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

790
MinimallyInvasiveSpine Procedures: Cervical
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Figure 107-5
(A) A small Kerrison rongeur being usedto begin the foraminal exposure. (8) Drilling of the facet overlying the axilla and proximal
takeoff of the corresponding nerve root is performed. (C) The laminoforaminotomy is continued. (D) A microcurette is utilized to further decom-
pressthe nerveroot. (E) Nerve hook being passedalong the courseof the exiting root to ensureadequate decompression. If needed, a diskectomy
canbeperformed.(F) A blunt hook dissector isutilized to confirm the foraminal decompression.INF,inferior; LAT,lateral.
osteophytes and bone spurs can be flattened or resected.
Paracentral disk herniations or osteophytes can sometimes
be decompressed aswell. However, it is difficult to address
truly central canal pathology through the MEF approach
and caution should be exercised not to exert undue medial
retraction
on the spinal cord. Far-lateral
foraminal
stenosis
or disk herniations can be decompressed through the MEF
approach
by either
extending
or beginning
the exposure
more laterally. Because the nerve root often passes in close
proximity
to the vertebral
artery laterally, particular
atten-
tion should be paid during decompression
in this area. In-
advertent passage of instruments beyond the margin of the
foramen transversarium
in the coronal plane should be
avoided. Briskdark bleeding is often encountered fromthe
rich venous plexus that typically surrounds
the space
around the vertebral artery. When encountered, such bleed-
ing should serve as a useful warning to limit further dissec-
tion and avoid inadvertent arterial injury. Upon completion
of the diskectomy and decompression, the nerve hookis
again passed along the exiting root to confirm its free
passage, and a lateral fluoroscopic image is obtained
(Fig.107-6A).It is important to ensure that the nerveroot
be palpated along its anterior surface to ensure that thereis
no residual compression along its course. This is particu-
larlytrue at the axillaand shoulderwhereitjoinsthe spinal
cord. Unnecessary excessive decompression
of the facet

~
107
CervicalEndoscopic Foraminotomy
791
Figure107-6
(A) Confirmation
of the decompression
is obtained
by passing an instrument
freely through
the foramen.
If needed, a diskectomy
canbeperformed. (8) Postoperative
CTM showing foraminotomy
defect.
shouldbe avoidedto prevent iatrogenicinstabilityof the
cervicalmotion segment. Raynor concluded that the in-
tegrityof the majority of the facet joint is essential for
stabilityand that no more than 50%of the facet should be
removedto maintain its integrity.12Fig. 107-68 illustrates
thetypicalforaminotomy defect that is obtained after MEF
withgoodpreservation of the lateral mass integrity.
Closure
Afterinspection of the nerve root, meticulous hemostasis
shouldbe obtained by a combination of bipolar cautery and
gentletamponade with thrombin-soaked Gelfoampledgets.
Thearea is then copiously irrigated with lactated Ringer's
impregnatedwith bacitracin antibiotics. Although optional,
wehaveusually gently placed a small pledget of Gelfoam
soakedwith Solumedrol over the laminoforaminotomy de-
fect.Useof epidural morphine paste or similar cocktails is
reasonableif there is no evidence of dural erosion or tear.
Suchagentsmayhelp to reducepostoperativepain and al-
lowformore rapid recovery and ambulation. The tubular re-
tractorand endoscope are then cautiously removed and a
routineclosure of the fascia and skin performed. Antibiotic
irrigationshould be used to copiously wash this soft tissue
corridorprior to placing sutures. Because the defect is typi-
callyquite small, only a limited amount of closure need
beperformed and a drain is not needed. A O-Vicryltype
References
1. FrykholmR.CelVicalnelVeroot compression resulting from disk degen-
eration and root sleeve fibrosis. Acta Chir Scand 1951;160:1-149
2. Krupp W, Schattke H, Muke R.Clinical results ofthe foraminotomy
as
described by Frykholm for the treatment
of lateral celVical disk her-
niation. Acta Neurochir (Wien) 1990;107:22-29
3. ScovilleWB, Dohrman GJ, Corkill G. Late results
of cervical
disk
surgery.JNeurosurg 1976;45:203-210
reabsorbable stitch is used to close the lumbodorsal fascia in
a figure of eight. Marcaine (0.25%)is used to inject the skin
edges and superficial musculature prior to closure. Inverted
2-0 Vicryl stitches are used to close subcutaneous layer. A
4-0 clear Vicrylsubcuticular closure is then used to carefully
reapproximate the skin,with care paid to avoid inversion of
the edges. Either Steri-Strips or Dermabond can then be
used to cover the skin. Dermabond is attractive because it
keeps the skin edges closelyapproximated for a 7- to 10-day
period as well as providinga waterproof barrier. The patient
can thus shower almost immediately after surgery.
For cases where a CSFleak has occurred, direct repair is
difficult because the durotomy is small and the access lim-
ited. Thus we have routinely employed a lumbar drain for 2
to 3 days postoperatively to help close the small dural tear.
Additional adjuncts such as fibrin glue, fat, or muscle grafts
can also be used. Spinal headaches and nausea associated
with the lumbar drainage are treated symptomatically with
nonsteroidal anti-inflammatory medications and bed rest.
For large dural tears, direct repair can be attempted if spe-
cialized instruments are available for use through the endo-
scopic tube. Castro-Viejo type needle holders and long
forceps are particularly useful in this regard. In rare in-
stances, conversion to an open procedure may be necessary
to close large dural violations. To date, we have not had
problems with delayed pseudomeningoceles
or CSFleaks
after simple lumbar drainage.
4.
ScovilleWB,Whitcomb BB.Lateral rupture of celVical intelVertebral
disks. Postgrad Med 1966;39: 174-180
5. ScovilleWB,Whitcomb BB.Lateral rupture of celVical intelVertebral
disks. Postgrad Med 1966;39:174-180
6.
Aldrich F.Posterolateral
microdiskectomy
for cervical monoradicu-
lopathy
caused by posterolateral
soft cervical disk sequestration.
JNeurosurg 1990;72:370-377

792
Minimally InvasiveSpineProcedures:Cervical
7. Henderson
CM. Hennessy RG. Shuey HJ. et at. Posterior-lateral
foraminotomy as an exclusive operative technique for cervical radicu-
lopathy: a review of 846 consecutively operated cases.Neurosurgery
1983;13:504-521
8.
Murphey F.Simmons JCH. Brunson B. Cervical treatment
of laterally
ruptured cervical disks: review of 648 cases. 1939-1972. J Neurosurg
1973;38:679-683
9.
Odom GL. Finney W. Woodhall
B. Cervical disk lesions. JAMA 1958;
166:23-28
10.
Raaf JE. Surgical treatment
of patients
with
cervical disk lesions. J
Trauma 1969;9:327-338
11.
Woertgen C. Holzschuh M. Rothoerl RD. et at. Prognostic factors of
posterior cervical disk surgery: a prospective. consecutive study of 54
patients. Neurosurgery 1997;40:724-729
12.
Raynor R. Anterior
or posterior
approach to the cervical spine:an
anatomical
and radiographic
evaluation
and comparison. Neuro-
surgery 1983;12:7-13
13.
Roh SW. Kim DH. Cardoso AC. Fessler RG. Endoscopic foramino-
tomy using MED system in cadaveric specimens. Spine 2000;25:
260-264
14.
Zeidman
SM. Ducker TB. Posterior cervical
laminoforaminotomy
for radiculopathy: review of 172 cases.Neurosurgery 1993;33:
356-362
15.
Fessler RG. Khoo LT. Minimally
invasive cervical microendoscopic
foraminotomy
(MEF): an initial
clinical experience. Neurosurgery.In
press

..
108
ThoracicEndoscopicSympathectomy
CurtisA.Dickman, Jonathan J. Baskin, and Nicholas Theodore
. Indications
. Contraindications
. Advantages
. Disadvantages
. Palmar,Axillary, and Plantar Hyperhidrosis
. UpperExtremity Pain Syndromes
. IschemicSyndromes
. CancerPain
. CardiacArrhythmia
Severalclinical syndromes that result from pathologically
elevatedsympathetic
tone can be treated surgically by tho-
racicsympathectomy.These entities include palmar or axil-
laryhyperhidrosis,pain syndromes involving the upper ex-
tremities such as reflex sympathetic
dystrophy
(RSD),
ischemicsyndromes
ofthe
hand such as Raynaud's disease,
andmalignant tachyarrhythmias
refractory to medical man-
agement.Physiologically, these disease processes
are medi-
atedprimarily through
the second,
third, and sometimes
fourthsympathetic ganglia.
Open surgical
approaches
previously
described
for le-
sioningthese structures
include
the extrapleural
or sub-
pleuralposterior
approach,
the transaxillary
approach,
the
supraclavicular approach,
or the anterior
thoracotomy
ap-
proach.I-3When these autonomic syndromes threaten nei-
therlife nor limb, many patients choose to live with
theirdebility rather than undergo the major surgery in-
volvedwith open surgical procedures. Thoracic endoscopic
sympathectomy, a technique
first described
-50
years ago,4
providesan appealing
alternative
for patients
with condi-
tionsthat are treatable by sympathetic denervation.
Theevolution of video-assisted
thoracoscopes
and related
instrumentation
allows
sympathectomy
to be performed
safelyand efficiently
through
a minimally
invasive tech-
niquethat is appealing
for several reasons.
Patients
com-
plainofrelatively little pain after the thoracoscopic proce-
dure.Theyare seldom hospitalized longer than a single day
aftersurgery. Furthermore,
the time within which patients
return to work is significantly
accelerated
when compared
withopen thoracic procedures.
We describe
the preferred
. Goals
.
Surgical Technique
Positioning
Incision and Instrument Placement
Anatomical Orientation
Sympathectomy
Closure
.
Outcomes
.
Complications
.
Conclusion
method for performing this procedure by the senior author
(CAD)as learned through his experience with more than
100 such cases.
.
Indications
.
Hyperhidrosis
. Palmar
. Axillary
. Plantar
.
Pain syndromes
.
Posttraumatic (complex regional pain syndrome)
. RSD
.
Phantom pain
.
Cancer pain
.
Pancreatic pain
.
Ischemic syndromes
.
Raynaud's disease
.
Tachyarrhythmia
.
Contraindications
. Previous ipsilateral thoracotomy or thoracoscopy
(relativecontraindication)
. Previousradiofrequencyor alcoholsympathectomy
(relative contraindication)
793

794
Minimally InvasiveSpineProcedures:Thoracic
. Previouspleural inflammatory disease
. Cardiacor pulmonary disease precluding unilateral
ventilation
. Densepleuraladhesions
. Previoussurgical procedures or pulmonary infections
that causedpleuralscarring
.
Advantages
. Lessapproach morbidity compared with open procedure
.
Shorter hospital stay and quicker return to work
.
Reduced postoperative pain
.
Superior outcomes compared with medical therapies
.
Effectivenessequivalent to open procedures
.
Disadvantages
. Learning curve associated
with using endoscope
. RiskofHorner'ssyndrome
. Endoscopylimited by scarring or inability to tolerate
single-lungventilation
. Potentialforinjurytogreatvesselsandforpneumothorax
. Possiblepostoperativecompensatoryhyperhidrosissyn-
drome
.
Palmar,Axillary,and Plantar
Hyperhidrosis
Atour institution, idiopathic (essential) palmar hyperhidrosis
isthe most common indication for thoracoscopic sympathec-
tomy.Most patients who receive a neurosurgical referral for
this condition have been evaluated for metabolic (hyperthy-
roidism) or neoplastic etiologies and have failed efforts at
medicalmanagement with topical and anticholinergicagents.
Hyperhidrosis is a significantly disabling condition that
affects patients both sociaIlyand professionaIly. Frequently,
there is a positive family history for this condition. Hyper-
hydrosis can adversely affect the ability to hold children
safely,write, shake hands, handle papers, use a computer,
and maintain relationships. In its most severe incarnation,
hyperhidrosis can cause sweat to drip spontaneously from a
patient's hands and feet. Symptoms are exacerbated by
even mildly stressful situations, exercise, or warm weather.
Whereas systemic drugs and topical agents provide only
temporary
or
partial
symptomatic
relief
of
these
symptoms,I-3.5the success rate of sympathectomy for per-
manent relief of palmar hyperhidrosis ranges from 90 to
100% in clinical series.1-3.6-13Axillary hyperhidrosis and
bromhidrosis
(axillary malodor) can also be addressed
through a sympathectomy that targets the 13 and T4ganglia.6
Associated plantar hyperhidrosis often (50%)resolves when
hyperhidrosis of the upper extremities is relieved and is re-
ferred to as a "dividend benefit" of the procedure becauseit
is not an expected effect of transecting the upper thoracic
sympathetic chain.
. Upper Extremity PainSyndromes
RSDis one of several pain syndromes that typicaIly follow
trauma. In addition to pain, RSDis characterized
by vasomo-
tor changes, edema, and trophic changes to the extremity.14
Current evidence suggests that an upregulated
sensitivity of
ex-adrenoreceptors
for catecholamines
in the injured limb
may induce RSD. Medical therapy tends to be ineffective in
terms of both the degree and the duration
of relief. Patients
who
experience
symptomatic
relief
after
percutaneous
blocks of the steIlate ganglion
with local anesthetic
agents
are considered
candidates
for surgical sympathectomy.2.7.11
Long-term clinical benefits have been reported for thisindi-
cation in more than 50%of patients.15.16Due to the uncer-
tainty of its pathogenesis,
RSD has been renamed
complex
regional pain syndrome
type 1.17
. IschemicSyndromes
Patients with severe upper extremity
ischemia
due to Ray-
naud's disease or related disorders may also benefit from
sympathectomyp.1I Although the ischemic process is typi-
caIly progressive, sympathectomy
can be used to avoid limb
amputation and to improve the associated complaints ofpain.
.
Cancer Pain
Sympathectomy can also effectively relieve pain relatedto
pancreatic
carcinoma.
IS This procedure
entails lesioning the
sympathetic ganglia on the left side from T5 through 19to
denervate the greater splanchnic nerve and the no andT11
ganglia to denervate the lesser splanchnic nerve.
. CardiacArrhythmia
Relativehyperactivityof left-sided sympathetic tonein-
creases the QTinterval on electrocardiography.15.19
Con-
versely, stimulation on the right side from the n
through
T4 ganglia decreases the QTinterval. Lesioning the ganglia
on the left side from n through T4 shortens the QTinterval
and reduces the risk of experiencing a malignant arrhyth-
mia in conjunction with a prolonged QTintervaJ.2o
. Goals
Sympathetic denervation can be achieved through several
actions. The autonomic
tissue can be resected or the
connectionsbetween the gangliaand the autonomicchain
can be disrupted using sharp transection or with thermal
methods. With regard to the latter modality, monopolar
electrocoagulation, percutaneous radiofrequency rhizotomy,

andlaservaporization have all been used. Our practice has
shiftedfromen bloc excision of these neural structures (gan-
gliawiththe interval sympathetic chain) to sharp transec-
tionofthegangliaand sympathetic chain with cauterization
andscissors.
Whilethis procedure is performed, the accessory inner-
vationsto the sympathetic chain must also be addressed.
Theaccessory nerve of Kuntz, if present,
arises
from the
sympathetictrunk at the level of n,
12, or 13. It must be
transectedto optimize
the chances
of the sympathectomy
beingeffective.21Preserving
the rostral
half of the stellate
ganglionin its position overlying the first rib head avoids
incurringaHorner's syndrome during the sympathectomy.
. SurgicalTechnique
Positioning
Weconductthe procedure with the patient in a lateral
decubitusposition (Fig. 108-1). This position permits
dependent
retractionofthe lungand rapidconversiontoan
Figure108-1
Patientpositioningfor left-sidedsympathectomy.The
patientisplacedina right lateraldecubitus position.Theleft upper ex-
tremityand right axilla are padded (as are the hips and knees). Asingle
portalisplaced for the thoracoscope
(posterior axillary line, fifth inter-
costalspace), and then a second "working channel" incision is placed
(anterioraxillaryline, third intercostal space). (With permission from
BarrowNeurologicalInstitute.)
108
Thoracic Endoscopic Sympathectomy
795
open procedure if necessary.Sympathectomy has also been
reported using a supine position.13 Regardless of position-
ing, patients are placed under general anesthesia after
intubation with a double-lumen
endotracheal tube. A pro-
phylactic dose of antibiotic is administered.
If a bilateral sympathectomy is necessary, the procedures
are performed sequentially under the same anesthetic with
the patient being repositioned and red raped between pro-
cedures. The patient's arm is abducted and elevated 90 de-
grees to the chest wall to expose the axilla, and the arm is
flexed 90 degrees at the elbow. After the arm has been
padded, it is secured to an arm board. A towel roll pads the
dependent axilla. The lateral thoracic wall and axilla are
broadly prepared in the event that conversion to an open
thoracotomy should become necessary, and the patient is
taped securely to the table. Palmar temperature is moni-
tored bilaterally to document vasodilatation related to the
sympathectomy.
With
the surgeon standing ventral to the patient, the
patient is rotated -40 degreestoward the surgeon.This ori-
entation allows gravity to retract the lung and brings the
thoracic vertebral column within view. A mild reverseTren-
delenburg position allows the lung to fall away from the
apex of the pleural cavity. The ipsilateral lung is selectively
deflated
by the anesthesiologist,
and oxygenation
and
ventilation
are maintained through the contralateral lung.
Freedom to move the operating table is particularly
impor-
tant because pleural insufflation
is not used to facilitate
exposure.
Incision and Instrument Placement
The sympathectomy procedure is performed through two
incisions (5 mm each) in the chest wall. Asingle 5 mm di-
ameter portal (KarlStorz, Tuttlingen, Germany) is placed in
the middle or posterior axillary line within the fourth or
fifth intercostal space with care exerted to avoid the inter-
costal bundle along the caudal aspect of the rostral rib.
The 5 mm diameter rigid rod-lens thoracoscope is passed
through this portal (Table 108-1). A second 5 mm inci-
sion is placed in the anterior axillary line within the third
intercostal space, and a hemostat is used to perforate the
parietal pleura under direct visualization with the thoraco-
scope. Care is taken to avoid the subclavian vessels near the
firstand secondintercostalspaces.The5 mm diameteren-
doscopic monopolar scissors are passed over the hemostat
into the thoracic cavity and the hemostat is then removed.
Limiting the number of portals within the intercostal space
lessens the risk of the patient developing postoperative in-
Table 108-1
Instrumentation forThoracoscopic
Sympathectomy
Thoracoscope (5 mm diameter telescope)
Endoscopic monopolar cauterization scissors
Two 5 mm endoscope ports with trocars
Three-chip endoscopic video system
High-resolution monitor

796
MinimallyInvasiveSpine Procedures: Thoracic
tercostal neuralgia. Gently patting the deflated lung with an
endoscopic dissection tool produces further atelectasis and
improves the visualization of the spinal column. Ifthe lung
continues to obscure exposure. a third incision can be made
so that a lung (fan) retractor can be placed.
Anatomical Orientation
Typically,the stellate ganglion. sympathetic chain. and ac-
cessory sympathetic innervation can be visualized beneath
the parietal pleura. The sympathetic chain is recognized as
it crosses over the rib heads (Fig. 108-2). The first rib can be
palpated. and the second through fourth ribs can be visual-
ized directly. The stellate ganglion is located directly over
the head of the first rib and typically is surrounded by a fat
pad within the thoracic outlet, adjacent to the subclavian
vasculature.
Care must be taken to avoid injuring the several large re-
gional vessels. Tributaries of the second, third. and fourth
intercostal veins merge to form the superior intercostal
vein, which then empties into the azygos vein. The first in-
tercostal vein drains directly into the brachiocephalic vein.
Because the sympathetic chain is positioned superficial to
the segmental and intercostal vessels. it can be transected
without sacrificingany of these vessels.
Sympathectomy
At the levels of interest. autonomic tissue is transected us-
ing the monopolar cauterization scissors (Fig. 108-3). We
routinely isolate the T2ganglia for palmar hyperhidrosis by
transecting the sympathetic chain over the second and third
rib heads and include the T3 and T4ganglia for axillary hy-
perhidrosis. In our experience. results with this technique
are comparable to those obtained following an en bloc re-
section of the sympathetic chain. Because the sympathetic
chain does not have to be dissected away from the vertebral
..
Figure 108-2
Illustration of the left pleural
cavity. The ipsilateral
lung has been deflated,
and the vertebral column. rib heads. and overly.
ing sympathetic
chain are visible. (With permis-
sion from Barrow Neurological Institute.)
column,this modifiedprocedureis saferand fasterto per-
form. It has less blood loss and requires fewer portals.The
scissors are used to "hook" and elevate the sympathetic
ganglia away from the rib head. The tissue is then sweptlat-
erally (away from the segmental vessels) and coagulated.
When the monopolar scissors are used, care must be ex-
erted to ensurethat the lungparenchymaisprotectedfrom
thermal injury. Centering the dissection directly overtherib
head protects the intercostal nerve.
The effectiveness of the sympathectomy isjudged intra-
operatively by monitoring
palmar skin temperature. A
unilateral increase of 1 to 3°C occurs when an adequate
sympathectomy has been performed.6.10.12This increasein
Figure 108-3
Illustration demonstrating
the use of monopolar
cauterization to dissect the sympathetic ganglia laterally alongthe
corresponding rib and then to transect the sympathetic chain com.
pletely. (With permissionfrom BarrowNeurological Institute.)

