lamina, the Stein-
mann pin is removed (Fig.116-2B).Aslight medial angula-
tion is desirable at this point to ensure optimal visualization
of the interlaminar space and lateral recess during the pro-
cedure. Confirmatory radiographs are taken. Some surgeons
favor using the initial dilator to palpate the lamina in both
the coronal and the sagittal planes. This maneuver helps to
feel the anatomy and also sweeps the paraspinal muscula-
ture off the laminar edge facilitating soft tissue removal.
Care must be taken if this is attempted because this tech-
nique runs the risk of injuring adjacent neural structures.
Subsequent dilators are sequentially placed over the ini-
tial dilator down to the lamina. X-rays are taken after each
passage to confirm that the dilators remain in position
(Figs. 116-2C and 116-2D). Finally,once the desired work-
ing dimension is obtained, the working channel/tubular
retractor is placed over the dilators and confirmed with flu-
oroscopy. The flexible arm, which is secured to the table, is
attached to the tubular retractor to hold it firmly in place.
The dilators are removed, establishing an operative corridor
to the lamina and interlaminar space. Positioning is final-
ized with fluoroscopy.
The endoscope is then inserted into the tubular retractor
(Fig. 116-3A,B). The locking arm on the ring attachment
secures the endoscope
to the tubular
retractor. Initial
placement of the endoscope should be in its most retracted
position to avoid contact of the endoscope with soft tissue
'and subsequent smudging. When this occurs, remove the

854
Minimally InvasiveSpineProcedures:Lumbar
A
,h'.~..
.1:1..B
c
.~..
1Iii...~-~
::i
D
Figure116-2
An example of serial dilation.
(A) Steinmann
pin placed percutaneously
down to the level of the dorsallamina/facet.
(B-D) Sequen-
tial dilations are used to dilate a track through
the paraspinal muscles.
A
Figure 116-3
The working
channel in position.
(A) View
seen on the fluoroscopic
monitor.
(B) Position of the work-
ing channel with respect to the anatomy.
B

..
116
MicroendoscopicDecompressionfor LumbarStenosis
855
A
Figure116-4
(A) Drawing and (8) x-ray views of the curette
beginning
the initial dissection
of the ligament.
endoscope
from the tubular retractor and clean the lens
usingantifog solution and gauze. The endoscope should
befocusedand orientated to the standard position (on the
videoscreen, up is medial). AV-shaped indicator has been
placedon the video image to represent the position of
the endoscope
within
the
tubular
retractor.
The
V-shapedindicator on the video screen should mirror the
endoscope'sposition with respect to the tubular retractor.
Wheneverthe endoscope is turned. the orientation should
becorrected.
Anatomical Localization
ABovieelectrocautery can be used to dissect any soft tissue
presentin the operative
field. It is best to begin this dissec-
tionlaterally where the bone is clearly felt. Remaining
tissueis removed with a pituitary rongeur. It is essential to
remove all residual soft tissue in the operative corridor to
B
maximize the working space within the tubular retractor.
Soft tissue removal helps to identify the edge of the lamina
and interlaminar space, and the position of the retractor
with reference to the facet. It is this anatomy that aids in
correctly performing the laminotomy. The working channel
should be repositioned, if necessary. so that the medial
facet. lateral lamina, and small amount of interlaminar
space are present within the surgeon's view.
Laminectomy
Theligamentumflavumisthendetachedfromthe undersur-
face of the lamina with a small curved curette (Fig. 116-4).
Endoscopic Kerrison rongeurs are used to remove the lam-
ina and medial aspect of the facet (Fig. 116-5). To ensure
adaquate visualization of the contralateral side. which will
be required to perform the contralateral
decompression
later in the case. care is taken to remove the lamina
A
Figure 116-5
(A) Drawing and (8) x-ray views of the Kerrison rongeur removing
the superior lamina.
B

856
MinimallyInvasiveSpine Procedures: Lumbar
medially up to the level of the spinous process. Apart from
the limitations of working through a tubular retractor, the
bony removal is fairlysimilar to an exaggerated microscopic
diskectomy. At times, the facet and lamina may require
drilling to thin the bone for safe removal with a rongeur.
Through the use of a high-speed
drill and Kerrison
roungeur, the hemilaminotomy, facetectomy, and foramino-
tomy over the ipsilateral nerve root are completed. If the
free edge of the ligamentum flavum is visualized, a nerve
hook can be used to elevate it from the underlying thecal
sac. When not visible, the ligament can be opened with an
up-angled curette worked into the epidural space utilizing a
twisting motion. Once freed, the ligament is lifted then
resected with a Kerrison punch. In doing so, the thecal
sac and root are exposed.
Diskectomy
In the case of concomitant disk rupture, at this point in the
case a diskectomy can be performed using the same tech-
niques utilized for a standard microendoscopic diskectomy.
Specifically,through the use of a Penfield dissector, the lat-
eral aspect of the thecal sac can be identified. The freed
nerve root and thecal sac are then retracted medially using
a suction retractor (Fig. 116-6). Epidural veins may be
cauterized with bipolar cautery and divided with microscis-
sors. A no. 10 blade is used to open the disk space. Small
pituitary
rongeurs aid in evacuating the disk material
(Fig.116-7).
A
--
--
Figure 116-6
Representation of the viewseen onthe monilo'"
one retracts the root medially to expose the disk.
Contralateral
Decompression
Once the ipsilateral pathology has been removed,attentior
is shifted toward the contralateral
side. Two techniquesare
critical for the endoscopic surgeon to master to gainthe
ability to perform increasingly complex surgeriesthroug;
minimally
invasive
approaches.
The first, wandingOT
angling the ventral end of the scope, affordstheabilitytt
B
Figure 116-7
(A) Drawing and (B) x-ray views of the
pituitary
rongeur
removing
the offending
disk material.

..
116 MicroendoscopicDecompressionfor lumbar Stenosis
857
increasethe dimension of the decompression without in-
creasing
the superficial dissection and tissue manipulation.
Second,because the 30 degree angle endoscope employed
forthisprocedure has been designed to visualize the ipsi-
laterallateralrecessand foramen, simply rotating the scope
tothesideclosest to the surgeon affords the same improved
visualizationof the contralateral side. Once the scope has
beenrepositionedand the working channel angled toward
theoppositeside, significantly
more bone and ligament
ex-
istwithinthe operative field to be removed (Fig.116-8).
Figure 116-8
Angling
the working
channel
expands
the area of
pathologythat may be addressed without
increasing the muscular dis-
section.Bywanding
the working
channel medially, the area under the
spinousprocess and contralateral
lamina may be seen. This visualiza-
tionmay be further
improved
by rotating
the endoscope to the lateral
aspectof the working
channel.
Figure
116-9
A high-speed
drill is used to remove
the bone under
the spinous process and lamina. While working
across the thecal sac, it
may be protected
from overlying
instruments
by using a suction
as a
retractor,
displacing the thecal sac ventral and medial.
Initially, it is helpful to begin to drill off the most ventral
aspect ofthe spinous processand contralateral lamina. In this
fashion, the "bone work" for the opposite side may be com-
pleted without disturbing any of the overlying structures. A
suction is useful to retract the thecal sac away from the drill
and thereby protect the underlying nervous structures from
the drill (Fig. 116-9). After completing the bone removal, a
Kerrisonrongeur can once againbe used to remove the liga-
ment underlying the partiallyresected lamina.Asthe decom-
pression proceedstoward the contralateralforamen,an up-an-
gled curette can be used to removethe ligament compressing
the root as it exits the spine.Thedecompression iscompleted
once the surgeon canpalpateboth the ipsilateralas well as the
contralateralpedicle.lateralrecess,and foramen.
In cases of multiple adjacent-level stenosis. the initial
placement of the dilators and tubular retractor should be
midway between the stenotic levels. In a patient with both
L3-L4and L4-L5stenosis, for example, the working channel
should be first docked on the L4 lamina and then swung
caudal to decompress the L4-L5level and then cephalad to
subsequently decompress the L3-L4level. For patients with
a larger vertical distance between spinal segments, sharp
incision of the lumbodorsal
fascia and superoinferior
translation of the working channel may also be needed
(Figs.116-10 and 116-11).
Closure
Periosteal and bone bleeding are addressed with bone wax
and cautery. Soft tissue hemostasis is obtained by bipolar
cautery
and gentle tamponade
with
thrombin-soaked
Gelfoam. The area is then copiously irrigated with lactated
Ringer's impregnated with bacitracin antibiotics prior to
closure. The fascia is closed with interrupted absorbable su-
tures.
Inverted subcutaneous
interrupted
sutures
are
placed, and a running subcuticular is used to close the skin.
Steri-Strips (3M Health Care, St. Paul, MN) and a dressing
are applied to the wound.

858
MinimallyInvasiveSpineProcedures:lumbar
Figure 116-10
The extent of multilevel decompression that canbe
obtained through repositioning of the working channel through asingle
incision.
A
B
Figure116-11
A typical
decompression
achieved via microendoscopic
decompression
forstenosis for a representative
case of lumbar stenosis.
Suggested
Readings
1. Guiot BH.KhooLT.FesslerRG.A minimally invasive technique
for
decompression of the lumbar spine. Spine 2002:27:432-438
2. SpetzgerU, Bertalanffy H. ReingesMH. GilsbachJM. Unilateral
laminotomy for bilateral decompression of lumbar spinal stenosis. II:
Clinical experiences. Acta Neurochir (Wien) 1997;139:397-403
3.
Spetzger U, Bertalanffy H. Naujokat C.von Keyserlingk DG. Gilsbach
JM. Unilateral
laminotomy
for bilateral
decompression
of lumbar
spinal stenosis. I: Anatomical and surgical considerations. Acta Neu-
rochir (Wien) 1997:139:392-396
4.
Thomas NW. ReaGL. Pikul BK. Mervis LJ.Irsik R. McGregor JM.Quan-
titative
outcome
and radiographic
comparisons
between laminec.
tomy and laminotomy
in the treatment
of acquired lumbar stenosis.
Neurosurgery 1997:41:567-575
S.
Tsai RY.Yang RS.Bray RSJr. Microscopic laminotomies
for degenera-
tive lumbar spinal stenosis.J Spinal Disord 1998;11 :389-394
6.
Young S. Veerapen. O'Laire SA. Relief of lumbar canal stenosis using
multilevel subarticular fenestrations asan alternative to wide laminec.
tomy: preliminary
report. Neurosurgery 1988:23:628-633

117
Microendoscopically Assisted Transforaminal
! LumbarInterbody Fusion
i RobertE.Isaacs, Paul Santiago, Richard G. Fessler, and Lacey Bresnahan
. Advantages
. Disadvantages
. SurgicalTechnique
Preoperative Planning
and Setup
Positioning
Incisionand Localization
SerialDilation
lumbarinterbody fusions have gained popularity as a
meansto address instability
in the lumbar spine since their
introductionto medicine
by Cloward.! The result of a com-
binedanterior and posterior
spinal fusion or 360 degree fu-
sionisadvocated by some surgeons as a means to increase
thefusion rate, increase
the surface area for fusion, allow
fusionunder compression, open the foramen by way of dis-
traction,and limit paraspinal
muscle dissection. As a way to
replicatethe success rate of anterior lumbar interbody fu-
sion(AUF)while minimizing the potential risks associated
withthevascular and visceral structures that lie anterior to
thespine, many surgeons
favor a 360 degree
fusion from a
singleposterior approach. Posterior lumbar interbody fu-
sion(PUF)has been advocated as a way to lessen the risks
tothe retroperitoneal
and peritoneal
structures,
avoid the
needfor an approach surgeon, and perform posterior in-
strumentation to augment
fusion without
adding a second
surgicalprocedure. Unfortunately,
the standard
approach
to
PLiF requires partial removal of both facet joints and a
ratheraggressivemobilization of the thecal sac (and there-
forethecauda equina) medially. Traction injury to the tra-
versingnerve root is a well-known
complication.2
Based on
themanner in which the interbody
fusion is performed
for
atransforaminallumbar
interbody
fusion (TLIF),which uti-
lizesa unilateral approach
after a more aggressive
facet re-
movalon one side, it is not surprising
that investigators
havebeenable to show a decrease in surgical morbidity re-
latedtothis procedure.3Giventhe laterality of the approach
intothedisk space, less retraction is required on the thecal
sac.Herein we describe
our minimally
invasive method
of
performing a TLIF, which
utilizes
a unilateral,
muscle-
splittingapproach, and percutaneous
pedicle screw instru-
mentation.
Anatomical Localization
Laminectomy
Diskectomy
Interbody Fusion
Pedicle Screw Instrumentation
Closure
.
Advantages
. Avoids potential vascular and visceral complications of
anterior approaches
.
Less retraction of thecal sac yielding fewer nerve root
complications
.
Small skin incision
.
Disadvantages
. Learning curve
.
Limited visual field
. SurgicalTechnique
Preoperative Planning and Setup
After appropriate
preoperative
evaluation
and medical
clearance, the patient is brought to the operative suite. We
routinely utilize intraoperative somatosensory evoked po-
tential (SSEP)monitoringof the operated dermatomes(to
monitor the nerve roots at both the level above and the
level below the disk space involved) as well as electromyo-
graphic recordings (EMGs).With electrophysiological moni-
toring, motor integrity of the involved roots can be assessed
and stimulated after pedicle screw placement to ensure
that the pedicle has not been breached. After the initial in-
duction of anesthesia, we also refrain from the use of neu-
romuscular paralytics to allow for improved feedback from
the nerve root during the operation.
859

