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

27
CervicalLaminectomy
NitinTandon and Dennis G.Vollmer
. Indications
. Contraindications
. Advantages
. Disadvantages
. SurgicalTechnique
Theincreasedpopularity of the anterior surgical approach for
degenerativeand traumatic disorders of the cervical spine
has,overtime narrowed the indications for cervicallaminec-
tomy.Nonetheless,this standard approach remains the pre-
ferredroute for treating a variety of conditions affecting the
cervicalregion (seeChapter 26,Table26-1). Multilevel cer-
vicalstenosiswith preservation of a normal lordotic curve
maybe the primary
present-day
indication
for cervical
laminectomy.Additional examples where laminectomy
is the
approachof choice include
the continuous
form of ossifi-
caitonof the posterior
longitudinal
ligament
(OPLL), in-
traduralneoplasms, or vascular lesions and other lesions af-
fectingthe dorsal aspect of the spinal canal, especially at the
cervicothoracicjunction. Advantages of laminectomy
include
thefactthat all neurosurgeons are very familiar with it, that
itisa potentially extensile approach, that it provides the abil-
ityto decompress multiple
neural foramina, and that fusion
isusually more an option than a necessity, an attribute
that
helpswiththe preservation of motion segments.
. Indications
. Multilevelstenosis with preservation of lordosis
. Posteriorexposureofcord (tumor,abscess,hematoma)
. Contraindications
. Kyphoticdeformity
. Advantages
. Familiarapproach
. Easein exposure of multiple levels
. Noriskof injury to anterior neck structures
Lateral Dissection
Drilling Technique
Closure
.
Complications
.
Conclusions
.
Disadvantages
. Extensive
denervation
of
posterior
musculature
.
Cannot address anterior pathology
.
Potentially destabilizing
.
Surgical Technique
Severalvariationsin techniquehavebeen describedfor
achieving the chief goal of cervical laminectomy; namely, an
efficient removal of the offending laminae without trauma-
tizing the spinal cord or producing an unstable cervical
spine. These include the traditional use of a Leksellrongeur,
laminectomy performed with a high-speed bur, and the en
bloc laminectomy, in which laminae are thinned using a bur
and then are removed en bloc.
Thedetailsof relevantsurgicalanatomy,positioning,and
soft tissue dissection are discussed in Chapter 26. Avoid-
ance of hyperflexion is extremely important in the context
of cervical
canal
stenosis.
Furthermore,
hyperflexion
should be avoided when a fusion is incorporated into the
operative plan, to prevent fixation of the patient's spine in
a more kyphotic posture than would be otherwise neces-
sary.
Lateral Dissection
Lateraldissectionshouldtypicallystopat the beginningof
the lateral masses; exposureof the entiretyof the lateral
masses is necessary only if posterior instrumentation
is
planned. Care should be taken to perform the exposure in a
subperiosteal plane and to use curettes to remove excess
soft tissue prior to using a high-speed drill for the laminec-
tomy.Airdrills often grab the tissue and this can cause them
to skip, increasing the risk of inadvertent tissue injury.
Whichever method is used for the laminectomy, strict
233

234
MidcervicalSpine:PosteriorApproach
adherence to a few basic principles is essential to prevent ia-
trogenic insults to the spinal cord and nerve roots. The
placement of instruments into the stenotic spinal canal (e.g.,
Kerrison footplate) must be avoided; maneuvers directed at
bony removal should not create significant intersegmental
motion where significant cord compression exists; finally,
the laminectomy must spare the facets sufficiently to avoid
destabilizing the spine producing subluxations or kyphosis.
The authors prefer the use of a high-speed drill for most cer-
vical laminectomies. Spinous processes are first removed
with a Horsley rongeur (Fig. 27-1). Bleeding surfaces are
waxed and remaining soft tissue, which can cause the drill
bit to skip, is removed with curettes. Although an en bloc
removal, similar to the performance of a laminoplasty, is oc-
casionally utilized (Figs. 27-2, 27-3), we prefer to thin the
entire lamina and then remove the remaining paper-thin
bone along with the ligaments using soft tissue instruments
(Figs.27-4, 27-5, 27-6, 27-7).
Drilling Technique
Several points can be made about drilling techniques. First,
the surgeon should be able to comfortably control motion of
the drill at all times. A drill that is not sufficiently long
enough to allow the surgeon's hands to rest comfortably
outside the wound can result in loss of visualization and fine
motor control. Second, a two-handed approach using gentle
counterpressure with the nondominant hand reduces the
Figure 27-1
Removal of the spinous processes using a Horsley
rongeur.
likelihood of uncontrolled movement. Third, all attempts
should be made to minimize the exposure of the thecalsac
to a drill bit rotating at high speeds. Drilling should be initi-
ated contralateral to the surgeon to prevent the need to
reach across an exposed thecal sac to complete the expo-
sure. Likewisewhen a foraminotomy or a lateral mass fusion
with instrumentation
is indicated, it may be advisableto
performthis at the outset when the spinalcordisstillpro-
tected and relatively invulnerable. Lastly,continuous irriga-
tion should be used to avoid thermal injury to bone andto
facilitate visualization when it is combined with suctioning.
We prefer using a small cutting bur to work through the
outer cortical and cancellous bone, leaving a thin inner
cortical layer. This inner cortex can then be more precisely
thinned (Fig. 27-4). Ifdesired, a coarse diamond bur may
be used at this stage. It is important to remember that the
superior extent of the lamina is not underlain by ligamen-
tum flavum so that
there
is little
or no soft tissue
between the bone and dural sac here. Also, the laminaeof
the cervical spine are shingled and the areas of laminar
overlap take more time and attention to drill away thanthe
remaining lamina. Often a complete laminectomy obligates
a partial inferior laminectomy of the vertebral levelabove.
In addition to a sense of increased pliability when most
of the laminar thickness has been drilled away, another
clue that only paper-thin
bone remains is the change
in color from a bluish gray to a translucent
yellow
(Fig.27-5).

Figure27-2
En bloc removal of spinous processesand laminae-
drillingoftroughs.
Figure 27-3
Lifting up the spinous processes and the laminae en bloc.
27
Cervicallaminectomy
235
Figure 27-4
Theuseof a high-speed drill to thin out the laminae.
Figure 27-5
Paper-thinlaminae.

236
MidcervicalSpine:Posterior Approach
r
Figure 27-6
Schematic representation
in axial section of the process
of thinning the laminae. Care istaken not to enter the joint capsule on
either side.
Once the lamina bone is paper-thin, a pair of fine-toothed
forceps are used to grasp and elevate the ligamenta flava,
which are then split along the midline raphe. The paper-thin
residual lamina is easily fractured, and the ligament and
residual lamina can be removed with a no. 15 blade or scis-
sors (Fig.27 -7). Additional bone work is performed with an-
gled Kerrison rongeurs or a diamond bur. Either before, as
suggested earlier, or after the completion of the laminec-
tomy, foraminotomies are performed where clinically indi-
cated, using a coarse diamond bur and a small (1-2 mm),
thin, footplated, 45 degree Kerrison rongeur. Generally, an
adequate foraminotomy can be performed with removal of
Figure 27-7
Removal of the thinned laminae and ligamentum
flavum.Thiscommonly occurs piecemeal as portions of laminaeand
ligamentbreakofffromtheirattachments.
no more than one third of the facet complex (Figs. 27-8,
27 -9). Greater degrees of facet removal or removal ofthe
joint capsule can be associated with instability and may
predispose to the development of kyphotic deformity or
translation.!
- 3
Closure
Reapproximation of the soft tissues in the midline is an
important step toward minimizing postoperative neck
pain and possiblythe development of a kyphotic defor-
mity. Closure should preferably be accomplished
using
only the fascial layers. It is the authors' belief that sutur-
ing muscle bellies to one another is associated with sig-
nificant muscle ischemia and a concomitant
increase in
postoperative pain. If,however, muscle layers must be ap-
proximated to reduce dead space or due to concerns of
spinal fluid leakage, either nonabsorbable
suture or ab-
sorbable suture with a resorption
time of greater than
6 weeks should be utilized. Drains can be used at the dis-
cretion of the surgeon but not as a substitute for adequate
hemostasis.

27
CervicalLaminectomy
237
Figure27-8
"Keyhole" laminoforaminotomy.
Only the medial portion of the joint capsule is disrupted.
Figure27-9
Use of a pituitary rongeur to remove a "soft disk" from
theaxillaofthe nerve root.
.
Complications
General complications related to positioning and the poste-
rior approach have been discussed in Chapter 26. A stan-
dard laminectomy poses very little risk to soft tissue struc-
tures as compared with the anterior approaches, though
overly aggressive dissection lateral to the lateral mass can
pose some risk to nerve roots or the vertebral arteries. The
potential for direct intraoperative injury of the spinal cord
or nerve roots during a laminectomy is obvious, though
only limited statistical data regarding the frequency of this
are available.4
Neurological deficits following cervical laminectomy,un-
related to direct injury of neural elements, have been well
described. These deficits can relate to either the spinal cord
or the nerve roots. Nonradicular postlaminectomy neurolog-
ical deterioration is not well understood and several mecha-
nisms, including the cord ischemias and the development of
syringomyelia,6 have been proposed to explain its occur-
rence. Arare (incidence -1.5%of all laminectomiesf but po-
tentially
reversible cause of progressive
postoperative

238
MidcervicalSpine:PosteriorApproach
---
deficits following a laminectomy is the development of an
epidural hematoma. It can be most readily diagnosed by a
cervical computed tomographic (CT)scan, although mag-
netic resonance imaging (MRI)scans are also useful. As a
corollary,the temptation to use gelatin sponges to facilitate
hemostasisina closedspace should be resisted because they
do expandand can produce delayed neurological deficits.s
Afifth or sometimes a sixth cervical nerve radiculopathy
can occur a few hours or even a day after a laminectomy or
laminoplasty procedure. The incidence ranges from 2.69to
12.9%10
andmaybegreaterfollowinglaminoplastythan af-
ter laminectomy. The etiology is thought to be traction on
the extradural components of the anterior and posterior
roots due to a posteromedial shift of the cord and expansion
ofthe dural sac followingthe laminectomy.The fact that the
C5 nerve rootlet is usually at the epicenter of the decom-
pression and is one of the shortest cervical rootlets is felt to
be the basis for the relative frequency of radiculopathy at
this leveJ.7It may possibly be exacerbated by hyperflexion
and adduction of the patient's arms during surgery.l1The
performance of a longitudinal durotomy, with preservation
of the integrity of the arachnoid, has been recommended as
a preventative and possibly curative strategy.12Conservative
management usually leads to a good recovery, but this may
take as longas a year.1O
References
1.
Albert Tj, Vaccaro
A. Postlaminectomy
kyphosis.
Spine
1998:23:
2738-2745
2.
Zdeblick TA,Abitbol JJ, Kunz DN, McCabe RP, Garfin S. Cervical stabil-
ity after sequential
capsule resection.
Spine 1993:18:2005-2008
3.
White M, Panjabi MM. Biomechanic considerations
in the surgical man-
agement of cervical spondylitic myelopathy. Spine 1988;13:856-860
4.
Zeidman SM, Ducker TB, Raycroft J. Trends and complications
in cer-
vical spinal surgery. 1989-1993.j
Spinal Disord 1997:10:523-526
5.
Cybulski GR,D'Angelo CM. Neurological
deterioration
after laminec-
tomy for spondylotic cervical myeloradiculopathy:
the putative
role of
spinal cord ischemia.j
Neurol Neurosurg
Psychiatry
1988;51:717-718
6.
Middleton
TH, AI-Mefty
0,
Haekey
LH, Parent
AD. Fox jL. Sy-
ringomyelia after decompressive
laminectomy
for cervical spondylo-
sis. Surg NeuroI1987;28:458-462
7.
Yonenobu K,Okada K,Fuji T, Fujiwara
K,Yamashita
K, Ono K.Causes
of neurologic
deterioration
following
surgical
treatment
of cervical
myelopathy. Spine 1986;11 :818-823
8.
Alander
DH, Stauffer S. Gelfoam-induced
acute
quadriparesis
after
cervical decompression
and fusion. Spine 1995;20:970-971
9.
Yonenobu
K,Hosono N, Iwasaki M, Asano M, Ono K. Neurologic
com-
plications
of surgery
for cervical
compression
myelopathy.
Spine
1991 :16:1277-1282
Postlaminectomy kyphosis is a well-recognized complica-
tion that appears to result from the muscle imbalance
produced by detachment of the paraspinous musculature
from the spinous process. Its incidence varies with the pa-
tient's age,13,14the degree of prior spondylosis,1 and the ex-
tent of facetectomy and capsular resection.2,15As already
noted,
we
recommend
laminectomy
in
spondylotic
myelopathy only for patients who exhibit excellent preser-
vation of cervical spine lordosis.
Cervical pseudomeningoceles, though rare,16occur ifthe
dura mater was intentionally or inadvertently opened. They
can usually be prevented by the judicious prophylactic use
of lumbar spinal fluid drainage. Diagnosis is often facilitated
by the use of a myelogram in conjunction with a CTscan.
.
Conclusions
Laminectomy techniques are important tools in the spine
surgeon's armamentarium.
Laminectomy remains a safe
and effective procedure in the management
of a well-
selected patient population. The use of meticulous surgical
technique during posterior decompression will yield results
comparable to and in some cases superior to anterior and
laminoplasty te~hniques.
10.
Dai L, Ni B, Yuan W, jia L. Radiculopathy
after laminectomy
for cervi-
cal compression
myelopathy.j
Bonejoint
Surg Br 1998:80:846-849
11.
Epstein jA. Extradural
tethering
effects as one mechanism
of radicu-
lopathy
complicating
posterior
decompression
ofthe
cervical spinal
cord. Spine 1996:21: 1839-1840
12.
Tsuzuki
N. Abe R, Saiki K. Zhongshi
L. Extradural
tethering
effect as
one mechanism
of radiculopathy
complicating
posterior
decompres-
sion of the cervical spinal cord. Spine 1996:21 :203-211
13.
Mikawa y, Shikata j, Tamamuro
T. Spinal deformity
and instability af-
ter multilevel
cervical laminectomy.
Spine 1987:12:6-11
14.
Yasuoka
S, Peterson
HA, Laws ERjr, MacCarty
CS. Pathogenesis
and
prophylaxis
of post laminectomy
deformity
ofthe
spine after multiple
level laminectomy:
difference
between
children
and adults.
Neuro-
surgery
1981 :9: 145-152
15.
Panjabi MM, White M III.Johnson
RM. Cervical spine mechanics asa
function
of transection
of components.j
Biomech 1975:8:327-336
16.
Maiuri F, Corriero
G, Giamundo
A, Donati
P, Gambardella
A. Postop-
erative
cervical
pseudo-meningocele.
Neurochirurgia
(Stuttg)
1988:31 :29-31