108
Thoracic
Endoscopic
Sympathectomy
797
Figure108-4
Intraoperative
view of completed
12, 13, and 14 sym-
pathectomy.
temperaturetypically occurs over 10 to 20 minutes. If pal-
marskin temperature
fails to increase,
the presence
of an
aberrantaccessory
sympathetic
supply
that is still func-
tionalmust be sought.
Another
possibility
is that
the
inferiorthird of the stellate ganglion is contributing sympa-
theticinputthat needs to be addressed.
Closure
Afterlesioning is completed (Fig. 108-4), a small diame-
ter(22French) apical chest tube is inserted through the
sameincisionthat was used to insert the monopolar scis-
sors.The lung is reinflated
by the anesthesiologist
under
directthoracoscopic
visualization.
The chest tube
is
connected
to suction to evacuate intrapleural
air. If a
contralateral
sympathectomy
is to be performed.
the
chest tube is left in place with an occlusive dressing. This
strategy protects against difficulties with oxygenation or
ventilation
related to the deflation of both lungs. After
the contralateral sympathectomy has been completed, the
contralateral lung is reinflated and the chest tubes are re-
moved bilaterally. Incisions are closed using subcuticular
sutures and Steri-Strips. Achest radiograph (upright, an-
teroposterior
view at end expiration) is obtained in the
recovery room to confirm the absence of persistent pneu-
mothoraces. Patients are observed on a regular hospital
floor and typically discharged within
24 hours of the
procedure.
.
Outcomes
Among the autonomic-mediated
syndromes, the success
rate of endoscopic sympathectomy is highest for treating
palmar hyperhidrosis. Several series, which reflect the
prevalence of this disease in Asian populations, have re-
ported success rates between 95 and 100%for a combined
population of more than 500 patients (Table 108_2).1-3.6-12
Lesioningthe sympathetic chain with a subsequent increase
in the intraoperative palmar temperature of at least 3°( has
provided the best immediate and long-term clinical out-
comes. In these series, the sympathetic chain was resected
en bloc to minimize the risk of recurrent hyperhidrosis. As
noted, our practice of transecting the ganglia at the level of
the respective rib heads has provided clinically equivalent
results. Sympathectomy for palmar hyperhidrosis will re-
lieve plantar hyperhidrosis in half to two thirds of cases.6
Axillary hyperhidrosis and bromhidrosis will improve in
80%of patients who undergo lesioning of the 13 and T4
ganglia.6
Table108-2
Thoracoscopic Sympathectomy
for Palmar Hyperhidrosis
Dividend Benefits
Complications
Reliefof
Plantar
Axillary
No.
Palmar
Hyperhidro-
Hyperhidro-
Compensatory
Gustatory
Horner's
No.
Sympa-
Hyperhidrosis
sis Relief
sis Relief
Hyperhidro-
Sweating
Syndrome
Author Year
Patients
thectomies
No.(%)
No.(%)
No.(%)
sis No.(%)
No.(%)
No. (%)
Kux,81978
63
124
63(100)
-
51 (81)
28(44)
2
0
Lin,91990
21
42
42 (100)
3 (14)
-
1 (5)
-
0
Robertson et al,21993
22
-
22 (100)
-
-
3 (14)
0
1 (5)
(transient)
Kaoet al,l 1994
300
600
287 (96)
210(70)
19/24 (79)
150 (50)
3 (1)
0
leeand Hwang,I8 1996
82
164
164(100)
41 (50)
-
50 (61)
0
0
Johnsonet ai,221996
65
112
48(100)
-
-
11 (16.9)
2 (3)
8 (12.3)
(7 tran-
sient)
lai et al,131997
72
144
67 (93.1)
-
-
71 (99)
12(16.7)
5(6.9)

798
MinimallyInvasiveSpineProcedures:Thoracic
.
Complications
In a significant number of patients, sympathectomy
for
hyperhidrosis can cause a postoperative compensatory hy-
perhidrosis syndrome (CHS,Table 108-3). Aretrospective
review of 104 patients in Taiwan treated with thoracoscopic
sympathectomy reported CHSin 71 of the 72 patients avail-
able for follow-up.13CHSinvolves increased sweating of the
chest, abdomen, legs, and/or back (nondenervated
ar-
eas).3.6.tO.22
The severity of this response does not appear to
be influenced by the extent of preoperative hyperhidrosis or
by family history.13CHSsymptoms typically improve or re-
solve within 6 months of surgery.toThe incidence of CHSaf-
ter sympathectomy in patients living in Israel, Austria, Ire-
land, and England ranges between 40 and 75%.13Most
patients who develop CHShave mild or moderate sweating
and are satisfied with the effects of their relief of palmar
sweating. Only 5 to 10%of patients who develop CHShave
severe sweating that drenches their clothing and bedsheets
and creates a disabling problem. The CHSreflects the im-
portant thermoregulatory
need for sweating to dissipate
heat and ongoing generalized sympathetic hyperreactivity.
Vascularinjury requiring conversion to an open procedure
has not occurred in any of our cases and can be minimized
Table 108-3
Complications ofThoracoscopic Sympathectomy
Compensatory hyperhidrosis syndrome (CHS)
Horner's syndrome
Intercostal neuralgia
Pneumothorax
Gustatory sweating
Vascular injury
References
1.
Kao M-C. TsaiJ-C, Lai D-M, et al. Autonomic
activities
in hyperhidrosis
patients
before. during,
and after endoscopic
laser sympathectomy.
Neurosurgery
1994;34:262-268
2.
Robertson
DP. Simpson
RK, Rose JE, et al. Video-assisted
endoscopic
thoracic ganglionectomY.J
Neurosurg
1993;79:238-240
3.
Cloward RB.Hyperhydrosis.J
Neurosurg
1969;30:545-551
4.
Kux E.The endoscopic
approach
to the vegetative
nervous
system and
its therapeutic
possibilities.
Dis Chest 1951 ;20: 139-147
5.
Shelley WB, Florence
R. Compensatory
hyperhidrosis
of sympathec-
tomy. N EnglJ Med 1960;263:1056-1058
6.
Kao Me. Video endoscopic
sympathectomy
using
a fiberoptic
C02
laser to treat palmar
hyperhidrosis.
Neurosurgery
1992;30: 131-135
7.
Kuntz A. Distribution
of the sympathetic
rami to the brachial
plexus:
its relation
to sympathectomy
affecting
the upper
extremity.
Arch
Surg 1927; 15:871-877
8.
Kux M. Thoracic
endoscopic
sympathectomy
in palmar
and axillary
hyperhidrosis.
Arch Surg 1978;113:264-266
9.
tin
Ce. A new
method
of thoracoscopic
sympathectomy
in hyper-
hidrosis
palmaris.
Surg Endosc 1990;4:224-226
10.
Ray B. Sympathectomy
of the upper extremity:
evaluation
of surgical
methods.J
Neurosurg
1953;10:624-633
11.
Shih CJ,Wang ye. Thoracic sympathectomy
for palmar hyperhidrosis:
report of 457 cases. Surg NeuroI1978;10:291-296
12.
Stolman
LP.Treatment
of excess sweating
of palms by iontophoresis.
Arch DermatoI1987;123:893-896
by defining the regional anatomy with the thoracoscopebe-
fore other endoscopic instruments are placed. Pneumotho-
rax requiring replacement of a chest tube is rare as longas
the visceral pleura of the lung is not violated during the
procedure. Intercostal neuralgia is avoided by minimizing
dissection and traction against the intercostal
bundle.
Horner'ssyndromeisavoidedbysparingthe rostralstellate
gangliaand usuallyresolvesspontaneouslyeven ifitdoes
occur. Electrical or mechanical stimulation of this structure
causes pupillary dilation that can be observed by the anes-
thesiologist. It has been reported as a useful test forthis
structure.16In our experience, no procedures have required
conversion to thoracotomy. Furthermore, no patients have
required a second procedure because their preoperative
complaints failed to improve or because they developed
recurrent
hyperhidrosis. Gustatory sweating, the result
of aberrant
synapses developing between
sympathetic
fibers and the vagus nerve, has been reported in 1 to 2%of
patients.13
.
Conclusion
Thoracic endoscopic sympathectomy is an efficaciousand
minimally invasive means of providing significant relieffor
patients with sympathetically
mediated autonomic syn-
dromes. Comparedwith the previousalternatives ofpos-
terolateral thoracic sympathectomy and open thoracotomy
techniques, patients experience significantly less muscle
pain, which results in shorter hospital stays and a more
rapid return to work. Our practice of ablating the sympa-
theticgangliabymonopolarcauterizationhas furthershort-
ened operative times, reduced blood loss, and improved
cosmetic results. Bilateral sympathectomies
can nowbe
performed in 5 to 10 minutes of operative time per side.
13. LaiV-ToYangL-H.Chio C-C,et al. Complications in patients withpal-
mar hyperhidrosis
treated
with transthoracic
endoscopic
sympathec-
tomy. Neurosurgery
1997;41 :110-115
14. van der LaanL.ter LaakHJ.Gabreels-Festen A.et al. Complexregional
pain syndrome
type I (RSD): pathology
of skeletal muscle and periph-
eral nerve. Neurology
1998;51 :20-25
15.
Johnson
JP, Ahn SS. Thoracoscopic
sympathectomy.
Techniques in
Neurosurgery
1997;3:308-314
16.
Segal R. Ferson PM, Nemoto
E, et al. Blood flow-monitored
transtho-
racic endoscopic
sympathectomy.
In: Rengachary
SS, Wilkins RH,eds.
Neurosurgical
Operative
Atlas. Park Ridge. lL: American Association of
Neurological
Surgeons;
1998:163-171
17.
Stanton-Hicks
M,Janig
W. Hassenbiusch
S, et al. Reflex sympathetic
dystrophy:
changing
concepts
and taxonomy.
Pain 1995;63:127-133
18. Lee KH,Hwang PYK.Video endoscopic sympathectomy
for palmar
hyperhidrosis.J
Neurosurg
1996;84:484-486
19.
Schwartz
PJ. Locati E, Priori
SG. et al. The idiopathic
long QT syn-
drome.
In: Zipes
DP, Jalife
J. eds.
Cardiac
Electrophysiology:
From Cell
to Bedside. Philadelphia:
WB Saunders;
1990:589-605
20.
Ouriel
K, Moss AJ. Long QT syndrome:
an indication
for cervicotho-
racic sympathectomy.
Cardiovasc Surg 1995;3:475-478
21.
Worsey J. Ferson PF, Keenan RJ,et al. Thoracoscopic
pancreatic
dener-
vation
for pain
control
in irresectable
pancreatic
cancer.
Br J Surg
1993;80:1051-1052
22.
JohnsonJP,
Obasi C. Hahn MS. et al. Endoscopic
thoracic
sympathec-
tomy. J Neurosurg
Spine 1999;91 :90-97

109
ThoracoscopicallyAssistedSpinalSurgery
DanielT.Laich,John K.Song, and Fred H. Geisler
. Indications
. Contraindications
. Advantages
. Disadvantages
. Objective
. PreoperativePlanning
. PatientPreparation
. SurgicalTechnique
Placingthe Thoracoscope
Anesthesia
Positioningand Room Setup
Incisionsand Portal Placement
. Diskectomy
SurgicalTechnique
Indications
Objective
Pathologyofthe thoracic spine, including disk herniation,
fracture,and tumors, is uncommon
compared
with similar
lesionsin the cervical and lumbar spine. Many surgeons
are less familiar
with
the
appropriate
techniques
to
safelyaddressthese problems. An important
issue that often
~vespauseisaccess to thoracic spinal pathology. Traditional
opentechniques can be associated
with significant
morbid-
ity,includinginjury to the lung, great vessels, and medi-
astinumin additionto being painful.Thorascopic techniques
havebeendevelopedto provide access to the thoracic spine
withminimaltissuemorbidity.
Thedevelopmentof endoscopic procedures dates back
to1806,but not until the 1980s and 1990s did a revolution
inendoscopictechnology and techniques allow significant
applicationin spinal surgery. Today, although still limited
initswidespreaduse, thorascopic surgery clearly allows
safeaccessto the spine without the significant morbidity
associatedwith other operative approaches. The thoras-
copicapproachallows the same anterolateral exposure of
thespineand spinal cord as does open thoracotomy. This
Spinal and SpinalCanal Exposure
DiskResection
.
Thoracoscopic
Corpectomy
and Vertebral
Reconstruction
.
Indications
.
Corpectomy
Objectives
Surgical Technique
Vertebral Reconstruction
.
Thoracoscopic Anterior Internal Stabilization
Surgical Technique
.
Indications
. Objective
.
Thoracoscopic Anterior Internal Stabilization
. Closure
thorascopic anterolateral view allows decompression
of
the neural elements, and reconstruction and internal sta-
bilization if necessary. Neither trans pedicular nor costo-
transversectomy approaches afford this view or these ad-
vantages. In difficult cases, converting a thorascopic case
to an open procedure is always a consideration.
.
Indications
.
Diskectomy
.
Vertebrectomy
.
Sympathectomy
.
Biopsyof tumor or infection
.
Anterior release
Indications for thoracoscopy can include any of the usual
justifications for procedures requiring open thoracotomy.
The specific indications for each procedure (diskectomy,
799
n__:-:-_'''
'-
_._u_,._____
.~

800
MinimallyInvasiveSpineProcedures:Thoracic
carpectomy, and internal stabilization) will be listed in the
appropriate sections followinghere.
.
Contraindications
Noabsolute contraindications exist for thoracoscopy except
severe cardiopulmonary disease with restricted function
not medically manageable for surgery or anesthesia. In ad-
dition, thoracoscopic surgery is not usually feasible for disk
herniations above 13. However, relative contraindications
do exist, with the main contraindications revolving around
pulmonary pathology. Selective intubation is preferred but
in many cases may not obviate thoracoscopic surgery. Rela-
tive contraindications include:
.
Acute respiratory distress syndrome
.
cardiac disease
.
Coagulopathy
.
Inability to tolerate general anesthesia
.
Intradural disk
.
Limited life expectancy
.
Patients in whom one-lung ventilation is not possible
.
Pleural empyema
.
Previous thoracotomy or thoracic surgery
.
Prior sclerotherapy
.
Significant pulmonary disease with restricted cardiopul-
monary function
.
Vascular anomalies such as ateriorvenous malformation
(AVM),azygos vein, lateral or ectatic aortic arch
.
Advantages
Minimizes morbidity of approach, and treats pathology
equal to open procedures such as posterior trans pedicular,
posterior lateral, costotransversectomy,
thoracotomy, or
minithoracotomy.
.
Lowerperioperative and postoperative wound pain
.
Noto minimal rib retraction
.
Nopostthoracotomy syndrome
.
Shorterrehabilitation
.
Shorterstay in intensive care unit and hospital
.
Small skin incisions
. Allowsfull,directviewof anterioripsilateralspinal
cord/dura allowing decompression,
and arthrodesis
with internal stabilization as needed
.
Allows safe and effective anterior canal decompression
. Thoracoscopic access surgeon may not be required
.
Disadvantages
Surgery-specific
disadvantages:
.
Increased anesthetic monitoring and preparation
.
Increased surgical time
.
Longersurgical instruments
.
More difficult management of sagittal alignment
.
More difficult to perform if significant pulmonary disease
.
No access to posterior or contralateral neural elements
.
Surgery may be limited by significant pulmonary adhe-
sions.
Surgeon-specific
disadvantages:
. Significantindividuallearningcurve
. Need to develop new visual-motor
skills and sensorimo-
tor skills
.
Thoracoscopic access surgeon required (secondary tole-
gal issues or institutional restrictions)
.
Objective
To provide adequate
access to the thoracic spine while min-
imizing access morbidity
.
PreoperativePlanning
In addition to routine medical and anesthetic evaluation,
preoperative
planning
involves assessing
patient for appro-
priateness
of thorascopic
surgery in light of factors that may
hinder
thoracoscopic
techniques.
Many of these issues are
outlined in the Contraindications
section preceding
here.
Preoperative
imaging studies should include anteroposte-
rior (AP) and lateral flexion extension
(FIE) x-rays (as stabil-
ity allows), magnetic
resonance
imaging
(MRI), or myelo-
gram
with
post-computed
tomography
(CT). Special
attention
should be paid to the size and location of thoracic
blood vessels and association
to pathology.
Intraoperative
neuroradiological
consultation
is often useful. Coordination
of soft disk herniation
on MRI and fluoroscopic
localization
of level at surgery may be difficult.
.
PatientPreparation
In addition to routine prophylactic antibiotics (e.g., van-
comycin 16 IVPBand ceftazidime 16 IVPB),prophylactic
methylprednisolone
may be warranted (standard trauma
dose:
30 mg/kg bolus over 20 minutes
followed by
5.4 mg/kg/h throughout surgery. Dosewill be stopped post-
operatively ifno neurologicalinjury issuspected). It shouldbe
noted that the trauma protocol as established has not been
proven to be either efficaciousor safe in the multitrauma pa-
tient. Asusual, gastrointestinal protection (e.g.,Pepcid20mg
NPB/POq 12 hours) should be used with large doses of
steroids.Other important preoperative measures include:
.
Prophylactic respiratory treatment
.
Heparin (5,000 units, q12 hours)
.
Antiembolic stockings and compression boots
.
Pulse oximetry
.
Continuous capnography