860
Minimally InvasiveSpineProcedures:Lumbar
Positioning
The patient is turned into the prone position. Care is made
to insure adequate padding of all pressure points and ex-
tremities. Once the patient is prepped, the surgeon stands
on the same side as the patient's worst pathology. For dis-
ease that is equivalent on both sides, right-handed
sur-
geons may favor the left side of the patient. All other
equipment including the table mount with flexible arm at-
tached to the working channel, the fluoroscopic unit's base,
and the video monitor are placed on the contralateral side.
This allows the surgeon to face forward
throughout
the
procedure (Fig.117-1).
Incision and Localization
Thelumbar level to beapproachedis confirmed using lat-
eralfluoroscopy.Forthis, it is usefulto use a 20gaugenee-
dleinsertedintothe paraspinalmusculature-3 to 4 cmlat-
eral to the midline. The needle is repositioned until it is
directly over the disk space.Marcaine(0.25-0.5%)is in-
jected into the muscle as the needle is withdrawn, and
again at each facet complex and along the lamina at the
levelabove.Finally,local is injected along the intended skin
incision.
The needle is removed and a vertical puncture is made
with a no. 11 blade knife. A Steinmann pin is placed
perpendicularly through the puncture site and directed to-
wardthe inferioraspectofthesuperiorlaminaunderlateral
fluoroscopy.Onceconfirmed(Fig.117-2A),the incisionis
lengthened symmetrically and should match the diameter
of the respective tubular retractor. To place an interbody de-
vice using the Tangent system (Medtronic-Sofamor Danek,
Memphis, TN), at least a 20 mm working channel is needed
(Fig. 117-3A-D).
Therefore, the incision must be this length
or longer to accommodate
the retractor.
Figure 117-1
Exampleofthe operatingro-
setup. The surgeon stands ipsilateralto thepi
tient's worst pathology and faces the endoscOt
monitor across the table.
Serial Dilation
Utilizing
a twisting
motion, sequential soft tissuedilatof\
are inserted. Once the initial dilator is safelydockedontc
the laminofacet
junction
of the superior
lamina, the Steir.
mann pin is removed. A slight medial angulation isdeslr
able at this point
to ensure optimal
visualization
of them
terlaminar
space and lateral
recess during
the opening.
Confirmatory
radiographs
are obtained. Somesurgeons
favor using the initial
dilator
to palpate the lamina inbot~
the coronal
and the sagittal
planes. This maneuver help'
to feel the anatomy
and also sweeps the paraspinal mus.
culature
off the
laminar
edge facilitating
soft tissuereo
moval. Care must be taken if this is attempted because
this technique runs the risk of injuring
adjacentneur.l
structures.
Subsequent
dilators (Fig. 117-3A) are sequentially placec
over the initial dilator down to the lamina (Fig.117-28
Fluoroscopic
images are taken after each passageto confinr
that the dilators remain in position. Finally,oncethe
desired
working
dimension
is
obtained,
the workin~
channel/tubular
retractor
is placed
over
the dilators am:
confirmed
with fluoroscopy. The flexible arm (Fig. 117-3C
which is secured
to the table, is attached
to the tubularre.
tractor to hold it firmly in place. The dilators are removed.
establishing
an operative
corridor to the lamina and inter.
laminar
space (Fig. 117-2C). Positioning
is finalizedwitt
fluoroscopy.
The locking arm on the ring attachment
secures theen.
doscope
to the tubular
retractor. The endoscope is thenm.
serted into the tubular retractor (Fig.117-4).The endoscopt
should be focused and orientated
to the standard positio'
(on the video screen, up is medial). AV-shaped indicat~.
has been placed on the video image to represent thepOSI
tion of the endoscope within the tubular retractor.Tht
V-shaped
indicator
on the video
screen
should
mirrortht
1

117
MicroendoscopicallyAssistedTliF
861
A
B
D
Figure
117-2
TheMETRxendoscopicsystem(Medtronic-SofamorDanek;Memphis,TN)includes(A)asetofmetalsequentialsofttissuedilators,
18)a22mmworkingchannel,(C)aflexiblebed-rail-mountedretractorarm,and(D)a30degreeendoscope.
A
B
(
Figure 117-3
Aseriesof images demonstrating the (A)
placement of the initial Steinmann pin down to the opera-
tive level,(B) the sequential passageof the tubular soft tis-
sue dilators, which gently spread the posterior muscula-
ture, and (C) a working channel with an angled curette at
the laminofacetjunction.
.........

862
Minimally InvasiveSpineProcedures:Lumbar
Figure 117-4
Anintraoperative photo ofthe adjustable endoscopic
holder attached to the workingchannel.
endoscope's position with respect to the tubular retractor.
Whenever the endoscope is turned, the orientation should
be corrected.
Anatomical Localization
A monopolar electrocautery can be used to dissect any soft
tissue present in the operative field. It is best to begin this
dissection laterally where the bone is apparent. Remaining
tissue is removed with a pituitary rongeur. It is essential to
remove all residual soft tissue in the operative corridor to
maximize the working space within the tubular retractor.
Soft tissue removal helps to identify the edge of the lamina
and interlaminar space, and the position of the retractor
with reference to the facet (Fig. 117-5). It is this anatomy
that aids in correctly performing the laminotomy. The
Figure 117-5
The correct visualizationinsidethe tubular retractor
with a straight curette at the laminofacet junction. Confirmingthis
anatomyfacilitatesthe casesubstantially.
working
channel
should
be repositioned,
if necessary,~
that the medial facet, lateral lamina, and interlaminarspao
are within the surgeon's view.
Laminectomy
Tosafely place an interbody device, the surgeon mustex
pose the nerve roots above and below the disk space.Theil'
fore, a fairly generous
laminectomy
and facetectomy mil!
be performed. The laminectomy proceeds as it wouldwith,
standard
microendoscopic
diskectomy.
The ligamentlJ:"
fIavum is first detached
from the undersurface
of thelar
ina
with
a small
curved
curette.
Endoscopic
Kernso.
rongeurs
are used to remove the lamina and the facet.W,
tend to favor performing the facetectomy without drilliw
significant bone away,and saving as much bone aspossi~
for
the
posterolateral
and
interbody
arthrodesis (Fi~
117-6). Using the Kerrison rongeur, the hemilaminotom
'
facetectomy, and foraminotomy over the nerve rootbela.
are completed.
The ligamentum
fIavum is eventuallyfret\
after enough bone has been removed. The ligamentisliftel.
then resected with a Kerrison punch. In doing so,thelateij
i
thecal sac and root are exposed. Attention is then shifted'
the nerve root above the disk space. Working from thetbo
cal sac superiorly
and laterally,
the proximal
aspect oft~
root above is identified.
The nerve is then traced lateraP
exposing this root as it exits into its foramen. Oncethere
I
complete visualization of both roots, it is safe to perforc
the diskectomy.
Diskectomy
Giventhe angle of the approach,the lateral aspectoft/"i
thecal sac should be well visualized upon removaloft/'I
yellow ligament. Utilizing a Penfield dissector. the."1 i
I
Figure 117-6
As with an open transforaminal lumbarinterbOi
fusion procedure, the hatch-marked area needs to be removed:
safelyplaceaninterbody device.

117
Microendoscopically Assisted TLiF
863
A
~
~
B
Figure117-7
The endoscopic
image of (A) the disk space with a nerve root retractor at the lateral edge of the dura and (8) a pituitary rongeur
removingthe intervertebral
disk.
saccan be freed of any attachments
so that it may be mobi-
lized.The freed nerve root and thecal sac are then gently re-
tracted medially
using a suction
retractor
(Fig. 117-7A).
Epiduralveins overlying
the disk space may be cauterized
withbipolar cautery and divided with microscissors. Are-
tractablescalpel with a no. 15 blade is used to open the disk
space,and pituitary
rongeurs
aid in evacuating
the disk
material(Fig. 117-78).
InterbodyFusion
Withthe thecal sac retracted medially, the initial bone graft
canbeplaced.The method for this depends upon the nature
ofthe interbody device utilized. For the Tangent system
:Medtronic-SofamorDanek, Memphis, TN),the remaining
diskmaterialisremovedwith the aidofa diskspacereamer
followedby an end plate scraper (Fig. 117-88). This allows
thediskspace to be prepared for the graft material. It is im-
portantto protect the dura and adjacent nerve roots while
performingthe interbody portion of the procedure. The
r
judicious use of fluoroscopy allows the surgeon to have
knowledge of the depth of the instrumentation placed into
the disk space (Fig. 117-8A). Achisel is used to prepare a
corridor for the bone graft, then the graft follows under flu-
oroscopic guidance (Fig.117-8C).Autograft collected locally
from the laminectomy isadded to the interspace. The work-
ing channel is then angled back toward the ipsilateral side
and the process is repeated for the second bone graft. Once
the interbody fusion is complete, the working channel can
be further angled toward the surgeon, and a posterolateral
fusion can be performed.
Pedicle Screw Instrumentation
The working channel is removed and the fluoroscope is
brought in for an anteroposterior (AP)radiograph. Using the
technique similar to vertebroplasty, a Jamshidi bone biopsy
needle is placed through the prior incision. The fluoroscope
is angled to "Bull's-eye" the pedicle so that the x-ray beam
is shot down the length of the pedicle. TheJamshidi, once in
A-(
Figure117-8
A series of operative, lateral fluoroscopic, and reference images demonstrating
the interbody preparation and graft placement: (A) a
dilatoris utilized to open the intervertebral
space and estimate the size of the graft, (8) a rotating disk cutter is used to remove a significant portion
ofthe intervertebral disk, and (C) a chisel is used to remove the end plates and create a corridor for the interbody graft.