28
CervicalLaminoplasty
NitinTandonand Dennis G. Vollmer
. Indications
. Advantages
. Disadvantages
. SurgicalTechniques
UnilateralEnlargement
(Open-Door)
Laminoplasty
MidlineEnlargement
Laminoplasty
Cervicallaminoplastyis a surgical technique developed in
responseto someof the delayed complicationsthat may
occurafter a conventional
multilevel cervical laminec-
tomy.Laminoplastytechniques all serve to expand the cer-
vicalspinal canal while maintaining the integrity of the
dorsallaminar arch to some degree. These procedures
wereprimarilyused for the management of the continu-
ousformof ossification of the posterior longitudinalliga-
ment(OPLL).Because OPLLis more commonly seen in the
Japanese
populationand in racialgroups from southeast-
ernandeastern parts of Asia,1,2the bulk of the published
literatureon laminoplasty is derived from the experience
ofJapanese spine surgeons. Initially, laminoplasty
was
mostoftenrecommended for OPLLextending over more
thanthree segments, where multilevel corpectomy and fu-
sionseemeddifficult or impractical. Increasingly, however,
theoperation has been applied to other conditions tradi-
tionallytreated by multilevel laminectomy. Laminoplasty
isnowused for the management of a wide variety of cervi-
calspinecompressive lesions as is evidenced by the expo-
nentialgrowth in the number
of publications
on the
subject(Medline search-textword
"Iaminoplasty") (Fig.
28-1).
SinceOyamaand Hattori's first description of a lamino-
plastyprocedureforOPLLabout 3 decades ago,numerous
differentechniques (Table 28-1 )3-22have been described
withthecommongoalofexpandingthe spinalcanalusing
eitheror both local bony elements and allograft while
preservingthe dorsal bony arch of the spinal canal. Some
ofthese publications have used the term laminoplasty
inappropriately(as pointed out by Yucesoy23).The term
laminoplastyshould probably be restricted to describing the
surgicalprocess where the laminae are expanded to aug-
mentthe sizeof the spinal canal.
.
Outcomes
.
Complications
.
Conclusions
There are numerous potential advantages attributed to pre-
serving the posterior elements (laminar arch, ligamenta flava,
and in some ofthe procedures, spinous processes).It has been
suggested that preservation of these structures reduces the
incidence of postlaminectomy kyphosis, provides greater
rigidity and strength to the cervical spine, decreases forma-
tion of a "postlaminectomy membrane," provides protection
to the cord from mechanical injury,and alters the rate of pro-
gression ofOPLLin comparison to laminectomy.Most ofthese
advantages are based upon theoretical considerations that are
for the most part unsupported by conclusiveevidence.
. Indications
In the absence of a prospective, randomized study contrast-
ing laminoplasty with laminectomy or with a multilevel
anterior operation,24 definitive indications for the perfor-
mance of the procedure are not available. Forthe most part,
laminoplasty seems to be a reasonable strategy when the
decompression of the cervical spine has to extend over mul-
tiple levels, especially in younger patient populations25or
when the posterior approach is being used to approach a
spinal cord tumor rather than for cervical spondylotic
myelopathy (CSM).26Even in the absence of definitive proof
that laminoplasty is advantageous, there seem to be few
disadvantages to its broader application in patients who
would normally undergo laminectomy aside from a slightly
greater time to accomplish the operation.
Some have combined a laminoplasty with foramino-
tomy15.27.28
to manage cases where nerve root compression
coexists with a stenotic, minimally kyphotic cervical spine.
Again, there is no good evidence to suggest that this
239

240
MidcervicalSpine:PosteriorApproach
Table 28-1
Outline of Variations of Cervical Laminoplasty Techniques by Different Authors (in Chronological Order)
70
60
50
~ 40
.!2~ 30
(,)
20
10
o
1985-'87
1998-'90
1991-'93
Time Interval (years)
Variation
Original description of laminoplasty procedure
Laminar hinge ("open door") held open by suture
No suture/wire used to hold the laminar hinge open
Wire holds hinge open and holds spinous process in place over
opened lamina
ICBGinserted to expand spinous process
Laminae are opened and attached to paraspinous muscles for support
Ceramic lamina attached to edges of opened laminae with wire/suture
Post ligaments (tension band) left intact; ceramic spacer used
HAspacers used to augment lamina in midline
Tipofspinousprocessleft attached to ligaments; ICBGused to aug-
ment lamina
Laminectomy followed by laminar remodeling-held
with titanium
miniplates
Spinous process fabricated into a T-shaped graft and sutured into
opening
Laminoplasty plus bilateral foraminotomy;
lamina augmented
with
HAspacer
Spinous process sutured to widened laminae
Titanium miniplates cover opening and hold lamina in place
SpinousprocesssplitbyT-saw;ICBG/HAspacersheldwithwire/suture
Rib allograft-held
in place by structural molding, no hardware used
Hinge held open by an anchor system
Fenestrated Teflon spacer with titanium spring-wound clip holds
hinge open
Spinous processes partly resected, titanium mesh used to augment
lamina
1994-'96
Figure28-1
Increaseinthe numberof pub-
lications with the textword
"Iaminoplasty.
over the past 15 years.
1997- '99
Proposedby
Typeof expansion
1
Oyama, Hattori 19733
Z-shaped enlargement
2
Hirabayashi 19784
Unilateral (uncovered)
3
Tsuji 19825
Unilateral (uncovered)
4
Itoh, Tsuji19856
Unilateral (covered)
5
Kurokawa 19827
Midline (covered)
6
Oomori 19838
Midline (uncovered)
7
Hase et al19919
Midline (covered)
8
Tzusuki et al199110
Unilateral (covered)
9
Nakano etal199211
Midline (covered)
10
Yoshida et a11992'2
Midline (covered)
11
Frank, Keenen 199413
Bilateral (covered)
12
Hamburger 199514
Midline (covered)
13
Koshu et al199515
Midline (covered)
14
Morimoto et aI1996'6
Midline (covered)
15
O'Brien et al199617
Unilateral (covered)
16
Tomita et al199818
Midline (covered)
17
Lee et al199719
Unilateral (covered)
18
Wang et al199820
Unilateral (uncovered)
19
Gillett et al199921
Unilateral (covered)
20
Fornari et al199922
Midline (covered)
ICBG,iliaccrest bone graft; HA,hydroxyapatite.

.....
28
CervicalLaminoplasty
241
strategy results
in better
outcomes
than
a laminectomy
with bilateralforaminotomies or an anterior approach, es-
peciallyif pathology exists at only one or two levels.29 The
sameistrue for the application of laminoplasty in the man-
agement of herniated
disks in the cervical spine because it
isgenerally best to use an anterior approach
for an anterior
compression.30
Somesurgeons have also applied the laminoplasty ap-
proachto decompressions performed in the thoracic and
lumbarspine31,32in the hope of decreasing the incidence of
postoperativemusculoskeletal pain. Although the basic sur-
gicalprocedureremainsthe same,the pathologicaland bio-
mechanicalprocesses in the thoracic and lumbar spine are
dissimilarto those in the cervical spine and are outside the
scope of this chapter.
. Advantages
. Reducesthe incidence of postlaminectomy
kyphosis
. Provides greater
rigidity
and strength
to the cervical
spine
. Mayalter the rate of progression
of OPLLin comparison
to laminectomy
. Disadvantages
. Restenosismay occur from laminar arch collapse.
. Neck,shoulder pain, and radiculopathy (C5 most com-
monly)can take months to resolve.
. Occurrenceof a boomerang deformity of the cervical
spinalcord
. Surgical Techniques
Sincethe original descriptions of laminoplasty in the litera-
ture,numerous variations on the original operative tech-
niquehavebeen put forth. Although these variations carry
theirown advantages and disadvantages, the goal of the
procedureremains the same: to preserve the dorsal aspect
ofthebonycanalwhileexpandingits cross-sectionalarea.
Mostvariations in technique may be subdivided into
threebasic groups: Unilateral canal enlargement, central
canalenlargement, and Z-shaped enlargement.
Each of
thesethreetypesofprocedurehas distinct limitationsand
advantages.Unilateral techniques such as the open-door
laminoplastymay pose risks for injury to the nerve roots
andtothe dura because the ligamentum flavum is typically
notas thick laterally as in the midline; also, spontaneous
re-
closureof a unilateral type laminoplasty may occur more
readily than a midline type. On the other hand, the risk of
cord injury with midline and Z-shaped approaches may be
greater because drilling is performed directly over the cord.
The Z-shaped technique is somewhat more technically de-
manding and time consuming compared with the other
methods and is usually associated with greater intraopera-
tive blood loss.33Because it does not offer any obvious ad-
vantages over the two methods detailed in the following
sections, we do not use it in our practice and omit its
description here.
Unilateral Enlargement
(Open-Door) Laminoplasty
The operative position for cervicallaminoplastyis as for
laminectomy discussed in the previous chapters. We prefer
to use the Mayfield headholder, which offers rigid immobi-
lization of the cervical spine without the risks of orbital and
facial pressure. A "military" head tuck provides sufficient
flexion for surgical access to the subaxial cervicalspine. Fol-
lowing exposure of the dorsal aspect of the cervical spine as
previously described, the spinous processes of C3through
C7arecutat the basewith aHorseleyrongeurand savedfor
use as bone graft. Hemostasis of the bleeding bone is se-
cured using bone wax. The medial aspect of the facet com-
plex is identified at each level as the landmark for making
the bilateral troughs. The side that is to be the hinge of the
"open door" is generally drilled first. The decision as to
which side should be opened is made after review of the
patient's physical complaints and the preoperative images.
If there is a component of unilateral radiculopathy,the
opening is ipsilateral to the symptoms thus facilitatinga
concomitant keyhole laminoforaminotomy. In the absence
of lateralizing symptoms or radiographs, the choice is the
surgeon's preference.
Usingahigh-speeddrill fitted with a small(2 mm)cut-
ting bur, a trough is made across each lamina. -2 mm in
depth. This trough should thin the bone, perforating it in-
completely (Fig. 28-2A). There is a tendency to inade-
quately thin the rostral and caudal aspects of the laminae so
special care should be taken at these sites. The side to be
opened is cut in similar fashion but the inner cortex is com-
pletely cut through. It should be remembered
that the
ligamentumflavumwill be absent belowa portion of the
rostral aspect of each lamina, so added caution is required.
Occasionally, a thin footplate, 1 mm Kerrison rongeur may
facilitatethe completionof the trough.Aftercuttingboth
troughs the laminae should be slightly mobile. A blunt
nerve hook can be used to separate the ligamentum flavum
from the underlying dura, facilitatingthe openingof the
laminaeoverthe extentof thelaminoplasty.Cuttingthe lig-
amenta on the open side and gently elevating the laminae
will expand the canal. Epidural bleeding is managed with
bipolar cautery and thrombin-soaked
Gelfoam. At this
point, aforaminotomyto decompressthe ipsilateralnerve
root may be performed.

242
MidcervicalSpine: Posterior Approach
A
B
C
Figure 28-2
Unilateral expansion using autologous remodeled spinous process.
The decompression
is complete at this point and the
remaining steps are dictated by the surgeon's choice of ma-
terial to augment the lamina and its fixation.We use autolo-
gous spinous process segments that are secured in place
with nonabsorbable suture, wires (Fig.28-2B,C).or titanium
miniplates (Fig. 28-3). Titanium miniplates are easier to
place, and produce less artifact on postoperative magnetic
resonance imaging(MRI)scans than steel wire. Plates are at-
tached to the lamina and to the ipsilateral lateral mass with
4 to 6 mm screws. Ifsuture or wires are used a small wire-
pass drill is used to make holes in the trimmed spinous
process segments as well as the lateral mass and the edgeof
the laminar segment. In either case, care should be taken not
to disrupt the facet joint during the placement of the fixa-
tion devices. When suture is used, we use a braided nonab-
sorbable 0 or 00 suture. Advantages include the absence of

A
28
Cervical Laminoplasty
243
B
Figure28-3
Useof titanium miniplates to rigidly secure the bone graft used to expand the lamina.
anyradiographic artifact and low cost. A disadvantage
is a
slightdecreasein rigidity.The spinous process segments can
generallybe placed in such a way that they are relatively
rigidandproppedagainst the adjacent bone thereby resist-
ingclosure of the laminar arch. It should be mentioned
that
inmultilevellaminoplasties,
the segments
at either end of
thedecompression should be rigidly propped
open but that
anoccasionalintervening segment may be left ungrafted
es-
peciallyifa laminoforamenotomy
is performed.
Advantages
. Rapidand technically easy procedure, easily combined
withnerveroot decompression.
Disadvantages
. Thespinalcord decompression may remain unilateral in
somecases,with the full goal of the operation not being
accomplished.
. Radiculopathymay develop postoperatively on the side
thatwasnot decompressed.34.35
. Theriskof durotomy and accidental root injury may be
somewhathigher.
. Withthe standard open-door procedure, the spinous
processesare removed thus eliminating sites for poste-
riormusclereattachment.
MidlineEnlargement
Laminoplasty
Followinga standard posterior cervical exposure of the
laminaeand the medial aspect of the facet joints, bilateral
troughsaremadeas alreadydescribed.Thetroughshould
thin the bone almost to the point of perforating the inner
cortical layer. The spinous process is then divided in the
midline in one of three ways (Figs. 28-4, 28-5, 28-6). The
tip of the spinous process can be removed and the lamina
is divided in such a way that the two halves when approx-
imated expand the spinal canal (Fig. 28-4A,B). This cut
should be made with the smallest bur available (usually
1-1.5 mm), to prevent excessive thinning of the remaining
bone. The two overlapping leaves of the lamina thus cre-
ated are separated and the laminar halves are lifted up
and secured to each other at their tips with wires or
plates. Alternatively, the spinous process is divided verti-
cally in the midline, again with a small bur, the lamina is
elevated, and after hemostasis is achieved, a wedge of il-
iac crest bone graft is inserted between the cut edges and
secured in place with wire or plates (Fig. 28-5). Finally,
various implants such as ceramic spacers have been used
to hold the laminar halves apart, thus expanding the canal
(Fig. 28-6).
Advantages
.
A midline expansion opens both sides of the canal
equally.
.
Thedorsal projection of the spinous processesmaybe
better preservedprovidinga morephysiologicalmelieu
formusclereattachment.
Disadvantages
. Twotroughsplus a midlineosteotomyare required,
whichincreasesthe complexityofthe operation.
. The midline cuts may pose a greater risk to the spinal
cord.

244
MidcervicalSpine: Posterior Approach
...
A
Figure 28-4
Midline expansion laminoplasty
performed
without
the use of graft materials.
B
Figure 28-5
Midline expansion laminoplasty using an iliac crest
bone graft.
.
Outcomes
Most published reports of large series of cervicallamino-
plasties evaluate the success of the procedure against the
natural history of the pathological process rather than com-
paring it with laminectomy. Retrospective reviews of un-
controlled
cohorts
of patients
that
underwent
either
laminoplasty or a conventional laminectomy provide data
both supporting26.36.37and opposing38.39the notion that
laminoplasty results in a lower incidence of postoperative
spinal deformity. That having been said, in general, an im-
provement of the symptoms of myelopathy can be expected
in -60
to 85% of patients6.9.19.33,34,36,41,42
who undergo a
Figure 28-6
Midline enlargement laminoplasty using prosthetic
material (ceramicspacerin this case).
laminoplasty. These figures are relatively similar to the re-
sults for laminectomy. Patients' age, duration of symptoms
of myelopathy, severity of deficits, and preoperative bowel
and bladder function impact the operative outcome.19,43
Whether or not there is a real difference in the incidence
of postoperative kyphosis or loss of the cervical lordotic
curve following either laminectomy or laminoplasty,39.44it
seems that "buckling-type alignment," which is believedby
some authors37to correlatewith a poor neurologicalout-
come, develops less often following laminoplasty as com-
pared with laminectomy. Indeed the beneficial effects of
laminoplasty, perceived but not conclusively proven in
many Japanese series may result from at least two other