. Central
venous catheter (R internal jugular vein or nonde-
pendent subclavian vein) or Swan-Ganz
catheter
(recall
errorspossible with selective unilateral
intubation)
. Arterialline
. Foleycatheter
. Neuromuscularblockade (may be allowed to wear off
forneurophysiologicalmonitoring)
. Selectiveintubation and unilateral ventilation may be
extremelyhelpful but are not necessary if not possible
o.contraindicated
. Neurophysiologicalmonitoring,
routinely
both
so-
matosensory evoked potentials
(SSEPs) and motor
evokedpotentials (MEPs) as well as myoneurogenic
monitoringif available. SSEPsmonitor dorsal column
function,although they can correlate with anterior dys-
function,and MEPsmonitor anterior function.
. SurgicalTechnique
Placingthe Thoracoscope
Thoracoscopycan be used to complement
procedures
from
simplediskectomies to more extensive corpectomies and
eventoplacinginstrumentation for internal fixation.Safeuse
ofthe thoracoscope, however, requires
learning
new skills.
Theanatomyand instruments
are not visualized directly and
thethoracoscope typically only provides viewing angles of 0
or30degrees. Vision is restricted
to a monitor, and instru-
mentsmust be manipulated
within the limits of the portals.
Inaddition, although
thoracoscopic
spinal procedures
em-
ployfamiliarinstruments (albeit longer than open proce-
dures),thechest wall, portals, and length of the instruments
keepthesurgeon's hands far from the pathology. These fac-
torsallleadto a significant relearning curve to familiar pro-
cedures.Patience and training diligence are a must.
Inanimatelaboratories,
cadaver laboratories,
animallabo-
ratories, and performing
surgery
with
an experienced
thoracoscopicspine surgeon are highly recommended.
Sur-
geonswilldevelop skills of "tubeology" and "scopeology"
(keepingthe ports clean, keeping the scope clean, working
awayfromthe lens, keeping the scope stable, orienting the
scopecorrectly),endoscopic navigation, and triangulation.
Inreturn,the surgeon can acquire skills that can provide vi-
sualizationas good as if not better
than open techniques
whileminimizing patient morbidity.
Anesthesia
Thefocus is on extent of pulmonary
disease and cardiovas-
cularinvolvement. Specialized cardiopulmonary
studies
suchas pulmonary function studies may be warranted.
Evaluationfor "double-lumen
tube" intubation
is helpful.
Positioningand Room Setup
Formost thoracopic procedures, the patient is placed in a
lateralposition.Typically,the pathological side is placed up
109
Thoracoscopically Assisted Spinal Surgery
801
keeping in mind that having the left side up for most lesions
is the most advantageous anatomically to avoid vessels and
internal organs. Arm rests are used with arms placed up and
abducted -30 degrees and an axillary roll placed under the
dependent side. Sand bags,a "beanbag" and tape are used to
help stabilize the patient (Fig.109-lA).
The surgeon will most commonly stand on the dorsal as-
pect of the patient, although some surgeons will not follow
this practice. The assistant will most commonly stand on
the ventral side of the patient. The camera assistant will
stand superiorly or inferiorly (depending on the level in-
volved) on the dorsal aspect ofthe patient (Fig.109-18).
The (-arm should be positioned opposite the surgeon
such that adequate fluoroscopic images are obtained prior
to draping. Monitors should be positioned so that the sur-
geon, camera assistant, and operative assistant have clear
view. Monitors opposite to the surgeon are digitally re-
versed and inverted to allow accurate view for each person
involved in surgery.
Sterile cleansing and draping should include a region en-
compassing the axilla to the iliac crest and from the ster-
num to the spinous process. The need to obtain iliac crest
bone graft and to convert an endoscopic to an open proce-
dure must always be entertained.
Incisions and Portal Placement
Fluoroscopyis used to localize the pathologicallevel(s) (Fig.
109-2). The borders ofthe vertebral bodies, disk spaces, and
incision sites/portal positions are marked on the skin. Local
anesthetic (e.g., Marcaine 0.25%with epinephrine) is infil-
trated causing a wheal on the skin 7 minutes prior to incision.
A10 mm optic port is the first port placed. It is placed be-
tween two or three intercostal spaces superior (for caudal
pathology) or inferior (for mid and cephalad pathology) in
the spinal axis. The skin incision is made above the inter-
costal space running in line with the ribs.
Langenbeck hooks or a small Weitlander retractor is
placed in the incision and Metzenbaum scissors are used to
gently split the thoracic muscles. Blunt dissection is used to
enter the thoracic cavity to expose the parietal pleura. The
optic port is then introduced. Single-lung ventilation is ini-
tiated at this point to allow endoscopic visualization of tro-
car introduction of the other ports.
Three working ports are then introduced. A 12.5 mm
working port is centered over the target pathology in line
with the spinal axis and a 5 mm working port for the suc-
tion-irrigator is positioned 4.5 cm ventral and either cepha-
lad or caudad to the main working port depending on the
level of pathology. A7 mm working port for the retractor is
placed 4.5 cm anterior to the main working port again
cephalad or caudad to the main working port
.
Diskectomy
Surgical Technique
Diskectomyisthe basisformanythoracoscopicprocedures.
The basic procedure is similar to the familiar procedure

802
MinimallyInvasiveSpine Procedures: Thoracic
A
t
~
j
/
B
Figure 109-1
(A) The patient is placed in the lateral decubitus position with the access side up. An axillary roll is used to protect the dependent
axillae, brachial plexus. and scapula. The bony prominences
are padded. The portals, scapula, and a potential thoracotomy
incision are marked
on the chest wall. The upper arm is elevated to move the scapula cephalad and dorsally. (8) Figure depicts the intraoperative
setup for a thoraco-
scopic procedure.
performed in the lumbar spine, with caution paid tothe
proximity of the spinal cord.
Indications
Indications for thoracoscopic disk surgery are the same
as those for open thoracotomy. Neural compression is
the main indicator and associated symptomatology can
include:
.
Myelopathy. Surgery is performed to halt progressionof
neurological loss. Neurological loss that is already pre-
sent may not recover.
.
Radicular pain is usually a lancing, stabbing pain thatbe-
gins posteriorly and radiates in a dermatomal distribution.
Usually no loss of sensory or motor function is seen
secondary to overlap of innervation. Neurophysiological
testing is usually not of benefit. Failure of conser-
vative measures for 6 months should precede surgical
consideration.
.
Angina-like symptoms also may result from a broad-
based disk innervating the same plexus as with cardiac
angina.
Neurophysiological
testing
may
provide
some benefit. Negative cardiac workup and failureof
Figure 109-2
Patient positioning.the left lateralthoracotomy posi-
tion isprepared witha typicalportal arrangement.

109
ThoracoscopicallyAssisted SpinalSurgery
803
(
,.,
,
"/' -.
D
Figure109-3
(A)Anendoscopic fan retractor is used to gently retract the lung from the surface of the spine. The retractor must be used
carefullyto avoidinjuringthe lung. The retractor should be positioned, opened, and closed while it is directly visualized with the endoscope.
(8)Thepleura is incised and mobilized
over the proximal rib and disk space after identification
of the corresponding
rib. (e) The pleura
dissectoris being used to lift the parietal pleura away from the surface of the spine and to incise the pleura. (D) The segmental
arteries and veins ad-
jacenttothe disk space are ligated and a right-angle rib dissector is used to detach the costotransverse
ligaments from the lateral aspect of the rib.
conservative measures
for 6 months
is an indication
for
surgery.
. Axialbackpain is a poor indication for surgery and rarely
accepted by these
authors
for
thoracic
diskectomy.
Surgerymay be indicated
in patients
with a large disk
herniation on myelogram
and post-CT, delay in SSEPs,
andfailure of conservative measures for more than 6
months.
Objective
Tosafelydecompress the neural structures via an anterolateral
approachto the spine while
minimizing
access morbidity.
Spinaland Spinal Canal Exposure
Followingappropriate
placement
of the thoracoscope,
de-
compressionof the disk can be performed
with simple mi-
crosurgicaltools. Utilizing
the 30 degree
scope
a blunt
probeshouldbe placed through a working portal to famil-
iarizethe surgeon to the anatomy. A fan retractor may be
placedthrough
an anterior
port
to hold back the
lung
A
liing
,
.
J,
- -
i
'._
(.
,
\
I
Y
and/or diaphragm (Fig. t09-3A). Pathology involving the
thoracolumbar junction may require retraction of the di-
aphragm. With the harmonic scalpel or scissor electro-
cautery the diaphragm should be incised leaving a 1 em cuff
for later reattachment.
AStienmann pin is then placed through the working por-
tal, and the level is confirmed radiographically. Aharmonic
scalpel or scissor electrocautery is used to open the parietal
pleura over the disk space, vertebral bodies, and adjacent
rib heads (Fig. t09-3B,e). Segmental vessels are mobilized
and ligated with hemostatic clips.
Next, rib periosteum is exposed protecting the subjacent
neurovascular bundle. The rib head is then separated 25
mm distal to the head and bluntly freed from the ligamen-
tous attachments (costotransverse and costovertebralliga-
ments) with curettes or periosteal dissectors in a subpe-
riosteal fashion (Fig.t09-3D-F).
The inferior pedicle should be identified with a blunt
nerve hook and the soft tissue overlying the caudal pedicle
is coagulated with bipolar and swept away.The pedicle is
then removed (Kerrison rongeur or high speed drill) from a
caudal to cephalad direction. This exposes the epidural
space and the lateral aspect of the disk. With bipolar
B

..
804
MinimallyInvasiveSpine Procedures: Thoracic
E
'v
I:.IJ
F
G
,
,
\
H
Figure 109-3 (Continued)
(E) The Cobb periosteal eleva-
tor is inserted into the costovertebral
joint to cut the liga-
ments and disarticulate
the joint, (F) The head of the rib is
transected
and removed as a single piece, (G) The Kerrison
rongeur
is used to remove the cephalad
portion
of the
pedicle to expose the epidural space. (H) The pedicle is re-
moved to visualize the calcified disk and the dura adjacent
to the disk space. (I) The illustration shows a cavity drilled
into the dorsal disk space and vertebral body to expose the
ventral surface of the dura.
cautery and blunt dissection the anterolateral border of the
dura is visualized (Fig.t09-3G-I).
Disk Resection
require partial corpectomy to be safely performed. A large
cavity/partial vertebrectomy may require arthrodesis and
internal
stabilization.
Disk decompression
should be com.
plete enough to visualize
the medial aspect of the opposite
pedicle. Fluoroscopic
verification
of decompression
should
also be performed.
Anintradural herniation may also be removed. Primaryre
pair of the dura is possible with Prolene suture or dural clip
and sealed over with a tissue fibrin sealant.
A lumbar drain
Agross removal of disk is performed using standard tools.
Disk material in or near the spinal canal should be swept
down into the intervertebral cavity created by the initial
diskectomy.A sequestered cephalad or caudad disk may

or lumboperitoneal shunt
is placed
foIlowing either
situation.
. Thoracoscopic Corpectomy and
VertebralReconstruction
Often,removalof part or all of the vertebral body may be
necessaryto adequately
address
the patient's
pathology.
Thetechnique of thoracoscopic
corpectomy
and vertebral
bodyreconstruction builds upon the technique described
forthoracoscopic diskectomy.
. Indications
Indicationsfor thoracoscopic
corpectomy
and reconstruc-
tionarethe same as those for open thoracotomy:
. Fractures(conservative
vs surgical
indications
are
controversial)
. Acutefracture instability
(T4-L3)
. AOclassifications
of A1.2, A1.3, A2, A3, B, and C (type B
and( fractures require posterior
stabilization)
. Canalcompromise>
40%
. Kyphosis> 20 to 40 degrees
. Lossofvertebral height> 30%
. Symptomatic posttraumatic
deformity
. Degenerative
. Symptomatic herniated
disk with cephalad
or caudad
sequestration of fragments
. Symptomatic osteophytic
disease
. Infection
. Diskitis/spondylodiskitis
. Epiduralabscess
. Osteomyelitis
. Tumor(metastatic
or primary)
. Corpectomy
Objectives
Tosafelydecompress
the neural structures
via an anterolat-
eralapproach to the spine while minimizing
access morbid-
ity.Subsequent vertebral
body reconstruction
aims to safely
restoreanterior column support therby improving mechan-
icalstabilityand normal spinal balance.
SurgicalTechnique
Thecorpectomy first entails removing the disk on either
endof the vertebra of interest as already described. The
disksare removed sufficiently to aIlow exposure of the
109
Thoracoscopically Assisted Spinal Surgery
805
vertebral bone cephalad and caudad, delineating the cor-
pectomy margins (Fig.109-4A-C).
Next, the corpectomy is performed. This may be per-
formed with curettes,
high-speed
drill, osteotomes, or
rongeurs.The high-speed drill isespecially useful in resection
of the bone closeto the spinal canal followedby curreting any
remaining posterior cortical rim of bone. The posterior longi-
tudinalligament
and other compressive pathology should
also be removed.The corpectomy is completed removing all
soft tissue, disk, and vertebral end plates (Fig. 109-4D-E).
Ifincidental durotomy or intradural pathology is encoun-
tered, primary repair of the dura is possible with Prolene
suture or dural clips.Thiscan be sealed over with tissue fib-
rin glues or collagen sponges such as Tisseal, AGF,and
Gelfoam. A lumbar drain or lumboperitoneal
shunt
is
placed.
Vertebral Reconstruction
Vertebral reconstruction can then be performed via several
techniques following principles similar to the open proce-
dure (distraction, reduction, and compression). First, the
surgical defect is prepared to optimize bony fusion (fusion
is the goal in all cases except some tumor
surgery).
End plate preparation, decortication, bone mortise work,
and appropriate replacement sizing all remain essential
(Fig.109-5).
An anteriorly directed force at the site of the defect
(kyphotic apex) aids in both reestablishing sagittal balance
and obtaining appropriate sizing for the defect replacement
to be placed under compression. The replacement is over-
sized to assure compression. Sizing is performed using pre-
operative CTimagesand direct defect measurement.
Replacement grafts may be introduced via a guide sleeve.
The choice of graft isdependent on the surgeon and pathol-
ogy. As already mentioned, bone fusion to the graft is
almost always the goal.Graftoptions may include autograft
or cadaveric iliac crest/rib/femur/humerus.
In addition,
metal or polymer cages or spacers may be used with or
without bone graft. Typical commercial examples of these
sytems include:
. Singlefibercarbonvertebral bodyreplacement (DePuy
Acromed, Raynham, MA)
.
Titanium mesh cage (Harms Cage, DePuy Acromed,
Raynham, MA; Pyramesh, Medtronic Sofamor-Danek,
Memphis,TN)
.
Polymethylmethacrylate (PMMA)
.
PMMAis used knowing the low probability of fusion
across the reconstructed level in the cancer patient. This
is especiaIly true when radiation and chemotherapy are
needed.
.
The end plates of the defect adjacent superior and infe-
rior vertebral
bodies are prepared
with a drill and
curette making a hole measuring at least 5 mm deep in
each.
.
Silastic tube (e.g., chest tube) is cut 10 mm longer than
the defect. A hole is cut in the center of the tube and
PMMAis injected.