864
MinimallyInvasive Spine Procedures: lumbar
A ~","~dl
~"
B
Figure
117-9
An anteroposterior
fluoroscopic
image
demonstrating
(A) placement
of Steinmann
pins with the bull's-eye
technique,
(8) advance-
ment of Steinmann pins into the vertebral bodies.
line to this angle. will safely guide the K-wire through the
pedicle and into the body.Allfour K-wire pins are placed in
1 to 2 cm while being watched and confirmed with APfluo-
roscopy (Fig. 117-9A). Once safely in position. the fluoro-
scope is brought into position for a lateral x-ray, and the
steinmann pins are advanced to a total depth of about two
thirds of the vertebral body (Fig. 117-98).
A
Using canulated instruments, a tap is advanced overthe
K-wire. Finally, a cannulated screw attached to a screw
extender is placed over the wire (Fig. 117-10A). Multiple
x-rays must be taken to ensure
that the K-wire is notad.
vancing. The screw is advanced
until it is almost touching
the facet. If advanced
too far. the surgeon
is able to feelthat
the screw has limited polyaxial movement.
In this case,the
Figure 117-10
(A)The Sextant screwand rod assembly.(B)Intraoperative
use ofthe Sextant system. (C)Lateralfluoroscopicviewof the percutaneous
passageofthe rod through the polyaxialheadsofthe pediclescrews.
B
c

117
Microendoscopically Assisted TLiF
865
r
A
Figure117-11
Fluoroscopicimage depicting (A) a lateral view of the completed screwand rod assembly,(8) an anteroposterior view of the inter-
bodygraftand pediclescrewand rod construct.
B
screwwill need to be slightly withdrawn to regain the
polyaxial function
of the
screw.
The second
screw
on
thesame side is placed in the same manner, and the exten-
dersare connected
to each other. Using the Sextant
arm
(Fig.117-tOBJ, the rod is placed percutaneously
and brought
intothe gap between the screw head and the set screw
(Fig.117-tOC).Thisis watched under lateral fluoroscopyand
confirmedwith an AP image (Fig. 117-tOC). Once in place,
thescrews may be compressed
and the nuts tightened with a
torquewrench. Attention
is then shifted to the contralateral
sideand the process is repeated (Fig. 117- 11A,B).
Closure
Allopenings in the skin are copiously irrigated with antibi-
otic solution. The fascia is closed with interrupted
ab-
sorbable sutures. Inverted subcutaneous interrupted
su-
tures are placed, and a running subcuticular is used to close
the skin. Dermabond (3MHealth Care,St. Paul, MN) is used
to close the skin (Fig.117-t2A,B).
A
B
Figure117-12
Postoperative
axial computed tomographic image of (A) the interbody Tangentgraft and lateral mass fusion, (8) pedicle screws
traversingthe pediclewith transverse processfusion.
References
1. ClowardRB.The treatment
of ruptured
lumbar
intervertebral
disk by
vertebral fusion: indications.
operative
technique.
aftercare. J Neuro-
surg 1953;10:154-166
2. Branch CI., Branch CI.Jr. Posterior
lumbar
interbody
fusion with the
keystone graft: technique
and results.
Surg NeuroI1987:27:449-454
3.
Harms J.Rolinger H. A one-stager
procedure
in operative treat-
ment of spondylolisthesis:
dorsal traction-reposition
and anterior
fusion (author's
translation).
Z Orthop lhre Grenzgeb 1982:120:
343-347

118
Vertebroplasty and Kyphoplasty
Sean D. Christie, John K.Song, and Richard G. Fessler
.
Background
.
NaturalHistoryandConservativeManagement
.
PatientEvaluationand Selection
.
Advantages
.
Disadvantages
.
SurgicalTechnique
. Background
Vertebral compression fractures (VCFs),commonly caused
by osteoporosis and metastatic disease, are a significant
cause of morbidity and mortality in the elderly population.1
The risk of developing VCFshas been shown to increase
with age. Slightlyless than 25%of women over the age of 50
are afflicted by osteoporotic bone fractures.2 This number
increases only slightly into the seventies, after which there
is an abrupt rise into 40 to 50%range for female octogenari-
ans.3.4However, this is not solely a female disease; a recent
review by Olszynski et al demonstrated that VCFsoccur in
-40% of males surviving into their eighth decade.s Addi-
tional risk factors for developing VCFinclude menopause,
prolonged immobilization/immobility, chronic steroid ther-
apy,diabetes mellitus, rheumatoid arthritis, cirrhosis, renal
insufficiency, and malnutrition.6 The economic impact of
osteoporosis is substantial. The estimated cost of osteo-
porotic bone fractures within the United States in 1995 was
approximately $746 million.7 Given our aging population,
the prevalence and economic impact of this disease will
continue to magnify in the near future.
Osteoporosis isa systemic disorder and the most common
metabolic bone disorder, affecting more than 24 million
Americans.7Progressive loss of bone matrix and demineral-
ization occur,leavingthe vertebral column vulnerable to the
development of compression fractures after minimal to no
trauma.s The pain caused by vertebral fractures may last
months and prove to be severely debilitating. Unfortunately,
the use of primarily medical therapy occasionally results in
narcotic dependence. Ina predominantly elderly population,
this can alter mood and mental status, thus compounding the
patient's condition.9Chronicpain, sleep deprivation, depres-
sion, decreased mobility,and lossof independence are all se-
quelae ofVCFs.JO.lIlnaddition, both thoracic and lumbar com-
pression fractures can lead to a decrease in lungcapacity.12
866
Vertebroplasty
Kyphoplasty
.
Complications
.
Outcomes
.
Conclusions
Metastatic
disease
commonly
affects
the spine and
symptomatic in more than a third of patients afflictedwitt
cancer.13.14In -10% of cases, spinal metastases
are thepflo
senting symptom. ISBreast, lung, and prostate primariesac
count for -60% of cases, whereas
gastrointestinal
andreII'
malignancies
are each responsible
for 5%of cases.16Metal.
tases produce
osteolytic
lesions, which lead to subsequen
weakness and fracture of the vertebral bodies. Theselesio~
can result in debilitating
pain, deformity,
and neurolo~c~
compromise.13.14.16These sequelae
have a significantlydetr.
mental impact on the quality of life that these patientshalt
to endure.
Percutaneous
vertebroplasty
and kyphoplasty
havebeer
developed
since the mid-1980s
as a treatment
optionf~
compression
fractures.
The aim of vertebroplasty
istoim-
prove the strength and stability of the injured vertebr,
whereas
in kyphoplasty
the intention
is to restore theven~
bral
body
height
as well
as increasing
strength. Bott
treatments
have been employed
in the management ofos-
teoporotic
compression
fractures
and spinal
metastasel
This chapter
summarizes
the indications,
techniques.al1l.
complications
for both
vertebroplasty
and kyphoplas~
procedures.
.
Natural History and Conservative
Management
Osteoporosis-induced
VCFscan be a self-perpetuatingcyc!
Ross et al examined
how bone mass density and the prel'
ence
of VCFs predicted
the
development
of futu~
fracturesY
After a mean follow-up
of 4.7 years theycon.
cIuded that a patient
with a bone mass less than twostan-
dard deviations
from the mean has a fivefold increasedris.
of developing
VCFs. This fivefold
increased
risk wasthe

118
Vertebroplasty and Kyphoplasty
867
samefor patients with average bone density and a prior sin-
gleVCF.However, in the presence
of two or more VCFs this
riskismagnified to 12-fold. In the extreme setting of a pa-
tientwith a bone mass in the 33rd percentile
and two or
morefractures the risk of future fractures is increased by
75-foldcompared
with women
with
bone density
above
the67th percentile
and no prior VCF.Although this popula-
tionis at high risk for the development
of multiple
frac-
tures,it is fortunate
that
approximately
two
thirds
of
patientswith acute symptomatic
fractures
improve despite
themanagement initiated.18
Traditional conservative
treatment
includes
adequate
analgesicsand bed rest. However, bed rest accelerates
bone
lossand increases
the
risk of developing
deep
venous
thromboses, both of which have a negative
impact on the
patient.19.20An alternative
approach
is a course of physical
therapyand bracing to minimize
the deleterious
effects of
immobilization. As already
noted, the majority
of patients
improveregardless of the treatment
prescribed, usually
within4 to 6 weeks. Several additional medical treatments
havebeen studied with mixed results. The addition of bis-
phosphonates, calcitonin,
parathyroid
hormone,
or ralox-
ifenehas been shown to reduce subsequent fracture rates,
whereasthe results for calcitriol, etidronate, fluoride, and
pamidronate have been mixed and inconclusive.21 To com-
pareconservative
treatment
with vertebroplasty,
Diamond
etalconducted a prospective,
nonrandomized
trial of osteo-
poroticpatients with acute VCFs.22They demonstrated that
vertebroplasty provided a rapid and significant reduction
in
painand an improvement
in physical activity scores
comparedwith medical treatment
and concluded that it is a
viabletreatment option.
. Patient Evaluation and Selection
Aswith any spinal procedure,
it is mandatory
to perform
a
detailedneurological
examination
documenting
any motor
orsensory changes
and paying attention
to any existing
radiculopathies. Preoperative
investigations
should include
routinebloodwork
and coagulation
studies.
In addition,
if
malignancy is suspected,
an appropriate
workup
is indi-
cated,including the ascertainment
of a tissue diagnosis. Ra-
diologicalevaluation
includes anteroposterior
(AP) and lat-
eralradiographs of the spine and a thin-cut, reconstructed
computedtomographic
(CT) scan. The CT is scrutinized
to
evaluatethe integrity of the posterior cortex, which may
suggestan increased
risk of cement
extrusion
into the
spinalcanal during the procedure. If there is evidence on
physicalexamination
of myelopathy
or a suggestion
of soft
tissuewithin the spinal canal on imaging studies, magnetic
resonanceimaging (MRI) is useful to further
delineate
any
spinalcordcompression.
Theprimary indication for vertebroplasty
is failure of con-
servativemanagement
of a vertebral
fracture
in which pa-
tientscontinue to have debilitating
pain that affects their
mobilityand activities of daily living. The pain should be lo-
calizedandattributable to the fracture level.There is no evi-
dencetoguide the duration of conservative therapy before it
isdeemeda failure. We select patients whose duration of
pain from fracture is > 6 weeks but < 1 year. Others have
successfully treated painful fractures of 2 years' duration.23
Guidelines and reviews have been published to aid in the se-
lection of patients.24.25Painful osteoporotic and osteolytic
fractures without myelopathy should constitute the vast ma-
jority of cases. Contraindications for vertebroplasty include
severe wedge deformity with loss of > 90% of vertebral
height (vertebra plana), comminuted burst fracture, spinal
canal
compromise
> 20%, epidural
tumor
extension,
myelopathy,inability to lie prone, uncorrected coagulopathy,
inability to localize the source of pain, allergy to cement or
radiopaque dye, and infection (local or systemic). There has
been considerable debate into the merits of prophylactic
vertebroplasty in selected patients24.25;however, it is our
practice to include only symptomatic patients because a
large number of patients never develop clinicalsymptoms. It
is prudent to have the facilities available to perform emer-
gent decompressive surgery should extravasation of bone
cement into the spinal canal occur,causing myelopathy.
Kyphoplasty is a modification of the technique that was
developed in the late 1990s.26,27It is felt to enable the
restorationofvertebralbodyheightand the introductionof
cement into a lower pressure cavity.The indications mirror
those for vertebroplasty; however, given the goal of fracture
reduction, the age of the fracture effects the success rate,
although the exact timing has yet to be determined.25.28In
addition, technical considerations require at least 8 mm of
residual vertebral height to introduce the materials.25
.
Advantages
. Less invasive than open procedures
.
Rapid reduction in pain
.
Fast recovery time
.
Inexpensive (vertebroplasty)
.
Disadvantages
.
Kyphoplasty more expensive
.
Maynot restore lost height
.
Riskof adjacent level fractures
.
Radiation dose to patient and operator
.
Riskof cement extravasation
.
Surgical Technique
Vertebroplasty
After appropriate medical clearance and written, informed
consent the patient is brought to the interventional radiol-
ogy suite (Fig. 118-1). We prefer to perform the procedure
with a surgeon and a radiologist present, although in many
centers a single operator performs the procedure. The
patient is placed in the prone position with the arms above

