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Procedure 26 | Posterior Far Lateral Disk Herniation 259
P O S I TI O N I N G PE A R L S
• Positioning the patient on an Andrews
frame in a kneeling position allows
flexion of the lumbar spine and
opening of the intertransverse space,
therefore providing a better access to
the neural foramen.
• Clearing the abdomen from any
compression during positioning
prevents intraabdominal pressure–
related venous congestion, thereby
reducing the risk of bleeding and
helping in lumbar flexion.
P O S I TI O N I N G PI T FA L L S
• All pressure points should be well
padded, and arms should be positioned
under no tension to avoid brachial
plexus and ulnar nerve injuries.
P O S I TI O N I N G EQ U I P M EN T
• Various frames and positioning
equipments are available (Wilson frame,
Jackson table, Andrews frame,
Montreal mattress, chest-rolls, etc.)
P O RTA L S / E X P O S U R ES
P E A R LS
• True anteroposterior and lateral
fluoroscopic views are crucial for
accurate surgical site placement.
P O RTA L S / E X P O S U R ES
E Q U I PM E N T
• Preoperative and intraoperative use of
radiograph and/or C-arm fluoroscopy is
valuable to mark the correct level for
surgery.
• Modified Caspar speculum and
self-retaining lumbar retractors can help
with exposure.
• Tubular retractor systems are useful to
reach to extraforaminal zone.
Positioning
n
The prone position with abdomen free hanging is preferred by most surgeons.
n
Although both regional and general anesthesia have been described (Reulen
et al, 1996), general anesthesia with endotracheal intubation offers more
control of the airway and is preferred by the authors.
Portals/Exposures
n
Localization and placement of an accurate skin incision is made possible with
the use of plain radiographs or C-arm fluoroscopy (anteroposterior and lateral
views); following identification of the affected disk level, two horizontal and
two vertical lines are marked on the skin.
n
Horizontally, the upper line marks the inferior border of the transverse process
proximal to the affected disk, and the lower line marks the inferior border of
the affected disk space.
n
Vertically, one line is placed centrally, marking the midline overlying the spinous
processes, and a more lateral line (4- to 5-cm paramedian) marks the lateral
borders of the pedicles above and below the affected disk level.
n
The site of the skin incision (3 to 4 cm in length, and 4- to 5-cm paramedian)
is therefore outlined by these horizontal and vertical lines.
n
Muscle-splitting technique: Following skin incision, the thoracolumbar fascia is
identified and incised in line with the skin incision to expose the erector spinae
aponeurosis, which is cut longitudinally to expose the multifidus and longissimus
muscles. A blunt dissection is carried through the cleavage between the latter
muscles and a self-retaining (McCulloch or Gelpi) retractor is placed to expose
the “working zone.” This zone is located between the lower surface of the
superior transverse process proximally, the superior surface of the inferior transverse process distally, the lateral surface of the pars interarticularis medially, and
the tips of the transverse processes laterally (see Figure 26-3).
Procedure
Step 1
n
Surgical site marking, skin incision, and paraspinal muscles dissection (see
Portals/Exposures)
Step 2
n
Exposure of bony landmarks: transverse processes, facet joint, pars, and isthmus
n
Exposure of the intertransverse muscle
n
High-speed burr, or Kerrison rongeur, can be used to partially remove bony
overgrowth and improve exposure, as in cases of facet hypertrophy, at L5-S1
level, and around the lateral aspect of the pars.
P O RTA L S / E X P O S U R ES
C O N T RO V E R S IE S
• Transmuscular versus muscle-splitting
(intertransverse) approach
• At L5-S1, the exposure of surgical
site can be anatomically limited, and
therefore the approach can be modified
by removal of the L5 transverse process,
as required for a better exposure.
260 Procedure 26 | Posterior Far Lateral Disk Herniation
S T E P 1 P EA R L S
• Blunt finger dissection and palpation of
bony landmarks (transverse processes
and lateral aspect of the pars) can help
localize the “operative window.”
• A Kerrison rongeur can be used to
remove part of the facet pars laterally,
when necessary for adequate exposure.
• The soft tissue can be cleared off the
bony landmarks of the working zone
and the intertransverse membrane,
using a series of angled (3-0) curettes
and no. 2 curettes.
S T E P 1
I N S T RU M E N T A T I O N /
I M P L AN TAT IO N
• Surgical microscope: useful for
magnification and anatomic structures
differentiation
• Blunt dissectors
• Self-retaining retractors: Caspar
retractor, McCulloch retractor, or Gelpi
retractor can be used
• Curettes: no. 2 and angled 3-0
• High-speed burr with angled and long
handpiece
• Pituitary rongeur
S T E P 3 P EA R L S
• A direct view of the surgical “working
zone” can be enhanced by tilting the
operating table 15 to 20 degrees away
from the surgeon.