806
MinimallyInvasiveSpine Procedures: Thoracic
tJfJ:~
,
I
I
I
I
1
A
I
f
(
B
E
"'-
":
r-=---
F
Figure 109-4
(A) Pleural incision for a carpectomy.
(8) The ribs are removed
to expose the pedicles adjacent
to the involved vertebrae. (C)Tht
pedicles are removed
to observe the dura. (D) Disks are removed
to define the margins
of the vertebrectomy
resection.
(E) Corpectomy isPel'
formed with drill, curettes, and rongeurs. (F) Decompression
of the spinal canal and vertebrectomy
is performed
in a piecemeal fashion.
. PMMA
metacrylate pools into the vertebral body defect
and the surrounding bone. PMMA may then also be
placed anterior and lateral to the tube. Care must be
taken to prevent methyl methacrylate from compressing
the dura.
. Thoracoscopic Anterior Internal
Sta bilization
SurgicalTechnique
In some procedures, notably followingvertebral corpectomy
or trauma, additional stabilization may be needed. Thoraco-
scopic assistance can aid in the placement of appropriate
instrumentation, and endoscopic application ofanterior
in-
strumentation systems is virtually identical to openthora.
cotomy or minithoracotomy
application.
Position and flush seating of the anterior
thoracolumbar
plate to the lateral vertebral wall are essential in attaining
the highest
biomechanical
stability
possible.
Syndesmo-
phytic growths and irregular bone must be removedprior
to application
of some systems. This may be accomplished
with a high-speeddrillto allowflushseatingofinstrumen-
tation. Newer instrumentation systems deal betterwiththis
difficulty and offer higher biomechanical
stability.
Several systems are available for anterior thoracicstabi.
lization including:
. MACS
TL HMA Polyaxial
and
Monoaxial
(Aescula~
Tuttlingen,
GBR)
l'
C
I I
,-_.
Iv.
Iml_L:J..
1",,4.-.-
.4-/ ....
...
----- --
D

109
Thoracoscopically Assisted Spinal Surgery
807
Figure109-5
Allograft bone is placed within the corpectomy site.
. MACSTLTwin Screw (Aesculap, Tuttlingen,
GBR)
. Z-Plate (Medtronics
Sofamor-Danek,
Memphis,
TN)
Theseare representative instrumentation systems avail-
ableforendoscopic application. MACSTL(Modular Anterior
ConstructSystem) is a system specifically developed for en-
doscopicuse. The magnitude
of an ongoing series of endo-
scopicuse and three
distinct
unicortical
screw
systems
withinthe MACSTLsystem make this system the current
preferenceof this author.
Use of the MACSTL Twin Screw
systemwill be outlined
but the principles
discussed
can be
carriedover to all systems.
Decompressionand vertebral body replacement may pre-
cedeplacement of the anterior stabilization device or be
incorporatedinto placement of the anterior stabilization
device.Merits to both sequences exist. Which is utilized
dependsupon the specific case pathology and surgeon
preference.
Becauseother
sections
have covered thoracoscopic
diskectomy,thoracoscopic corpectomy, and thoracoscopic
vertebralbody reconstruction, this section outlines decom-
pressionrelated to thoracoscopic anterior stabilization.
Placementof an anterior internal stabilization device is
thenperformed.With a few modificationsthe technique
followsthe technique outlined following here.
. Indications
Thoracoscopicanterior
internal stabilization
is indicated for
anypathology normally
treated
by open internal
stabiliza-
tiontechniques, including:
. Fractures(conservative vs surgical indications are
controversial)
. Symptomatic posttraumatic
deformity
. Acutefracture (T4-L3)
.
Fractures with AOclassifications of A1.2,AI.3,A2, A3, B,
andC
. Type Band Cfractures require posterior stabilization
.
Canalcompromise> 40%
.
Kyphosis> 20 to 40 degrees
.
Lossofvertebral height> 30%
.
Postsurgical instability
.
Generous diskectomy
.
Secondary to a symptomatic disk herniation
.
Secondary to diskitis{spondylodiskitis
.
Corpectomy
. Secondarytoremovalofsymptomaticdiskherniation
. Secondarytotreatmentofinfection
. Diskitis
.
Epidural abscess
.
Osteomyelitis
.
Secondary to tumor removal
. Primary
.
Metastatic
.
Objective
Tosafely restore anterior column support and normal spinal
balance while minimizing access morbidity. Anterior thora-
columbar stabilization will provide a tension band with ex-
tension and a buttress plate with flexion.
. ThoracoscopicAnteriorInternal
Stabilization
First, the C-arm is aligned perpendicular to the spinal axis
(true lateral).AK-wireis inserted into the targeting and im-
paction tool. Under fluoroscopic guidance the K-wire is in-
serted into the appropriate vertebral body 1 cm from the
posterior vertebral margin and 1 cm from the vertebral end
plates. The radiolucent instrument is designed so that when
appropriately positioned under fluoroscopy the K-wire ap-
pears as a dark inner point surrounded by a concentric ring.
If this is not seen the K-wire is not positioned accurately.
This is repeated for each vertebral body to receive a screw
(Fig.109-6A).
With appropriate alignment verified, the K-wires are im-
pacted to 20 mm (a measurement that is identified with a
gray line on the impactor). Both targeting and impactor de-
vices are removed leaving the K-wires in place.
Acannulated punch is placed over the K-wireand used to
decorticate the bone. This eases the insertion of the cutting
polyaxial screw, thereby
eliminating
the need to tap
(Fig. 109-68). Exchange of the portal to the speculum is
performed via dilator rod.
Placement of bone screws is then performed as follows.A
cannulated polyaxial screw and stabilization clamp is pre-
assembled and then attached to an insertion sleeve and

808
MinimallyInvasiveSpine Procedures: Thoracic
D
A-C
F Ik...io..",-un:~l"~
l::I~
n
J;.~
~..Ii...~.}~"~
\~
,,..
rl
.W~
G
Figure 109-6
(A) Ashort Steinmann pin is placed with the special radiolucent targeting handle. (8) A cannulated awl and rasp are then placed over
these short guide pins to prepare for screw insertion. (C) The main twin screws, staples, and centralizers are then placed over the pins. (D) Adistrac.
tion devicecan be applied overthe centralizerguides ifdesired before graft placement. (E)Abone graft isthen placed into the corpectomydefect
(F) The twin screws can then be advanced to ensure the construct
is flush with the bodies, and the anterior guides are then placed. (G) The anterior
two screws are then placed through the guides and inserted until the reverse thread engages the plate.

109
ThoracoscopicallyAssisted SpinalSurgery
809
H
Figure109-6 (Continued)
(H) Locking screws are then placed into the two main screws. (I)The locking screws are tightened
to complete the
MACS-TL construct.
centralizer.The cannulated
polyaxial
screw-stabilization
clampcomplex (attached
to the insertion
sleeve and
centralizer)is introduced
into the thoracic cavity. The can-
nulatedpolyaxial screw is guided down the K-wire main-
taininganterior orientation of the stabilization clamp's free
screwhole (Fig. 109-6C). After partial insertion of the
polyaxialscrew into the vertebral
body, the K-wire is re-
movedbypassing the K-wire removal instrument through
thecannulated screw insertion
instrument.
This is threaded
intothe K-wire and removed. The screw is further inserted;
however,the position
of the stabilization
clamp
is kept
somewhatloose to maintain
the polyaxial
mobility
of the
screwhead. Position is verified with fluoroscopy. The same
stepsare replicated
with another
screw-clamp
assembly.
Last,the insertion instrument
is disconnected
from the cen-
tralizerand the insertion
instrument
is removed.
Nextan ultrasonic knife or bipolar scissor is used to incise
theparietal pleura in an area defined by the polyaxial
screws.Segmental vessels are mobilized with a right-an-
gledor rectangular-shaped
dissector. Hemoclips are applied
asappropriate and vessels are ligated. A diskectomy/cor-
pectomyisperformedas describedpreviously.Ameasuring
deviceisusedto showthe extent ofthe defect.Thisallows
sizingthe defect replacement. lliac crest autograft is ob-
tainedasdiscussedelsewhereinthis atlas.Thereplacement
shouldbe oversized to provide appropriate compression
aboutvertebralend plates.
Nextreduction and distraction are performed. Posteriorly
appliedforce ("knee in the back") at the site of the defect
(kyphoticapex) aids in both reduction and distraction. Re-
duction/distractioninstruments allow further manipulation
andmaintenance of alignment thus allowing the vertebral
replacementchoice to be placed under slight distraction.
Forthesystem described, the reduction/distraction
instru-
mentisplaced on the centralizers. Distraction is performed
withdistraction forceps and ratcheted distraction is main-
taineduntildefectreplacementis impacted(Fig.109-6D).
Asmallhole is drilled into the replacement graft to allow
attachmentof a graft holder. The replacement graft is intro-
ducedviaplastic sleeve through a portal and is placed into
thedefectand tapped into position (Fig. 109-6E). The graft
holderisunscrewed and removed. The ratcheted distractor
isrelaxedandfluoroscopicverificationofthe graftimplant
is performed. Once verified, the reduction/distractor
is
removed.
Last, stabilization must be completed. The stabilization
plate size is obtained by adding 30 mm to the distance
between the centralizers (distance is obtained with a mea-
suring device).The plate is inserted and placed over the cen-
tralizers onto the clamping elements using the plate-holding
forceps (rod insertion for multisegmental reconstruction
is also possible) (Fig. 109-6F). Fluoroscopic verification is
obtained.
The insertion sleeve is reattached to the centralizer. A
nut is attached via a nut driver (over the centralizer). A
countertorque
handle is attached to avoid tightening the
entire assembly. Final nut tightening is performed with a
torque wrench (15 Nm) (Fig. 109-6G). The nut driver and
centralizers are removed. The screws are further inserted
tightening down the plate securely in contact with the ver-
tebral bodies and again verification is performed with fluo-
roscopy.
The anterior screw guide is attached to the insertion
sleeve. This anterior screw-targeting complex is then at-
tached (as the centralizer was previously) to the polyaxial
head. With the targeting device seated, a reamer punch is
used to decorticate the anterior screw site. Self-lockingan-
terior screws are introduced and tightened (Fig. 109-6H).
The insertional device with attached targeting guide is re-
moved. Once again, verification is performed with fluo-
roscopy.
The locking screw is then placed thereby blocking the
polyaxial mechanism (Fig. 109-61). Final tightening is per-
formed with a torque wrench (10 Nm). Final fluoroscopic
imaging isobtained.
. Closure
Hemostasis is obtained as with open thoracotomy. Bipolar
electrocautery, Avitene, Surgicel, Gelfoam, Proceed, AGF,
and spray thrombin all may be beneficial in obtaining
hemostasis. Antibiotic irrigation is performed as routine.
Final inspection of neural elements, lung, and portals is
performed prior to removal of the endoscope. Chest tube

810
MinimallyInvasiveSpineProcedures:Thoracic
placement is performed under endoscopic visualization.
Anylacerationof the lung must be repaired.
Incisional closure is performed following infiltration of
the intercostal muscles with 0.25% Marcaine (this is not
used if intradural pathology is addressed. or incidental
durotomy has occurred). 3-0 Vicrylsuture in a simple inter-
rupted fashion is used to close the fascia. Intracuticular 5-0
Maxon suture in a simple interrupted
fashion is then
placed. Steri-Strips
or 4-0 nylon suture in a simple running
stitch
is used
to close the skin. The chest tube maybe
brought out an existing portal incision or tunneled to anew
incision distal to the surgical portals. 2-0 silk or nylon purse
string suture closes the skin and secures the chest tube.Oc-
clusive dressings are applied.

110
LumbarChemonucleolysis
Manucher J.Javid and Eugene J. Nordby
. Indications
. Contraindications
. Advantages
. Disadvantages
. SurgicalTechnique
RadiologicalEvaluation
Anesthesia
Positioning
Preparationand Instrumentation
NeedleInsertion
Chemonucleolysis, using
chymopapain,
is an enzymatic
treatmentof herniated
nucleus pulposus causing intractable
sciatica.It is an effective, cost-efficient
alternative to surgical
removalof the disk in the majority of patients.!
It is the least
invasiveof all the minimally invasive procedures.
Afterthe isolation of chymopapain
by Jansen and Balls in
19412and its intravenous injection by Thomas in 1956,3
Smithand Garvin,4 after extensive
animal experiments,
in-
jectedchymopapain into nucleus pulposus for the relief of
sciaticain human
subjects
in 1963 and coined
the term
chemonucleolysis(CNL).Following a multicenter, random-
ized,double-blind study5 comparing chymopapain with
saline,the efficacy of chemonucleolysis
was confirmed
and
theU.S.Food and Drug Administration
approved
the proce-
durein November 1982.
. Indications
. Thepatient must be a candidate for surgical diskectomy.
. Unremitting sciatica in spite of at least 6 weeks of con-
servativetherapy
. Sciaticpain should be more severe than back pain and
neurologicalsigns well correlated with symptoms
. Theideal age is between 18 and 55 years, but chemonu-
cIeolysisis effective in adolescents and patients older
than55 years of age.
. Chemofast-FluorallerGosorbent sensitivity test to deter-
mine immunoglobulin e (IgE)serum content should be
negative. (The incidence of anaphylaxis in the United
States is 0.3%,predictability of anaphylaxis not occur-
ring after a negative report is 99.6%,predictability
of
anaphylaxis occurring after positive report is 41.2%.)
Premedication with HI and H2 blockers may modify a
reaction should it occur.
.
Magnetic resonance imaging (MRI)or computed tomo-
graphic (CT)myelogram should show definite evidence
of nerve root involvement due to a disk that is pro-
truded or extruded in contiguity with the interspace.
.
Repeat chemonucleolysis may be performed in patients
who have recurrent herniated disk or a herniated disk at
another level.6IgEtest must be negative.
.
May be done in patients who have recurrent herniated
disk after successful surgery and no evidence of scarring
on MRIwith contrast
.
Contraindications
. Allergyto chymopapain
. Lumbarstenosisor lateralrecessstenosis
.
Migrateddisk
.
Rapidlyprogressiveneurologicaldeficit
. Caudaequinasyndromebladder and boweldysfunction
.
Perineuralfibrosis,arachnoiditis,frompreviousdiskec-
tomy
811

812
MinimallyInvasiveSpine Procedures: Lumbar
. Unsuccessfulresult of surgery at symptomatic level
.
Pregnancy
.
Severe(grades 3 or more) spondylolisthesis
.
Diabeticpolyneuropathy
.
Oldinfection of the disk or vertebra
.
Psychiatricdisturbances
. Advantages
.
Lackof scarring
.
Ambulatory procedure
.
Maybe performed in neuroradiology suite
.
Lesscostly than diskectomy
.
Saferprocedure than diskectomy
.
Disadvantages
.
Postchemonucleolysis
stiffness or spasm (severe in
-25%of patients)
.
Possible anaphylaxis (incidence 0.3%)
. In some patients
relief of pain is initially delayed
although ultimate results of both procedures (chemonu-
cIeolysis; diskectomy) are similar.
.
Possible sensitivity to chymopapain
.
Indications for chemonucleosis less versatile than surgi-
cal diskectomy
.
SurgicalTechnique
Prior to the performance of the procedure. it is important to
discuss the management of herniated disk. conservative
versus chemonucleolysis or laminectomy. in detail with the
patient,
including postchemonucleolysis
stiffness or spasm
which is mild or moderate in -50% of patients andmayb:
severe in -25% of patients. The stiffness
may last forafev.
days or several weeks and is controlled with medicatio~
The technique
for lateral lumbar chemonucleolysis
requim
a C-arm image intensifier
(Fig. 110-1) and a suitably elm
environment
to ensure satisfactory
requirements
foraster-
ile procedure
under either local or general anesthesia.
Radiological Evaluation
Anteroposterior
and lateral lumbar spine images are essen.
tial to the procedure.
In addition
oblique views of thelum.
bar spine will provide additional
information
regardingthe
position of the needle in relationship to the facet.Taking
this view was recommended
to one of us (M.J.J.)by Dr.lin.
dell R.Gentry. neuroradiologist
at the University ofWiseon-
sin Hospital. Chemonucleolysis requires practice and exper-
tise to achieve the expected effective outcome.
Chemonucleolysis may be performed in the radiology
suite or the operating room. The operating surgeonusesa
lead apron under the sterile gown and adheres to sterile
technique. A tray is set up to include a steel centimeter
ruler. sterile draping towels. 4 x 4 gauze sponges,amedi-
cine glass for contrast material if a diskogram is done.
a basin for skin prep. four towel clips, three 2 mLglass
syringes,
two 10 mL syringes.
one 25 gauge hypodermic
needle. one 1.5in. 18gauge needle. three 6 in. 18gaugenee.
dies, a 21 gauge 6 in. needle. and a 4 in. 18 gauge needleifa
double-needle
technique is used. In extremely obesepa.
tients an 8 in. 18 gauge needle may be used.
Anesthesia
Itis preferableto dochemonucleolysisunder localanesthe.
sia. Some surgeons prefer endotracheal general anesthesia.
It is imperative that this procedure be performed withan
anesthesiologist present. The lateral approach for lumbar
diskography was first performed by Brown in 19527and
Figure 110-1
Typicalarrangement forperforminglat.
erallumbar
chemonucleolysis
with image intensifier.
anesthesiologist.
neuroradiologist.
technician, andsur.
geon in place.

110
LumbarChemonucleolysis
813
;
-
--\~
~
.
'
..
'
...
'
.
~..
".
..
;,".,
Posterior
(contraindicated)
Figure110-2
Approaches to the nucleus pulposus. Only the lateral
approachof Brown is recommended
because it avoids nerve root and
thecalsac.
isthe only accepted technique. Under no circumstance
should posterior or posterolateral
techniques
be used
(Fig.110-2).
Positioning
Most surgeonsprefer the left lateral position recommended
byLymanSmith.Some surgeons prefer the right lateral posi-
tionorplacingthe patient such that the site of pain isup. Lac-
tatedRinger'ssolution is placed in the left arm and an elbow
protector isused about the left forearm. Apneumatic or rub-
berbolsteris placed to give a relative right lumbar scoliosis
andthe hipsare flexedas nearlyto a right anglewith the trunk
aspossible.Apillow is placed between the knees and adhesive
strappingis used
to maintain
this position
(Fig. 110-3).
Protective padding is used at the extremities as needed.
A few surgeons prefer the prone position.s
Preparation and Instrumentation
Afull surgical skin preparation is done after images reveal
the spine to be in position. The back is draped with four
towels and held with clips away from the field, especially
over the iliac crest, where they would obscure needle visu-
alization.Drapesareplacedinthe usualmanner.Mostsur-
geons prefer the single-needle technique. However, some
surgeons use the double-needle technique as follows.9The
needle inserted through the skin stops at the anulus and
then asmallerneedlegoesthroughthat needleandintothe
nucleus pulposus (Fig. 110-4). The inner needle is curved
and canbe controlledby rotatingit so that the tip may be
placed in the most optimal position. The double-needle
technique may be helpful to avoid multiple passes by
the nerve root and may possibly prevent infection that oc-
curs in extremely rare situations.
The fluoroscopic image intensifier is used to view the lat-
erallumbosacral spine, and a steel rule, Steinmann pin, or
the like is used to identify the L4-L5 interspace. The
usual relationship may be altered by the positioning. The
ruler is then used to measure 8 to 10 cm up from the spin-
ous processat the L4-L5level,dependingon the bodysize
(Fig. 110-3). At this point, local anesthetic is placed, fol-
lowed by placing the 18 gauge needle at about a 40 to 45
degree angle. The needle is advanced and viewed intermit-
tently in the monitor as it proceeds toward the interspace,
adjusting the angle on two planes to approach the interver-
tebral disk from the lateral aspect and avoiding the spinal
canal. The oblique view of the lumbar spine is very helpful.
If the needle is too posterior in relationship to the facet it
may enter intrathechally. Advancement of the needle
should be done in 1 to 2 cm increments, then reviewed on
the monitor with repetition until the firm resistance of the
anulus is felt. Anindication of the proper angulation of the
needlemaybedeterminedbynotingthe penetrationofthe
needle outside the skin and comparing the penetration of
the needle tip in the monitor. It is important to proceed
very slowly in case the nerve root is touched, causing sciatic
pain, in which case the needle should be partially with-
drawn and redirected. Then the needle
is introduced
through the anulus (Fig.110-5). The sensation is similar to
Figure110-3
Leftlateral position with appropriate padding. Hipsand knees flexed and held by adhesive strapping. Midlineand iliaccrest
landmarkand injection site are depicted.