868
Minimally InvasiveSpineProcedures:Lumbar
\
,.....
~ .
,j
_#8,....
Figure 118-1
(A)Patient positioning and angiography suite setup
with biplanarfluoroscopy.(8) Basicsurgical supplies needed to per-
formpercutaneousvertebroplasty.
the head and adequately padded for comfort to prevent pe-
ripheral neuropathies. Oncevenous access is obtained, mild
sedation and analgesia may be administered. We have not
found it necessary to induce general anesthesia; rather, we
feel that it is better to have an awake and interactive patient
to enable neurological assessment throughout the proce-
dure. Continual monitoring of oxygen saturation, blood
pressure, and heart rate are performed. The skin in the re-
gion of interest is then prepped and draped in strict sterile
fashion to minimize the chance of a postoperative infection.
Once the patient is satisfactorily positioned the fracture
site isthen identified using bi-planar fluoroscopy. Although
some authors have advocated IT scanning to facilitate nee-
dle placement,23,29it is our experience that IT guidance is
necessary only in a few rare instances when anatomical
constraints prohibit easy identification of an appropriate
trajectory and placement of the needle. Amark is placed on
the skin overlying the pedicle of interest. The skin is infil-
trated with a buffered anesthetic solution containing 0.5%
or 0.25%Marcaine,1:200,000 epinephrine (AbbotLaborato-
ries; Chicago,IL),and Sodium Bicarbonate (American Phar-
maceutical Partners; LosAngeles, CA)down to the level of
the periosteum over the pedicle.
There are currently a wide selection of needles and ce-
ment that can be used for percutaneous vertebroplasty. In
addition
there
is no standardized
technique
for needle
placement.
We use either a transpedicular
or a parapedicu.
lar approach,
with
the
latter
being
the preferred (Fig.
118-2). Foreither approach biplanar fluoroscopyisusedtc
confirm
the appropriate
trajectory
(Fig. 118-3). A2 mrn
stab incision is created with a no. 11 scalpel blade lateraltc
the midline at the point previously
marked to identifythe
pedicle. A no. 11Jamshidi
needle with the trocar inplaceIS
introduced.
In the transpedicular
approach (Fig. 118-4)the
needle is advanced
until it docks onto the pedicle. Theideal
penetration
point is at the upper and outer quadrant ofthe
pedicle because perforation
at this location has fewconse.
quences compared
with the inferomedial quadrant inwhich
the exiting nerve root is in jeopardy.
The needle formsthe
"bull's eye" with the cortex of the pedicle as the outerring.
Once the location
and trajectory
are again confirmed with
fluoroscopy, the needle is advanced into the vertebralbody.
The procedure is then repeated for the contralateralpedicle.
In using the para pedicular approach (Fig.118-5)onlya
unilateral
cannulization
is necessary
because the morelat.
eral approach
allows for a more centrally directed needle,
The Jamshidi
needle
is docked
on the transverse process
and advanced immediately caudal to the transverseprocess
The appropriate entry point is at the lateral vertebralbody
on the AP projection
and at, or immediately
ventral to.the
posterior
cortex on the lateral fluoroscopic
image.Thebi-
planar fluoroscopic
images are used to help guide thenee.
die trajectory, keeping the needle tip equidistant fromthe
vertebral
body on both AP and lateral views. Oncetheverte.
bral body is encountered
the needle is advanced towardthe
center
of the body. There is a theoretical
increased risko[
pneumothorax
and bleeding with this approach30; however,
it has been our experience
that the complication ratesare
similar between
the two approaches.
Regardless
ofthe
route used, the needle tip shouldbein
the anterior
half of the vertebral
body on the lateralviews
and the medial one third in the AP views. The bevelofthe
needle can be directed in the most optimal directionfor
each given patient.
Given the frequency
of fluoroscopicim.
age acquisition, we suggest the use of a clamp to stabilize
the needle during imaging to minimize
the exposure ofthe
operator's hand. We also prefer to cannulate allthelevelstc
be treated prior to the injection of the cement.
Intraosseous venography had been advocated in some
centers, particularly
within the United States, prior toinjec.
tion of cement.31-33However, as more centers increased
their experience
with this technique
it has become appar-
ent that there is no increase
in safety afforded byvenogra-
phy.34-36We no longer
routinely
use venography priorto
cement injection. Toavoid the introduction ofairduringthe
injections,
the needle
is filled with sterile saline afterade.
quate placement
has been confirmed.
There are several cement
products
and suppliers avail.
able and the choice is left to the individual performingthe
procedure
based on the person's
experience
and training.
The increased
application
of percutaneous
vertebroplasry
has led to advances in the mixing and administrationde-
vices so as to achieve
a uniform,
consistent
product and
minimize
exposure
to vapors.
Polymethyl
methacrylate
(PMMA) is provided
in two separate
components,
a methyl
methacrylate polymer in powder form and a liquidmeth~

118
Vertebroplasty and Kyphoplasty
869
Figure118-2
Model illustrations depicting the entry points and needle trajectories for both the (A,B) transpedicular and (C,D) parapedicular
approaches.
methacrylatemonomer. Once combined an exothermic
polymerization reaction
occurs
and the
resulting
com-
poundprogresses from a liquid to a solid state. The ideal
timeforinjection is when the polymer is of the consistency
oftoothpaste. The timing
will vary depending
upon
the
productused. Most commercially
available products
come
withan aliquot of a radiopaque
marker, which is combined
withthe PMMAto facilitate visualization during the injec-
tionprocess.Ifnot available sterile barium sulfate powder
canbe added
to the
methyl
methacrylate
polymer
and
mixedthoroughly
prior
to reacting
the compound.
The
thickened PMMAsolution is poured into a 10 mLsyringe or
one of the many commercial delivery devices available. The
delivery device is then attached to the hub of the Jamshidi
needle and, under intermittent fluoroscopic monitoring the
PMMAis injected slowly under a consistent pressure (Fig.
118-5). In general, it is possible to inject 5 to 10 mL of
PMMAinto each treated vertebral body; the thoracic spine
accepts less volume than the lumbar spine due to their rel-
ative sizes. Extravasation of cement beyond the confines of
the vertebral body is an indication to stop the injection. It
is not clear what volume of cement is needed to reliably

870
Minimally Invasive Spine Procedures: Lumbar
----
B
Figure 118-3
(A) Percutaneous access to both pedicles with 11-
gauge biopsy needles. (8) Radiographic confirmation of adequate
placementofthe needlesisobtained on lateralfluoroscopy.
produce pain relief, nor is it known by what mechanism
the pain relief is achieved. Possible proposed mechanisms
include mechanical stabilization of the fracture site30and
neural thermal necrosis secondary to the heat generated
during the curing processY
Once the operator is satisfied with the injection theinner
cannula is replaced and the needle is removed with atwist-
ing motion. Closure of the wound is usually unnecessary. Oc-
casional bleeding is controlled with direct pressure.Patients
are kept recumbent
for 2 hours and are then allowed tosit
and ambulate with assistance. We routinely obtain a postop-
erative cr scan of the region treated to assess the degreeof
vertebral
body filling and to rule out any occult spinal cord
compression.
Patients
are then discharged
home on nons.
teroidal
anti-inflammatory
drugs (NSAIDS)and musclere-
laxants
later the same day. Ambulation
is encouraged and
participation
in activities of daily living is emphasized.
Kyphoplasty
Kyphoplasty is a procedure whereby an inflatable bone
tamp or balloon is inserted into the vertebral body.The
procedure attempts to restore the vertebral bodyto itsorig-
inal height. In doing so it is felt that a low-pressure
cavityis
created
within
the bone that may then be filled with ceo
ment.27.38Expansion
of the vertebral
body is followed radio
ographically by placing contrast medium in the balloon.
The following
is a summary
of the kyphoplasty
proce.
dure.
as first described
by Garfin
and coworkers.27 The
bone
tamp
is placed
using
either
the trans pedicular or
para pedicular
approach.
This is accomplished
with theaid
of a guide pin and biplanar
fluoroscopy.
Once cannulation
of the vertebral
body has occurred.
an obturator
is passed
over the guidewire
and inserted
into the vertebral body.
Aworking cannula is then passed over the obturator until
the cannula
tip is in the posterior
portion
of the vertebral
body. The inflatable
tamp is passed through
a corridor cre-
ated by drilling along the cannula
path. Once in place,the
device is inflated under fluoroscopic
guidance
to a pressure
of no more than 220 psi. An in-line
pressure
gauge allows
for constant pressure monitoring within the balloon.Once
a sufficiently
sized cavity has been created
and the maxi-
mum allowable reduction has been obtained, the PMMA
cement is prepared. At this point. smaller cannulas filled
with cement are inserted
into the working cannula. Thece-
ment is allowed to thicken prior to its application; thisis
determined by repeat suspension of a 2 cm3bolus froma
spatula until it is observed that cement does not fallfrom
the spatula.
At this point.
the viscosity
of the cement is
considered
sufficient
to permit injection. The cement-filled
cannula
is inserted
into the working
cannula,
with subse.
quent
passage into the anterior
vertebral
body wall.
A plunger-like effect is obtained by using a stainless stee
stylet to extrude the cement into its target location.Filling
the
cavity
with
cement
continues
under
lateral
fluoro.
scopic
guidance
and ceases
when
a mantle
of cement
reaches back about two thirds to the cortex of the posterio
portion of the vertebral
body.

T
118
Vertebroplasty and Kyphoplasty
871
Figure 118-4
Illustration
of the transpedicular
approach.
A 46-year-old
man suffered traumatic
compression
fractures
at L1 and L3. He com-
plainedof chronic back pain for several months following
the injury. which was localizable
to the L3 level. (A) Lateral lumbosacral
x-ray and (8) axial
computedtomographic
(CT) scan demonstrate
the L3 fracture.
He underwent
vertebroplasty
with bipedicular injection
of polymethyl
methacrylate.
(e)Lateralx-rayand (D) axialCTscanshowgood placementof cement in the anterior third of the vertebralbody.

Figure 118-5
Illustration
of the parapedicular
approach.
A 64-year-old
woman
presented
with a complaint
of back pain. There was no historyd
trauma or malignancy. Compressionfractures of T8 andTl 0 were identified and both felt to besymptomatic. (A) Lateral thoracic
x-ray demonstrat~
the fractures.
(8) Lateral and (C) anteroposterior
(AP) images confirming
the cannulation
ofT8. (D) Lateral and (E) AP images after injection ofT8aoc
during injection
of Tl O. (F) Postoperative computed
tomographic
scan demonstrates
good filling of the anterior portion
of the T8 vertebral body.
872

. Complications
118
Vertebroplasty and Kyphoplasty
873
Overallcomplicationrates are in the range of 1 to 2%for
osteoporoticfractures and 5 to 10% for metastatic
le-
sions.24.30
Themostcommoncomplicationfollowingverte-
broplastyis a transient increase in pain at the injected
level.Thisis readily treated with NSAIDsand typically re-
solveswithin 48 hours.3oAcute radiculopathy has been re-
portedto occur in up to 5%of cases. The symptoms are of-
tentransientand a short course of steroids may be helpful;
however,in some cases surgical decompression is neces-
sary.Therelatively higher complication rate in malignancy
isnowwell recognized.24 Chiras et al reported on a series
ofvertebroplasty cases and documented a complication
rateof1.3%in osteoporotic compression fractures, whereas
highercomplicationrates were noted with moredestruc-
tivebonelesionssuch as hemangiomas(2.5%)and verte-
bralmalignancies(10%).39Cement leakage is a common
problem,particularly in lytic lesions,30 and has been re-
portedin up to 30 to 70%of cases; fortunately, most of
theseoccurrences are asymptomatic.40Other reported
complicationsinclude fractures of the rib or pedicle, pneu-
mothorax,spinal cord compression, and infection. There
havebeen rare reports of serious complicationssuch as
pulmonaryembolism41.42and death43.44occurring during or
shortlyafter vertebroplasty. The cause of these events has
notbeendelineated; however, it has been postulated that
cementwith low viscosity and a large number of levels
treatedat a single sitting may playa role.30
Fracture of adjacent vertebral
levels following verte-
broplastydoes occur. The cause is most li.kelymultifacto-
rialand may include the diffuse nature of the osteo-
poroticdisease, relief of pain with a subsequent return to
ahigherlevel of physical activity, and increased strength
invertebrae that are subject to increased
loads from
kyphoticdeformity. Linet al reviewed their series of pa-
tientstreated with vertebroplasty
for compression frac-
tures.They concluded that cement leakage into adjacent
diskspaceswas related to an increased rate of adjacent-
levelfracture.45Gradual increase in activity and contin-
ueduse of orthotic devices (for 6 weeks following verte-
broplasty), may help prevent adjacent-level
fracture in
thoseat high risk.
Nocomplications related to balloon tamps have been re-
portedduring kyphoplasty procedures.46.47Several compli-
cations,all related in some way to needle insertion, have
beendocumented.Duringphase I testing of an inflatable
bonetamp,Liebermanet al found that kyphoplastywas a
safeprocedure;they had no significantcomplicationsre-
latedto their device.Cement extravasationwas the most
common problem occurring in 8.6% of their patients,47
Therewere no clinical sequelae resulting from cement ex-
travasation.Furthermore, the authors were encouraged that
ratesofcement extravasation during their kyphoplasty pro-
cedurewere lower than those of published vertebroplasty
series.
The exposure to ionizing radiation must be considered for
both the patient and the treating team. Mehdizade and
coworkers evaluated the radiation dose received by opera-
tors in a series of 11 cases.48They noted significant radia-
tion dosage measurements, particularly on the operators'
hands. Krugerand Faciszewski made a similar observation;
however, they were able to demonstrate that proper shield-
ing and limiting the radiation used significantly reduced the
measured exposure.49
.
Outcomes
There are no randomized, controlled
trials comparing
the outcomes of vertebroplasty and kyphoplasty to each
other or to conventional medical therapies. Most of the data
available are derived from retrospective studies, although
there have been a few reports on prospective, observational
cohorts.
Vertebroplasty can reduce pain in 90 to 95%of patients
suffering osteoporotic vertebral fractures.23.40,50Addition-
ally, improvements in mobility and in activities of daily liv-
ing occur. Also of note, patients who have undergone per-
cutaneous vertebroplasty decrease their use of narcotic
pain medications. Furthermore, the reduction in pain is
rapid, usually within 48 to 72 hours.28The analgesic effect
has been shown to persist in a cohort of patients followed
prospectively for a minimum of 5 years.51The success rate
is slightly lower in patients with metastatic disease, with
-65
to 80% reporting significant improvement
in pain
scores.30,52
In 2001, Lieberman et al reported the results of a phase 1
clinical trial examining the efficacyof kyphoplasty in osteo-
porotic fractures.38Theyreported that in 70%of levels oper-
ated, a mean restoration of 47%of the lost vertebral body
height was achieved.In addition, the patients demonstrated
a significant improvement in measures of pain, activity, and
energy. Similar results have been reported in patients with
multiple myeloma.53
. Conclusions
Percutaneous vertebroplasty
and kyphoplasty are mini-
mally invasive options for the management of osteoporotic
and osteolytic VCFs.These techniques provide substantial
pain relief and support without having to sacrifice mobil-
ity, as with conventional bed rest, and have an acceptable
complication rate. However, clinical trials need to be done
comparing these various approaches for different indica-
tions so that we will be able to best direct the care of our
patients. We also must scrutinize any new treatment as to
its cost effectiveness. Currently, the cost of kyphoplasty is
significantly greater than that of vertebroplasty. Tojustify