28
Cervicallaminoplasty
245
factorsbesidesthe muchtouted preservationof posterior
elementsof the cervical spine. The range of movement of
the cervical spine after laminoplasty is significantly de-
creasedas compared with laminectomy (i.e., greater stiff-
nessofthe spine).9.45.46
Additionally the spinal cord is given
roomtomigratedorsallyandto enlarge47-the extentofthis
movementcorrelates with neurological recovery following
decompression.48.49
Theinitial impetus behind the development of lamino-
plastywasthe prevention of the development of postopera-
tivekyphosisfollowing a multilevel laminectomy. Despite
multipleinnovations in the technique of laminoplasty, in-
cludingsparing the interspinous Iigaments12and reattach-
mentofnuchal muscles to the axis,6 spinal malalignment
doesdevelopto some extent50and some atrophy of nuchal
musclesdoesoccur. Perhaps comparative studies with very
long-termfollow-up will reveal a higher stability rate fol-
lowinglaminoplastyascomparedwith laminectomy.
Froma practical standpoint, basic surgical steps such as
thepreservationof the attachment of nuchal musculature
tothespinous process of (2 and preservation of the liga-
mentumfIavumat (2-(344 may decrease the incidence and
severityofpostoperative kyphosis.
Lastly,preserving the dorsal elements of the spine proba-
blydoesprotect the cord from compression by nuchal mus-
culature51or external elements,52 though such circum-
stancesare uncommon.
. Complications
Theoverallincidence of surgical complications
of a multilevel
laminoplastyare lower than those following a corpectomy of
similarsegmental extent.50.53Besides complications
common
toanyoperation on the cervical spine (i.e., infection, spinal
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S. A new method
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for patients
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to so-called
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thoracic
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Spine 1982;7:28-34
6. ltoh T,Tsuji H. Technical improvements
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Orthopedic
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us-
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cord injury, nerve root injury, and cerebrospinal fluid leak-
age), a few particular complications follow laminoplasty.
Restenosis may occur from laminar arch collapse,6,34,35.45
resulting in a radiculopathy. The use of titanium miniplates
to secure the construct minimizes the chances of this
occurrence. Neck and shoulder pain54 may occur in a
significant percentage of patients and may take several
months to resolve. Radiculopathy of a spinal nerve, espe-
cially of (5, is another complication that may take a long
time to resolve, and recovery of function may not be com-
plete.55 A rarer
complication
is the occurrence
of a
boomerang deformity of the cervical spinal cord due to
excessive dorsal migration between the split laminae of the
laminoplasty.56.57
.
Conclusions
Laminoplasty should be considered in cases of cervical
myelopathy resulting from multilevel spondylosis, develop-
mental canal stenosis, or OPLLwhen anterior decompression
would require more than a three-level corpectomy, provided
there is preservation of cervical lordosis. Posterior cord im-
pingement
by ligamentum
flavum is also treatable by
laminoplasty. Because of the problem with adjacent seg-
ment degeneration following anterior cervical fusion, we
occasionally broaden the indications for laminoplasty to
two-level disease in younger patients as in cases of spinal
cord tumors. At the current time, most of the support in fa-
vor of laminoplasty derives from theoretical considerations,
retrospective reviews with poorly matched controls, and
anecdotal evidence. Its definitive place in the management
of cervical stenosis will be better defined by well-designed,
long-term, prospective, randomized analyses comparing it
with laminectomy and anterior cervical approaches.
12.
Yoshida M, Otani K, Shibasaki
K, Ueda S. Expansive
laminoplasty
with
reattachment
of spinous
process
and extensor
musculature
for cervi-
cal myelopathy.
Spine 1992;17:491-497
13.
Frank E, Keenen TL. A technique
for cervicallaminoplasty
using mini
plates. Br J Neurosurg
1994;8:197-199
14.
Hamburger
C. T-laminoplasty:
a surgical
approach
for
cervical
spondylotic
myelopathy.
Technical
note.
Acta
Neurochir
(Wien)
1995;132:131-133
15.
Koshu K.Tominaga
T, Yoshimoto
T. Spinous
process-splitting
lamino-
plasty
with
an extended
foraminotomy
for cervical
myelopathy.
Neurosurgery
1995;37:430-434
16.
Morimoto
T, Yamada T, Okumura
Y,et al. Expanding
laminoplasty
for
cervical
myelopathy-spinous
process
roofing technique.
Acta Neuro-
chir (Wien) 1996;138:720-725
17.
O'Brien MF, Peterson
D, Casey AT,Crockard
HA. A novel technique
for
laminoplasty
augmentation
of spinal canal area using titanium
mini-
plate stabilization:
a computerized
morphometric
analysis [see com-
ments I. Spine 1996;21 :474-483
18.
Tomita
K, Kawahara
N, Toribatake
Y,Heller JG. Expansive
midline
T-
saw laminoplasty
(modified
spinous
process-splitting)
for the man-
agement
of cervical myelopathy.
Spine 1998;23:32-37
19.
Lee IT, Manzano
GR,Green BA.Modified open-door
cervical expansive
laminoplasty
for spondylotic
myelopathy:
operative
technique,
out-
come, and predictors
for gait improvement.J
Neurosurg
1997:86:64-68
20.
Wang JM, Roh KJ, Kim DJ, et al. A new method
of stabilising
the ele-
vated laminae
in open-door
laminoplasty
using an anchor
system.
J
Bone Joint Surg Br 1998;80:1005-1008

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40.
.,..
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Gillett
GR. Erasmus
AM. Lind CR. CG-clip
expansive
open-door
laminoplasty:
a technical
note. Br J Neurosurg
1999;13:405-408
22.
Fornari M. Luccarelli
G. Giombini
S. Chiapparini
L.Artificial
lamina-
assisted
laminoplasty
performed
in seven
cases. J Neurosurg
Spine
1999;91 :43-49
23.
Yucesoy
K, Sonntag
VK. Terminology
confusion
in spinal
surgery:
laminotomy.laminoplasty,
laminectomy.
J Neurosurg
2000;92:371
24.
Orr RD.Zdeblick TA. Cervical spondylotic
myelopathy.
Approaches
to
surgical treatment.
Clin Orthop
1999;359:58-66
25.
Shaffrey
CI. Wiggins
GC. Piccirilli
CB. Young IN, Lovell LR. Modified
open-door
laminoplasty
for treatment
of neurological
deficits
in
younger
patients
with congenital
spinal stenosis:
analysis of clinical
and radiographic
data.J Neurosurg
1999;90(4
Suppl):170-t77
26.
Inoue A, Ikata T. Katoh S. Spinal deformity
following surgery for spinal
cord tumors
and tumorous
lesions:
analysis
based on an assessment
ofthe
spinal functional
curve. Spinal Cord 1996;34:536-542
27.
Iwasaki
M. Ebara S. Miyamoto
S, Wada
E. Yonenobu
K. Expansive
laminoplasty
for cervical
radiculomyelopathy
due to soft disk hernia-
tion. Spine 1996;21 :32-38
28.
Baba H, Chen Q. Uchida K. et al. Laminoplasty
with foraminotomy
for
coexisting
cervical
myelopathy
and unilateral
radiculopathy:
a pre-
liminary
report. Spine 1996b;21 :196-202
29.
Hirabayashi K,Bohlman HH. Controversy: multilevel cervical spondylosis.
Laminoplasty
versus anterior decompression.
Spine 1995;20: 1732- 1734
30.
Yoshida
M, Tamaki T. Kawakami
M. et al. Indication
and clinical
re-
sults of laminoplasty
for cervical myelopathy
caused by disk hernia-
tion with developmental
canal stenosis. Spine 1998;23:2391 -2397
31.
Tsuji H. Itoh T, Sekido H. et al. Expansive
laminoplasty
for lumbar
spinal stenosis.lnt
Orthop 1990;14:309-314
32.
Cobb MA. Boop FA.Replacement
laminoplasty
in selective dorsal rhi-
zotomy:
possible
protection
against
the
development
of muscu-
loskeletal
pain. Pediatr Neurosurg
1994;21 :237 -242
33.
Naito M. Ogata K. Kurose S, Oyama M. Canal-expansive
laminoplasty
in 83 patients
with cervical myelopathy:
a comparative
study ofthree
different
procedures.lnt
Orthop 1994;18:347-351
34.
Hirabayashi
K. Watanabe
K. Wakano
K, et al. Expansive
open-door
laminoplasty
for
cervical
spinal
stenotic
myelopathy.
Spine
1983;8:693-699
35.
Hirabayashi
K. Satomi
K. Operative
procedure
and results
of expan-
sive open-door
laminoplasty.
Spine 1988;13:870-876
36.
Tomita K,Nomura S, Umeda S, et al. Cervicallaminoplasty
to enlarge the
spinal canal in multilevel
ossification of the posterior
longitudinalliga-
ment with myelopathy. Arch Orthop Trauma Surg 1988;107:148- 153
37.
Matsunaga
S. Sakou T, Nakanisi K.Analysis of the cervical spine align-
ment
following
laminoplasty
and
laminectomy.
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1999;37:20-24
38.
Nakano N, Nakano T. Nakano K.Comparison
of the results of laminec-
tomy
and open-door
laminoplasty
for cervical
spondylotic
myelo-
radiculopathy
and ossification
of the posterior
longitudinal
ligament.
Spine 1988;13:792-794
39.
Hukuda
S. Ogata M. Mochizuki
T. Shichikawa
K. Laminectomy
versus
laminoplasty
for cervical
myelopathy:
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Br 1988;70:325-326
Satomi
K. Nishu Y. Kohno T. et al. Long-term
follow-up studiesof
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expansive
laminoplasty
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Spine 1994;19:507-510
Kawai S, Sunago K, Doi K, et al. Cervical laminoplasty (Hattori's
method).
Procedure
and follow-up
results. Spine 1988;13:1245-1250
Kohno K, Kumon Y. Oka Y,et al. Evaluation
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HN. A comparison
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Aita I. Hayashi K, Wadano
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N, Azuchi M. Imura S.Lor-
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56.

r, 29
PosteriorCervical Foraminotomy
NoamY.Stadlan
. Indications
. Contraindications
. Advantages
. Disadvantages
. SurgicalTechniques
Compression
ofa cervical nerve root in the neural foramen
isafrequentcause of radiculopathy. The compression can
occursecondaryto spondylosis and without an associated
diskherniation.In these cases, the posterior approach to
thedecompression of a cervical
foramen
is a very direct
methodfor the relief of foraminal compression
causing cer-
vicalradiculopathy.
. Indications
. Cervicalforaminal stenosis
with symptoms
that corre-
lateto the affected nerve root documented
on computed
tomography (Cf), magnetic
resonance
imaging
(MRI),
and/ormyelogram(foraminal stenosis may not be evi-
dent on the plain myelogram,
and CT is quite helpful,
andinsome cases imperative)
. Symptomsrefractory to conservative
treatment
. Nomyelopathy
. Contraindications
. Significantkyphosis or mechanical instability at the
levelto be addressed
. Signsorsymptomsof cervical myelopathy
. Spinalcord compression on studies
. Localskininfection
. Symptomsnot referable to the pathology seen on studies
. Significantdisk herniation
compressing
the nerve root
(considerdiskectomy, either anterior or posterior)
Anesthesia and Positioning
Approach
Foraminotomy
Closure
.
Postoperative care
.
Advantages
. Does not destabilize the disk space
.
Does not require fusion
.
Avoids the risks of the anterior approach (Le., carotid
injury, esophageal injury and hypomotility, recurrent la-
ryngeal nerve injury, hoarseness)
. Easy direct approach, which directly decompresses the
foramen
.
Disadvantages
. More dissection of the large extensor spine muscle
mass, with possible increase in postoperative neck pain
.
Inability to deal directly with pathology affecting the
central aspect of the canal
.
SurgicalTechniques
Anesthesia and Positioning
The procedure must be done under general anesthesia. The
patient can be positioned either prone or sitting, but the sit-
ting position has more risks, and is more tiring for the sur-
geon. For the prone position, the Wilson frame or similar
bolsters are used under the torso. The author uses three-pin
Mayfield fixation, although a well-padded horseshoe is
an option. The neck should not be hyperextended, and a
"military" posture with the chin slightly tucked aids in the
approach. The shoulders are gently taped down to allow
better radiographic views of the neck. All possible neural
247

248
MidcervicalSpine:PosteriorApproach
..
compression points should be checked and padded, espe-
ciallythe elbows,which are kept at the patient's sides.
Approach
Amidline incision is marked and infiltrated with local anes-
thesia (Fig.29-1). Usuallya 1 in. incision is all that is neces-
sary. The length of the incision represents a compromise
between keeping the incision as small as possible and
avoiding excessive retraction on the muscle. X-ray or fluo-
roscopy is useful, not only in assuring good spine alignment
but also in placement of the incision, to minimize the
length and the extent of the muscle dissection. A subpe-
riosteal dissection is done over the laminae of the vertebral
bodies adjacent to the disk only on the side of the pathol-
ogy. The muscle should be dissected to expose the medial
50%of the facet. Further dissection laterally is unnecessary
and may destabilize the joint. Once the proper levels have
been confirmed and adequate exposure achieved, self-re-
taining retractors are placed (Fig.29-2).
Foraminotomy
The line marking the junction of the lamina and.facet is
identified. Bony removal begins just medial to this. The in-
ferior aspect of the superior lamina is separated from the
ligamentum fIavum with small angled curettes or a dissec-
tor. Bone removal can be done with a drill or with thin-
footed Kerrison rongeurs.Thevery lateral aspect of the lam-
ina is removed, and the thecal sac visualized (Fig. 29-3).
Part of the superior aspect of the inferior lamina can also be
removed to help identify the inferior pedicle. The ligamen-
tum fIavumusually has been opened with the bone removal.
If not, it can be gently dissected with a small dissector or
nerve hook, care being taken not to compress or puncture
/
Figure 29-1
Theincisionismade inthe midline,-1 in.long.
Figure 29-2
The laminae are exposed only at the level of the pathol.
ogy, taking care to leave the lateral 50%of the facet intact.
the underlying dura. The nerve root is then seen coursing
laterally from the thecal sac into the foramen (Fig.29-4).
The foramen can be palpated with a small nerve hook.
Further bone dorsal to the nerve root and overlying the
foramen can be thinned down with the drill, such as the
Midas AM-8(Midas Rex, Ft. Worth, TX),until only a small
shell remains. This shell can be removed with a smallsharp
curette.Careshouldbetakennot toforceinstrumentsintoa
Figure29-3
Thelaterallamina is removed to expose the central dura.
...

Figure 29-4
The nerve root is exposed and followed out to the
foramen.
tight foramen (Fig.29-5). If room allows, 1 or 2 mm thin-
footed Kerrisons can be used to remove the thinned bone.
Thecompression can be secondary to bony overgrowth. lig-
amentous hypertrophy, or both, so all nonneural tissue dor-
sal to the nerve root should be removed. The nerve root
should be followed out laterally until it is well decom-
pressed. Rarely does more than 30 to 50%of the foramen
need to be unroofed. The compression can come at several
sites in the foramen. The nerve may appear discolored or
thinned at these areas. The preoperative studies should be a
guide to the extent of decompression, but palpation with a
nerve hook should reveal a well-decompressed
nerve root
all the way out the foramen by the end of the procedure.
The decompression sometimes needs to be extended to the
limits of the pedicles superiorly and inferiorly. Some have
advocated drilling the pedicle, but this is usually not neces-
sary. Ifthe foramen is still tight, despite removal of all the
dorsal compression and in the absence of a soft disk mass,
the superior part of the inferior pedicle can be carefully re-
moved with a drill. Obviously the nerve root needs to be
well protected during this maneuver. If a larger anterior
disk fragment is noted, a diskectomy should also be per-
formed. Small anterior osteophytes can usually be ignored
Suggested
Readings
Collias JC. Roberts Melville P. Posterior surgical approaches
for cervical disk
herniation
and spondylotic
myleopathy.ln:
Schmidek, Sweet. eds. Operative
Neurosurgical Techniques. New York: WB Saunders;
1995: 1805-1816
Mosdal C. Overgaard J.Lateral cervical facetectomy.The surgical pathology
of radicular
brachialgia. Acta Neurochir
(Wien)
1984;70:199-205
29
Posterior Cervical Foraminotomy
249
Figure 29-5
Decompression should be performed until palpation
showsno further nerveroot compression.
but can be curetted with small curettes. Significant bleeding
can be encountered, and this is stopped with accurate bipo-
lar coagulation or gently tamponaded
with Gelfoam or
Avitene.Asmuch hemostatic material as possible should be
removed prior to closure.
Closure
The wound is copiously irrigated with antibiotic solution,
hemostasis checked, and Gelfoam placed over the exposed
dura. A drain can be used if significant oozing continues.
The fascia is reapproximated. and the wound is closed in
layers.
.
Postoperativecare
A neck brace is not necessary, but some patients find a
soft collar to be beneficial for a few days to weeks. Routine
x-rays are not needed. Patients are usually monitored
overnight, but the incidence of complications is very low.
Routine activities can be resumed as soon as tolerated.
Williams
RW. Microcervical
foramenotomy:
a surgical
alternative
for in-
tractable
radicular
pain. Spine 1983;8:708-716
Zeidman
SM. Ducker
TB. Posterior
cervical
laminoforamenotomy
for
radiculopathy:
review of 172 cases. Neurosurgery
1993;33:356-362