814
MinimallyInvasiveSpine Procedures: Lumbar
Figure 110-4
Double-needle technique showing the 18 gauge
guide needle tip at the L5-S1 anulus. The 22 gauge needle will be
insertedto the nucleuspulposuscenter.
inserting a needle through an unripe pear. Asa rough guide,
if 1 cm externally equals 1 cm in the monitor, one should be
at the proper centering angle. If 1 cm externally appears as
2 or more centimeters in the monitor, the needle placement
is too lateral, whereas appearance of one half or less pene-
tration of what the external monitor shows indicates needle
placement that is too medial.
Needle Insertion
In LS-S1,the insertion of the needle into the disk may be
difficult, and occasionally frustrating, especially in men, in
whom the iliac crest is higher. Until the surgeon has gained
some experience, it may be a good idea to insert the L4-LS
Figure 110-5
Single-needletechnique showingtip approximating
anulus at L4-L5prior to being inserted to the center of the nucleus
pulposus.
needle toward the L4-LS interspace without penetrating
the disk and use this needle as a guideline for insertionofar
second needle directed at LS-S1.The LS-S1needlemaybef
started
1 cm caudally to the first needle. It should beangletiI
almost
30 degrees
caudally, at about the same 45 degreti
vertical angle as the first needle. The position maybe modi-
I
fied due to anatomical
variations
and the position ofthet
needle
may have to be adjusted
to avoid the iliac crest.IIr
there is a large right LS transverse
process, a facetjoint,or
sacral prominence,
hitting
the articular
facet and walking
the needle
point along it will usually allow sliding by.The
rotation
of the needle
bevel 180 degrees is also helpfulat
times (Fig. 110-6).
One should
keep the vertical angleas
acute as possible to allow entering the nucleus pulposus.
Anteroposterior
and lateral
images are taken to veri~
centering
of the needle
in the disk. If not well placed,it
should be retracted
and the angle changed before replacin~
Saline or water acceptance test is done to makesure
the
needle
is in the
nucleus
pulposus.
Sciatica maybe
reproduced
or aggravated
by this maneuver. Occasionally
A
c
Figure
110-6
(A) Needle tip impaling
iliac crest. (B) Withdr;n,
slightly and rotate 180 degrees to disengage. (C) Needle willslideOYe!
iliaccrest.

~
Thisprocedurewilldetermineconfigurationofthe diskas
wellasepiduralleakageof the contrast medium in some
cases.Theleakageof contrast material, whether epidural or
posteriorlongitudinal ligament, is not a contraindication to
performingchemonucleolysis.
Fortreatment of the disk with chymodiactin. the vial of
enzymeshould be reconstituted
with sterile water and
drawnintothesterilesyringeforinjectionthroughthe nee-
dleinthe disk.Alcohol used to sterilize the vials should be
vaponzedbefore inserting the needle in order not to neu-
tralizethe enzyme. One milliliter of chymopapain (2000
units)isinjected slowly to avoid increasing pressure suffi-
cientofurther dislodge some nuclear material (Fig. 110-7).
(Somesurgeonsuse 1000units ofchymopapainin 1 mLof
water.)The needle is kept in place for -5 minutes before
withdrawing.The anesthesiologist
observes the patient
continuously,checking on pulse rate and blood pressure,
withepinephrine (1:10,000 solution) ready to inject in the
extremelyrare situation
that
the patient
experiences
anaphylaxis.Postinjection, the patient should be continu-
ouslymonitoredin the recoveryroomfor 1 hour and then
ontheambulatory surgery floor for a few hours prior to dis-
charge.Medications are prescribed for the relief of pain as
indicated.
References
1.
Javid Mj. Chemonucleolysis
verses laminectomy:
a cohort
comparison
ofeffectiveness and cost. Spine 1995;20:2016-2022
2.
Jansen EF.Balls AK. Chymopapain:
a new crystalline
proteinase
from
papaya latex.j
Bioi Chern 1941 :137:459-460
3.
Thomas L.Reversible
collapse
of rabbit ears after intravenous
papain
and prevention of recovery by cortisone.j
Exp Med 1956;104:245-252
4.
Smith L. Garvin Pj. Jennings
RB. Enzyme
dissolution
of the nucleus
pulposus. Nature 1963:198:1311-1312
5.
Javid Mj. Nordby Ej. Ford LT.et al. Safety and efficacy of chymopapain
(chymodiactin)
in herniated
nucleus
polposus
with sciatica: results of
a randomized double-blind
study. jAMA 1983;249:2489-2491
110
LumbarChemonucleolysis
815
Figure110-7
Slowly injecting 1 mL of chymodiactin (2000units) to
avoid increasedintradiskal pressure.
6.
Sutton jc. Repeat chemonucleolysis.
Clin Orthop 1986;206:45-49
7.
Brown jE. Lateral approach
for lumbar discography
and chemonucle-
olysis.ln:
BrownjE.
Nordby Ej, Smith L.eds. Chemonucleolysis.
Tho-
rofare. Nj: Slack; 1985:113-118
8.
Parkinson
D, Shields
C. Treatment
of protruded
lumbar
intertebral
discs with chymopapain.j
Neurosurg
1973;39:203-208
9.
Thomas jC, Wiltse
LL.The double needle technique
using local anes-
thesia.ln:
BrownjE,
Nordby Ej. Smith L.eds. Chemonucleolysis.
Tho-
rofare, Nj: Slack; 1985:129-142

111
Arthroscopic and Endoscopic Microdiskectomy
via Posterolateral Access
Parviz Kambin
.
Indications
.
Contraindications
. Advantages
.
Disadvantages
. Anatomy
.
Radiological Evaluation
.
Surgical Technique
Positioning
InstrumentPlacement
The retrieval of offending herniated disk tissue via a postero-
lateralapproach requiresprecise positioningof the instrument
adjacent to the spinal canalunder fluoroscopicmonitoring,vi-
sualization, and identification of normal and pathologicaltis-
sue with the aid ofa high-resolutionglassendoscope.
The traditional lumbar diskectomy, whether it is per-
formed with a naked eye, Ioupes, microscope, or translami-
nar endoscopy, follows the teachings of Mixter and Barr!
and Dandy,2 which call for exploration of spinal canal
content, visualization of the compressive elements, epidural
hemostasis, retraction ofthe nerve root, and removal of her-
niated fragments. In contrast, the arthroscopic or endoscopic
disk surgery via a posterolateral approach emphasizes the
protection of spinal canal content, including its vascular and
neural structures.
The concept of posterolateral mechanical decompression
of the herniated lumbar disk was introduced independently
in 19733and 1975.4The availability of small-caliber arthro-
scopes in the mid-to late 1980s combined with the under-
standing of anatomical structures of the posterolateral
anulus5-7 promoted the principle and necessity of endo-
scopic visualization during arthroscopic or endoscopic disk
surgery.3.5.8Therefore during the 1990s the concept of blind
816
Replacement of 5 x 5 mm IDCannula by5 x 8mm
IDCannula
Retrieval of a Contained or Nonmigrated
Sequestered DiskHerniation
Transforaminal Accessto Sequestered Disk
Fragments
Retrieval of Foraminal and Extraforaminal
Herniation
Biportal Accessto the Intervertebral Disk
. Outcome
.
Conclusion
nucleotomy was advanced to resection of sequestereddisk
fragments under arthroscopic or endoscopic magnification
and iIIumination.8.g
Proper patient
selection
is the key to the successfulout.
come of arthroscopic
or endoscopic
spinal surgery viaa
paramedial
approach.
Individuals
who are not suitablefor
open laminotomy
procedures
are not good candidates for
minimally invasive arthroscopic
microdiskectomy. Failureof
a rigid program of nonoperative
measures,
presence ofposi.
tive tension
signs, correlative
dermatomal
distribution of
pain, and imaging studies are at the least four preoperative
requirements
for arthroscopic
microdiskectomy.
Individuals
presenting
with signs and symptoms
of cauda equina syn-
drome are best treated
with an open laminectomy andde.
compressive
procedure.
The relation
of the iliac crest to the L5-S1 intervertebral
disk should be predetermined
by a plane preoperative x-ray
study of the lumbar spine. The retrieval of a largecentral
herniation or nonmigrated sequestered fragment atlS-$1
in individualswith elevatediliaccrestis difficult.However,
a small paramedial, foraminal, or extraforaminal herniation
at L5-S1 may be accessed via a posterolateral approachin
the majority of patients.

111
Arthroscopicand EndoscopicMicrodiskectomy
817
. Indications
.
Disadvantages
. Failureto respond to nonoperative measures
. Correlativedermatomal
pain distribution
. Positivetension signs
. Positivecorrelative imaging studies
. Withor without presence
of neurological
deficit
. Contraindications
. Caudaequina syndrome
. Advantages
. Nerveroots and thecal sac are not retracted or disturbed
. Perineuraland epidural scar formation are eliminated or
minimized
. Endoscopicspinal surgery using image modification
technology provides superior visualization.
. Supportive myoligamentous
structures
are not dis-
turbed.
. Postoperativemorbidity, hospital stay, and cost are min-
imized.
Arthroscopicand endoscopic microdiskectomy is fash-
ionedonthe principle of laminotomy and diskectomy,which
requiresaccess and retrieval of herniated and symptom-
producingdisk fragments.3 Toavoid the entry to the spinal
canalandprevent the postoperativedevelopmentof per-
ineuraland epidural fibrosis, HultlOin the early 1950s
advocatedthe anterior retroperitoneal approach to the inter-
vertebraldisks. Smith et alII in the mid-1960s used chy-
mopapainvia a posterolateral access for the treatment of
herniatednucleus pulposus. Manual and automated me-
chanicaltoo1S4.12
and laser13.14have been utilized to achieve
thesameresult. In contrast to the preceding, where the in-
strumentsare placed in the center of the intervertebral disk,
arthroscopicmicrodiskectomycalls for posterior and subliga-
mentousor intracanalicular positioning of the instruments.
Thecontents of the spinal canal are not disturbed when a
subligamentousaccess to the herniated disk fragments is uti-
Iized.9Thereforethe epidural venous system is not disturbed
andtheincidence of postoperative venous stasis, which may
be associated with
chronic
nerve
root
swelling,
is
minimized.15.16
In addition to the preceding, the tethering of
thenerveroots and the dural sac by the scar tissue, which
mayinterferewith its smooth gliding and mobility in flexion
andextension, is avoided. Scarring and denervation of
paraspinalmuscles,II.17-20which may be associated with
chronicfatigueand discomfort followingan open diskectomy
procedure,are rare in individuals who have undergone
arthroscopicdisk extraction. The preliminary data suggest
that the incidence of postoperative
degenerative
spondylolis-
thesismay be reduced
following arthroscopic
fragmentec-
tomy.21Arthroscopic
microdiskectomy
has been associated
withshorter hospitalization, less postoperative morbidity,
fasterrecovery, and resumption
of work and activities.9
. Arthroscopicand endoscopicspine surgeryhas a learn-
ingcurve
. Unableto addressmigrateddiskfragments
. Unabletoaddressbonyorligamentouspathology
. Transforaminalor subligamentousaccessto L5-S1in in-
dividualspresentingwithhighiliaccrestmaybedifficult
The disadvantage of arthroscopic and endoscopic mi-
crodiskectomy may be related to unfamiliarity of most spine
surgeons with visualization of anatomical and pathological
structures
via a posterolateral access. Lack of exposure
during the residency program and the required learning
curve in mastering the technology have been sources of dis-
couragement among certain orthopedic and neurological
surgeons.
When lateral recess stenosis is associated with disk her-
niation and is deemed to be responsible for presenting
symptomatology the decompression of the lateral recess via
minimally invasive techniques may have to be undertaken
during the same operative setting or at a latter date.
. Anatomy
During the posterolateral paramedial approach, the inserted
instruments penetrate the skin, subcutaneous adipose tis-
sue, thoracolumbar fascia, and fibers of the sacrospinalis,
quadratus lumbrium, and psoas major muscles. The instru-
ments then enter the triangular working zone5.6(Fig.111-1),
which is located on the dorsolateral corner of the anulus.
Figure 111-1
The triangular
working
zone is bordered
medially
by
the traversing
root and the dural sac (A,B) inferiorly,
(B,C) by the prox-
imal plate of the inferior
lumbar
segment
and anteriorly,
(A-C)
by the
exiting root.

818
MinimallyInvasiveSpine Procedures: Lumbar
A
The traversing root and the dural sac (Fig. 11t-tA,B) lim-
its the medial boundary of the triangular working zone. The
intervertebral disk and the posterior boundary of the adja-
cent vertebral bodies form the ventral surface of the trian-
gular working zone.
The posterior longitudinal ligament expands to the pos-
terolateral anulus in the triangular working zone. The pre-
ceding structures are highly innervated by the fibers of the
synovertebral nerve and must be anesthetized in the course
of minimally invasivespinal procedures.
The exiting root departs the nerve root foramina, then it
descends anteriorly and laterally and lays anterior to the
transverse process of the distal spinal segment. The exiting
root forms the anterolateral boundary of the working zone.
The broad anteroposterior
diameter of the triangular
working zone (Fig. 11t-tB-C) combined with a certain de-
gree of mobility of the nerve roots allows for a safe inser-
tion of instruments with a wide base and limited height
into the intervertebral disks.
Generally the triangular working zone voids neural struc-
tures. However, on very rare occasions, a small communi-
cating root may be observed in this region. The traversing
root and the dural sac may be observed by passing the 0 or
30 degree endoscope through the nerve root foramina.
However, the epidural
fat and venous
bleeding
may
obstruct the clear visualization of intracanalicular struc-
tures. The roots have a reddish-white color and are clearly
identified by small vessels that are observed on their sur-
face (Fig. t11-2A). The exiting root is best seen with a 30
degree diskoscope prior to its descent to the anterior sur-
face of the transverse process of the distal lumbar vertebra
(Fig.t11-28). The ligamentum fIavum or capsular ligamen-
tous complex may be observed
when
the foraminal
approach to the spinal canal is being attempted.
.
Radiological Evaluation
The proper position of the instruments at the outset of the
operative procedure is done under fluoroscopic control. In
the anteroposterior (AP)and lateral fluoroscopic projection,
Figure 111-2
(A) The medial endoft~
cannula is tilted cephalad. The traversill9
root
and its accompanying
vessels areVI-
sualized.
On the
top
of the photo a se-
questered
disk (arrow) is seen underthe
inflamed nerve root. (B) Theexitingroot
is observed
as it departs
the nerve root
foramina and descends distallyandlate!'
B
ally (arrow).
the pedicles are visualized
as a circle located lateral tothe
spinal
processes
(Fig. 11t-3).
The medial surfaces ofthe
pedicles
form the lateral
wall of the spinal canal andthe
medial boundary
of the triangular
working zone.
The exiting root departs
the nerve root foramen atthe
lateral pedicular
line. Positioning
of the instruments atthe
mid pedicular
region at the outset
of the operative proce-
dure is the position
of choice for most minimally invasive
posterolateral approaches to the lumbar spine. However,
when the retrieval of an extraforaminal herniationisbeing
attempted,
a lateral pedicular
line positioning of the instru.
ments may be necessary.
The posterolateral anulus in the triangular workingzone
is covered by a loosely woven adipose tissue, whichis
rather immobile.
Figure 111-3
Radiographicappearanceof the pedicleinanteropos-
terior projection. A, medialpedicularline;B,midpedicularline;C.
lateral pedicular line.

111
Arthroscopic and Endoscopic Microdiskectomy
819
. SurgicalTechnique
Positioning
Thepatient is positioned
prone on a radiolucent
frame and
operatingroom table. In contrast
to the Wilson frame, the
bolstersof the frame, which
is used for arthroscopic
mi-
crodiskectomy,may be adjusted
according to the size of the
patient.In addition,
the bolsters
may be converged
to pro-
videsupport under the anterior superior iliac spine of the
patientwhile allowing
the flexion of the hip joints.
The
kneesare also maintained in flexion for comfort. This posi-
tioningallows the flattening of the lumbar lordosis, which
isessential for posterolateral
access to the intervertebral
disks.
The(-arm is covered with a sterile plastic sheet and is
usuallypositioned on the symptomatic side of the patient.
Onehasto make certain that the sterile cover of the (-arm
isnotinterferingwith its free rotation and is able to provide
reproducibleAPand lateral imaging during the surgery.
InstrumentPlacement
Arthroscopicand endoscopic
microdiskectomy
is per-
formedthrougha small-calibercannula,whichis inserted
dorsolaterallyand positioned in the triangular working
zone.
Threesizes of cannulas are available for spinal surgery.
Theuniversal access cannula with 5 mm inner diameter
(ID)and6.4mm outer diameter (OD)(Fig.111-4)is most
commonlyused and must be properly positioned prior to
theintroduction of a larger-caliber instrument. Although
theheightof the triangular working zone is limited by the
widthof the intervertebral
disk, the anatomical studies
haveshown that cannulas with a limited height and
broaderbase22may be positioned in the triangular working
-
Figure111-4
Two access cannulas
that are commonly
used for
arthroscopic and endoscopic
diskectomy. Top: Universal access can-
nula5x 5mm ID.Bottom:Ovalcannula8 x 5mm ID.
zone without the risk of causing neural injury. Two sizes of
ovalcannulas are available(5 x 8 mm IDand 5 x 10 mm ID).
The 5 x 10 mm IDoval cannula permits the passage of
larger instruments
such as curettes
and decorticators,
which are necessary for removal of the cartilaginous plates
of the vertebrae in preparation of arthroscopic interbody
fusion.23
The 5 x 8 mm ID oval cannula is commonly used for
arthroscopic disk surgery. The design of the ovaljig and the
auxiliary obturator permits the dilatation of the annular
fibers and passage of the cannulas into the disk space. The
oval cannula allows for simultaneous passage of a 0 or 30
degree diskoscope in conjunction with a straight or upbit-
ing forceps for identification and retrieval of herniated disk
material (Fig.111-5).
Positioning of the instruments begins with placement of
the tip of an 18 gauge needle into the midpedicular line of
the triangular working zone. The (-arm is properly posi-
tioned for lateral fluoroscopicexamination of the lumbar or
lower thoracic spine.The(-arm is maneuvered until the ver-
tebral plates at the index level are seen as two parallel lines.
The skin entry is -10 to 12 cm from the midline and the
spinal processes. The rotary movements of the needle as it
is being inserted permit palpatory tissue differentiation and
prevent the premature insertion of the needle into the anu-
lar fibers. The safe insertion of the needle is assured when
the needle is introduced closer to a horizontal plane and the
facet joints are palpated. At this time the surgeon may
slightly withdraw the needle and reinsert it in a more verti-
cal direction and position the tip of the needle in the trian-
gular working zone. The correct position of the tip of the
needle should be radiographically confirmed and docu-
mented in both anteroposterior and lateral projection (Fig.
111-6A,B).The periannular injection of a mixture of 1 cm3
of Fentanyl (Elkins-Sinn, Inc.,(herry Hill, NJ)with 3 mLof
normal saline solution may reduce the incidence of inter-
and postoperative pain and discomfort.
Figure 111-5
A30 degree arthroscopic and an upbiting forceps is
passed through the lumen of a 5 x 8 mm ovalcannula for identifica-
tion and removalof herniated diskfragments.