874
Minimally InvasiveSpineProcedures:Lumbar
the additional cost, kyphoplasty must be shown to be safer
or to provide added clinical benefit such as greater stabil-
ity, better pain relief, or reduced operating time. Most pub-
lished studies demonstrate equivalent results in stability
and pain relief as well as complication rates. In addition,
References
1.
Kado DM. Browner WS, Palmero
L, Nevitt MC. Genant
HK. Cummings
SR. Study of Osteoporotic
Fractures
Research
Group. Vertebral
frac-
tures and mortality
in older women:
a prospective
study. Arch Intern
Med 1999;159:1215-1220
2.
Lyles KW. Management
of patients
with vertebral
compression
frac-
tures. Pharmacotherapy
1999;19:215-245
3.
Cooper C. Atkinson
EJ,Jacobsen
SJ. O'Fallon WM, Melton
LJ III. Inci-
dence of clinically
diagnosed
vertebral
fractures:
a population-based
study
in
Rochester.
Minnesota.
1985-1989.
J Bone Miner Res
1993;7:221-227
4.
Melton LJIII. Epidemiology
worldwide.
Endocrinol
Metab Clin North
Am 2003;32:1-13
5.
OIszynski WP. Davison KS. Adachi JD. Brown JP. Cummings
SR. Osteo-
porosis
in men: epidemiology.
diagnosis.
prevention.
and treatment.
Clin Ther 2004;26:15-28
6.
Rao RD. Singrakhia
MD. Painful
osteoporotic
vertebral
fracture:
pathogenesis.
evaluation.
and roles of vertebroplasty
and kyphoplasty
in its management.
J Bone Joint Surg Am 2003;85-A:201O-2022
7.
Ray NF. Chan JK. Thamer
M. Melton
LJ III. Medical
expenditures
for
the treatment
of osteoporotic
fractures
in the United States in 1995:
report
from the National
Osteoporosis
Foundation.
J Bone Miner Res
1997; 12:24-35
8.
Riggs BL. Melton LJ III. Involutional osteoporosis.
N Engl J Med
1986;314:1676-1686
9.
Silverman
SL. The clinical
consequences
of vertebral
compression
fracture. Bone 1992; 13(Suppl 2):5527-5531
10.
Cook DJ. Guyatt GH. Adachi JD. et al. Quality of life issues in women
with
vertebral
fractures
due
to
osteoporosis.
Arthritis
Rheum
1993;36:750-756
11.
Gold DT.The clinical
impact
of vertebral
fractures:
quality
of life in
women
with osteoporosis.
Bone 1996;18(SuppI3):185S-
1895
12.
Schlaich
C. Minnie
HW. Bruckner
T. et al. Reduced
pulmonary
func-
tion in patients
with
spinal
osteoporotic
fractures.
Osteoporos
Int
1998;8:261-267
13. Wise 11. Fischgrund JS. Herkowitz HN.Montgomery D, Kurz LT.Com-
plication.
survival rates. and risk factors of surgery
for metastatic
dis-
ease of the spine. Spine 1999;24: 1943-1951
14.
Fourney DR. Schomer
DF. Nader R. et al. Percutaneous
vertebroplasty
and kyphoplasty
for painful
vertebral
body fractures
in cancer
pa-
tients. J Neurosurg
Spine 2003 ;98 :21- 30
15.
Greenlee
RT, Murray T, Bolden 5, Wingo
PA. Cancer
statistics.
2000.
CACancer J Clin 2000;50:7-33
16.
Aebi M. Spinal metastasis
in the elderly.
Eur Spine J 2003;12(Suppl
2):5202-5213
17.
Ross PD. Davis JW, Epstein RS,Wasnich
RD. Pre-existing
fractures
and
bone mass predict vertebral
fracture
incidence
in women. Ann Intern
Med 1991 ;114:919-923
18.
Lieberman
I. Vertebral
augmentation
for osteoporotic
and osteolytic
vertebral compression
fractures:
vertebroplasty
and kyphoplasty.
In:
Haid RW. Subach BR. Rodts GEJr.. eds. Advances
in Spinal Stabiliza-
tion. Prog Neuro Surg vol 16.2003:240-250
19.
Convertino
VA, Bloomfield
SA. Greenleaf
JE. An overview
of the is-
sues: physiological
effects of bed rest and restricted
physical activity.
Med Sci Sports Exerc 1997;29:187-190
20.
Uthoff HK.Jaworski ZF.Bone loss in response
in response
to long term
immoblization.J
Bone Joint Surg Br 1978;60:420-429NIM
21.
Lippuner K. Medical treatment
of vertebral
osteoporosis.
Eur Spine J
2003; 12(SuppI2):S132-S141
both procedures utilize a similar technique and appear
roughly equivalent
in technical ease/difficulty. Therefore.a!
this time, it seems reasonable to question the costbenefit
ratio of the kyphoplasty
procedure
compared
with verte.
broplasty.
22. Diamond TA,Champion B, Clark WA.Management of acuteosteo-
porotic vertebral
fractures:
a non-randomized
trial comparing pe[(t
taneous
vertebroplasty
with
conservative
treatment.
Am J Me..
2003;114:257-265
23.
Barr JD. Barr MS. Lemley TJ. McCann RM. Percutaneous
vertebroplasty
for pain relief and spinal stabilization.
Spine 2000;25:923-928
24.
McGrawJK.Cardella J, BarrJD,et al. Society of InterventionalRadio
ogy quality improvement
guidelines
for percutaneous
vertebroplast)
J Vasc Interv RadioI2003;14:S311-S315
25. Stallmeyer MJB.Zoarski GH.Obuchowski AM.Optimizingpatientse-
lection
in
percutaneous
vertebroplasty.
J
Vasc
Interv Radiol
2003;14:683-696
26.
Garfin SR. Lin G. Lieberman
I. et al. Retrospective
analysis ofthe out-
comes
of balloon
kyphoplasty
to treat
vertebral
body compressior
fracture (VCF) refractory to medical management. Eur SpineI
2001; 10(Suppl1):S7
27.
Garfin SR. Yuan HA. Reiley MA. Kyphoplasty
and vertebroplastyk
the treatment
of painful
osteoporotic
compression
fractures. Spill'
2001 ;26: 1511-1515
28.
Phillips FM.Minimally invasive treatments of osteoporoticvertebral
compression
fractures.
Spine 2003;28:545-553
29.
Gangi
A. Kastler
BA. Dietemann
JL. Percutaneous
vertebroplasr
guided
by a combination
of CT and fluoroscopy.
AJNRAm] Neurora-
dioI1994;15:83-86
30.
Mathis JM. Wong W. Percutaneous
vertebroplasty:
technical consid-
erations.J
Vasc Interv RadioI2003;14:953-960
31.
Jensen
ME. Evans AJ,Mathis JM. Kallmes DF.Cloft HJ.DionJE.Percuu-
neous polymethylmethacrylate
vertebroplasty
in the treatment of01.
teoporotic vertebral body compression fractures: technicalaspect.
AJNRAmJ NeuroradioI1997;18:1897-
1904
32.
Do HM. Intraosseous
venography
during
percutaneous
vertebra-
plasty: is it needed?
AJNR AmJ NeuroradioI2002;23:508-509
33.
McGraw JK. Heatwole
EV,Strnad BT.Silber JS. Patzilk 58. BoorsteinjM.
Predictive
value of intraosseous
venography
before percutaneousver-
tebroplasty.
J Vasc Interv Radiol 2002; 13: 149-153
34.
Wong W. Mathis J. Is intraosseous
venography
a significant safe!)
measure
in performance
of vertebroplasty?
J Vasc Interv RadifJ.
2002;13:137-138
35.
Gaughen
JR Jr, Jensen
ME. Schweickert
PA. Kaufmann T]. MarxWF,
Kallmes
DF. Relevance
of antecedent
venography
in percutan_
vertebroplasty
for the treatment
of osteoporotic
compression frac-
tures. AJNRAmJ NeuroradioI2002;23:594-600
36.
Vasconcelos
C, Gailloud p. Beauchamp
NJ. Heck DV. Murphy K].ls per-
cutaneous
vertebroplasty
without
pretreatment
venography safe'
Evaluation
of 205 consecutives
procedures.
AJNR Am J Neuroradit
2002;23:913-917
37.
Belkoff SM. Molloy S. Temperature
measurement
during polymeriza-
tion
of polymethylmethacrylate
cement
used
for vertebroplasty.
Spine 2003;28:1555-1559
38.
Lieberman
IH. Dudeney
5, Reinhardt
M-K. Bell G.lnitial
outcomeaiIG
efficacy of'kyphoplasty'
in the treatment
of painful osteoporoticver-
tebral compression
fractures.
Spine 2001 ;26:1631-1638
39.
Chiras
J.Depriester
C.
Weill
A.Sola-Martinez
MT,
Deramond
H. Verte-
broplasties
percutenees:
technique et indications. J Neuroradio'
1997;24:45-59
40.
Cortet B,Cotton A.Boutry N,et al. Percutaneous vertebroplastyinthe
treatment of osteoporotic vertebral compression fractures:anopen
prospective study.JRheumatoI1999;26:2222-2228
-