30
Posterior Cervical Diskectomy
NoamY.Stadlan
.
Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
SurgicalTechniques
Several options are available for the treatment of the herni-
ated cervical disk causing unilateral radiculopathy.The pos-
terior cervical approach is the simplest and most direct
surgical option. Thisapproach avoidsthe delicate structures
in the neck, provides for direct visualization and decom-
pression of the affected nerve root, and, when properly
done, does not destabilize the spine or require an associated
fusion.
.
Indications
. Cervical disk herniation with symptoms that correlate
to the affected nerve root
.
Pain or weakness refractory to conservative treatment
.
Nerve root compression documented on computed to-
mography (CT), magnetic resonance imaging (MRI),
and/or myelogram
. No myelopathy
.
Disk fragment extends laterally beyond the lateral ex-
tent of the thecal sac
.
Contraindications
. Significantkyphosisor mechanicalinstabilityat the
levelto beaddressed
.
Signsor symptomsofcervicalmyelopathy
.
Spinalcordcompressionon studies
.
Localskininfection
.
Symptomsnotreferableto the pathologyseenonstudies
. The majority of the disk herniation is anterior to the
spinalcord,not lateral.
250
Anesthesia and Positioning
Approach
Diskectomy
Closure
.
Postoperative Care
.
Advantages
. Does not destabilize the disk space
.
Does not require fusion
.
Avoidsthe risksofthe anteriorapproach(Le.,carotidin-
jury, esophagealinjury and hypomotility,recurrentla-
ryngeal nerve injury, hoarseness)
. Easydirect approach
.
Canalso address foraminal stenosis easily
.
Disadvantages
. More dissection of the large extensor spine muscle
mass,with possibleincreasein postoperativeneckpain
.
Inabilityto dealwith pathologyaffectingthe centralas-
pect of the canal
. SurgicalTechniques
Anesthesia and Positioning
Theproceduremustbedoneunder generalanesthesia.The
patient can be positioned either prone or sitting, but the
sittingpositionhas morerisksandis moretiringforthesur-
geon. For the prone position, the Wilson frame or similar
bolsters are used under the torso. The author uses three-pin
Mayfield fixation, although a well-padded horseshoe isan
option. The neck should not be hyperextended, and a "mili-
tary" posture with the chin slightly tucked aids in the ap-
proach. The shoulders are gently taped down to allow better
radiographic views of the neck. Allpossible neural compres-
sion points should be checked and padded, especially the
elbows, which are kept at the patient's sides.

.....
Approach
30
Posterior Cervical Diskectomy
251
Amidlineincisionismarked and infiltrated with local anes-
thesia.Usually a 1 in. incision is all that is necessary to
exposeone foramen (Fig.30-1). The length of the incision
representsa compromise between keeping the incision as
smallaspossibleand avoidingexcessiveretractionon the
muscle.X-rayor fluoroscopy is useful, not only in assuring
goodspinealignment but also in placement of the incision.A
subperiostealdissection isdone over the laminae of the ver-
tebralbodies adjacent to the disk, only on the side of the
pathology.The muscle should be dissected to expose the
medial50%of the facet. Further dissection laterally may
destabilizethe joint. Once the proper levels have been con-
firmedand adequate exposure achieved, self-retaining re-
tractorsare placed (Fig. 30-2). The junction of the lamina
andfacetshould be identified. This is evident by a groove
wherethe angleofthe bone changes.The lamina isdissected
freeofthe ligamentum fIavum with a small angled curette,
ordissector. The bone removal can initially be done with a
drillor with thin-footed Kerrison rongeurs (at our institution,
the footplate of the rongeur
is drilled
down
so that
the
amountof compression
exerted
by the foot is significantly
reduced).The very lateral and inferior aspect of the superior
laminais removed, and the thecal sac visualized.
A small
amountofthe inferior lamina can also be removed to better
identifythe pedicle (Fig. 30-3).
The ligamentum
fIavum is
gentlyremoved,and the nerve root identified. The foramen
canbe palpated with a small nerve hook. Further bone dorsal
tothe nerve root and overlying the foramen can be thinned
down with the
drill,
using
a bit
like the
Midas AM-S,
untilonly a small shell remains. This shell can be removed
withasmall,sharp curette. Careshould be taken not to force
instrumentsinto a tight foramen. If room allows, 1 and 2 mm
cut-down Kerrisons
can be used. The nerve
root should
be followed out
laterally
until
it is well
decompressed
/
Figure30-1
The incision is made in the midline, -1 in. long.
Figure 30-2
The laminaare exposed onlyat the levelofthe pathol-
ogy,taking careto leavethe lateral50%ofthe facet intact.
(Fig.30-4). Rarelydoes more than 30 to 50%of the foramen
need to be unroofed. The nerve root should not be manipu-
lated until it has been well decompressed posteriorly.
Diskectomy
Once the foramen has been decompressed, the area around
the nerve root is explored. This should be done under the
microscope or high magnification Ioupes. The pedicles that
form the superior and inferior borders of the foramen
Figure 30-3
The lateral lamina is removed to expose the central dura.

252
MidcervicalSpine:Posterior Approach
I
j,
I
Figure 30-4
The nerve root is exposed and followed out to the
foramen.
should be palpated. Most fragments will be found coming
up from the caudal side of the root because the disk space is
caudal to the root (Fig. 30-5). Occasionally the superior
aspect of the root will also need decompression. The preop-
erative studies should indicate approximately where the
disk herniation
is located. The root is usually gently
retracted
superiorly and the floor of the canal probed
(Fig. 30-6). The posterior longitudinal ligament is incised
when necessary to remove a subligamentous disk fragment.
This is done with a no. 15blade, directing the incision infe-
riorly and laterally, away from the root and central dura.
The motor root exits more ventrally and sometimes can be
mistaken for a disk fragment. The fragments can be teased
up using small nerve hooks, with a sweeping motion, and
Figure 30-5
The disk fragment is usually found on the inferior
aspect ofthe root, comingfromthe diskspace.
Figure 30-6
After the foramenotomy
is complete,
the nerve rootis
gently deflected cephalad to expose the disk fragment.
graspedwith micropituitaryforceps.Thenervehookshould
be swept under the root to assure total decompression.An-
terior osteophytes generally do not cause significant com-
pression if the foramen has been well decompressed. How-
ever, if these significantly indent the root, they can be
removed with curettes. Bleeding can be brisk as epidural
veins are decompressed, and this is usually easily handled
with accurate bipolar coagulation of the offending vesselif
it can be identified, or by gently tamponading with Surgicel.
As much hemostatic material should be removed as possi-
ble at the end of the case. Palpation with a nerve hookall
around the nerve, including ventrally and then directedout
the foramen, should be done at the end of the procedureto
be sure that it is adequately decompressed
(Fig. 30-7).
Figure 30-7
Palpation should show the nerve root well decom-
pressedfromthe thecal sac allthe wayout the foramen.

30
PosteriorCervicalDiskectomy
253
Fragments that are more medial
can be pulled
laterally,
but
great care should be taken to avoid any compression
of the
thecal sac.If there is significant
medial
compression,
an al-
ternate approach should be utilized.
Closure
Thewound is copiously irrigated with antibiotic
solution,
hemostasischecked.and Gelfoam placed over the exposed
dura.A drain can be used if significant oozing continues.
Suggested Readings
ColliasJC,Roberts Melville P. Posterior surgical approaches
for cervical disk
herniation
and spondylotic
myleopathy.
In: Schmidek,
Sweet,
eds.
Operative
NeurosurgicalTechniques. New York: WB Saunders:
1995:1805-1816
HerkowitzHN, Kruz, LT,Overholt
DP. Surgical management
of cervical soft
discherniation: a comparison between the anterior and posterior ap-
proach.Spine 1990;15:1026-1030
MosdalC,Overgaard].
Lateral cervical facetectomy.
The surgical pathology
ofradicular brachialgia. Acta Neurochir
(Wien) 1984;70:199-205
The fascia is reapproximated, and the wound closed in
layers.
.
PostoperativeCare
A neckbraceis not necessary, but some patients find a
soft collarto be beneficialfor afewdaysto weeks.Routine
x-rays are not needed. Patients are usually monitored
overnight,but the incidenceof complicationsis very low.
Routine activities can be resumed as soon as tolerated
Schmidekn
HH, Sweet, WHo Posterior
surgical
approaches
for cervical disc
herniation
and spondylotic
myelopathy.
In: Collia JF, Roberts MP,eds. Oper-
ative Neurosurgical
Technique.
New York: WB Saunders;
1995:1805-1816
Williams
RW. Microcervical
foramenotomy:
a surgical
alternative
for in-
tractable
radicular
pain. Spine 1983;8:708-716
Zeidman SM, Ducker TB. Posterior cervical laminoforamenotomy for
radiculopathy:
review of 172 cases. Neurosurgery
1993;33:356-362

31
-
Posterior Stabilization Using the Bohlman
Triple-Wire Technique
Paul K. Maurer
.
Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
SurgicalTechniques
Awide variety of pathologies may degrade the stability of
the cervical spine such that stabilization-fusion
proce-
dures are indicated. Asignificant armamentarium of both
anterior and posterior options now exists to deal with
such problems.I-4 The patient is best served by utilizing a
portfolio of options tailored to the individual case, rather
than forcing a single procedure to address alI pathological
issues. An escalating degree of complexity is involved
with the various anterior and posterior stabilization pro-
cedures. The operation selected should be as complex as
necessary but avoid "excessive technique" that only en-
genders greater morbidity without substantial gain. Pos-
terior exposure is safe and routine.3 The triple-wire tech-
nique,
popularized
by Bohlman,
represents
a very
efficient
means of providing interspinous
process fu-
sion.5.6The earliest and simplest form of spinous process
fusion was a simple, single-cerclage wire wrapped around
the spinous processes. The Bohlman triple-wire technique
expands on this procedure to increase effectiveness but
retains the inherent simplicity and safety of the original
operation.1.5-7 No significant anatomical structures with
associated morbidity are encountered during the expo-
sure of the spine itself. The triple-wire technique is a low-
complexity option to address a variety of cervical spine
problems.
In general. the technique has been employed for stabiliza-
tion of single-level pathologies (e.g.,unibevel fracture-dis-
locations), although variations on the technique can extend
to multilevel diseases.1.5The associated blood loss. time re-
quired for the procedure, and equipment requirements are
minimal. The simplicity and expeditious nature of the oper-
ation make this particularly attractive in the elderly or se-
verely ill patient who is less able to withstand the rigors of
more involvedoptions.
254
Anesthesia
and Positioning
Incision and Initial Dissection
Preparation
of the Lamina and Spinous
Processes
Wire/Cable
Passage
Closure
.
Indications
.
Traumaticfracture-dislocationinjuries of the subaxial
cervical spine with associated facet capsule/ligamentous
disruption
.
Effectivewith pure ligamentous insults and dynamicin-
stability as welI as unilateral or bilateral facet dislocations
.
Neoplasmswith lossofstability
.
Thetriple-wiretechniquewould generallybe usedina
combined anterior-posterior
procedure in this setting.
.
Contraindications
.
Fractures with significant vertebral body compression
. The ventral structures of the spine (vertebral body and
anterior longitudinal ligament) should be relatively pre-
served. Posteriorinstrumentation and fusion can pro-
vide significant resistance to flexion forces but are not
capable of providing fulIstability if axial integrity islost
(Fig. 31 - 1).
.
Dramatic loss of vertebral height secondary to extensive
tumor destruction
or severe traumatic
compression
fracture (> 50%,etc.) may require a pure anterior ap-
proach, or a combined anterior and posterior approach.2
.
Fractures with laminar destruction or significant facet
bone disruption
.
The spinous process fusion techniques require laminar
integrity to adequately fix the spine in position. Simi-
larly, significant bone damage to the facets themselves
can alIow the vertebrae to shift in a sagittal dimension.

31
PosteriorStabilizationUsingthe BohlmanTriple-Wire Technique
255
Figure31-1 Posteriortechnique alone wil not provide adequate
supportwith major anterior
element
disruption.
. Pathologiesrequiring decompressive laminectomy and,
therefore,removal of the spinous process
. Multilevelcervical instability owed to trauma, neoplasm,
or other destructive
process.
Although
the
spinous
processfusion techniques
can be employed
for multi-
levelproblems,the rigidity of fixation is generally sub-
optimalin such settings.2
. Advantages
. Exposureisrapid, simple, and associated with low mor-
bidity
. Providesafe immobilization-fusion in cases requiring
"tension-band"restriction of flexion forces
. Canbe performed even in the elderly and severely ill
givenitsinherent simplicity and rapidity
. Requireslittle in the way of complex instrumentation
and associated
training
. Disadvantages
. Doesnot provide rigid resistance
to extension
or rota-
tionalmovements.
This factor
makes
it less effective
withpureextension injuries to the spine, loss of ante-
riorligaments, ete.
. Cannotbe used if simultaneous decompressive laminec-
tomyisrequired or in the patient with a prior laminec-
tomy
. Cannotbe used in the patient with significant vertebral
bodycollapse/compressiondue to inability to withstand
significantaxial loads
. SurgicalTechniques
Anesthesia and Positioning
General anesthesia is used following induction with a
fiberoptic technique. The nature of induction and intubation
to a large degree depends on the pathology at hand. In cases
of unstable fracture-dislocation, the patient will be in trac-
tion or a cervical immobilization device (halo. collar, etc.)
and intubation must be in a very neutral manner and main-
tained in a neutral position throughout the transition to the
final prone position. The author has generally placed a
Philadelphia or other firm collar prior to rolling the patient
into the prone position regardless of the nature of the
pathology because it has afforded stable, neutral, and safe
rolling of the patient. The patient is maintained in the neu-
tral cervical position with a Mayfieldthree-point headholder
or a halo apparatus. Radiographic confirmation ofthe posi-
tion is attained before moving on to the surgical procedure.
Incision and Initial Dissection
The general principles of posterior exposure to the lamina
are reviewed previously. A skin incision commensurate
with the area of involvement is used and a standard subpe-
riosteal dissection completed.
Preparationof the lamina andSpinousProcesses
The subperiosteal muscle dissection should not violate any
segment above or below the area to be fused.Adequate expo-
sure of both the lamina involved as well as the associated
spinous processes is necessary. but extension of the muscle
dissection to the lamina above and below the area of fusion
only incurs ligamentous disruption at adjacent levels (Fig.
31-2A).Afterfusion has occurred. the levels above and below
the fusion are subjected to greater stresses and such excess
ligament disruption can cause delayed hypermotility and an-
gulation deformities (kyphosis).The degree ofdissection over
the facets can be determined on a case by case nature. Ifthe
patient has a fracture dislocation with a locked facet, it may
be necessary to expose the entire facet to allow open reduc-
tion and subsequent fixation. Ifthe disease process does not
require exposure of the facet. there is no motive to increase
soft tissue-ligamentous disruption with further dissection.
The spinous
process is penetrated
with
a cervical
Joplin-towel clipdevice (Fig.31-28). Standard towel clipsare
not sufficiently rugged to make an adequate hole forwire or
cable passage; the large towel clamps can be so large as to
damage an excessofspinous process.Alternatively,a right-an-
gle drillcan be used, or the cortexpenetrated with a 3 mm bur
and a standard towel clip simply used to enlarge the softer
bone within the spinous process itself. The upper spinous
process hole should be at the base of the process.just above
the laminar junction and slightly rostral in position (Fig.
31-2C).The lower hole should be similarlylocatedexceptthat
it rests in a more caudal position to minimize "pull-through,"
Wire/Cable
Passage
The triple-wire technique has traditionally been described
utilizing monofilament
wire, generally 18-gauge wire,s