820
MinimallyInvasiveSpine Procedures: Lumbar
A
~, .
~.
".MIIl!!;
1.B!!8
B
Figure 111-6
(A) Intraoperative anteroposterior
examination shows proper positioning of the tip of the inserted needle at the midpedicularline~
the triangular working zone. (8) The lateral projection
of needle positioning shown in (A). The tip of the needle is in alignment with the posterior
boundary
of the adjacent
vertebral
bodies.
At this time a rigid Kirschner wire is passed through the
lumen of the 18gauge needle and the needle is removed.
This step is followed by introduction of a blunt-end, can-
nulated obturator (soft tissue dilator) and insertion of the
5 x 5 mm IDcannula (Fig. 111-7). The obturator must be
held tightly against the anulus in the triangular working
zone while the cannula is being introduced.
Figure 111-7
A blunt-end cannulated obturator (soft tissue dilator)
is passed over a guide pin, which was inserted into the lumen of the
previouslypositioned 18gauge needleat L4-L5. Intraoperativefluoro-
scopic examination shows that the obturator is following the exact di-
rection of the inserted needle toward the triangular working zone.
While the surgeon is holding the cannula firmlyagainst
the annular
surface, the sealing fluid adapter is attachedto
the proximal end of the cannula and a working channel
scope is inserted for diskoscopic visualization of theanu-
lotomy site. The posterior
subligamentous
positioningof
the cannula is essential for access and retrieval of theherni-
ated disk fragments.
The surgeon may tilt the medial endor
the inserted
cannula dorsally for a quick look at the content
of the spinal canal (Fig. 111-8A,B). The medial end ofthe
cannula is then tilted ventrally
for the visualization ofperi-
annular adipose tissue in preparation of anulotomyadja-
cent to the spinal canal (Fig. 111-8(,D). The instrumentsin-
serted through the above posteriorly positioned cannula
(Fig. 111-8E) will have a tendency to sweep underthe
traversing root and lateral dura, thus permitting theevacua-
tion of herniated disk tissue.
The adipose tissue on the surface of the anulus maybe
removed (Fig.111-8F) and hemostasis is accomplishedwith
the aid of a radiofrequency probe. In the course of arthro-
scopic microdiskectomy,
the surgeon should be able todif-
ferentiate the epidural adipose tissue from the perianular
fat. The globs of the epidural fat move in and out ofthecan-
nula as the patient breathes whereas the perianular adipose
tissue is rather immobile.
Anular fenestration
is accomplished
either
through the
working channel scope or via a specially designed trephine,
which allows only 2 cm penetration
into the intervertebral
disk.
To prevent
the perianular
migration
of the cannula, the
medial end of the cannula should be anchored
in the anular
fibers for a distance of2 or 3 mm prior to the use ofvarious
resecting forceps and instruments. It has been our experi-
ence that the vibration
of powered
shavers and diskotomes
may contribute to postoperative development of causalgic-
type pain, which we have previously reported.s

111
Arthroscopicand EndoscopicMicrodiskectomy
821
A
B
..
F
ngure111-8
(A)The content of the spinalcanalisobserved bydepressingthe outer end ofthe cannulaand tilting its inner end dorsallytoward
thespinalcanal. (B) Intraoperative
photograph
demonstrates
the traversing root (arrows) and the epidural adipose tissue on the top right. (C) The
ventraltiltofthe medial end of the cannula in preparation of the anulotomy site adjacent to the spinal canal. (D) Intraoperative
photograph
demon-
stratestheperianularadiposetissue coveringthe anulotomysiteviaa 0 degree workingchannelscope.(E)Followingthe extraction ofthe perianular
fattytissueviaaworkingchannelscope. part ofthe coarse anularfibersare visualized.Notethe remainderof adipose tissue extending from 6to 12
o'clock.(F)Intraoperative photograph
via a 30 degree diskoscope demonstrates
the posterior subligamentous
positioning of the anular fenestra-
tion.(arrow).Note the content of the spinal canal on top of the photograph. The removal of the fibers of the posterior longitudinal ligament and torn
anularfiberswillprovide broad access to the ventral surface of the dura and the nerve root.

822
MinimallyInvasiveSpine Procedures: Lumbar
.
Replacement
of 5 x 5 mm IDCannula
by 5 x 8 mm IDCannula
In contrast to a working channel scope, the larger lumen of
the ovalcannula allows the utilization of a larger straight or
upbiting forceps in conjunction with a 0 or 30 degree disko-
scope for retrieval of disk fragments under diskoscopic illu-
mination and magnification. The inflow of the saline solu-
tion is attached to the irrigation sheath of the diskoscope
while the free outflow of fluid is permitted from the open
end of the oval cannula. This arrangement provides clear vi-
sualization of the various structures at the surgical site
without interference of air bubbles, which may enter the
surgical site when suction is being used.
Forpositioning of the oval cannula, the cannulated obtu-
rator is passed through the lumen of the already positioned
working cannula, and its blunt end is positioned inside of
the intervertebral disk. Aspecially designed jig permits the
parallel introduction of an auxiliary cannula to the interver-
tebral disk at the index level. The blunt end of the auxiliary
obturator will have a tendency to dilate the anular opening
as it enters the disk space (Fig. 111-9A).The withdrawal of
the jig permits the introduction of the oval cannula into the
superficial layers of the anulus (Fig.111-9B).
Retrieval of a Contained
or Nonmigrated
Sequestered
Disk Herniation
Aworking channel scope or an oval cannula (5 x 8 mm 10)
(Fig. 111-4) may be used for retrieval of a contained disk
herniation or extraction of an extruded disk where part of
the herniated disk fragment has remained within the anular
confinement. Proper subligamentous positioning of the can-
nula was described previously. Following engagement of
the cannula in the superficial layer of the posterolateral
anulus, a small cavity is created ventral to the posterior
longitudinal ligamentum with the aid of a radiofrequency
probe.Theherniateddiskfragmentsarethen retrievedwith
forceps under arthroscopic visualization.9.24
Transforaminal Accessto Sequestered
DiskFragments
Positioning of the cannula in the subligamentous regionof
the triangular working zone was described previously.A
working channel scope, which is inserted into a 5 x 5mm
10 cannula
or at times
a 5 x 8 mm 10 oval cannula
(Fig.111-5), may be utilized.
Similar to the subligamentous
approach, partial nu-
cIeotomy is performed and a small cavity is first createdad-
jacent to the herniation site. This step is then followedby
removal or ablation of the torn anular fibers and the poste-
rior longitudinal ligamentum adjacent to the tip ofthein-
serted cannula (Fig. 111-10A).The removalof the torn
fibers of the anulus and posterior longitudinal ligamentum
provides ample exposure and visualization of the contents
of the spinal canal,ventral dura, and traversingroot.The
herniated disk fragments are then visualized, grasped,and
retrieved (Fig. 111-10B).At times the epidural adiposetis-
sue and bleeding may interfere with clear visualizationof
the content of the spinal canal. The bleeding maybe con-
trolled with local application of topical coagulants, useof
cold irrigation fluid, increase of inflow pressure, anduseof
radiofrequency coagula tors. The radiofrequency probeis
also a useful tool for partial vaporization of the epidural
adipose tissue if deemed necessary.
Retrieval of Foraminal and Extraforaminal
Herniation
In the opinion of this author the arthroscopic
posterolateral
access is the procedure
of choice for the retrieval offorami-
nal and extraforaminal
herniations.
A
-8
Figure 111-9
(A) Intraoperative lateral fluoroscopic examination demonstrates
the positioning of an obturator and auxiliary obturator insidethe
LS-Sl intervertebral disk. (8) A5 x 8 mm IDoval cannula is passed over the obturators shown in (A) and inserted into the superficial layers ofthean.
ulus fibrosis. The obturator isthen withdrawn.

111
Arthroscopic and Endoscopic Microdiskectomy
823
A
B
Figure111-10
(A) The use of a radiofrequency,
and probe for vaporization
of the torn anular fibers and the posterior
longitudinal
ligamentum
to
accessthe sequestered
disk fragment,
ventral dura, and traversing
root. (B) Intraoperative
photo demonstrates
the exposure of a large sequestered
diskfragment that is being grasped by forceps and retrieved.
A, rim of the inserted cannula; B, traversing
root that is displaced and partially
covered
withdisk fragments
and epidural
hematoma;
C, herniated disk fragment.
Toaccessthe preceding herniation the cannula may have
tobepositioned over the lateral pedicular line. Following
routinearthroscopic
visualization
of the herniation
site
whilethe surgeon is holding the medial end of the cannula
againsthe anular surface, the cannula is moved laterally
andfurther evacuation is accomplished under diskoscopic
control.This maneuver will have the tendency to move the
exitingroot laterally and out of the path of the forceps and
theresectinginstruments.
BiportalAccess to the Intervertebral
Disk
Theavailability of the oval cannula and subligamentous po-
sitioningof the instrument
have reduced the need for bi-
portalaccessto the herniation
site. However, the evacua-
tion of a large
central
herniation
or
retri\val
of
a
nonmigratedsequestered disk may be accomplished via a
bilateralbiportal access(Fig. 111-11). The communication
betweenthe right and left ports may be time-consuming.
However,the ipsilateral use of an oval cannula will facili-
taterapid communication
and provides more maneuver-
abilityfor the inserted instruments
within
the interverte-
braldisk that is necessary for localization
and removal of
herniateddisk fragments. In recent years we have success-
fullyuseda radiofrequency coagulator for nuclear ablation
andcreation of a cavity ventral
to the posterior
anular
fibersin preparation for access and retrieval of herniated
diskfragments.
During a bilateral biportal access the medial end of the
cannulasare first centered over the herniation site and a 30
or70degree diskoscope is inserted from one portal while
resectingand deflecting instruments
are introduced from
theopposite port. The triangulation
in the cavity that is lo-
catedbehind the inner fibers of the posterior anulus pro-
..
videsampleintradiskal exposureof the herniation site,the
ventral dura, and the posterior longitudinal ligamentum
(Fig.111-12A-C).
Abroad APdimension of the triangular working zone ac-
commodates insertion of two parallel or converging cannu-
las between the traversing and exiting roots.23One of the
cannulas can be used for introduction of the arthroscope
while the second cannula is utilized for insertion of resect-
ing instruments.
Figure 111-11
Intraoperative anteroposterior x-ray demonstrates a
biportal approach to L4-L5 disk herniation. Note that the medial end
of the cannulasare centered over the spinal canalfor the retrieval of a
central disk herniation.

824
MinimallyInvasiveSpine Procedures: Lumbar
A-C
Figure 111-12
(A)Intradiskalviewofa largenonmigrated central diskherniationthat isaccessedviaa biportal approach. Notethat theherniated
fragment is grasped with a forceps and is being withdrawn.
(B) The ventral dura (arrows) is visualized and being palpated with an instrurnentro
ensure that allofthe fragments havebeen evacuated. (C)The partiallytorn avascularfibersofthe posterior longitudinalligament(arrow)areseell
via a 70 degree diskoscope that is passed ventral to it.
. Outcome
Many authors have contributed to the growing literature
on efficacy of arthroscopic and endoscopic microdiskec-
tomy.l.4-tO.15.16.18.19.21-28In
a recent prospective study of 169
consecutive
patients8
who
underwent
arthroscopic
microdiskectomy
the authors
reported
a satisfactory
outcome of 88%following uniportal access and 92%for a
biportal approach for the retrieval of a disk herniation.
Five individuals in this study developed postoperative
causalgic-type pain associated with skin hypersensitivity
of the involved extremity -4 to 5 days following their sur-
gical procedure. All of these patients were treated with lo-
cal foraminal injection of a steroid and systemic use of
analgesics. A satisfactory outcome and cessation of the
symptoms followed. The intraoperative periannular injec-
tion of Fentanyl and avoidance of the use of motorized
vibratory shaving devices in recent years has virtually
eliminated the postoperative causalgk-type
pain and dis-
comfort.
References
1.
Mixter WJ, Barr JS. Rupture
of the intervertebral
disk with
involve-
ment of the spinal canal. N Engl J Med 1934;211 :205-210
2.
Dandy WE. loose cartilage
from intervertebral
disk simulating
tumor
of the spinal cord. Arch Surg 1929;19:660-672
3.
Kambin P,Zhou L History and current
status
of percutaneous
arthro-
scopic disk surgery. Spine 1996;21(SuppI24):57S-61S
4.
Hijikata S. Percutaneous
nucleotomy:
a new concept and 12 years' ex-
perience.
Clin Orthop 1989;238:9-23
5.
Kambin
P. Arthroscopic
microdiskectomy.
Arthroscopy
1992;8:
287-295
6.
Kambin
P. Percutaneous
lumbar
diskectomy:
current
practice.
Surg
Rounds Orthop 1988; 31-35
7.
Kambin
P, McCullen G, Parke W, Regan JJ, Schaffer JI., Yuan H. Mini-
mally
invasive
arthroscopic
spinal
surgery.
Instr
Course
Lect
1997;46: 143-161
8.
Kambin
P, O'Brien E, Zhou L, Schaffer JL Arthroscopic
microdiscec-
tomy and selective
fragmentectomy.
Clin Orthop
1998;347:150-167
9.
Hermantin
FU, Peters T, Quartararo
L. Kambin P. A prospective,
ran-
domized
study comparing
the results of open diskectomy
with those
In addition to the preceding, a randomized prospective
study of 60 patients9 who underwent
arthroscopicmi.
crodiskectomy
and
laminotomy
diskectomy
indicated
equally satisfactory outcomes in both groups. However,the
length of postoperative morbidity and time loss following!
laminotomy procedure
were longer than those of the
arthroscopic microdiskectomy group. In addition, thedevel.
opment of chronic back pain was more predominant inthe
open laminotomy group.
. Conclusion
The available data suggest that arthroscopic microdiskec.
tomy represents an alternative method of treatment for
symptom-producing lumbar disk herniations and shouldbe
included in the armamentarium
for treatment of lumbar
radiculopathydue to herniated lumbar or lowerthoracic
disks.
of video-assisted arthroscopic microdiskectomy. J BoneJoint SurgAm
1999;81 :958-965
10.
Hult L Retroperitoneal
disk fenestration
in low-back
pain and sciat.
ica: a preliminary
report. Acta Orthop Scand 1951 ;20:342-348
11.
Smith L, Gorvin
PJ, Gesler RM, Gennings
RB. Enzyme
dissolution of
the anulus
pulposus.
Nature 1963;198:1311-1312
12. Onik G, Helms CA,Ginsburg L,Hoaglund FT,Morris J.Percutaneous
lumbar
diskectomy
using
a
new
aspiration
probe.
AJR AmJ
RoentgenoI1985;144:1137-1140
13.
Cummings
RS, Progoehl JA, Hermantin
FU, Rhodes A, Sherk HH.Per.
cutaneous
laserdiskectomy
using a flexible endoscope:
technical con.
siderations.
Spine State of the Art Reviews 1993;7:37-40
14.
Choy DSJ, Case RE, Fielding
WE. Percutaneous
laser nucleolysis 01
lumbar
disks. N Englj Med 1987;118:771-772
15.
Hoyland JA, Freemont
AJ,Jayson
MI. Intervertebral
foramen
venous
obstruction:
a
cause
of
periradicular
pain
fibrosis?
Spine
1989;14:558-568
16.
Parke WW. The significance
of venous
return
in ischemic
radiculopa-
thy and myelopathy.
Orthop Clin North Am 1991 ;22:213-221

111
Arthroscopicand EndoscopicMicrodiskectomy
825
17. Rantanen J. Hurme
M. Falck B, et al. The lumbar
multifidus
muscle
five years after surgery
for a lumbar
intervertebral
disk herniation.
Spine 1993:18:568-574
18. Savitz MH. Same-day
microsurgical
arthroscopic
lateral-approach
laser-assisted (SMALL)fluoroscopic
diskectomy.
J Neurosurg
1994:80:
1039-1045
19. SchafferJL.Kambin P. Percutaneous
posterolateral
lumbar diskectomy
and decompression
with a 6.9-millimeter
cannula:
analysis of opera-
tivefailures and complications.
J Bone Joint Surg Am 1991 ;73:822-831
20. Weber BR,Grob D, Dvorak J, Muntener
M. Posterior
surgical approach
to the lumbar
spine
and its effect
on the multifidus
muscle.
Spine
1997;22:1765-1772
21. Kambin P,Cohen L, Brooks ML. Schaffer JL. Development
of degenera-
tive spondylosis
of the lumbar
spine
after partial
diskectomy:
com-
parison of laminotomy,
diskectomy
and posterolateral
diskectomy.
Spine 1994;20:599-607
22. MirkovicSR,Schwartz DG, Glazier KD. Anatomic considerations
in lum-
bar posterolateral
percutaneous
procedures.
Spine 1995;20:1965-1971
23.
Kambin P.Arthroscopic
lumbar
intervertebral
fusion. In: Frymoyer J,
Ducker T, Hadler
N. et ai, eds. The Adult Spine:
Principles
and Prac-
tice. 2nd ed. New York: Raven: 1996:2037-2046
24.
Kambin P, Gennarelli
T. Hermantin
FU. Minimally
invasive techniques
in spinal surgery:
current
practice.
Neurosurg
Focus 1998:4:1-10
25.
Kambin P, Casey K, O'Brien E, Zhou L.Transforaminal
arthroscopic
de-
compression
of
the
lateral
recess
stenosis.
J
Neurosurg
1996:84:462-467
26.
Kambin
P, Schaffer JL, Zhou L. Incidence
of complications
following
percutaneous
posterolateral
arthroscopic
disk surgery. Orthop Trans-
actions
1995:19:404-405
27.
Mayer HM, Brock M. Percutaneous
endoscopic
diskectomy:
surgical
technique
and preliminary
results compared
to microsurgical
diskec-
tomY.J Neurosurg
1993:78:216-225
28.
Peterson
RH. Posterolateral
microdiskectomy
in a general orthopaedic
practice. Seminars
in Orthopaedics
1991 :6:117