41.PadovaniB, Kasriel
0, Brunner
P, Peretti-Vi ton p, Pulmonary
em-
bolismcaused by acrylic cement:
a rare complication
of percutaneous
vertebroplasty. AJNR AmJ NeuroradioI1999:20:375-377
42. YooKY,Jeong SW. Yoon W. Lee j. Acute respiratory
distress
syndrome
associated with
pulmonary
cement
embolism
following
percuta-
neousvertebroplasty
with polymethylmethacrylate.
Spine 2004:29:
E294-E297
43. ChildersJC Jr. Cardiovascular
collapse
and death
during
vertebro-
plasty.Radiology 2003:228:902
44.JensenME,Evans AJ.Author's
reply. Radiology 2003:228:902-903
45. LinEP,Ekholm S, Hiwatashi
A, Westesson
PL. Vertebroplasty:
cement
leakageinto the disk increases the risk of new fracture of adjacent
vertebral body. AJNRAm J Neuroradiol
2004:25:175-180
46.GarfinSR,Yuan HA,Reiley MA.Kyphoplasty and vertebroplasty for
the treatment
of painful
osteoporotic
compression
fractures.
Spine
2001 :26:1511-1515
47. Lieberman IH, Dudeney
S. Reinhardt
M-K. Bell G. Initial outcome
and
efficacyof kyphoplasty
in the treatment
of painful
osteoporotic
ver-
tebralcompression
fractures.
Spine 2001 :26: 1631-1638
118
Vertebroplastyand Kyphoplasty
875
48.
Mehdizade
A, Lovblad KO. Wilhelm
KE.et al. Radiation
dose in verte-
broplasty.
Neuroradiology
2004:46:243-245
49.
Kruger
R, Faciszewski
T. Radiation
dose
reduction
to medical
staff
during
vertebroplasty:
a review
of techniques
and methods
to miti-
gate occupational
dose. Spine 2003:28:1608-1613
50.
Deramond
H, Depriester
C. Galipert
P. Le Gars D. Percutaneous
verte-
broplasty
with polymethylmethacrylate:
technique,
indications,
and
results. Radiol Clin North Am 1998:36:533-546
51.
Perez-Higueras
A. Alveraz L. Rossi RE, Quinones
D. AI-Assir I. Percuta-
neous vertebroplasty:
long-term
clinical
and radiological
outcome.
Neuroradiology
2002:44:950-954
52.
Cortet B. Cotton A. Boutry N, et al. Percutaneous
vertebroplasty
in pa-
tients
with
osteolytic
metastases
or multiple
myeloma.
Rev Rhum
Engl Ed 1997:64:177-183
53.
Dudeney
S. Lieberman
IH. Reinhardt
MK. Hussein
M. Kyphoplasty
in
the treatment
of osteolytic vertebral
compression
fractures
as a result
of multiple
myeloma.J
Clin OncoI2002:20:2382-2387

Section VII
PeripheralNerve
A.Pathology of the BrachialPlexus
. 119. Neoplasms of Peripheral Nerves
. 120. Evaluation and Treatment of
Traumatic Peripheral Nerve
Injuries
. 121. Compressive lesions of the
Peripheral Nerve
B. Brachial Plexus
. 122. Supraclavicular Approach to
Brachial Plexus Surgery
. 123. Infraclavicular Approach to
Brachial Plexus Surgery
. 124. Surgical Approach to the Spinal
Accessory Nerve
. 125. Surgical Approach to the Axillary
Nerve
. 126. The Musculocutaneous Nerve
. 127. The Median Nerve
. 128. Radial and Ulnar Nerves
C. Pathologyofthe LumbosacralPlexus
.
129. Traumato the lumbosacral
Plexus
.
130. Tumorsofthe lumbosacral
Plexus
D. Lumbosacral Plexus
.
131. Approach to Nerves of the lower
Extremity
.
132. SuralNerve
E. Other Nerves
.
133. Intercostal Nerve
.
134. Surgical Management of
Ilioinguinal Neuralgia
. 135. Surgical Management of
Genitofemoral Neuralgia
.
136. lateral Femoral Cutaneous Nerve
and Intercostal Nerve
.
137. Nerve Graft Harvesting and
Repair Techniques

119
Neoplasms of Peripheral Nerves
AllanJ. Belzberg and Michael J. Dorsi
. Indications
. Advantages
. Disadvantages
. Schwannoma
Pathology
Management
Surgical Removal of an Ulnar Nerve Schwannoma
Neurosurgeonsare called upon with regularity to diagnose
andtreat tumors involving the peripheral nervous system.
Theprimary tumors are derived either from components of
thenerve sheath (Schwann cells, perineural cells, fibrob-
lasts)or from neurons. Among the neoplasms, benign
tumorsgreatly outnumber malignant ones. There is no reli-
ableestimate of the total number of benign nerve sheath
tumorsdiagnosed annually; however, there are probably
overseveral thousand
cases.!
There has been debate
for decades as to whether
certain
benign nerve sheath tumors can safely be treated surgically.
Muchof the concern has focused on the potential
for neuro-
logicaldamage associated with attempting
to separate tumor
fromnerve fascicles.It is often thought that the entire cross
section of the nerve is composed
of tumor
and removal of
suchwill destroy the nerve; however, frequently, only one or
twofascicles contain tumor and the remaining
ones can be
spared.Our experience
leads us to believe that by employing
microsurgical technique, peripheral nerve sheath tumors can,
inmost instances, be safely resected with little or no neuro-
logicalsequelae. This chapter describes the surgical treatment
ofthree types of nerve sheath tumors: peripheral neurofibro-
mas,peripheral schwannomas,
and spinal dumbbell tumors.
.
Indications
. Diagnosis
. Pain
. Cosmeticconsiderations
. Progressiveneurological deficit
. Compressionof adjacent tissue
. Suspicionof malignancy
.
Neurofibroma
Pathology
Management
Surgical Removal of Globular Neurofibroma
.
Special Focus:Dumbbell Tumors
Management
Surgical Removal of a Dumbbell Tumor
.
Advantages
. Painrelief
.
Preservation of function in uninvolved fascicles
.
Prevention of malignant transformation
.
Tissue diagnosis
.
Disadvantages
. Riskof creating permanent neurological deficit in unin-
volved fascicles
. Risk of surgery versus very small risk of malignant
transformation
.
Potential for painful neuroma formation
. Schwannoma
Schwannomas (neurilemmomas) are benign, often solitary,
slowly growing nerve sheath tumors. They can arise from
any peripheral nerve with a Schwann cell including distal
portions of cranial nerves. The presence of bilateral acoustic
schwannomas is diagnostic of neurofibromatosis
type II;
however, there
is no association
between
peripheral
schwannomaandneurofibromatosistype J.2
Pathology
On gross examination the tumor appears shiny, tan-yellow,
and encapsulated.
It is distinguished
from other nerve sheath
tumors histologically by the presence
of only schwann cells;
perineural
cells and fibroblasts are not present.3 Tumor cells
879

880
Peripheral Nerve: Pathology of the BrachialPlexus
can be arranged in alternating hypercellular palisading re-
gions(AntoniA)and hypocellular loosely meshed (Antoni B)
regionsor there can be a predominance of only one pattern.
Acrucial histological feature is that, unlike neurofibromas,
these lesions grow within the nerve sheath displacing the
fasciclesand typically do not envelop the axonal processes.
Despite this characterization, one can almost always find a
small fascicle entering or exiting the proximal and distal
polesofthe tumor.4
Management
The natural history of a schwannoma is to be slow growing.
They become well encapsulated by the epineurium and
push aside adjacent fascicles.3They are frequently soft to
palpation and can be cystic. ATinel's sign is regularly pre-
sent. Imaging studies can provide information concerning
the extent, anatomical location, size, and relationship of the
tumor to the surrounding structures.5-8
The treatment of symptomatic schwannomas is operative
excision. Unless the tumor is massive, or prior surgery has
been performed. operative excision can be accomplished
with little or no injury to the parent nerve. Recurrences af-
ter removal are infrequent.
In some circumstances the tumor isenveloped wi~hfasci-
cles,and the appearance on first inspection may suggest that
the tumor cannot be resected. Aninternal neurolysiswith pa-
tient separation of the fascicleswill revealthat the tumor can
be separated from the fascicles.Ifrequired. to ease the dissec-
tion the capsule can be opened and the tumor debulked from
within. Verylarge tumors may require debulking with the aid
ofan ultrasonicaspirator.Nervegraftingshould be considered
anytimea significantfascicleissacrificed.
Surgical Removal of an Ulnar Nerve Schwannoma
Anesthesia and Positioning
General,regional, or local anesthesia can be used; however,
only general or regional anesthesia allows for use of a
tourniquet, which will greatly ease the dissection by provid-
ing a dry field. Muscle relaxant is avoided because this will
prevent the use of nerve stimulation. The patient is posi-
tioned to maximize exposure ofthe tumor. Positioning also
requires attention to the possible need for nerve grafting
and harvesting of a donor nerve.
Incision and Dissection
The skin incision courses over the nerve beginning 2 to 4
cm proximalto and extending 2 to 4 cm distal to the tumor
(Fig. 119-1). Dissection continues through the subcuta-
neous tissues, with close attention paid to hemostasis. As
the nerve is approached, the exposure begins in a region of
normal anatomy and extends into the region of tumor for-
mation (Fig.119-2, 119-3). Loopmagnification or an oper-
ating microscope isessential for identification of the fasci-
cles coursing over the tumor. Electrical nerve stimulation is
also used to differentiate fascicles from tumor. Adissection
plane is now established by gently separating and elevating
the fascicles from the surface of the tumor (Fig. 119-4).
/
I,,
./
"
*",,"
"
Figure 119-1
Skin incision for ulnar nerve schwannoma. Thetumor
is palpated
to determine
its proximal
and distal edges.
A skin incisionis
made
over the course
of the
nerve
beginning
2 to 4 cm proximalto
and extending
2 to 4 cm distal to the tumor.
Figure 119-2
Exposure of ulnar nerve schwannoma. Dissectioncon-
tinues through subcutaneous
fat to reveal a solid well-circumscribed
mass involving the ulnar nerve.
There may be a thin capsule (epineurium) that requires
opening
to allow easier dissection
of tumor from nerve.A
second deeper tissue plane may be present
that also hasto
be entered to allow dissection of tumor from nerve.
If ongoing electromyographic
(EMG) activity is beingmoni-
tored from muscles innervated by the nerve, feedback canbe
gained concerning aggressive manipulation
of the fascicles.As
the tumor is mobilized,
there may be a single fascicleseen
entering and exiting the mass. Electrical stimulationwill

119
Neoplasmsof PeripheralNerves
881
determine if this is a motor
fascicle and still functional.
Dependingon the clinical scenario, the surgeon will determine
ifsacrificeof the fascicle necessitates a nerve graft repair.
Most schwannomas
can be removed en bloc. Although of-
ten splayed and thinned,
the intact
fascicles
should
still
function.The tumor bed is inspected
for any evidence of di-
videdfascicles (Fig. 119-5). If a divided fascicle is found, the
distalend can be electrically
stimulated
to determine
if it is
a motor fascicle and what
muscles
are innervated
by the
fascicle.The decision as to the need for a nerve graft repair
isbasedon the degree of anticipated deficit from the di-
videdfascicle. The need for a nerve graft repair after re-
movalofa schwannoma is rare.
Noattempt is made to remove remaining tumor capsule
becausethe presence of tumor capsule is not associated
Figure 119-3
Ulnar nerve schwannoma. Under loop
magnification, dissection is continued along the ulnar
nerve to expose the proximal and distal pole of the
tumor with the ulnar nerve entering and exiting the
tumor.
Figure
119-4
Removal of ulnar nerve schwannoma.
Loupe magnification
or an operating
microscope
is re-
quired
for identification
of the fascicles
coursing
over
the tumor.
Electrical stimulation
is also used to differen-
tiate fascicles from tumor
and to identify
any functional
motorfascicles
coursing over the tumor.
There may be a
thin capsule (epineurium)
that requires opening to allow
easier dissection
of tumor
from
nerve.
A dissection
plane is established
by gently
separating
and elevating
the
fascicles
from
the
surface
of
the
tumor.
Most
schwannomas
can be removed
en bloc. If the tumor
is
large and undue manipulation
of fascicles seems immi-
nent, the tumor
should
be internally
debulked
and re-
moved in pieces.
with tumor recurrence. Frozen sections of the tumor are al-
ways obtained to determine if a malignancy (malignant pe-
ripheral nerve sheath tumor) is present. Wound closure is
performed in layers with care not to entrap the nerve in a
tight compartment.
.
Neurofibroma
Neurofibromas may involve small cutaneous nerves and
present as numerous subcutaneous nodules. Ifsurgical inter-
vention is required, they are easily resected from surround-
ing tissues. There is little or no sequelae associated with
sacrificing the sensory nerve containing the neurofibroma.
When they involve large nerves, elephantiasis neuromatosa