256
MidcervicalSpine: Posterior Approach
.
B
(
limit lateral
dissection
of soft tissue
to prevent
potentiation
of instability
A
Figure 31-2
(A) Exposure of the cervical spine should not extend the muscle-soft
tissue beyond the laminar-facet
groove (to avoid facet capsule
disruption). (B) A towel clip or similar instrument isusedto perforate the baseof the spinous process.Exercisecare to avoid penetratingthe spin.J1
canal. (C)The upper spinous process perforation
should be slightly rostral in the process, the lower spinous process slightly caudal.
Technological advances over the last decade have afforded
the option of using multifilament cable as an alternative to
monofilament wire. The cables are considerably stronger
than monofilament wire and have considerably greater
resistance
to failure under stress.B.9Additionally, they
are more malleable than monofilament wire and therefore
are much easier to use during the procedure. Finally,
the current generation of cables are made of titanium
alloys and are magnetic resonance imaging (MRI)compati-
ble, less prone to cause artifact in postoperative studies, and
so forth.BWhether using wire or cable, the process is the
same with the exception of the technique to "crimp," or
tighten, the cable material.B.9Eachcable manufacturer has a
system that readily tightens the cables. The cable is passed
through the superior spinous process hole and wrapped
around through the inferior hole (Fig. 31-3). The cable (or
wire) is then tightened into position. Firmbut not excessive
tension should be applied. Elderly patients, relatively soft
bone, or diminutive
spinous processes can allow pull-
through if truly excessive tension is applied while tightening.
Two more cables (or 0 silk sutures) are now passed
through the holes (Fig.31-3). Permanent suture material ti-
tanium cables or similar material may be used for graft fixa-
tion. Do not mix metallic materials in the fusion construct.
such as a mixture of titanium cables and steel wire. The
combination of metals can generate an undesirable electri-
cal current. Iliaccrest (or appropriate substitute) is fed over
the cables. Prior to fixation of the graft to the spinous
processes, a high-speed bur is used to gently decorticate the
surface to allow fusion. Donot excessivelyscruff the surface
such that integrity of the spinous process is jeopardized.
The iliac crest
grafts
are
approximated
to the spinous
processes, again under appropriate but not excessiveten-
sion. Some surgeons
have favored an H-shaped
iliaccrest
graft so that some of the graft is interposed
between the
spinous processes. This may afford some increase in resis-
tance to extension
movement
and also allows placementof
the graft under compression, thereby encouragingfusion. If
this technique
is used, the H graft must be inserted priorto
tightening
of the initial cable. The laminae are scuffedand
the facet exposed so that extra bone material may be placed
for a greater fusion surface. How effectively bonegrowth
occurs
is uncertain
when
no compressive
forces are in-
volved, but all available
surfaces
should be utilized
(Fig. 31-3).
Closure
Following hemostasis,
which is generally easily achieved,the
wound is closed in the standard fashion. The author hasbeen
using 2-0 absorbable
sutures in the cervical fascia followed
by a similar inverted interrupted
technique
in the fat/subcu-
taneous
plane. No staples or skin sutures
have been usedin
several years. Rigorous hemostasis
is essential in the cervical
spine. We have used no drains in the last several years unless
an unusual difficulty was encountered
in achieving very ade-
quate hemostasis.
The patient is placed back in the Philadel-
phia (or alternative)
collar and rolled from the operating
table. Prompt extubation
is favored as long as no knownneu-
rological
injury
is present
to preclude
such an option.

31
PosteriorStabilizationUsingthe BohlmanTriple-Wire Technique
257
"0" silk suture
to affix bone graft
shingles to construct
Figure31-3
A cable is passed through
the upper and lower hole and tightened
into position.
Silk sutures are passed through
drill holes in bone
graft'shingles. to affix them to gently decorticated
recipient
surfaces.
References
1. AnHS.Internal
fixation
of the posterior
cervical
spine. Seminars
in
SpineSurgery1992:3:42-151
2. BenzelEC.Posterior
distraction
fixation.
In: Biomechanics
of Spine
Stabilization. New York: McGraw-Hill;
1995:195-203
3. Cooper PRoCohen A.Rosiello
A. Koslow M. Posterior
stabilization
of
cervical spine fractures
and subluxations
using
plates
and screws.
Neurosurgery 1988:23:300-306
4. FehlingsMG. Cooper PRoErrico TJ. Posterior plates in the manage-
ment of cervical instability:
long-term
results
in 44 patients.
J Neuro-
surg 1994;81:341-349
5. BohlmanHH. Acute fractures and dislocations of the cervical spine:
ananalysisof three hundred hospitalized patients and review of the
Iiterature.JBoneJoint Surg Am 1979:61:1119-1142
Suggested Readings
DickmanCA.CrawfordNR. Paramore CG.Biomechanical characteristics of
CI-C2cable fixations.J
Neurosurg
1996;85:316-322
DickmanCA. Papadopoulos SM. Sonntag VK. Hadley MN. The inter-
spinousmethod of posterior
atlantoaxial
arthrodesis.
J Neurosurg
1991 ;74:
190-198
6.
McAfee PC.Bohlman HH.Wilson WL.The triple-wire technique for
stabilization
of acute cervical
fracture
dislocations.
Trans Orthoped
1985: 142
7.
Benzel EC.Kesterson L.Posterior cervical interspinous compression
wiring and fusion for mid- to low cervical
spine injuries. J Neurosurg
1989;70:893-899
8.
Crockard HA. Evaluation
of spinal
laminar
fixation
by a new. flexible
stainless
steel
cable
(Sofwire):
early
results.
Neurosurgery
1994:35:92-899
9.
Songer MN.Spencer DL. Meyer PRoet al. The use of sublaminar cables
to replace Lugre wires. Spine 1991 ;16:S418-S421
Roy-Camille.Masel C. Saillant G.Treatment of cervical spine injuries by a
posterior
technique
with
plates
and screws.
In: Kehr D. Weidner A. eds.
Cervical Spine l. New York: Springer-Verlag:
1987:163
Segal D. Whitelaw GP.Gumbs
V. Pick RY.Tension band fixation of acute
cervical spine fractures.
Clin Orthop1981 :159:211-222

32
Posterior Stabilization Using the Titanium
Rectangle Technique
Paul K. Maurer
.
Indications
.
Contraindications
. Advantages
.
Disadvantages
. SurgicalTechnique
Posterior stabilization using titanium frames (Ii-Frame) or
various metal rectangles (Luque, Hartshill, ete.) affords a
safe, relatively simple, and strong method of multilevel
fixation in the cervical spine.I-3The incorporation of the al-
loy frame markedly increases the resistance to extension
and rotational forces when compared with simple poste-
rior process cable or wire techniques.2 Although lateral
mass screw-plate techniques are often preferred for poste-
rior multilevel cervical fusion, frame-rectangle options re-
main applicable in specific circumstances. Similar tech-
niques, such as described by Luque, were proven in the
lumbar and thoracic spine and subsequently employed in
the
cervical region.3,4 The techniques
are
relatively
simplistic, require a moderate
amount
of specialized
equipment, and, once mastered, can be utilized over a
wide region of the cervical spine and cervicothoracic
junction
in the treatment
of an extensive number
of
pathologies.I-3
Although the technique historically used monofilament
wire, the advent of cable technology markedly improved
both the strength and the safety of posterior instrumenta-
tion.2.5The multifilament cables are soft, pliable, and much
less intrusive during placement, particularly in the sublami-
nar location.
.
Indications
.
Traumatic fracture-dislocation
. The techniquecan be used throughoutthe cervical
spine, from the cervical-occipital region through the
cervical-thoracic junction.
.
Neoplasms with loss of stability
258
Preparation of the lamina and Facets
Passage of Facet Cables
Spinous Process and Sublaminar Cable Technique
Decompressive laminectomy
Fixation of the Frame-Rectangle
. This technique would generally be used in combination
with an anterior resection technique to afford added
integrity. It may, however, be used in isolation if anterior
axial integrity is adequate.
.
Multilevel cervical spondylotic myelopathy (CSM)
.
Asignificant portion of the pathogenesis of CSMmayre-
side in the dynamic motion of the spine and associated
distraction of the spinal cord within a reduced spinal
canaI.6.3,7,SWhen combined with posterior decompres-
sion, this affords a ready means of multilevel immobi-
lization to reduce dynamic forces accelerating the
myelopathic progression.3
.
Contraindications
. Lossof significant vertebral body integrity/height such
that axial stability is degraded
.
Substantial loss of vertebral height requires either an
anterior approach to reconstruct vertebral integrity ora
combined anterior and posterior approach.
. Well-defined facet-lateral mass integrity and anatomy,
which may favor a lateral mass screw-plate technique,
Lateral mass screw techniques do not require extra lev-
els to be incorporated in the fusion, and as such, areof-
ten preferred if the anatomy visualized at the timeof
exposure lends itself to safe and effective screw place-
ment and purchase.
.
Advantages
. Exposure is safe, simple, and associated
with a low long-
term morbidity.9,lo

32
Posterior Stabilization Usingthe Titanium Rectangle Technique
259
. Multilevelposterior dissection does not require trans-
gressionof anatomical regions involving major arteries.
the recurrent laryngeal nerve. the thoracic duct. or the
esophagusas can be encountered with multilevel ante-
rior dissections.8
. Minimalinherent destabilization of the spine with the
procedure.Becauseaxial integrity of the cervical spine is
not affected with posterior decompression and fusion
techniques.the demands placed on the instrumentation
areconsiderably reduced (vertebral body height, ante-
riorlongitudinal ligament. posterior longitudinal liga-
ment,and disk are all left intact, so instrumentation and
graftstressesare accordingly lessened).
. Multiplelevels can be easily addressed by simply ex-
tendingthe muscle dissection in a superior or inferior
direction.
. Disadvantages
. Morecumbersome technically than lateral mass screw-
platetechniques
. Incorporatesadditional segments of fusion. increasing
hypermotility at the junctions
above and below the
fusion
. Low frequency albeit
potentially
significant
insult
to neural elements
if the sublaminar
technique
is
employed
. SurgicalTechnique
Thegeneralprinciples of posterior exposure to the lamina
havebeenreviewed previously. Afairly generous skin inci-
sioninthe relevant area will facilitate the procedure.
Preparation of the lamina
and Facets
Thesoft tissue dissection should fully expose the entire
lamina,the laminar facet groove, and the majority of the
facet(Fig.32-1). It is not necessary to carry the lateral dis-
sectionas far as would be the case with lateral mass plates.
Screwplacement for lateral mass plates requires very exact
anatomicalparameters to avoid the nerve root or vertebral
artery.l1Facet cable placement
only involves passage
throughone articular surface, and injury to these structures
isnota likelyevent. It is quite important to fully clear the
softtissue in the facet groove as well as the interspinous
processregion if a sublaminar technique is to be utilized
(suchasin the C1-C2zone or the C7-T1 region, where facet
cablesareanatomically less advantageous).
Facetcable fixation can be readily and safely accom-
plishedif rigorous attention to several details is observed
(Fig.32-2):
Figure 32-1
The muscle and soft tissue (omitted for clarity)should
be dissected laterallyto includemost ofthe facet surface.Thesoft tis-
sues rostraland caudalofthe areas to be fused should be preservedas
much as possible to avoid angulation deformities in areas of hyper-
motility (above and below fusion masses). A fine-angled cervical
curette isused to scrape the facet articular surface inpreparation for
bone graft. Aspinous process towel clipis used to open the articular
surface.
1.
Place a submucous dissector in the facet joint articular
surface to provide a "backstop" for drilling with a 3 mm
diamond bur.
2.
The hole should be angled laterally and inferiorly to fa-
cilitate cable passage, at the same time leavingsufficient
bone surface to afford proper strength. Drillinglaterally
also limits the likelihood of accidental impacts on the
spinal cord. The facet holes are drilled prior to the
laminectomy for purposes of safety.
3.
Cartilage is scraped from the facet articular surface
with a 0000 cervical straight and angled curette, care
always taken to scrape medially to laterally in the inter-
est of spinal cord protection (Fig.32-1).

260
Midcervical Spine: Posterior Approach
...
Passage
of Facet Cables
Figure 32-2
A hole is drilled in the facet to allow cable placement
through the facet. A submucous
dissector
is inserted in the articular
surface as a "back stop" for the drill. The hole should be angled inferi-
orlyand laterally to allow for easier cable passage.
Figure 32-3
The cable ispulled through the facet holewith afine-
angled clamp.
A single-strand multifilament cable is passed through the
facet hole while a fine-tipped, angled coronary clampis
used to grasp the tip of the cable. As always, the direction
and force of the instruments should always be directedlat-
erallyto avoidinadvertent intrusion into the spinalcanal.
The cable is pulled through and clamped with a rubber-
shod clamp (Fig.32-3).
Spinous
Process
and Sublaminar
Cable Technique
Over the last several years, the author has gravitated,
almost exclusively, toward spinous process and facetcable
fixation of the frame to the spine. This option obviates
the need to pass any device over the neural elements
at
any time.
Nevertheless,
in some
regions of the
cervical spine ((1-(2,
C7-T1) or in instances of poor
bone integrity at the facets, sublaminar techniques canbe
very helpful. It should be emphasized
that sublaminar
passage is much easier and safer with multifilament cable
than was the case historically,when monofilamentwire
predominated.2
An appropriate hole for a spinous process cable fixation
point is made with a towel clip. The hole should be nearthe
base of the spinous process to provide good purchase (see
chapter on Bohlman technique).
Sublaminar cable passage begins with a central leader
loop (a double cable preformed at manufacture) being
formed into a "lazy C"shape (Fig. 32-4A). Proper bending
of the tip of the double cable will allow smooth passage
under the laminar surface. It is essential that the durabe
well visualized at the midline superiorly and inferiorly
where the cable passage is planned. Proper visualizationof
this key anatomical structure will prevent a sublaminar
passage that would unknowingly compress the spinal cord.
The dura can be exposed by clearing the ligamentum
fIavum with a thin-footplate cervical Kerrison instrument
and pituitary forceps. As soon as the tip of the central
leader cable is visualized emerging from under the lamina,
it is grasped with a blunt nerve hook (Fig. 32-4A). Always
pull the cable through, rather than pushing the cable.
Pullingthe cablewith the nervehookpreventsexcesscable
from"bunching"under the laminaand causingspinalcord
compression.Thecentral leadertip is cut and a singlesub-
laminarpassagethus affordstwo cablesforsublaminarfix-
ation (Fig.32-48).
Decompressive
Laminectomy
The technique of decompressive laminectomy is reviewed
elsewhere in this text. Ifa decompression is to be a partof
the procedure, as will often be the case, it is appropriate to
perform the decompression at this point. The various fixa-
tion cables are in position and the risk of injury to the cord
is now reduced. The author generally uses the new thin-
footplate 2 mm Kerrison instruments at the laminar facet

32
Posterior Stabilization Usingthe Titanium Rectangle Technique
261
A
Figure32-4
(A) Sublaminar cable passagerequires a clear view of
theduraabove and below the lamina. A gentle "lazy C" is made with
thecableand it isslowly pushedin the epidural compartment just until
theloopcan be grasped with a blunt hook. The cable is now pulled
(neverpushed)to bring it under the lamina. (8) Oncethe double "cen-
tralleader"cable iscut, two sublaminar anchoring cables have been
prepared.
grooveto remove the laminar segment en bloc. Many other
techniques,such as a high-speed drill and Leksell rongeurs,
areequallyapplicable.
Fixationof the Frame-Rectangle
Onceall of the cables are in position, the frame may be
broughtinto the field for fixation (Fig. 32-5). The cablesare
slidinto the frame (inferior
cable goes inside the frame at
eachregion).The frame has been sized and bent slightly as
8
needed to conform to the desired angle of the spine. The
cables are tightened
sequentially,
much as one would
tighten the lug nuts on the wheel of an automobile. The al-
ternate tightening will prevent the frame from torquing in
position. The tightening and crimping devices are unique to
each cable system/manufacture. Although eachsystem does
share the principle of the cable being tightened and locked
in position with a "crimping" barrel of one type or another.2
The cables thus fixate the frame in position to act asa rigid
stabilizer whereas bone graft placed into the facet articular
surfaces leads to long-term fusion2.3(Fig.32-6).