112
Foraminal Epidural Endoscopic Diskectomy
Hallett H. Mathews and Brenda H. Long
. Indications
.
Contraindications
.
Relative Contraindications
.
Advantages
.
Disadvantages
.
Diagnostic Imaging
.
Anatomy
.
Preoperative Planning
.
Surgical Technique
Patient Preparation
Anesthesia
Decadesago,the earliest reports on endoscopic visualization
of spinal elements as well as applications to spine surgery
achieved widespread awareness. The early trend-setting
techniques featured rudimentary scopes and very basic light
sources. These achievements ignited a desire in successive
generations rI spine surgeons to develop a surgicaltechnique
forlumbar disk herniations that provided optimum intraoper-
ativevisualization and access to pathology while minimizing
the surgicalmorbidities including but not limited to muscu-
loskeletaldestabilization. Williams was the first surgicalclin-
icianto refine a less traumatic procedure, microdiskectomy,
featuring less incisional trauma and enhanced visualization
utilizingthe operative microscope.! However.the procedure
failedto provideforwide surgicalexcursion.
With ongoing technological research and development.
refinement of fiberoptic visualization adjuncts. and the evo-
lution of surgical knowledge and skill. endoscopic spine
surgery was conceived and refined. The ultimate outcome
was a technique that expanded the capabilities associated
with microdiskectomy and provided for more potential
clinical applications. That technique was foraminal epidural
endoscopic diskectomy.
Bycomparison, where microdiskectomy provides for visu-
alization of anatomy and diagnosed pathology, it allows only
limited excursion to seek out occultpathology such as free or
migrated nuclear fragments. Furthermore. microdiskectomy
often requires movement of neurovascular anatomy to reach
826
Approach
Closure
.
Postoperative Care
Intermediate
.
Follow-Up
.
Complications
.
Outcomes
.
Conclusions
.
Acknowledgment
offending pathology. Conversely, foraminal epidural endo-
scopic diskectomy requires an endoscope that has the small-
est outer diameter with the largest possible working channel
The scope may be fiberoptic versus rod lens by design.
Endoscopes with varying fields of vision based on lens
angles allow for visualization
of pathology and avoidanceof
neurovascular
structures
at risk. Visualization
and video-
graphic
documentation
of the surgical
intervention
isa
valuable
feature of this technique
along with the abilityto
visualize and document the operative outcome prior to con.
clusion of the procedure
as demonstrated
by absence ofthe
presurgical
pathology.
Foraminal
epidural
endoscopic
diskectomy
might well be analogized
as microdiskectomy-
through a cannula.2
.
Indications
. Legpain greater than back pain
.
Failureof conservative care
.
Virginparamedian.foraminal,or extraforaminalherni-
ated nucleus pulposus
. HNPis containedor noncontainedat < 50%ofthespinal
canal diameter within the confines of the axilla andthe
pedicle
.
Absence of bulges or stenosis

.
. Contraindications
112
Foraminal Epidural Endoscopic Diskectomy
827
. Previousspine surgery
. Multilevel or pure central pathology
. Sequestered pathology
at the pedicular
level
. Stenosisor disk bulge
. Epiduralfibrosis
. Grossinstability
. D~enerative
disk disease
with disk space collapse
re-
sulting in foraminal narrowing
. Lumbarstenosis
. Foraminal stenosis
. Centralor lateral stenosis
. Sequestered disk at pedicle
. Chronicpain history
. Multilevel or pure central disk herniations
. Epidural fibrosis
. Instability
. Diskspace collapse and foraminal stenosis
. Recurretdisk herniation with fibrosis
. RelativeContraindications
. Morbidobesity
. Steep iliac wing anatomy
that may make an LS-Sl disk
inaccessible
. Compensationstatus: extended workers' compensation
orpersonal injury
..
. Advantages
. Shorthospital stay
. Reducedpotential for fibrosis
. Minimallyinvasive
. Maintainposterior spinal musculature
. Earlyreturn to activities of daily living
. Outpatientsurgical procedure
. Shortoperative time
. Minimaltissue disruption
. Lowcomplication rate
. Disadvantages
. Unableto accessLS-Sl in patient with steep iliacwing
anatomy
. Steep learning curve to master
.
Unable to address bony or ligamentous pathology
.
Difficultto perform with stenosis and fibrosis
.
Additional training required
.
Patient selection is paramount
. "Restrictedapplications
. Instrumentcosts
.
DiagnosticImaging
A magnetic resonance imaging (MRI) scan is the test of
choice to clearly display the disk herniation and identify if
there are disk fragments accessible endoscopically. MRIcan
also provide images of comorbid conditions that might con-
traindicate the foraminal endoscopic approach. Surgeons
performing this procedure should be skilled in interpreting
MRIstudies relative to surgical planning. Surgicaldecision-
making should never be based solely on a radiological re-
port of an MRI.Furthermore. the diagnostic MRIshould al-
ways be displayed
in the operating
room during the
procedure.
. Anatomy
An understanding
of foraminal anatomy and procedural
landmarks is essential to a successful operative excursion.
The foramen may be considered a dome that is accessed via
the foraminal ligament extending from the ligamentum
flavum. which underlies the junction of the superior articu-
lar facet and the pars interarticularis (Fig. 112-1). The dome
is the key orientation structure for gaining access to the safe
neural working zone. This safe zone in the epidural space is
demarcated by three structures!: the exiting nerve root at
the level ofpathology,2 the traversing nerve root lying me-
dial to the disk and exiting via the adjacent caudal foramen,
and3 the disk.3In this safe neural working zone, nerve roots
can be identified by their respective vascular supplies.
Figure 112-1
Foraminalanatomy.

828
MinimallyInvasiveSpine Procedures: lumbar
Figure 112-2
The safe neural working zone. Note the vascularrib-
bon sign.
which demonstrate pulsation in syncronization with the
electrocardiogram as well as the associated ribbon sign
(Fig.112-2).
.
Preoperative Planning
Once there is correlation of the patient's symptomatology
with the imaging studies and the decision for surgery has
been agreed upon between the patient and the surgeon. the
remaining crucial element is informed consent through pa-
tient education relttrve to risks. benefits. and alternatives to
surgical intervention. The patient education should suc-
cinctlydescribe the procedure. Postoperative guidelines and
restrictions should be outlined and information on average
recovery time with regard to return to work and other ac-
tivities of daily living should also be provided. Once a clear
diagnosis is established through the steps described. a good
surgicalplan is defined. and an informed patient is assured.
it isappropriate to proceed with surgical intervention.
.
SurgicalTechnique
Patient Preparation
The patient is placed prone on a padded radiolucent frame
and is prepped and draped in the usual fashion. The endo-
scopic monitor and light source are placed at the foot of the
operating table for easy visualization by the surgeon who
is positioned at the side of the patient consistent with
location of the pathology. A fluoroscopy unit is placed
across the table from the surgeon and is positioned to allow
for ease of anteroposterior
(AP) and lateral
imaging
throughout the procedure. Surgical tools and suppliesare
placed on a stand at a location consistent with surgeon
preference but usually across the operating room table
midway between the surgeon's position and the endoscopic
monitoring
equipment.
The patient
is given a broad-
spectrum IVantibiotic just prior to the procedure.
Anesthesia
Local anesthesia
to the skin and muscle along the approach
pathway is employed. taking care that no anesthetic effect
reaches the periforaminal surgical target. In addition.light
IV sedation
is provided
by way of monitored
anesthesia
care. This allows the patient
to be conversant
with the sur-
geon with regard to sensations.
particularly
those warning
of neural impingement.
Anesthesia
standby also facilitates
timely and efficient induction of general anesthesia should
conversion to an open procedure
be required.
Approach
Initially the surgical level is verified via fluoroscopicimag-
ing of a K-wire placed at the level of pathology. Onocca-
sion. diskography
may precede
the procedure if it is
deemed necessary to validate MRIfindings relative tothe
contained versus noncontained status of the herniatednu-
clear pathology.
Commencing the planned procedure, the approachbegins
at 9 to 13 cm from the midline. A diskogram or similar
sturdyneedleofsufficientlengthis advancedwithdocking
onthe parsthen medialprogression,landingontheforami-
nalligament (Fig.112-3).Acannulais then passedoverthe
needle and the needle is removed (Fig. 112-4). Theendo-
scope is then passed through the cannula (Fig. 112-5).Illu-
mination facilitates passage of surgical tools throughthe
Figure 112-3
The landmarks and technique for the foraminal
approach.

112
Foraminal Epidural Endoscopic Diskectomy
829
Figure112-4
Insertion of initial surgical tools for foraminal epidural
endoscopicdiskectomy.
workingchannel to dissect through the foraminalligament,
reachingthe foramen
with arrival into the epidural
space.
Cool(62°F) free-flow irrigant (normal saline or lactated
Ringer's),delivered via an endoscope
channel, quickly opens
upaworking space. With this opened "surgical field," one is
assuredby previously
listed landmarks
as being in the safe
workingzone. As epidural
fat, debris,
and offending
disk
pathologyare dissected,
passive outflow of irrigant continu-
allyclearsthe working space. The cool irrigant serves addi-
tionalpurposes. Intraoperative hemostasis is promoted plus
thereis local analgesic effect. Furthermore,
bubbles that re-
sultfrom irrigation will migrate poster~rly, creating the
Figure112-5
Deliveryofthe endoscope through the cannula. Note
agrasperthat has been passed through the working channel of the en-
doscopeand is positioned for manual approach to the disk herniation.
..
Figure 112-6
Endoscopic view of foraminal epidural endoscopic
diskectomyinprogress. Notethe bubbles,whichrepresent the bubble
signthat aidsinmaintenanceofsurgicalspecialorientation.
bubble sign that aids in the maintenance of surgical spatial
orientation. The irrigant-generated working space provides
ease ofendoscopic navigation intradiskally and/or epidurally
to directly identify and dissect the targeted pathology and
document operative results3(Fig.112-6).
Closure
Upon completion of the procedure, the endoscope and can-
nula are removed. The approach site is closed with sterile
adhesive strips and covered with standard adhesive strip
bandages. When being moved from the operating table to
the bed, the patient is placed in a neoprene corset with a
pocket for ice packs for the purposes of analgesia and to re-
tard postoperative swelling.
.
PostoperativeCare
Intermediate
Patients are held in a postanesthesia care area until they
are awake and alert, are taking fluids without suggestion
of nausea and vomiting, and are able to ambulate safely. It
is of interest to note that many patients report immediate
relief of radicular symptoms with intraoperative
removal
of the pathology and this is usually confirmed by their
ability to ambulate independently
and virtually pain free
prior to release from the surgical facility. Patients are given
a mild to moderate oral analgesic medication to take at
home as needed for pain. Upon discharge from the surgical
facility, they are counseled that their only exercise is to be
walking with the avoidance of bending, extended sitting,
twisting, or lifting> 10 lb. For this procedure, total time in
the surgical facility from registration to discharge averages
4 hours.

830
Minimally Invasive Spine Procedures: Lumbar
.
Follow-Up
Patients are seen in the office at approximately 1 week to
monitor progress. With rare exception, they are doing well
and can be released to return to work or other daily pur-
suits as well as routine activities of daily living.They are ad-
vised to avoid vigorous activity or high impact/competitive
sports for approximately 6 weeks. On occasion, patients
may be kept out of work for 3 to 6 weeks if their job is par-
ticularly active and may involve a lot of bending, lifting, or
twisting. Formalphysical therapy is not usually necessitated
in these patients.
.
Complications
Because foraminal epidural endoscopic diskectomy is a
thoroughly visualized procedure performed on an awake
patient, the chan~e of complications, real or potential, is
low.
Several factors not directly related to the operative proce-
dure per se are crucial, however, with relation to avoidance
of complications. First is ideal patient selection. The second
is a complete visual familiarity with anatomy, pathology,
and structures at risk. Also required is a keen sense of spa-
cial orientation in the operative field. Furthermore, this pro-
cedure has a steep learning curve that should be fostered by
formal education and proctoring. Once "mastery" of the
technique is achieved, it must be maintained by regular ap-
plication in the appropriate patient circumstances. This is
not an occasional procedure to be listed in the surgical ar-
mamentarium of a surgical generalist.
Relative to actual or potential complications, a relatively
low number can be cited. Certainly nerve root impingement
and associated repercussions is possible but this is reduced
given an awake patient, optimum use of biplanar fluo-
roscopy, and skill in needle placement. Other potential
complications inclu.e diskitis, hematoma, and recurrent
disk herniation. Use of operative IVantibiotics, verification
of hemostasis prior to conclusion of the procedure, and
clear activity guidelines, respectively, will reduce the likeli-
hood of these
complications.
Postprocedure
headache
responsive to a blood patch has been observed without ex-
planation as to the etiology due to no documented evidence
of intraoperative insult to the dura. Although not a compli-
References
1.
Williams
RW. Microlumbar
diskectomy:
a conservative
surgical
ap-
proach to the virgin herniated
lumbar
disk. Spine 1978;3:175-182
2.
Mathews
HH. Transforaminal
endoscopic
microdiskectomy.
Neuro-
surg Clin North Am 1996;7:59-63
cation, an occasional L5-S1 foraminal epidural endoscopic
procedure may not be possible if a steep iliaccrest posesan
anatomical obstruction to the approach trajectory.
.
Outcomes
A discussion of outcomes seems appropriately linkedto
complications in that both categories relate to the patient's
subjective perception exclusive of the surgeon's clinicalin.
terpretation
of operative
results.
Less than satisfying
outcomes often relate back to the aforementioned con.
traindications to patient selection. Patients with chronic
pain history may have histiochemical neural changesand/or
psychosocialissuesthat alter subjectiveevaluationofpain
reduction
despite removal of the causative pathology.
Patients with potential vicarious gain such as long-term
workers' compensation recipients or patients with litigation
issues tend to have less than satisfying outcomes thanthe
patients who satisfy pure selection criteria.
. Conclusions
Foraminal epidural endoscopic diskectomy is a technique
that has significantlyrespondedto the challengeofthede-
velopment of a spine surgery technique that wouldallow
for maximum surgical capability with minimal technique
morbidity.Assurgicalvariationsofthe foraminaltechnique
have evolved,it continues to be a safe,viable,andeffica.
cious surgicalprocedure in the appropriate patienttoad.
dress paramedian, foraminal, and extraforaminalHNP.
Microdiskectomythrougha cannulais an excellentsurgical
option for the right patient dating from the recent past,in
the present, and into the future.
.
Acknowledgment
The authors wish to acknowledge our illustrator, Robert
R.
Edwards
of Richmond,
Virginia, for his extraordinaryart-
work that brings this chapter to life.Histalent and diligence
are an ongoing
source
of inspiration
in our collaborative
relationship.
3.
Mathews HH, Mathern BE.Percutaneous procedures in the lumbar
spine.
In: An HS, ed. Principles
and Techniques
of Spine Surgery.
Baltimore:
Williams
&Wilkins;
1998:731-745
~

..
113
Percutaneous Spinal Cord Stimulator
Implantation
GregoryN. Arends and Robert E.Windsor
. Indications
. Contraindications
. Advantages
. Disadvantages
. Objective
. Advantages over Open Technique
. Disadvantages Compared with Open Technique
. PatientSelection
Thefirst implantation
of a spinal cord stimulation (SCS)
systemwas reported by Shealy in 1967.Since then. signifi-
cantadvancesin SCS/neuroaugmentation have been made.
Thedevicesare now more durable and more effective than
earliersystems and can be implanted percutaneously un-
derfluoroscopic guidance. whict*educes
morbidity and
recoverytime. It is now the standard of care to implant
thesedevicesusing conscious sedation. which allows oper-
ator-patientinteraction and thus more accurate position-
ingofSCSleads. Although the exact mechanism for pain
controlfrom SCSis not entirely understood. it is believed to
resultfromdirect or facilitated inhibition of pain transmis-
sion.
. Indications
. Neuropathicor nociceptive pain in extremities. neck. or
back
. Chronicradiculopathy
. Failedbacksurgery
. Perineuralfibrosis
. Complexregional pain syndrome
. Neuropathicor mixed neuropathic nociceptive pain in
the low back and lower extremities or neck and upper
extremitiesfrom a static disease or injury state
.
Surgical Technique
Anesthesia and Positioning
Epidural Needle Placement
SCSLead Placement
Intraoperative Trialof SCS
LeadAnchoring, Subcutaneous
Pocket, and Tunnel
Formation
PulseGenerator/ReceiverImplantation
.
PostoperativeCareand Follow-Up
.
Complications
.
Contraindications
.
Patient with cardiac-demand pacemaker
.
Patients requiring exposure to magnetic resonance
imaging
. Patientsonanticoagulation
. Systemicinfection
. Unsuccessfulspinalcordstimulatortrial(relative)
. Rapidlyevolvingpainpattern (relative)
.
Psychosocialcondition that may predispose to device
failure(relative)
.
Advantages
.
50%or greater long-term pain relief
.
Potential to increase functionality and improve quality
of life
.
Reduce oral narcotic demand
.
Reduce medical system reliance
.
Minimally invasive
.
Relativelyinexpensive
. Pain control option for patients who have failed surgical
and or medical intervention
831

832
Minimally InvasiveSpineProcedures:Lumbar
.
.
Disadvantages
.
Implanted device
.
Device'can fail
.
Leadscan migrate
.
Objective
Toachieve50%or greater pain relief long term, improve
qualityoflife,increasefunctionality,reducethe use ofthe
medicalsystem,reducethe useofnarcoticmedication
.
Advantages 0'ter Open Technique
.
Minimallyinvasive
.
Abilityto "trial-stimulate" and "troll" lead during proce-
dure
. Easyremoval of spinal lead if trial not efficacious
.
Lowermorbidity
.
Lesscostly
.
Disadvantages Compared with Open
Technique
. Anchoring of lead not as secure
. Maybemoredifficultto positionlead
.
PatientSelection
ASCSsystem should be consi~red for patients in whom all
less invasive therapies have failed, reasonable surgical solu-
tions have been ruled out, and a reasonable amount of time
has been allowed to recover from the painful condition,
usually 6 to 12 months. An ideal patient
should be
motivated, compliant, and free of drug dependence or drug
addiction. Psychological screening is recommended to ex-
cludeconditions that predispose to failure of the procedure.
When considering pain topography, extremity pain re-
sponds better than axial pain, and the more distal the ex-
tremity pain the greater the clinical response to SCS.The
torso is best stimulated, and in general is more likely to re-
ceive benefit, in the lower lumbar and cervicothoracic re-
gions. Painin the middle and upper lumbar, middle and up-
per cervical, thoracic, and chest wall are difficult to
adequately control and maintain long term. Central pain
syndromes such as thalamic pain and spinal cord injury do
not respond to SCSand are best treated by other modalities.
Anesthesia dolorosa, pain overlying a region of numbness, is
also often poorly treated with SCSand may also be better
treated using other methods. Diagnoses that are typical in-
dications for SCSinclude chronic radiculopathy, perineural
fibrosis, neuropathic pain, and complex regional pain syn-
drome. In Europe, SCSis also used for claudication pain sec-
ondary to peripheral vascular disease with excellent results.
In the United States, peripheral
vascular disease is not aU.S.
Food and Drug Administration-approved
indication.
The use of 3- to 7-day outpatient
trials with an SCSsystem
has proved helpful in determining
which patients willreo
spond well enough to warrant a permanent
implantation.If
the lead is tunneled
laterally 8 to 10 cm, an extended trialof
up to several weeks may be performed, which mayprovide
the patient and the physician additional informationregard.
ing long-term tolerance, efficacy, and change in functionality.
Absolute criteria that must be present for a patient tohavea
positive trial include tolerance of paresthesia, > 50%pain reo
lief, and overall patient
satisfaction.
Relative criteria fora
positive trial include an improved
functional
level andreo
duced
pain medication
consumption.
It is recommended,
however, that a patient undergoing a trial of SCSnot decrease
pain medication consumption during the trial totrulyassess
the efficacyof SCS.The technique outlined followinghereis
for implantation
of a permanent
SCSsystem. The implanta.
tion of a trial lead follows the same technique exceptthatit
does not include lead-anchoring
and pocket formation steps.
At this juncture in a trial, the lead is securely tapedoran.
chored to the skin forconnection to the stimulatordevice.
. SurgicalTechnique
Anesthesia and Positioning
Intravenous
conscious-sedation
is optional, though it makes
patients
more comfortable
and does not compromise the
reliability
of the
patient-physician
communication. The
procedure
must be interactive
because proper placementof
the electrode
is paramount
to the success of the procedure.
Preprocedure
antibiotics
and antibiotics
during the trial
are optional but recommended. Patients are placedprone
on the procedure table. Placinga bolster under the thoraxis
optional. It is important to consider the posture thepatient
stands and walks in when considering the patient's position
on the table because the position of the spinal cordwithin
the spinal canal may be influenced by posture. Asaresult,if
the lead is placed with the patient in a position significant~
different than the person's normal standing andwalking
posture, the stimulation obtained on the table mayalsobe
significantly
different
from the stimulation
obtained while
standing and walking. The posterior aspect of the torsois
prepared
antiseptically
and draped in sterile fashion.
Epidural Needle Placement
The T12-L1 interlaminar space is localized under fluoro-
scopic visualization as the point of entry to the epidural
space. The L1-L2 interlaminar
space
may be used ifthe
T12-L1 space is determined to be too small for maneuver.
ing the epidural
needle. After choosing
which space toen.
ter, the physician must determine the optimal skin entrance
site. Site selection is important
because the final restingpo-
sition of the epidural needle should be no more than 30de.
grees off the midline and 45 degrees from the surfaceofthe
patient's
back (Fig. 113-1). The skin entrance canbe
determined by using the following vector method: under