882
PeripheralNerve:Pathologyof the BrachialPlexus
or local gigantism can occur. On occasion a solitary neurofi-
broma is seen in isolation, but more frequently it is seen as
part of neurofibromatosis type I.
Pathology
Neurofibromas can span large segments of nerve (plexi-
form) or occur as a localized mass (globular, solitary). The
plexiform tumors can form large masses deforming an
extremity. The globular tumors are well circumscribed,
ovoid,pale gray,and translucent. On histological evaluation,
neurofibromas are unencapsulated tumors. Based on gross
appearance and resectability, it appears that most neurofi-
bromas do indeed have a capsule (likely perineurium) and
fascicles are often peripherally enclosed in its layers.4Neu-
rofibromas are composed of a mixture of proliferating nerve
sheath cells likely arising from the perineural fibroblast9
and are intimately associated with the nerve fibers. Prolifer-
ating cells expand the fascicle and envelop the axonal
processes. A crucial histological feature is that, unlike
schwannomas, the tumor involves the entire cross section
of the fascicle resulting in a lack of surgical cleavage plane
between nerve fibers and tumor. Thus, by necessity, when
neurofibromas are removed the axons enveloped by the tu-
mor must also be removed. Fortunately, in many instances
fasciclesthat are not expanded by tumors can be spared.
Management
Patients suffering from neurofibromatosis type I can have
hundreds of tumors; thus the management of a particular
neurofibroma reflects the severity of the symptoms associ-
ated with it. Globularneurofibromas are most often slowly
enlarging, painless masses.Neurofibromas developing in the
deep large nerves are commonly plexiform and may extend
the length of the nerve, coursing into multiple branches.
Symptoms arise from axonal compression with neurological
deficits (including pain) or secondary to compression of
Figure 119-5
En bloc removalof ulnarnero.
schwannoma. After meticulous dissection,
schwannoma may typically beremovedenbb.
The extracted tumor is then inspectedfortt-c
presence of transected fascicles.Thetumor
sent for permanent pathologicalevaluation
L.
lessthere is a question of diagnosisandfroz~
section isrequired to guidethe surgicaldecisiO'
making.
neighboring
tissues. Physical examination revealsa soft,mo
bile mass. A Tinel's sign occurs with percussion ofthemass
Imaging
studies
can provide
information
concerningth,
anatomical
location and extent of the tumor.4-6,10-14
Neithel
magnetic
resonance
imaging (MRI) nor computed tomogra.
phy (CT)are able to differentiate schwannomasfromneu.
rofibromas nor benign from malignant nervesheathtumor.;
Ifevidence exists of proximal tumor involvement, then pre.
operative
investigation
of the spine is performed to delin.
eate intraspinal
extension of tumor.15.16
Fine-needle
aspiration,
used in conjunction with needk
core biopsy, may distinguish a large neurofibromafrom.
neurogenicsarcoma,I? but we have seen casesinwhichnee.
dIe biopsy failed to diagnose malignancy due to sampling
error. Percutaneous biopsies also risk injuringnervefasCI-
cles running over the tumor surface.
Neurofibromas typically do not need to be excised.Nev.
ertheless,there areoccasionswhenexplorationisindicated.
The most common indication for removalofa neurofibroma
is pain. Typically these lesions involvesmallfasciclesofcu.
taneous nerves and can be excised without creating.
meaningful
neurological
deficit. Even when globulartumors
involve a major nerve, often only one fascicleis involved.
Sacrificeofthis singlefascicleisnotassociatedwithfurther
loss of neurological function. When loss of functionis.
concern, nerve graft repair should be considered.
The situation for plexiform neurofibromas isquitediffer.
ent. These lesions are typically asymptomatic,
but onocca.
sion, pain is prominent. This occurs particularly whenthe
neurofibromais trapped in a compartment.Theselesions
extend over considerable lengths of the nerve.Although
they may only be arising from one fascicle, the tumor can
expand to envelop multiple fascicles. Either the same or dif.
ferent fascicles can be involved, with tumor at multiple
points
along the course
of the nerve creating a stringof
pearls appearance.
If only one fascicle is involved with the
tumor,excisionis possible:however,completeremovalof
the tumor will often effect a neurological deficit.Itmay~

119
Neoplasms of Peripheral Nerves
883
possibleto ameliorate the symptoms by performing an ex-
ternalneurolysis of the nerve combined with enlarging the
surround(e.g., foraminotomy). Debulking the tumor may
amelioratesymptoms while preserving function.
SurgicalRemovalof Globular Neurofibroma
Anesthesiaand Positioning
Thisis the same as for a schwannoma
resection (see
previous).
Incisionand Dissection
Theexposure of a neurofibroma is similar to that of a
schwannoma.A plexifom neurofibroma may be encoun-
tered,which may limit the ability to fully excise the tumor.
Oncethe region of the nerve containing the tumor is
exposed,magnification is employed. Ifthe tumor is not visi-
bleonthe surface of the nerve, an internal neurolysis is re-
quired.Asthe epineurium is opened the tumor can be iden-
tified(Fig.119-6). Frequently there is a psuedocapsule
envelopingthe tumor that requires opening. Once in the
correctplane, the surgeon will usually be able to preserve
someofthe fasciclesbyseparatingtumor fromnerve.One
ormore fascicles will be seen entering and exiting the
tumorand will have to be sacrificed (Fig. 119-7). The tumor
canthen be gently dissected away from the remaining
fascicles.
./
~Eplneurlum
/
(capsule)
I)"
V
I:;
Expanded
fascicles
withtumor
_/
Uninvolved
fascicles
Electrical stimulation can determine if the fascicles en-
larged by tumor provide motor function. Unlike the fasci-
cle entering a schwannoma, those entering a neurofibroma
are often stiII functioning. Ifthere is concern about neuro-
logical sequelae, a nerve graft repair is performed. Individ-
ual fascicles can be grafted using a perineurial technique
(Fig. 119-8) or, alternatively, if the entire cross section of
nerve has been destroyed
an epineurial
repair is per-
formed. Either 9-0 or 10-0 nonabsorbable filament suture
is utilized although some surgeons have converted to us-
ing glue (Tisseal) to secure the grafts. The sural nerve fre-
quently serves as the donor nerve. When working in the
upper extremity the medial antebrachial cutaneous nerve
or sensory radial nerve can be considered
for use as a
donor nerve.
Closure of the wound is achieved in layers with care not
to entrap the nerve. Ifa nerve graft was required. splinting
is employed for 2 to 4 weeks.
.
Special Focus: Dumbbell Tumors
Both neurofibromas and schwannomas have the potential
to develop into large tumors with an intra- and extras pinal
component connected through the intervertebral foramen
by a narrowed segment of tumor; hence the descriptive
term dumbbell(Fig.119-9). Neurological symptoms occur in
more than 60%of patients. IS The slow growth of the tumor
Figure 119-6
Exposureof ulnar nerve neurofibroma. Aninter-
nal neurolysisisrequired to separate out the nerve fasciclesand
determine which ones are intimately involved and likelyto be
sacrificedwiththe tumor. Theinvolvedfasciclesappear bulkyand
distended. Some ofthe spared fasciclesmayappear flattened or
splayed around the tumor. There is a psuedocapsule over the
tumor that needs to be opened for tumor dissection and
removal.
..

884
PeripheralNerve:Pathologyof the BrachialPlexus
can result in extensive bony erosion. Dumbbell tumors are
most commonlyfound in the thoracic spine.
Management
Prior to planning removal of an intraspinal nerve sheath tu-
mor, it is essential to evaluate the lesion for the possible
presence of a dumbbell tumor. MRIis especially important
for distinguishing a nerve root sheath tumor from an
intra/extraforaminal intervertebral disk prolapse.19Cf/myel-
ography allows delineation ofthe bony anatomy and the re-
Figure 119-7
En bloc removal of ulnar
nerve neurofibroma.
Loupe magnification or
an operating microscope is useful for identifi.
cation
of the
fascicles
coursing
over the
tumor. Electrical stimulation
is also usedto
differentiate fascicles from tumor and to iden.
tify any functional
motor fascicles coursing
the tumor. Once in the correct plane, the sur.
geon will usually be able to preserve someof
the fascicles. One or more fascicles willbeen.
gulfed by the tumor and will have to be sacri.
ficed to remove the tumor. The tumor and
engulfed portions of transected
fascicles are
removed en bloc.
Figure 119-8
Placement of nerve grafts. Transectionofafunc.
tional motor fasciclesoften requires placement of nerve grafts.A
localsensory nerve isharvested to serve a donor nerve. Underthe
operating microscope, the proximaland distal ends of the nerve
graft are secured to the proximaland distal stumps of the tran.
sected fascicleswith one to three 10-0 silksutures or fibronectin
glue.
lation of such to the neural elements. Ifthe tumor is located
in the lower thoracic region, spinal arteriography can beper-
formed to determine the blood supply of the spinal cord.In
addition, very large tumors can be embolized to ease surgical
removal.
We suggest, whenever
possible. employing a single-
staged combined intraspinal and thoracic approach tore-
move all aspects of the tumor. The intraspinal component
should be removed first because spinal cord compressionis
often the major source of concern. Once the intraspinal
component
is removed, the thoracic approach (thora-
coscopy or thoracotomy) is performed to remove intratho-

Dura
racicportions of the tumor not accessible via the posterior
spinalapproach. In older or debilitated patients. it may be
appropriateto forgo removal of the extraspinal
component.
Oncethe tumor removal is complete. the dura mater is
sealed(often requiring
a graft). Unilateral
loss of a facet
jointin the thoracic spine is easily tolerated.
In the cervical
orlumbar spine. a dumbell
tumor
resection
often requires
stabilization of the spine utilizing
bony fusion techniques.
SurgicalRemoval of a Dumbbell Tumor
Anesthesiaand Positioning
Thesurgery is performed
under general anesthesia.
A dou-
ble-lumen endotracheal
tube is placed
for selective
lung
collapse.The patient
is positioned
to allow for exposure
of
boththe posterior
and the anterior
spine (Fig. 119-10). The
lateralposition
requires
attention
to the dependent
arm
witha roll placed in the axilla to avoid pressure on the
brachialplexus. The extent of thoracotomy
to be performed
willbe dictated
by the size and position
of the extraspinal
tumor.For small tumors. taking the posterior
spinal dissec-
tionlateralto include removal of the head of the rib and full
facetectomyprovides adequate
exposure.
Larger tumors re-
quirethorascopic or thoracotomy
approaches
(Fig. 119-10).
Spinalcord monitoring
is employed
and steroids are admin-
istered.
119
Neoplasms of Peripheral Nerves
885
-----.........." ,,,\
\\
\
\
I
J,,
I
I
I
I
/
/
/
.-
.-
'"
""'"
Extentof
extradural
tumor
Figure 119-9
Exposureof intraspinal por-
tion of dumbbell tumor. Amidline skin inci-
sionismade overthe spine.Dissectioncontin-
ues to the spine followed by a subperiosteal
takedown of the paraspinous musculature.
Laminectomy isperformed and the dura and
arachnoid are opened with the aid ofthe op-
erating microscope. and retracting sutures
are placed in the dural edges. Ifrequired. a
facetectomy is performed to further expose
tumor. The dura isoften resected withthe tu-
mor necessitating a duralpatch.
Incision and Dissection
A midline skin incision is made over the spine. Dissection
continues to the spine by performing a subperiosteal take-
down of the paraspinous musculature. A paramedian ap-
proach can be considered if there is only a minimal in-
traspinal component. For small tumors a hemilaminectomy
can be accomplished but we usually opt for a complete
laminectomy because this provides better exposure (Fig.
119-9). The foramen involved by tumor is often enlarged.
and with subsequent surgical removal of the facet there is
ample room for surgical work.
We endeavor to remove the intradural tumor component
first. The dura and arachnoid are opened with the aid of the
operating microscope and retracting sutures are placed in
the dural edges. The bulk of the tumor can be separated
from the spinal cord using a microdissection
technique.
There may be several rootlets adherent to the tumor; some
can be dissected off the tumor whereas others will need to
be sacrificed. Adecision is made as to the likelihood of pro-
ducing a neurological deficit from tumor removal. Ifthe tu-
mor involves one or more of the cervical roots (5 to n. re-
moval of the tumor and associated rootlets may not be
warranted and debulking the tumor becomes a more pru-
dent course of action. In the thoracic spine. sacrifice of
rootlets is usually well tolerated.
The dura overlying the tumor at the foramen is often re-
moved with the tumor. The tumor can then be followed into