262
MidcervicalSpine:PosteriorApproach
~-'-
Figure 32-5
Anchoring
cables are in position.
In this case, spinous
process cables (at the superior
and inferior
positions)
and facet cables
have been used.
References
1. BridwellK.Treatment of markedly
displaced
Hanman's
fracture
with
a Lugre rectangle and posterior
fusion. Spine 1986: :49-52
2.
Crockard HA. Evaluation
of spinal laminar
fixation
by a new, flexible
stainless steel cable (Sorwire):
early results.
Neurosurgery
1994;35:
892-899
3.
Maurer PK, Ellenbogen RG. Ecklund J, et al. Cervical spondylotic
myelopathy:
treatment
with posterior
decompression
and Lugre rec-
tangle bone fusion.Neurosurgery 1991:28:680-684
4.
LugreER.The anatomic basis and development of segmental spinal
instrumentation.
Spine 1982; :256-259
5. Dickman CA,Crawford NR, Paramore
CG. Biomechanical
characteris-
tics ofC1-C2
cable fixations.J
Neurosurg
1996;85:316-322
6.
Barnes MP, Sanders
M. The effect of cervical
mobility
on the natural
history
of cervical
spondylotic
myelopathy.
J Neurol Neurosurg Psy-
chiatry
1984;37:17-20
Suggested Readings
Benzel
EC. Cervical spondylotic
myelopathy:
posterior
surgical approaches.
In: Cooper
PRo ed.
Degenerative
Diseases
of the
Cervical
Spine.
Park
Ridge.
IL: American Association
of Neurological Surgeons; 1993:91-104
Carol MP, Ducker
TB. Cervical
spondylitic
myelopathies:
surgical
treat-
ment.
J Spinal
Disord
1988;
1:59-65
Figure 32-6
Titanium rectangle frame in position.
7. RobertsAH. Myelopathy due to cervical spondylosis treatedbycollar
immobilization.
Neurology
1966;16:951-954
8.
Seifert V. StolkeD.Multisegmental cervical spondylosis:treatmentby
spondylectomy,
microsurgical
decompression
and osteosynthesis.
Neurosurgery
1991; :498-503
9.
FagerCA. Results of adequate posterior decompression inthereliefof
spondylotic
cervical myelopathY.J
Neurosurg
1973:38:684-692
10.
Hukuda S, Mochizuki
T, Ogata M, Shichikawa
K,Shimomura Y.Opera-
tions for cervical spondylotic
myelopathy:
a comparison
ofthe results
of anterior
and posterior
procedures.
J Bone Joint Surg Br 1985:67-
609-615
11.
Cooper PR, Cohen A, Rosiello A. et al. Posterior
stabilization of cervical
spine
fractures
using
plates
and
screws.
Neurosurgery1988:
:300-306
laRocca
H. Cervical
spondylotic
myelopathy:
natural
history. Spine
1988;13:854-855
Yasuoka S, Peterson HA,MacCarty CS.Incidence of spinal columndefor-
mity after multilevel laminectomy in children and adults. JNeurosuf!
1982;57:441-445

r
33
PosteriorExposure and Release
oflocked/perched
Facets
KirkWayne Jobe
. Indications
. Contraindications
. Advantages
. Disadvantages
. SurgicalTechnique
Lockedfacetsare among the most commontraumatic in-
juriesencountered in the cervical spine. In the literature,
theseinjuries have been referred to by many different
names,allrepresenting the same injury. Luxations,subluxa-
tions,jumped, perched. or dislocated facets, all refer to the
processofthe inferior facet of the superior vertebra moving
anteriorlyover the superior facet of the inferior vertebra
(Fig.33-1). A unilateral locked facet is thought to result
fromaflexion-rotationmechanismwhereasbilaterallocked
facetsresultfrom a straight flexion distraction.
Bothmechanisms of injury result in some of the most un-
stableinjuriesto the cervical spine. In unilateral locked
facets,there is usually extensive posterior ligamentous dis-
ruptioninvolving one or both facet capsules, the infra-
spinousand supraspinous ligaments, and the ligamenta
flava(Fig.33-2A,B). In addition, bilateral locked facets may
involvethe posterior and anterior longitudinal ligament
(Fig.33-2(,D). On plain films, subluxation of less than 50%
ofthewidth of the vertebral body is usually indicative of
unilateralockedfacets, and subluxation greater than 50%of
thebodyis a sign of bilateral locked facets. These injuries
mostcommonlyoccur at the (5-(6
or (6-(7
level.
Patientsoften have significant neurological deficits as a re-
sultofthe initial mechanism of injury and secondary to on-
goingcanalcompromisefrommisalignment.Mostauthors
willagreethat these injuries should be reduced because of
theinherentinstability of the injury as well as the presence
ofcompromisedneurological tissue. As with all injuries to
thespine,the goal of reduction is to prevent further injury,
decompressneural tissue, and restore normal alignment.
Anesthesia and Positioning
Incision and Dissection
Facet Reduction
Posterior Tension Band Reconstruction
Closure
The majority of literature recommend initially attempting
closed reduction of locked facets in an awake patient using
traction. Ifthis fails,as occurs up to 30%of the time, surgical
management is indicated. Asurgical approach is also indi-
cated when closed reduction is deemed dangerous sec-
ondary to adjacent fractures, preexisting spinal disease, evi-
dence of increasing distraction, or worsening neurological
exam upon distraction. Finally, an open approach can be
used for a redislocation after closed reduction and fixation,
which can occur up to 30%of the time.
Even though closed reduction may initially work, the
chance that the facets will spontaneously heal is low, and
progressive kyphotic deformity and pain are common se-
quelae. Forthis reason, many authors will recommend sur-
gical reduction and fusion be performed on all locked facets
to ensure stability and alignment.
When surgery is indicated, the posterior surgical ap-
proach to reduction of locked facets is the preferred and
most logical approach to the injury because most of the
pathology of locked facets exists posteriorly. The posterior
approach provides visualization of and manipulation of
the joint while allowing investigation of exiting nerve roots
and re-creation of the posterior tension band. The only
exception to this premise is in the presence of anterior com-
pression, for which an anterior approach is better suited
(Fig. 33-3). Therefore, prior to reduction, it is important to
identify the presence of a traumatic disk, which may occur
in 40 to 60%of these injuries. Ifa herniated disk is present
and compromising safe reduction, an anterior diskectomy
and fusion should be considered.
263

264
MidcervicalSpine:PosteriorApproach
.
Figure 33-1
Inferior lipof the C4 facet translated up and over the su-
perior lipof the C5 facet to become fixed anteriorly.
A
B
D
Figure 33-2
Various degrees of facet dislocation. (A) Occult dislocation with normal alignment of facets and bodies with disrupted posterior liga-
mentous complex. (8) Mild dislocation of facets with small subluxation of the body. (C) Moderate disclocation. with the facets tip to tip and moder.
ate subluxation of the bodies with disruption of the anterior and posterior longitudinal ligaments. (D) Complete dislocation of facets and disruption
of all ligamentous structures.

...
33
PosteriorExposureandReleaseof locked/Perched Facets
265
,
/
/
I
(
I!
I
\\
A
\
I,
j
J
j
/i
/
Figure33-3
Anterior comprimise
of spinal canal by traumatic
disk extru-
sion.(A) Initial misalignment
with disruption
of the disk and (B) after reduc-
tionwith continued anterior compromise
of canal and cord.
.
Indications
. Failureofclosedreduction
. Worseningneurological exam during closed reduction
. Increasingdistraction upon closed reduction
. Adjacentfractures
. Contraindications
. Evidence of anterior compression
. Advantages
. Allowsdirect visualization of the dislocation
. Allowsinvestigation of the foramina and exiting nerve
roots
. Allowsdirectmanipulationofthejoint
.
Posteriortensionbandcanbereconstructed
.
Disadvantages
. Does not allow for anterior decompression
.
Surgical Technique
Anesthesia and Positioning
The patient should be in skeletal traction on a turning
frame. and fiberoptic intubation should be performed while
the patient is awake. Aneurological exam can then be exe-
cuted prior to induction. Once general anesthesia has been
initiated, the patient is turned to the prone position and the
posterior neck is shaved and prepped. The region should be
prepared for a skin incision that will extend at least three
levels above and three levels below the injury, allowing for
instrumentation of the affected level. Landmarks helpful for
making the skin incision include finding the inion and pal-
pating down until the bifid spinous process of (2 can be
identified below the recess of the foramen magnum and (1
arch. The next easily identified structure is the prominent
spinous process of (7.
Incision and Dissection
Aposterior midline subperiosteal approach is performed to
expose the dislocated segments. The assistant stabilizes the
dislocated level with a Kocher clamp as the subperiosteal
dissection is carried laterally. The soft tissue dissection
must be carried to the lateral extent of the facets. Once the
spine is exposed posteriorly and laterally to the facet joints.
self-retaining
retractors
are placed and hemostasis
is
achieved. The dislocated segment is identified by intraoper-
ative examination where the inferior facet of the superior
vertebra is anterior and caught in front of the superior lipof
the superior facet of the inferior vertebra. An interoperative
x-ray can be used to confirm alignment and level of interest
at this time.
Facet Reduction
The lamina and facets of both involved vertebrae should be
inspected for fracture. If the facet is still intact with the
lamina. an attempt can be made at lifting the rostral lam-
ina/facet up and over the caudal lamina/facet using the
leverage of a Penfield 3 or similar instrument. Ifunable to
facilitate the reduction in this manner more weight can be
added to the traction and the maneuver can be performed
again. The surgeon can also grab the spinous process of the
superior vertebra and pull upward. which may allow the in-
ferior facet ofthe superior vertebra to dislodge posteriorly off
the lip of the facet of the vertebra below. Some authors have
also recently described an adaptation of an interlaminar

266
MidcervicalSpine:PosteriorApproach
Figure 33-4
Usage of intra laminar spreaderto allow controlled dis-
traction of affected levels.
spreader, which fits between the inferolateral border of the
superior lamina and the superolateral border of the inferior
lamina,allowing for controlled distraction of the facetjoint
at thedislocation(Fig.33-4). However,ifthese attemptsat
intraoperative manual reduction fail, a power bur can be
used to shave away enough of the superior tip of the facet of
theinferiorvertebrato allowreduction(Fig.33-5). If there
is a fracture of the facet that is impinging on the neural
foramen and root then a foraminotomy should be per-
formedto thoroughly decompress the root.
Posterior Tension Band Reconstruction
Tore-create the posterior tension band, lateral mass plating
and screw fixation are then performed through the level of
prior dislocation.The facet joint or joints are then packed
with cancellous bone fragments to facilitate fusion of the
Figure 33-5
Diamond bur used to remove the superior lip ofthe
inferior facet allowing the locked portion of the facet to moveposteri-
orly.
segment.
Lateral mass plating is performed
from one level
above the superior vertebra of the dislocation
to the inferior
vertebra of the dislocation,
spanning three levels. Postopera-
tively patients are kept in a rigid collar for 3 months.
Closure
Closure of the wound begins with generous irrigationwith
normal saline. Closure is then performed in layers with
muscle and ligamentum
nuchae closed separately
to avoid
dead space. A strong suture should be used for the ligamen-
tum nuchae to avoid separation
caused by the strong pullof
the trapezius.

34
PosteriorSubaxial Cervical SpineStabilization
UsingSublaminar Cables
Matthew T.Mayr,BarryD.Birch,andRegisW. Haid,Jr.
. Indications
. Contraindications
. Advantages
. Disadvantages
. Objective
. SurgicalTechnique
There
are many options for stabilization and fusion of the
cervicalspine.Inthe presence of intact laminae, a posterior
approachutilizing sublaminar wires or cables is an option.
Thisprocedure is especially useful at the cervicothoracic
junction.Atlantoaxialarthrodesis is best accomplished with
acableconstruct, with or without transfacet screws. How-
ever,this is discussed in another chapter. In patients with
poorbonequality or osteoporosis, sublaminar constructs of-
ferthe greatest rigidity and the highest pullout strength
as a
resultof their interface with intact cortical surfaces.1,2 Cables
mayalso be used in combination
with either or both plates
androds.The development
of multistranded
titanium cables
has reduced the risk of injury to the dura and underlying
spinalcord during passage of the wire or cable.
. Indications
. Poorbone quality/osteoporosis
. Supplementary fixation points when screws or hooks
areanatomically more difficult or profile is an issue
. Contraindications
. Previous laminectomy
. Anterior osteophytes/cervical
stenosis/congenital
steno-
sis (relative)
. Advantages
. Simple
. Highpullout strength-cables/wires are around fully
corticated surfaces.
Anesthesia and Positioning
Incisionand Dissection
Instrumentation
BoneGraft Harvest
Closure
.
PostoperativeCare
. Useful in osteoporosis/poor
bone quality
.
Usefulat cervicothoracic junction
.
Useful at atlantoaxial complex
.
More rigid than wire constructs
.
Disadvantages
.
Requiresintact lamina
.
Riskof injury to dura/spinal cord
.
More expensive than wire constructs
.
Objective
Tofacilitate fixation and subsequent bony fusion while pre-
serving or improving any neurological conditions associated
with spine pathology
.
SurgicalTechnique
AnesthesiaandPositioning
General anesthesia is used and the patient is placed in the
prone position for the procedure. Inthe setting of trauma or
instability, the patient may be intubated fiberoptically to
decrease the chance of iatrogenic spinal cord injury. An
appropriate prophylactic antibiotic isgiven before the skin
incision. Athree-point cranial pin fixation system is used
and the patient is turned prone. The neck is held neutral
with capital flexion. Alateral x-ray may be taken to ensure
satisfactory spine alignment. In some patients, axial trac-
tion may be utilized preoperatively and intraoperatively,
267

268
MidcervicalSpine:Posterior Approach
A
8
Figure 34-1
(A)The cable isbent into a Cshape on a round-handled instrument. (8) The cable isfurther contoured so that the surgeon'shand
remains out of the way during passage of the cable.
notably in traumatic cases. In these cases. skeletal traction
with appropriate
weight is utilized. The shoulders are
pulled down and held in place with adhesive tape. Allpres-
sure points are adequately padded prior to the start of the
procedure.
Incision and Dissection
The neck and iliac crest are prepped with antiseptic solu-
tion and draped with sterile towels followed by an antibi-
otic-impregnated drape. A midline incision is made and
electrocautery is used to perform a subperiosteal dissection
exposing the spinous processes and laminae out to the facet
joints bilaterally. Alateral x-ray may be taken to verify the
correct location. Allsoft and ligamentous tissue is removed
from the potential fusion surfaces.
Instrumentation
After the levels to be fused are identified, the ligamentum
fIavum is removed from the rostral and caudal aspect of
each lamina using curettes and Kerrison rongeurs. The liga-
mentum
fIavum has a median
raphe. which facilitates ac-
cess to the epidural space and aids in the removal of the lig-
ament. A Woodson
dental dissector
is then used to ensure
that the dura is free from ligamentous attachments andthat
there is adequate
room to pass the cable under the lamina.
Aflexible. multistrand. titanium cable is preferable towire
because there is less risk to the dura and spinal cord during
its passage.3 Either a single or a double cable may be used.If
a double cable is used, the cable is bent in half andthe
center portion is then bent in a C shape around a round-
handled
instrument
(such as a Cobb periosteal
elevator)
(Fig. 34-1). The cable is passed along the midline in acau-
dal to rostral direction because this conforms better to the
ventral contour of the lamina (Fig. 34-2). As the cable
passes under the lamina, it can be pulled through with a
small hemostat
or nerve hook (Fig. 34-3).
As the cable is
pulled through. pressure is kept on it to keep it in contact
with the underside of the lamina. Passage of the cableis
done one segment at a time to avoid spinal cord injury.
When passage is complete. the leader of the cable is cut
leaving a few millimeters
remaining
to aid passage through
the tightener.
There is then a single cable left under each
hemilamina
(Fig. 34-4).
The cables are then pulled to the
Figure 34-2
The cable is passedfrom caudal to rostral
along the midline.