113
Percutaneous Spinal Cord Stimulator Implantation
833
Figure113-1
Insert Tuohyneedle with be~eled edge facing inthe
cephalad direction.
fluoroscopicvisualization,a spinal needleis placedflaton
theskinof the patient's back so that its tip intersects the
caudalportion of the midline of the cephalad lamina of the
choseninterlaminar space. The needle position is then ro-
tatedonthe patient's skin so that its tip positiondoes not
change
but the shaft is movedto contactthe ipsilateralsu-
perolateralportion of the spinous process of the caudal ver-
tebraeofthe chosen interlaminarspace.Inother words,if
thephysicianplans to place a needle into the T12-Ll inter-
laminarfrom the left side, then the needle tip should be su-
perimposedover the caudal aspect of the T12 spinous.
processand its shaft should be superimposed over the left
superolateralaspect of the Ll spinous process as viewed
fluoroscopically.The approximate skin entrance site for a
large.medium, or small patient is 21/2,2, and 11/2vertebral
bodies,respectively, caudal to the space chosen along the
lineof the needle.1 At this point, the physician should
provideadequate local anesthesia along the ~rajectory the
needlewill ultimately take to reach the ipsi1'ctteralcaudal
laminaof the interlaminar space to be entered. Once the
patientis properly anesthetized, the epidural needle is ad-
vancedthrough the anesthetized soft tissues to the lamina
and"walkedoff the lamina in a cephalad and medial direc-
tion.Theneedle should penetrate the ligamentum flavum
inthemidline or 2 to 3 mm ipsilateral to the true midline
(Figure113-2). The epidural space is localized using stan-
dardlossofresistancetechnique(Figure113-3).
SCSLead Placement
TheSCSlead is advanced through the needle and cephalad
inthe posterior epidural space to the point of intended
stimulation.The ideal initial placement for stimulation of
thecordis for the tip of the stimulating electrode to reach
thesuperior end plate of T9 (Fig. 113-4) for lumbar and
lowerextremity coverage, and the midbody of C3-C7 for
cervicaland upper extremity coverage. The lead should be
placedin the midline if a bilateral stimulation pattern is
desired.slightly to the right if a right-sided stimulation
patternis desired, and slightly to the left if a left-sided
stimulationpattern is desired. If adhesions prevent initial
i
......
Figure 113-2
Anteroposterior radiograph depicting proper inser-
tion of epidural needle into the interlaminar space. Note that the
bevelededge isalwaysmaintained ina cephaladdirection.
Figure 113-3
Verification of entry in the epidural space isdetermined
by loss of resistance technique with a 20 mLsyringe containing air.
Figure 113-4
The lead isadvanced up the posterior epiduralspace
to approximatelythe midbodyofT10 inpreparation to initiate a stim-
ulationtrial.
advancement they may be slowly and cautiously lysed with
either a lead blank or the lead itself. The lead may be navi-
gated by alternately rotating the bent stylet from its proxi-
mal end (Figs.113-X and t13-Y).

834
MinimallyInvasiveSpine Procedures: Lumbar
Intraoperative
Trial of SCS
Figure 113-X
Rollingthe stylet handle between the thumb and
forefinger using fluoroscopic imaging willensure the proper place-
ment ofthe lead.
Figure 113-Y
Anteroposterior radiograph demonstrating correct
placementofthe singleleadinthe epiduralspaie.
The spinal lead is next attached to an extension lead andpro-
gramming device. The system is "trialed" with various frequen-
cies (Hz), pulse widths (stimulus
duration), and amplitudes
(volts). The pattern of paresthesia produced is observed.ldeal~
the paresthesia pattern covers the pain pattern adequatelyand
the stimulation
pattern
is comfortable
to the patient. Ifthe
paresthesia pattern is inadequate, a technique of "trolling"can
be used where the tip of the lead is positioned cephaladtothe
target stimulation
site and then retracted
caudally untilthe
"sweet-spot" of preferred neurostimulation
is found.lfabdomi.
nal stimulation occurs the pulse width may be toowide,the
lead may be too laterally placed in the canal, or the lead'sinter-
electrode distance may be too great. This is a rootlet patternof
stimulation
and may occur in addition to, or occasionallyin-
stead of,a posterior-column stimulation pattern. If the pulse
width is too large, narrowing the pulse width and increasingthe
amplitude may be all that is necessary to solve the problem.If
the lead is too laterally placed, simply repositioningthe lead
more medially is all that is required. If the interelectrodedis-
tance is too great then the lead must be removedandalead
with a smaller interelectrode distance inserted.
LeadAnchoring, Subcutaneous Pocket,
and Tunnel Formation
Once the stimulation pattern has been optimally positioned
over the patient's pain pattern, the patient isdeeplysedated
and the soft tissues around the epidural needle appropriately
infiltrated with local anesthetic in preparation for surgery.
The surgeon
makes
a longitudinal
incision
down to the
supraspinous
ligament. The incision should incorporatethe
epidural needle that should stillbe in placeto protectthe lead
(Fig. 113-5). The epidural needle is then removedusinga
push-pull
technique
under
fluoroscopic
visualizationto
\
Figure 113-5
After proper placement
is determined
with fluoroscopy
an incision is performed
to allow placement
of the lead anchor.

113
PercutaneousSpinalCordStimulatorImplantation
835
\
Figure113-6
The Tuohy needle is removed and the stylet is removed from the lead.
ensurethat the lead does not migrate (Figs.113-6 and 113-7).
Theleadis then tethered to the supraspinous
ligament with a
nondissolvablesuture using the anchor supplied for the lead
bythe company (Fig. 113-8). Once the lead is ad.quately
an-
chored,the incisionshould be packedwith gauzeand attention
should be turned to creation of the subcutaneous
pocket. The
position of the pocket should be determined
and agreed upon
with the patient before the procedure begins. It is usually cre-
ated in the gluteal region beneath the belt line and slightly lat-
eral to the longitudinal
midglutealline,
although
the lower
Figure113-7
The lead is carefully grasped while the Tuohy needle is removed from the incision.

836
MinimallyInvasiveSpineProcedures:lumbar
Figure113-8
The anchor isthen placed overthe lead and sutured
into placeinthe subcutaneous tissue.
abdomen is also utilized. The pocket should be no deeper than
1 to 2 cm deep to the skin and should be -8
x 8 cm in area.
The pocket should be created with primarily blunt dissection.
Good hemostasis
should be achieved. Once the pocket has
been made, the tract of tissue extending
from the caudal end
of the paramedian
incision to the superomedial
corneI*ofthe
pocket should be infiltrated
with local anesthetic
containing
epinephrine. Atunneling device with a tunneling tip should be
advanced subcutaneously
following the anesthetized
tract tak-
ing care to remain in the subcutaneous
space and to not vio-
late the peritoneal cavity or to advance too superficially. Once
the tunneling tip has advanced through the subcutaneous
tis-
sues, it should be removed and replaced with a farrying
tip.
The female end ofthe extension lead is then placet! in the car-
rying tip and the extension lead is pulled back through the soft
tissue tunnel and out the paramedian incision. A plastic boot is
placed over the caudal end of the SCSlead and then the exten-
sion lead is attached to the spinal lead. The plastic boot is then
sutured in place over the junction
of the SCSlead and the ex-
tension lead.!
Pulse Generator/Receiver
Implantation
The caudal end of the extension lead is attached to the
pulse generator (internally powered system) or receiver
(externally powered system) and the pulse generator or re-
ceiverisplaced in the pocket. Anyredundant extension lead
References
1.
Windsor
RE, Falco F, Pinzon
EG. Spinal
cord stimulation
in chronic
pain.
Pain
Procedures
in
Clinical
Practice
Ed. Lennard.
Chapt.
2000:31 :377-394
2.
Abram SE. Pain pathways
and mechanisms.
Seminars
in Anesthesia
XXXX:4:267-274
3.
Campbell IN. Examination
of possible
mechanisms
by which stimula-
tion
of the spinal
cord
in man
relieves
pain.
Appl
Neurophysiol
1981
;44:
181 - 186
4.
Bedder MD. Spinal cord stimulation
and intractable
pain: patient
se-
lection.
In: Waldman.
Winnie, eds. Interventional
Pain Management.
1st ed. Philadelphia:
WB Saunders;
1996:412-418
5.
Burchiel
KJ.Anderson
VC, Brown FD, et al. Prospective,
multicenter
study of spinal cord stimulation
for relief of chronic back and extrem-
ity pain. Spine 1996;21 :2786-2794
6.
Hoppenstein
R. Percutaneous
implantation
of chronic
spinal
cord
electrodes
for control
of intractable
pain: preliminary
report.
Surg
NeuroI1975;4:195-198
should be placed deep to the device in the pocket anda
small loop of the lead may be left at the caudal end ofthe
paramedian incision to help absorb shock to the leadfrom
unexpected, rapid tension. The pocket and the paramedian
incision should be closed with deep absorbable suturesand
the skin closed. After closing, there should be no tensionon
either suture line. Asterile pressure dressing should beap-
plied to the surgical sites. Please refer to the illustrationsin
this chapter for the tunneling, pocket formation, leadcon-
nection, and generator implantation.
.
Postoperative Careand Follow-Up
During the recovery period, the SCSprogramming is fine-
tuned and the patient
and patient's
family are educated on
how to use the programming device. The patient is toldto
keep the SCSarea clean and dry and not to bathe or shower
but to take sponge baths until the first follow-up
visit. Pa-
tients are instructed
to avoid excessive
lifting, bending, or
twisting because this may dislodge the SCSlead. In addition,
for trial stimulation
they are told not to dramatically alter
their medication
consumption
and to reasonably
maintain
their usual activity level. Follow-up is usually within 7 to10
days postop and the trial lead is removed. The efficacy ofthe
SCS is assessed
and it may need to be reprogrammed.
The
physician
should then determine
whether
to proceed with
permanent
SCSimplantation.
For permanent
implantation,
mild reduction
in activity level for 1 to 2 days is customary:
however, the patient should be encouraged
to walk as much
as reasonably possible. The first follow-up office is roughly7
days postoperative,
at which time any remaining
sutures or
staples are removed and the SCSsettings are fine-tuned,
.
Complications
Most complications from the temporary or permanent im-
plantations are minor and self-limitingand includepoor
stimulation coverage of the pain, failure of the paresthesia
to impede pain perception long term, lead migration,lead
fracture, pain at the pocket site or connection site, and
seroma formation within the pocket. More severe complica-
tions include spinal cord injury, epidural abscess, meningi-
tis, and epidural hematoma.
7.
Sweet W,Wepsic J. Stimulation of the posterior column of the spinal
cord for pain control:
indications,
technique
and results.
Clin Neuro-
surg 1974:21 :278-310
8.
Robb LG,Spector G, Robb MP. Spinal cord stimulation:
neuroaugmen-
tation
of the dorsal
columns
for pain relief. In: Weiner
RS, ed. Pain
Management:
A Practical
Guide for Clinicians.
5th ed. Boca Raton:Sl.
Lucie: 1998:271 -293
9.
Kumar K,Nath R,Wyant GM.Treatment of chronic pain by epidural spinal
cord stimulation:
10-year experience.J Neurosurg 1991:75:402-407
10.
Nielson KD, Adams JE. Hosobuchi
Y. Experience
with dorsal column
stimulation
for relief of chronic intractable
pain. Surg Neurol
1975:4: 148- 152
11.
Pineda A. Complications
of dorsal
column
stimulation.
J Neurosurg
1978:48:64-68
12.
Yaksh Tt. Neurological
mechanisms
of pain. In: Cousins
MJ. Briden.
baugh
PO, eds. Neural Blockade
in Clinical Anesthesia
and Manage-
ment of Pain. 2nd ed. Philadelphia:
JB Lippincott;
1988:791 -844

114
,
Retroperitoneal Exposure of the LumbarSpine
AnthonyK.Frempong-Boadu
. Retroperitoneal
Approach
. Indications
. Advantages
. Disadvantages
. SurgicalTechnique
Positioning
Approach
Incisionand Dissection
.
Surgicalapproaches to the lumbar spine, as at other levels
ofthe spine, are determined
by the location
of the patho-
logicalesion and are designed
to provide complete
visual-
izationof the lesion and surrounding
structures.
This allows
forthe safe treatment
of the pathological
process and pro-
videsaccess for reconstruction
and stabilization.1-3
Severaltechniques
have evolved to provide exposure
for
decompressionand stabilization
of the lumbar spine. These
approachesfall into three basic categories:
anterior, poster-
ior,and posterolateral.
Each approach
has advantages
and
disadvantages. This
chapter
describes
the
indications{
contraindications and the surgical technique
of the anterior
retroperitoneal approach to the lumbar spine.4
. Retroperitoneal
Approach
Anteriorexposure of the lumbar spine (L2-L5) is best
accomplishedvia the retroperitoneal
approach.2.3.5-8It
providesexcellent visualization and access to the anterior
vertebralcolumn and thecal sac with minimal manipulation
ofneuralstructures. Anterior column reconstruction and
stabilizationare also readily performed using this approach.
. Indications
Theretroperitoneal approach is used for debridement, re-
section,and reconstruction of anterior lumbar pathology
fromL2toL5.Inparticular,it is usedfortreatingdegenera-
tivediseases, deformity, infection, tumor, trauma, or any
otherpathological process that destroys or compromises
.
Decompressive Techniques
Diskectomy
Vertebrectomy
Vertebral Reconstruction
Anterior Instrumentation
Closure
.
Complications
.
Conclusions
the anterior load-bearing function of the lumbar spine or
causes anterior compression of the lumbar neurological ele-
ments.2.6.9
.
Retroperitoneal vertebrectomy
.
Anterior compression with significant osseous involve-
ment and deformity caused by osteomyelitis, neoplastic
lesions (metastatic lesions, primary bone tumors), burst
fractures (trauma or pathological), compression frac-
tures (trauma
or pathological),
fracture
dislocation
(trauma)
.
Retroperitoneal diskectomy
.
Diskitis with phlegmon
.
Anterior release for deformity correction
Harmon10first popularized the retroperitoneal approach
in the 1950s as a treatment for degenerative disk disease; it
is accomplished through an extension of the standard flank
incision commonly used by general surgeons
to treat
retroperitoneal pathology (Fig. 114-1). The advantages of
the retroperitoneal
approach are that it provides direct
broad exposure of the middle to lower lumbar vertebral
bodies (L2-L5),thecal sac, and upper sacrum with less risk
to the neural elements, viscera, and great vessels when
compared with other approaches. It also allows for exten-
sive direct decompression of anterior lumbar pathology
(Fig. 114-2) and reestablishment
of the anterior load-
bearing function of the lumbar spine as well as placement
of anterior lumbar spinal instrumentation.
The disadvan-
tages of this approach are that the vertebral bodies and in-
tervertebral disks are viewed from one side only. It is also
difficult to obtain realignment in patients with significant
837

838
MinimallyInvasiveSpine Procedures: Lumbar
Figure 114-2
Extentof decompression possiblewith the retroperi-
tonealapproach.
translational deformity using this approach and it requires a
second procedure for decompression of posterior pathology
and placement
of posterior
spinal instrumentation.2.8
Furthermore ifa right-sided approach is necessary, the size
and locationof the liver can hamper exposure.
.
Advantages
.
Excellent visualization and access to the anterior verte-
bral column (L2-LS)
. Abilityto accessthe ventralthecalsac
. Minimalmanipulationofneuralstructures
. Anteriorcolumnreconstructionand stabilizationisalso
readilyperformedusingthis approach
Figure 114-1
Cross-sectional anatomical relation.
shipsinretroperitonealapproaches.
.
Disadvantages
.
The vertebral bodies and intervertebral disks areviewed
from one side only
.
It is difficult to obtain realignment
in patients with
significant translational deformity
.
Requires a second procedure
for decompressionor
posterior pathology and placement of posterior spinal
instrumentation
.
The liver can limit a right-sided approach if necessary
. SurgicalTechnique
Positioning
The patient is positioned on the operating table inthelateral
decubitus
position with the side to be operated on tiltedup-
ward, at an angle of -60
degrees. The shoulder and hipsare
well padded and supported on beanbags or gel rolls. Thisshifts
the abdominal and retroperitoneal
contents toward the non-
operated,
dependent
side. The arm on the operated sideis
held across the chest and supported. The lower legiskept
straight
and the upper
leg and hip are flexed to facilitate
muscle retraction by relaxing the ipsilateral iliopsoasmuscle
(Fig. 114-3). An axillary roll is placed beneath the axilla,anda
pillow is placed between the legs. The surgeon stands anterior
to the patient, with the assistant standing posterior to thepa.
tient. All pressure points are padded and the patient issecured
to the operating
room table using heavy tape. Fluoroscopyor
plain x-rays are used to mark the level and plan the incision.
Approach
The spine is usually approached from the left side unless
the pathology
dictates
a right-sided
approach.
A left-sided
approach
is favored
because
the
liver limits
right-sided