886
Peripheral Nerve: Pathology of the BrachialPlexus
Proximal portion,
thoracotomy
Midlinethoracic
incision C7-T4
Figure 119-10
Patient positioning~
lateral
extracavitory
approach.
Thep<
tient is positioned
to allow for exposul
of both
the
posterior
and
the anteriu
spine. A roll is placed inthe axillatoavoi
pressure
on the
brachial
plexus. Theex.
tent
of thoracotomy
to be performedw
be dictated
by the
size and position,
the extraspinal
tumor.
For small tumoo. !
taking
the posterior
spinal dissection~t. !
eral to include
removal
of the headoflfuI
rib and
full facetectomy
provides ad! I
quate exposure. Larger tumors requireI
second
incision
for thorascopic
orthor. I
cotomy approaches.
'
the foramen. Care is taken to maintain blood supply to the
cord by preserving radicular arteries.
When there is a large intrathoracic
component
to the
tumor, a thoracotomy is required to complete the tumor
removal (Fig. 119-11). The thoracic
exposure
is per-
formed once the intraspinal
component
has been re-
moved. Having a second surgical team working expedites
the surgery and lessens the anxiety over the possibility
of uncontrolIed
bleeding from the foraminal portion of
the tumor. A retropleural
approach provides adequate
exposure. Invasion of pleura by the tumor suggests ma-
lignancy. With removal of the intrathoracic
component
of the tumor, the enlarged foramen provides a panoramic
view from the spinal incision through
to the thoracic
cavity, often a disconcerting
experience
for the uniniti-
ated.
A dural graft is used to replace that portion of duraadher-I
ent to tumor. If only debulking
of the tumor can beaccom-
plished,
measures
are taken
to provide
space for tumor
growth; a generous
dural graft is placed, the laminectomyI
widened, and foraminotomies are performed whereturno,
exits the canal. The dura is closed in watertight fashion..-
decision as to the need for fusion is made. Ifa unilateraltho-
racic facetectomy was performed a fusion is not require~
With cervical or lumbar tumors, extensive bonyremoval
III
surgical exposure
is often folIowed by performing afusior
Despite having opened
the dura, a drain is often placedIt
prevent
hematoma
formation.
The enlarged foramencar
transport both blood and cerebrospinal fluid(CSF)intoth:
chest cavity and we are less apt to employ a drain ifachesr
tube is placed. A CSF leak may go undiagnosed
because0
the ability to accumulate
the fluid in the chest cavity.
Figure
119-11
Axial
view
of dumbbell
tumor. Th'
schematic
illustrates
the intraspinal.
foraminal. andir.
trathoracic components of the dumbbelltumor.Noteti"
extent
of spinal cord compression
produced bytheel
panding
intraspinal
component.
In addition. expansior
the foraminal
component
widens the intervertebralfor
men. When there
is a large intrathoracic
component'.
the tumor.
thoracotomy
is required for completetumr
removal.
In general.
the
intraspinal
component islie
moved
and the spinal cord decompressed
astheinit,.
procedure.

References
1. Hajdu SI. Peripheral
nerve sheath
tumors:
histogenesis,
classification,
and prognosis, Cancer 1993:72:3549-3552
2. Martuza
RL, Eldridge
R. Neurofibromatosis
2.
N Engl J
Med
1988;318:684-688
3. Enzinger FM, Weiss SW. Soft Tissue
Tumors.
2nd ed. St. Louis: CV
Mosby: 1988:724-815
4. Donner TR, Voorhies
RM. Kline DG. Neural
sheath
tumors
of major
nerves.J Neurosurg
1994;81:362-373
5. Breidahl WHo Khangure
MS. MRI of lumbar
and sacral plexus
nerve
sheath tumours.
Australas
Radiol1991
:35:140-144
6. Cerofolini E, Landi A. DeSantis G. et al. MR of benign peripheral
nerve
sheath tumors.J
Comput AssistTomogr
1991 :15:593-597
7. SuhJS, Abenoza P, Galloway
HR, et al. Peripheral
(extracranial)
nerve
tumors: correlation
of MR imaging
and histologic
findings. Radiology
1992;183:341-346
8. Zingale A. Consoli V.Tigano G, et al. CT morphology
of a median
nerve
neurilemmoma
at the arm:
case report
and review. J Neurosurg
Sci
1993;37:57-59
9. Haraida S. Nerlich AG, Bise K, et al. Comparison
of various
basement
membrane
components
in benign
and malignant
peripheral
nerve
tumours.
Virchows
Arch
A Pathol
Anat
Histopathol
1992:421:
331-338
10. FoleyKM,Woodruff JM. Ellis FT,et al. Radiation-induced
malignant
and
atypical peripheral
nerve sheath
tumors.
Ann NeuroI1980:7:311-318
119
Neoplasmsof PeripheralNerves
887
11.
Friedman
DP. Segmental
neurofibromatosis
(NF-5):
a rare form of
neurofibromatosis.
AJNRAm J Neuroradiol1991;
12:971-972
12.
Harper CM Jr, Thomas JE. Cascino TL, et al. Distinction
between
neo-
plastic and radiation-induced
brachial
plexopathy,
with emphasis
on
the role ofEMG. Neurology
1989:39:502-506
13.
Smith W. Amis JA. Neurilemoma
of the tibial nerve:
a case report. J
Bone Joint Surg Am 1992:74:443-444
14.
Stout AP. Tumors of the peripheral
nervous
system.
In: National
Re-
search
Council Comimittee
on Pathology,
ed. Atlas ofTumor
Pathol-
ogy, Section
II, fascicle 6. Washington.
DC: Armed Forces Institute
of
Pathology:
1949
15.
Giacobbe A, Facciorusso
D. Conoscitore
P. et al. Granular
cell tumor
of
the esophagus.
Am J GastroenteroI1988:83:1398-1400
16.
Levy Dl. Bucci MN. Weatherbee
L, et al. Intradural
extramedullary
ganglioneuroma:
case report and review ofthe
literature.
Surg Neurol
1992;37:216-218
17.
Resnick
JM, Fanning
CV, Caraway
NP. et al. Percutaneous
needle
biopsy diagnosis
of benign neurogenic
neoplasms.
Diagn Cytopathol
1997:161 :17-25
18. Grillo HC. Ojemann RG.Scannell JG, et al. Combined approach to
"dumbbell" intrathoracic and intraspinal neurogenic tumors. Ann
Thorac Surg 1983;36:402-407
19. OberleJ. KahambaJ. Richter H-P.Peripheral nerve schwannomas: an
analysis of 16patients. Acta Neurochir (Wien) 1997;139:949-953

120
Evaluation and Treatment of Traumatic
Peripheral Nerve Injuries
Gerald A. Grant, Robert Goodkin, and Michel Kliot
. CaseHistory:PartI
.
Peripheral Nerve Anatomy
.
Preoperative Planning
. Grading
Neurapraxia
Axonotmesis
Neurotmesis
.
Case History: Part II
.
Electrodiagnostic Evaluation
Neurosurgeons encounter patients who sustain acute open
and closed peripheral nerve traumatic injuries. General
principles based on an understanding of the basic biology of
nerves and their response to injury can be used to diagnose
and manage peripheral nerve problems. We begin by de-
scribing peripheral nerve anatomy in a context that is rele-
vant to understanding the different grades of nerve injury.
Using a clinical case example of a lower extremity periph-
eral nerve traumatic injury, we illustrate how an under-
standing of the different grades of peripheral nerve injury
can be applied to clinical, electrodiagnostic, and magnetic
resonance imaging (MRI)findings to formulate an appropri-
ate treatment plan.
. Case History:Part I
A29-year-old man suffered an open traumatic laceration
of the right sciatic nerve in the lower thigh after falling
through a glass window. Immediately after the injury, he
888
.
Radiological Evaluation
.
Case History: Part III
.
Case History: Part IV
.
Electrophysiological
Monitoring
.
Surgical Techniques
.
Case History: Part V
.
Postoperative Care
.
Summary
was unable
to dorsiflex
his right foot and complained of
numbness
along
the
dorsum
of his foot. Emergent
exploration of his right posterior thigh and sciaticnerve
documented
a complete
transection
of the right common
peroneal nerve and partial transection of the tibialnerve
just
above the popliteal
fossa, both
of which were
surgically
reanastomosed
with interrupted
7-0 nylon
sutures.
.
Peripheral Nerve Anatomy
The lumbosacral
plexus arises from the first lumbar through
the fourth sacral spinal nerves. The femoral and obturator
nerves arise from the anterior divisions of L2-L4.Thesciatic
nerve is the largest nerve in the body and arises fromthe
L4-S4 spinal nerves. This nerve passes through the sciatic
notch
and
travels
down
the
back
of the
leg where it
branches into peroneal and tibial nerves, usuallyjust above
the popliteal fossa (Fig.120-1).
iI
I
l

Femoral
nelVe
Superficial
peroneal
nerve
Lateral femoral
cutaneous
nerve
Obturator
nerve
Deep
peroneal
nerve
Sciatic
nerve
1ibial
nerve
1ibial
nerve
.......
120
TraumaticPeripheralNerve Injuries
889
Common
peroneal
nerve
Figure 120-1
The lumbosacral plexus
and several of its major (A) anterior and
(B) posterior nerve branches.

890
Peripheral Nerve: Pathology of the BrachialPlexus
.
PreoperativePlanning
I
Open Injury
I
Traumatic peripheral nerve injuries can be classified into
open and closed injuries. Decision making for open injuries
is relatively straightforward in contrast to that for closed in-
juriesl-3 (Figs. 120-2 and 120-3). Immediate repair of acute
sharp lacerating injuries should be undertaken with the
goal of performing a primary end-to-end
suture repair
when possible. Ifthe nerve ends are ragged or contused. or
the trauma is thought to involve the transmission of blunt
force. a delayed surgical repair should be performed after
an interval of at least 2 to 3 weeks to allow for scar forma-
tion. This delay will then allow for demarcation of the
healthy proximal and distal nerve ends from the interven-
ing scarred segment. Surgicalresection of the fibrosed prox-
imal and distal nerve segments back to normal fascicular
structures at each end should then be performed followed
by a repair with or without interposition nerve grafts de-
pending on the gap length.
lesion In Discontinuity
1
lesion In
Continuity
!
Medical
management
and
close follow-up
with serial clinical,
electrodiagnostic,
and imaging
examinations
J
Sharp
transection
J
End-to-end
repair
!
Blunt
transection
J
Delayed repair
J
Resect
intraneuralscar
and perform
surgical repair
(:tgratt)
Figure 120-2
Guidelines in the management
of open traumaticj)e-
ripheral nerve injuries.
I Closed Injury
I
J
Clinical exam
Electrodiagnostic
studies (EMGlNCVlSSEP)
Imaging studies
(MRIIMRN)
Axonotmesls vs. Neurotmesls
vs. Spinal nerve root avulsion
t
Surgical exploration
withintraoperative
electrophysiological
monitoring
Neurapraxla
1
Medical
management
Axonotmesls
1
Medical
management
Recovery
over weeks
to months is
dependent
on multiple
factors
Excellent
recovery
inweeks
Spinal nerve
rootavulsion
confirmed by
absent SSEP
!
Neurotization
procedure
Absent nerve
conduction
response
across
lesion
1
Neurotmetic lesion:
Resect intraneural scar
and perform surgical
repair (:tgratt)
Positive nerve
conduction response
across lesion
1
Axonotmetic lesion:
medical management;
recovery over weeks to
months is dependent
on
multiple factors
Figure 120-3
Guidelines in the management
of closed traumatic
peripheral nerve injuries. EMG.electromyography;
MRI.magnetic resonanimaging; MRN.magnetic resonance neurography; NCV.; SSEP.somatosensory
evoked potential.lAQ5J