34
Posterior Subaxial CervicalSpine Stabilization UsingSublaminar Cables
269
Figure34-3
Thecable ispulled through with a small nerve hook or
hemostat.
sideunderthe lamina. The free end of the cable can then be
affixedto the drapes
with
a rubber
band to prevent
the
cablesfrom inadvertently
applying
pressure
on the neural
elements.
Rods
Rodsize selection varies with the size of the patient. We
prefer3/16 in. or 5 mm diameter rods. The CD. Horizon
Figure 34-4
The leader of the cable is cut leaving a single cable un-
dereach hemilamina.
5 mm knurled titanium rod (Medtronic Sofamor Danek,
Memphis, TN)is especially useful because it is low profile
and has diamond-shaped asperities to aid cable-rod fric-
tion. Once all the cables are passed. they may be affixed
around a bent rod, Luque rectangle. or Ti-Frame (Codman,
Johnson &Johnson Professional. Raynham, MA),which has
been contoured to the spinal sagittal alignment (Fig.34-5).
Finally,cables are sequentially tightened to the appropriate
tension.
CableSystems
There are several different cable systems that are commonly
used. These include the Codman Sof'wire Cable System
(Codman, Johnson &Johnson Professional, Raynham. MA),
the Songer Cable System (DuPuy-AcroMed,Cleveland, OH),
and the Atlas Cable System (Medtronic Sofamor Danek.
Memphis. TN).Each system has a slightly different method
for applying tension to the cable and fixing it in place. As
mentioned before, the use of a titanium cable has advan-
tages over wire in both strength4 and risk to the underlying
structures.3.5
Bone Graft Harvest
Autologous rib or iliac crest is preferable for the fusion. The
lamina and spinous processes are decorticated, and the graft
Figure 34-5
A Ti-frame
held in place with sublaminar
cables.

270
MidcervicalSpine:PosteriorApproach
.
is placed with the cancellous surface toward the decorti-
cated lamina if no rod or loop has been used. ForC1-C2 fu-
sion, the graft is placed between the posterior arches of C1
and C2 as described by Dickman et al.6 Alternatively, a
Brooks1or Gallie7fusion may be utilized. Fora subaxial fu-
sion an onlay bone graft is typically used. The cables are
then tightened around the graft in a sequential manner.
Closure
The wound is copiously irrigated with an antibiotic solu-
tion. Hemostasis is obtained with the use of monopolar or
bipolar electrocautery. A medium Hemovac drain (Bard
Medical, Covington, GA) is placed below the fascia. The
References
1.
Brooks AL.Jenkins
EB. Atlantoaxial
arthrodesis
by the wedge
com-
pression
method. J Bone Joint Surg Am 1978:60:279-284
2.
Ulrich C.Woersdoerfer
O. Kalff R.Claes L.Wilke HJ.Biomechanics of fix-
ation systems to the celVical spine. Spine 1991 :1698 suppl):S4-S9
3.
Songer MN. Spencer
DL.Meyer PRJr.Jayaraman
G. The use of sub lam-
inar
cables
to
replace
Luque
wires.
Spine
1991: 16(8
Suppl):
5418-5421
4.
Weis JC. Cunningham
BW. Kanayama
M. Parker L.McAfee Pc. In vitro
biomechanical
comparison
of multistrand
cables with conventional
celVical stabilization.
Spine 1996:21 :2108-2114
muscle and fascia are closed in anatomical layers.Theskin
is reapproximated with staples and an occlusive dressingis
applied. The drain is typically removed on the first postop-
erative day.
.
Postoperative Care
.
No nonsteroidal antiinflammatory drugs for 6 to 12
weeks
. Rigidorthosisfor3 months
. Cervicalspineflexionand extensionfilmsat 3 monthsto
assessstability
5.
Geremia
GK. Kim KS. Cerullo L.Calenoff L Complications
of sublami-
nar wiring. Surg NeuroI1985;23:629-635
6.
Dickman
CA. Sonntag
VK. Papadopoulos
SM. Hadley
MN. The inter-
spinous
method
of posterior
atlantoaxial
arthrodesis.
J Neurosurg
1991 ;74:190-198
7.
Gallie WE. Fractures
and dislocations
of the celVical spine. AmJ Surg
1939:46:495-499

35
PosteriorCervicalSpine Stabilization
UsingInterfacet Wires
MatthewT.Mayr, Barry D. Birch, and Regis W. Haid, Jr.
. Indications
. Contraindications
. Advantages
. Disadvantages
. Objective
. SurgicalTechnique
Robinsonand Southwickfirst described this technique in
1960.1
Theyweremotivatedbyan inabilityto performa si-
multaneousdecompressive laminectomy and stabilization
withanyofthe previouslydescribedposteriorwiringtech-
niques.Theirapproachpermits stabilizationin the setting
oflaminaror spinous process fractures, which render other
methodsof posterior wiring impossible. Callahan et aF re-
portedseveralrefinements to this technique, including
wiringthe inferior-most facet to the first intact spinous
processat the caudal end of the construct. This oblique
facetwiring is an option when there is a one-level laminar
fractureor laminectomy. With this technique, the facet is
wiredto the caudal spinous process bilaterally. This creates
astrongerconstruct against rotational forces than spinous
processwiring and may prevent subsequent deformity.3.4
. Indications
. Facetdislocation without fracture
. Fracturedspinous processes
. Priorlaminectomy
. Contraindications
. Facetfractures
. Anterioror three-column instability
. Advantages
. Donot need intact lamina or spinous processes
. Abilityto decompress the spine posteriorly while stabi-
lizingat the same time
Positioning
Incision and Dissection
Instrumentation
Bone Graft Harvest
Oblique Facet Wiring
Closure
.
Postoperative Care
. Disadvantages
.
Not as rigid as screw-plate or screw-rod constructs
.
Inferior
cable pullout
strength
when compared with
sublaminar cables
.
Poor axial-loading resistance
.
Requires inferior lamina for oblique techniques
.
Objective
Toobtain fixation and subsequentbony fusion while pre-
serving or improving any neurological conditions associated
with spine pathology
.
SurgicalTechnique
Positioning
The positioning and incision for interfacet wiring are simi-
lar to those for sublaminar wiring. General anesthesia is
used and the patient is placed in the prone position for the
procedure.Inthe settingof traumaor instability,the patient
may be intubated fiberopticallyto decreasethe chanceof
iatrogenic spinal cord injury. An appropriateprophylactic
antibiotic is given before the skin incision. A three-point
cranial pin fixation system is used and the patient is turned
prone. The neck is held neutral with capital flexion.Alateral
x-ray may be taken to ensure satisfactory spine alignment.
The shoulders are pulled down and held in place with adhe-
sive tape. Allpressure points are adequately padded prior to
the start of theprocedure.
271

Incision and Dissection
272
MidcervicalSpine:Posterior Approach
..
The neckand iliaccrest are prepped with an antiseptic solu-
tion and draped with sterile towels and an antibiotic-im-
pregnated drape. A midline incision is made and electro-
cautery is used to perform a subperiosteal
dissection
exposing the spinous processes and laminae. Forthe place-
ment of interfacet wires, the soft tissue dissection must
fullyexpose the facetjoints and lateral borders of the lateral
masses. All capsular ligaments and soft tissue around the
facets are removed. Frequently there is bleeding from the
venous plexus lateral to the lateral masses, which can be
stopped using bipolar electrocautery.
Instrumentation
The facet joint is opened using a small curette, and the ar-
ticular cartilage is removed. This can be done with either a
curette or a high-speed drill with a small bit. We prefer the
Midas Rex A-3 bit (Medtronic, Inc., Minneapolis, MN). A
Freer elevator or small osteotome is placed in the joint to
guard against injury to the underlying
superior
facet,
vertebral artery, or nerve root. A 2 mm hole is drilled
through the middle of the inferior facet at a right angle to
the joint (Fig.35-1). Asingle multistrand cable can then be
passed through the hole and pulled out through the joint
with a thin hemostat (Fig. 35-2). This is repeated through
eachfacetwith a separate strand of cable.
Figure 35-2
Asingle cable ispassed through the facet and pulled
out ofthe joint usinga smallhemostat.
Figure 35-1
A hole is drilled in the facet at a right angle to the joint.
Bone Graft Harvest
Posterior iliac crest or rib can be used for the fusion. Ifiliac
crest is used,the convexsurfaceofthe crest is usedtohelp
maintain the lordotic curve of the cervical spine. Holesare
then drilledinto the graft to pass eachset ofcables,which
are then secured to the lateral masses (Fig. 35-3). Priorto
placing the graft, the lateral masses can be decorticated
using a high-speed drill. In addition, cancellous bone can
be packed into the decorticated facet joints. Typicallythis
construct includes facet to spinous process fixation at its
caudal end. Ahole is made transversely through the spin-
ous process at the junction
of the spinous process and
lamina. The outer cortex should be driIled with a high-
speed driII on both sides, followed by a penetrating towel
clip to connect the holes (Fig. 35-4). Care must be taken
not to place this hole too far anterior, which may result in
injury to the dura or spinal cord. A cable is then passed
through the hole and connected to the inferior portion of
the bone graft.
Oblique Facet Wiring
If there is a single-level
lamina fracture or rotational
instability, oblique facet wiring as described by Cahillet
aP is also an option. In this case the cable is placed
through the inferior facet of the rostral lateral mass in the
manner
previously
described.
The
cable
is
then
passed through or around the spinous process of a caudal
vertebra (Fig. 35-5). This permits fusion of only the in-

...
35
PosteriorCervicalSpineStabilizationUsingInterfacet Wires
273
Figure35-3
Holesare drilledinto the graft, and the cable ispassed
throughthe holesto secure the graft.
Figure35-4
Passage of cable posterior to the spinal canal, avoiding
thespinalcord and dura.
References
1. Robinson RA. Southwick
WOo Indications
and techniques
for early
stabilization
of the neck in some fracture
dislocations
of the cervical
spine. South Med J 1960;53:565-579
2. Callahan RA,Johnson
RM, Margolis
RN, Keggi KJ.AlbrightJA,
South-
wick WOo Cervical
facet fusion
for control
of instability
following
laminectomY.JBoneJoint Surg Am 1977;59:991-1002
Figure
35-5
Oblique facet wiring-fixing the facet to the caudal
intact spinalprocessfor single-levellamina fracture or instability.
volved joint without extending the fusion to the lower
uninvolved joint.
Closure
Thewound is copiouslyirrigated with an antibiotic solu-
tion. Hemostasis is obtained with the use of monopolar or
bipolar electrocautery. A medium Hemovac drain (Bard
Medical, Covington, GA) is placed below the fascia. The
muscle and fascia are closed in anatomical layers. The skin
is reapproximated with staples and an occlusive dressing is
applied. The drain is typically removed on the first postop-
erative day.
.
Postoperative Care
.
No nonsteroidal anti-inflammatory drugs for 6 to 12
weeks
. Rigidorthosisfor3 months
. Cervicalspineflexionand extensionfilmsat 3 monthsto
assess stability
3.
Cahill OW, Bellegarrigue R, Ducker TB. Bilateral facet to spinous
process fusion: a new technique for posterior spinal fusion after
trauma.
Neurosurgery
1983;13:1-4
4.
Stauffer
ES. Wiring
techniques
of the posterior
cervical
spine for the
treatment of trauma. Orthopedics 1988;11:1543-1548

36
Posterior CervicalSpine Stabilization Using
LateralMass Plates
Matthew T.Mayr, Barry D. Birch, and Regis W. Haid, Jr.
.
Indications
.
Contraindications
.
Advantages
.
Disadvantages
.
Objective
.
SurgicalTechnique
The use of lateral mass plates marks an important
im-
provement in the treatment of patients with traumatic or
nontraumatic cervical spine instability. Roy-Camille1.2first
popularized this procedure using plates constructed of vi-
tallium (Roy-Camille plates, Benoist-Girard et Compagnie,
Bagneux,France). Haid subsequently developed a titanium
alloy implant in 1989 (AME Haid Universal Bone Plate
System, American Medical Electronics, Inc., Richardson,
TX).This produced fewer artifacts on x-ray and magnetic
resonance imaging (MRI)than stainless steel. Several com-
panies now produce systems for plating the lateral masses.
We currently prefer to use the AXIS fixation system
(Sofamor-Danek Group, Memphis, TN) for lateral mass
plating. The procedure for this system is described in this
chapter.
There are various methods for placement of screws into
the lateral masses. Roy-Camille initially described screw
placement directed straight forward and outward 10 de-
grees.1.2Asecond technique popularized by Magerl starts
at a point medial to the center of the facet and directs the
screw 25 degrees laterally and 40 to 60 degrees cephalad.3
Haid et al described a technique in which the entrance
point is 1 mm medial to the center of the lateral mass,
with the screws angled 15 to 20 degrees cephalad and lat-
erally 30 degrees.4 An et al studied these drilling tech-
niques in cadaveric specimens.s They found that more
cephalad and medial trajectories increased the risk of neu-
rological injury. They verified the findings of Haid et al and
also recommended
starting 1 mm medial to the center of
the lateral mass, with the screws angled 15 to 20 degrees
cephalad and laterally 30 degrees. We currently use this
technique.
Recently,advances in frameless stereotactic techniques in
the spine have improved our success with placing screws in
274
Positioning
Incision
Reduction
Instrumentation
Closure
.
PostoperativeCare
the pedic1es of not only C7 and T1 but also in the pars ofC2
while avoiding the nerve roots and vertebral arteryatthat
level.This chapter focuses on subaxial techniques.
.
Indications
.
Posttraumatic instability
.
Neoplasms
.
Degenerative instability
.
In conjunction with laminectomy in patients withmul-
tilevel stenosis, myelopathy, and loss of lordosis
.
Contraindications
.
Osteoporosis, metabolic
bone disease, osteomalacia.
osteodystrophy
.
Anterior compression by bone, disk, or soft tissue
.
Advantages
. Ease of application
.
Maybe used after laminectomy
.
Can be used when there are laminar or spinous process
fractures
.
Better resistance to rotational forces
.
Immediate semirigid fixation

36
PosteriorCervicalSpineStabilizationUsingLateralMassPlates
275
.
Disadvantages
Instrumentation
. Notoptimalfor kyphotic
reduction
. Potentialinjury to vertebral artery and neural structures
.
Objective
Toobtain fixation and subsequent bony fusion while pre-
servingor improving any neurological conditions associated
withspinepathology
. Surgical Technique
Positioning
Thepositioning and incision for lateral mass plating are as
describedfor sublaminar
wiring
and interfacet
wiring.
Generalanesthesia is used and the patient is placed in the
proneposition for the procedure. In the setting of trauma
orinstability,the patient may be intubated fiberoptically to
decreasethe chance of iatrogenic spinal cord injury. An
appropriateprophylactic antibiotic
is given before the skin
incision.Athree-point cranial pin fixation systemis used
andthe patient is turned prone. The neck is held neutral
withcapital flexion. A lateral x-ray may be taken to ensure
satisfactoryspine alignment.
The shoulders are pulled
downand held in place with adhesive tape. All pressure
pointsare adequately padded prior
to the start of the
procedure.
Incision
Theneck and iliac crest are prepped with
an antiseptic
solutionand draped with sterile towels and an antibiotic-
impregnated drape. A midline
incision
is made
and
electrocauteryis used to perform a subperiosteal dissec-
tion exposing
the
spinous
processes
and
lamina.
Forthe placement of lateral mass plates, the soft tissue
dissection must fully expose
the facet joints
and lateral
bordersof the lateral masses. All capsular ligaments and
soft tissue
around
the
facets
are
removed.
The
facet
jointsaboveand below the involved ligaments are left in-
tactto prevent late or subsequent instability or fusion at
thoselevels.Frequently there is bleeding from the venous
plexuslateral to the lateral masses, which can be stopped
usingbipolar electrocautery.
Reduction
If closed reduction
of a facet dislocation
is not successful,
openreduction can be performed.
A high-speed
drill is used
to remove part of the superior
articular
process of the infe-
rior vertebrae. This usually allows the facets to realign
in
their anatomical state.
If a laminectomy
will be performed,
the screw
sites are
marked,
drilled, and tapped
prior to removing
the lamina.
This method
protects
the dura
and
spinal
cord
during
drilIing. The entry point is approximately
1 mm medial
to
the center of the lateral mass (Fig. 36- t). The outer cortex
is pierced either with an awl or a high-speed
drill. This re-
duces the chance that the drill will slip over the lateral mass
instead of entering the bone. The AXISsystem contains
plates with interfacet distances of 11,13,and 15 mm. Tem-
plates are provided for choosing the appropriate-sized
plates
as well as for bending
the plate if necessary
(Fig. 36-2).
The figure-eight-shaped
slots usually allow
screw placement
in all of the lateral masses. The system in-
cludes an adjustable drill as well as 3.5 mm cancellous
screws in 2 mm increments from 10 to 24 mm. The rescue
screw is a 4.0 mm cancellous screw.
Typically 14 or 16 mm screws are used depending
on the
size of the lateral masses, which can be measured on the
computed tomographic (CT)scan. Asalready described, for
C3 to C6 (and sometimes
C7). we prefer
to drill the holes
with a 15 to 20 degree
cephalad
angle (Fig. 36-3)
and a
30 degree
lateral
trajectory
(Fig. 36-4).
This rostral
angle
targets the transverse process and decreases the chance of
violation of uninvolved joints. The vertebral artery usually
lies anterior to the valley created by the junction
of the
lamina and the lateral mass. By starting
1 mm medial to
the center of the lateral mass and directing the drill later-
ally, there
is less risk to the vertebral
artery
and nerve
roots.
After
drilIing,
the
dorsal
cortex
is tapped
using
the
3.5 mm cancellous tap. The joint cartilage from the facets is
removed and the joint is decorticated
using a high-speed drill
with a small bit. We prefer the Midas Rex(Medtronic, Inc.,
Minneapolis, MN) with an A-3 bit. Cancellous autologous
bone from the iliac crest is then packedinto the facetjoints.
The appropriate length plate is bent to conform to the
lordosisof the cervicalspine.Therostralandcaudalscrews
are initially placed and tightened halfway.The intervening
screws are placed and tightened halfway, and then all
screws are sequentially tightened.
At C7,a pedicle or lateral mass screw may be utilized. The
C7 lateral mass is much thinner than the rostral lateral
masses, which can make screw placement difficult.There is
usually no vertebral artery in the transverse foramen at this
level, which often permits safe pedicle screw placement
here and at Tl ForC7 pedicle screw placement, the drill is
angled25 to 30degreesmediallyand perpendicularto the
rostral-caudal plane. It is important to lookat the preopera-
tive CTscan to assess the pedicle size and gauge the appro-
priate angle. Typically a 4.0 mm cortical screw is used. A
small laminotomy can be made to directly palpate the pedi-
cle for safeplacement of the screw.ForT1 pedical screw
placement, the angle is usually 10 to 15 degrees medially
and 5 degreescaudally.
With the advent of frameless stereotactic
methods in
the
cervical
spine,
it is also possible
to place
pedicle
screws
rostral
to
C7. We
use
the
Stealth
System
(Medtronic, Sofamor Danek, Memphis, TN) for placement
of these screws, which allows virtual visualization of the

276
MidcervicalSpine: Posterior Approach
Figure 36-1
Entry point in the lateral mass.This is -1 mm medial
from the center of the lateral mass.
Figure 36-2
Templates and plate selection for the AXIS plating
system.
-
--
Figure 36-3
The hole is drilled at an angle of 15 to 20 degrees
cephaladto avoid the exiting nerveroot.
..
Figure 36-4
There is a 30 degree lateral trajectory to avoidthe
vertebral artery.
pedicle and its relationship to the spinal cord and trans-
verse foramen. Shown here is the surgical planning for
placement of a C6pedicle screw (Fig. 36-5) and a C3pedi-
cle screw (Fig. 36-6). Cervical pedicle screws may attain
greater pullout strength than lateral mass screws due to
the greater length and circumferential
cortical purchase.
They may also be used in levels where the lateral massis
fractured or unusable.
Closure
The wound is copiously irrigated with an antibiotic solu-
tion. Hemostasis is obtained with the use of monopolar or
bipolar electrocautery. A medium Hemovacdrain (Bard
Medical, Covington. GA)placed below the fascia. The mus-
cle and fascia are closed in anatomical layers. The skin is
reapproximated with staples and an occlusive dressing is
applied. The drain is typically removed on the first postop-
erative day.
.
Postoperative Care
.
No nonsteroidal antiinflammatory drugs for 6 to 12
weeks
.
Rigidorthosisfor3 months
.
Cervicalspine flexionand extension filmsat 3 months
to assess stability

....
36
PosteriorCervicalSpineStabilizationUsinglateral MassPlates
277
Figure36-5
Surgical planning using the
Stealth System for placement
of pedicle
screws at the (6 level.
Figure
36-6 Frameless stereotactic
planning can also be used at more difficult
levels such as (3.

278
MidcervicalSpine:PosteriorApproach
References
1.
Roy-Camille R.Saillant G.Judet T. at et al. Recent injuries
of the last 5
cervical
vertebrae
in the
adult.
Semaine
des
Hospitaux
1988;
59: 1478-1488.
2.
Roy-Camille R. Saillant
G. Mazel C. In: Sherk MM. ed. The Cervical
Spine. Philadelphia:
J8 Lippincott;
1989:390-421
3.
Grob D. Magerl F. Dorsal spondylodesis
of the cervical
spine using a
hooked plate. Orthopade
1987;16:55-61
4.
Haid RW Jr. Papadopoulos
S. Sonntag V. Lateral mass plating for celVi-
cal instability.
Presented
at The Congress
of Neurological
Surgeons,
October 22. 1990. Los Angeles. CA
5.
An HS. Gordin R. Renner
K.Anatomic
considerations
for plate-screw
fixation ofthe
cervical spine. Spine 1991 ;16:S548-S551

37
SurgicalManagement of Intramedullary
SpinalCordTumors
ShlomoConstantini. Vitaly Siomin.
and Fred Epstein
. Advantages
. Disadvantages
. Epidemiology
andPathology
. ClinicalPresentation
. Radiological Evaluation
Inthepast,and occasionally even today, intramedullary
as-
trocytomasand other gliomas have not been viewed with
surgicaloptimism. Except for ependymomas
of the cauda
equinaregion, there has been
little
impetus
to modify
theapproachof biopsy, dural decompression,
and radiation
therapy.This is particularly
unfortunate
because
most
oftheseneoplasms are low-grade
gliomas. These gliomas
aremicroscopically identical
to their "sister"
tumors
that
occurin the cerebellum
and are known
to be surgically
treatable.
Itisour opinion that extensive surgery for the removal of
mostintramedullaryspinal cord tumors (IMSCTs)can be
performedwith acceptable morbidity.
Our policy has been
totreat low-grade intramedullary
tumors
by attempting
grosstotalremoval alone, providing no other immediate
ad-
juvantreatment.!
Thischapterdescribes the overall approach to patients
withintramedullary spinal cord tumors, with special
attentionto surgical details. Most of the description
pertainstoastrocytomas and ependymomas. The content
ofthischapteris based on the senior author's (FE)expe-
riencewiththe radical excision of -500
intramedullary
spinalcordtumorsfrom 1980 to 1999.2-4This chapter
addressestreatment of IMSCTs in both children
and
adultsbecausemost surgical principles apply to both
groups.
. Advantages
. Abilityto provide tissue for diagnosis
. Cancuresome neoplasms
. Posteriorapproach is simple and widely known.
.
SurgicalTechnique
General Principles
Evoked Potentials
Monitoring
.
Complications
.
Disadvantages
. Riskof spinal cord or nerve root injury
.
Cerebrospinal fluid (CSF)leakage
. Some tumors do not have well-defined borders
. Riskof postoperative deformity
.
Epidemiology and Pathology
The glioma family accounts for the vast majority of IMSCTs.
Spinal cord tumors are relatively rare neoplasms, account-
ing for only 4 to 6%of central nervous system tumors. Al-
though intramedullary tumors constitute only -25% of all
intraspinal neoplasms in adults, the majority of the pediatric
spinal cord tumors are intramedullary.s
Ina typical sampling,from a group of226 patients (allages)
with IMSCTsoperated on in our service between 1985 and
1992,30%had astrocytomas, 29%had ependymomas, 14%had
gangliogliomas, 7%had other gliomas, and 20%had other le-
sions (including hemangioblastomas, primitive neuroectoder-
mal turmors (PNETs),lipomas,and ganglioneurocytomas).As-
trocytomas and gangliogliomas were especially prevalent in
the younger age group whereas ependymomas are more fre-
quent in the older age groups. The incidence ofhistologically
malignant versus benign tumors was stable at 20 to 30%ma-
lignant throughout the different agegroups.
.
ClinicalPresentation
The clinical evolution, in most cases, is indolent. The onset of
symptoms
is often related to some apparently
trivial injury.
279

280
MidcervicalSpine:Posterior Approach
-
The most common early symptom is local pain along the
spinal axis. Other symptoms include motor disturbance,
radicular pain, paresthesias,
dysesthesias,
and, rarely,
sphincter dysfunction.
. RadiologicalEvaluation
Today,magnetic resonance imaging (MRI)scanning has rel-
egated most invasive neurodiagnostic studies to history.6.7
TheMRIscan provides an excellent image of intramedullary
neoplasms. It is usually unnecessary to carry out other
studies,such as plain films, computed tomographic(CT)
scans, and myelography. It might still be necessary to per-
form a myelogram in patients with either severe scoliosis,
when it is impossible to obtain the mandatory midsagittal
images,or an artificial implant that produces magnetic arti-
facts.
The T1-weighted image is the most informative, disclos-
ing the presence of rostral and caudal cysts, intramedullary
cysts, and the solid component
of the tumor. The T2-
weighted image givesa myelographic appearance to the CSF
and cysts. Injection of gadolinium is mandatory for all
spinal cord tumors.8.9Gd-DTPAusually enhances the solid
component of the tumor and helps delineate it from sur-
rounding edema (Table 37-1).
.
SurgicalTechnique
General Principles
Spinal cord astrocytomas are relatively firm, occasionally
contain microscopic foci of calcium, and only rarely have a
cleavage plane to facilitate an en bloc resection. In the
overwhelming majority of cases, it is necessary to remove
the tumor from inside-out until the almost invariably pre-
sent "glia-tumor interface" is recognized as a change in
color and consistency between the tumor and adjacent
normal neural tissues. The principle of an initial central de-
bulking applies to ependymomas as well, even though they
often do have a discrete cleavage from the surrounding
white matter.
Table 37-1
SurgicalTreatmentof IntramedullarySpinalCord
Tumors(IMSCTs)at a Glance
IMSCTs are potentially
excisable lesions
Postop functional
outcome
is mainly determined
by the preop
status; therefore,
treat as early as possible
Laminotomy
is superior to laminectomy
Ultrasonic
guidance
is mandatory
Ultrasonic aspiration
is extremely
helpful
First debulk the tumor
from inside; then continue until glial-tumor
interface is recognized
Evoked potentials
are useful
Close the wound watertight
UltrasonicAspiratorand Laser
The development and application of the ultrasonic aspirator
(UA)systemprovideda significantimprovementovercon-
ventional systems.10Theultrasonic aspirator is the idealin-
strument to effectively debulk and removethe coreofa spinal
cord neoplasm.
The neurosurgical laser is similarly ideal for removingthe
residual fragments because the laser may be employedwith
great precision along the length of the glia-tumor interface.
Although the laser may be employed in place bf the UAfor
the initial tumor core debulking, it is extremely tediousand
time consuming when directed toward a very voluminous
intramedullary neoplasm. In addition, the resulting laser
char makes it difficult to recognize the glia-tumor interface,
mandating frequent interruptions of the ongoing resection
as the blackened tissues are gently removed with a small-
caliber suction.
Positioning
After intubation and insertion ofthe lines, monitors, andin-
dwelling urinary catheter, position the patient face down
with the head fixed in pins or in a soft horseshoe-like pad.Be-
cause surgery for an IMSCTmay take up to 6 to 8 hours,be
sure to cushion all areas of pressure to prevent pressuresores.
Laythe patient on two big jellyrolls placed perpendicu-
larly to the axis of the body: one roll elevates the pelvis
whereas the other one is placedunder the shoulders.This
allows for free chest movements and prevents an intra-
abdominal pressure rise (Fig.37-1).
Secure the hands at the sides for cervical and upper tho-
racic operations. Elevate the hands for lower thoracic and
lumbar procedures. Wrap the legs with pneumatic com-
pression boots or elastic bandages for deep venous throm-
bosis (DVT)prophylaxis.
Before prepping and draping, a lateral radiograph with
the needle inserted between the spinous processes maybe
obtained to facilitate the gross anatomical orientation.
Often, in pursuit of an upper or lower tumor border orfor
optimal closure, the surgeon has to extend the skin incision.
Therefore, a generous area above and below the initial inci-
sion should be prepped and left uncovered.
Incisionof theSoft Tissues
Cut the epidermis with a no. 10 blade. Then open the
subcutaneous tissue with the monopolar cautery down to
the fascial level. Make the incision long enough to exposeat
least one level above and below the anticipated lamino-
tomy. Place two self-retaining retractors.
Use a bipolar
cautery to achieve hemostasis. Open the fascia in the
midline using the monopolar cautery. Clean the spinous
processes and the laminae in a subperiosteal fashion as far
laterally as the facets. In pediatric patients it is usually
enough to use the monopolar cautery to dissect just the tips
of the spinous processes. Further dissection can easily be
accomplished by simply peeling the periost off the bone, ei-
ther with a periosteal elevator or by using a tonsillar dissec-
tor without cautery. This is not usually the case with adults.

37
SurgicalManagement of Intramedullary SpinalCordTumors
281
Figure37-1
The patient is positioned on two large jellyrolls (one elevates the pelvis and the other elevates the shoulders) to prevent pressure
soresand allow for free chest movement.
Laminotomy
Weusuallyperforman osteoplastic laminotomy on patients
whohavenot had previous surgery. This permits replacement
ofthebone, which is a nidus for subsequent
osteogenesis,
posteriorfusion,and protection against future local trauma. II
Trimthe spinous processes to prevent perforation
of
thefasciaafter closure. As a result of this trimming.
somextraspacefor a more convenient drilling becomes
available.
Exposethe epidural fat both above and below the
plannedlaminotomy. These openings
are analogous
to the
cranialbur holes, and serve as entry
or exit points.
Use a
high-speedcraniotome to cut the laminae (Fig. 37-2). The
drillingshouldbe centered between the facet and spinous
processes.
UltrasonicNavigationand Planning the Opening
Transduralultrasonography is critical to defining the loca-
tionofthetumor relative to the bone removal. 5,12Therefore.
afterthe laminotomy is completed, fill the wound with
salineand place the head of the 5 MHz transducer
probe
intogentlecontact with the dura (Fig. 37-3). With this
techniqueitispossibleto view the spinal cord in both sagit-
talandtransversesections. The rostral and caudal limits of
thetumor,aswellas the presence or absence of associated
cysts,areimmediatelyobvious. Usually,ependymomas are
homogeneouslyhyperechogenic vis-a-vis adjacent tissues.
Forthisreason,the tumor mass of an ependymoma may be
completelyvisualized.When working with astrocytomas,
thecordand tumor may have the same acoustic property
butthecordappearsdiffuselywidened over the bulk of the
tumor,with "tapering"at the rostral and caudal poles. Ifthe
laminotomyis not long enough to expose the entire solid
componentof the neoplasm,the laminotomy is lengthened.
segmentby segment,until the ultrasound verifies that the
entiretumormassisexposed.
Figure 37-2
Ahigh-speed craniotome isusedto perform an osteo-
plastic laminotomy. The drillingof the laminae should be centered
between the facetand the spinousprocess.