• The herniated disk fragment is often
sequestrated (50% of cases) and tends
to stretch and displace the spinal nerve
superiorly and laterally (see Figure
26-2).
Step 3
n
The “intertransverse membrane” is exposed after incising the medial half of the
intertransverse muscle, which is reflected laterally.
n
The posterior primary ramus is then identified, using a microscope as it crosses
the medial portion of the intertransverse membrane and before it innervates the
paraspinal muscles.
n
Using the posterior primary ramus as a reference, the dorsal root ganglion and
the spinal nerve are then located underneath the intertransverse membrane
surrounded by connective tissue and extraforaminal fat.
n
The spinal nerve is then handled very gently to avoid irritation of the dorsal root
ganglion.
n
Sweeping a ball-tipped probe beneath the nerve root, the herniated fragment
can be identified and removed.
n
Identification of the pedicle below offers an alternative option to locate the HNP
and the exiting nerve root (dorsal to the pedicle).
n
Underneath the intertransverse membrane, the nerve root/spinal nerve branches
are in close proximity to arterial-venous branches (lumbar artery) and herniated
disk material. The lumbar artery is a potential source of vigorous bleeding, and
should be spared whenever possible. Meticulous hemostasis using bipolar
cautery helps exposing the extruded disk herniation, if obscured by venous
bundles.
Step 4
n
Neurologic decompression: the extruded disk hernia is removed with a pituitary
rongeur, and although, in most cases, this is considered sufficient for symptoms
relief, further exploration and probing of the neuroforamen with a blunt probe,
searching for any residual sequestered disk material or associated foraminal
stenosis (notorious for unfavorable outcomes), may be necessary.
n
Following nerve root manipulation and probing, some surgeons prefer to place
a steroid-soaked Gelfoam pledget at the site.
Step 5
n
A surgical drain is not typically necessary.
n
Wound closure in layers: paraspinal muscles are usually reapproximated without
sutures, and the fascia/aponeurosis are stitched with absorbable sutures.
n
Local anesthetics (e.g., Marcaine [bupivicaine] without epinephrine) can be
generously infiltrated into the soft tissues for analgesia. Deep injection of the
local analgesics risks anesthetizing the exiting nerve root.
S T E P 3 P IT FA L L S
• Postoperative anterior thigh burning
sensation and dysesthesia may develop
secondary to excessive manipulation of
the dorsal ganglion during exposure.
However, spontaneous resolution is
expected.
• Persistent or recurrent leg pain occurs
in 21.7% of operated patients, and
development of foraminal stenosis or
the presence of double herniation
(combination of posterolateral and
FLDH) should be considered (Chang
et al, 2006).
Postoperative Care and Expected Outcomes
n
Postoperative care
• Ambulation and light activity are encouraged.
• The operation can be performed on an outpatient basis with most patients.
• Physical therapy promotes progressive mobilization and core strengthening.
• Restrictions are no heavy lifting and twisting/bending for 6 weeks postoperatively to avoid recurrent HNP.
• Return to work is permitted when tolerated.
S T E P 3
I N S T RU M E N T A T I O N /
I M P L AN TAT IO N
• Visualization: microscope (threedimensional view) versus binocular
loupe magnification with fiberoptic
headlight source
• Endoscopic or microsurgery: bayoneted
instruments
S T E P 3 C ON T R O V ER S I E S
• Anatomic and surgical landmarks
• Posterior ramus of the spinal nerve
(Fankhauser and de Tribolet, 1991)
• Lateral branch of posterior primary
ramus (O’Brien et al, 1995)
• Medial branch of the posterior primary
ramus (O’Hara and Marshall, 1997)
P O S T OP E R AT IV E P I T F A L L S
• Wrong-level surgery mandates revision
exploration and is prevented by use of
intraoperative C-arm fluoroscopy or
plain radiography.
• Spondylodiskitis should be treated with
immobilization and organism-specific
antibiotic therapy.
• Spinal instability, caused by excessive
pars excision, may promote accelerated
degeneration.
• Persistent/recurrent leg pain
may complicate a battered nerve
root syndrome, an inadequate
decompression, or wrong diagnosis
(20% of cases).
• Facet distress syndrome is leg pain
(pseudoradicular) with low back
pain, more often complicating an
L5-S1 interlaminar decompression.
Complication can be significantly
prevented (incidence rate decreased by
50%) with use of a muscle-splitting
technique instead.
Procedure 26 | Posterior Far Lateral Disk Herniation 261
n
Expected outcomes
• Most patients (89%) report neurologic improvement (Chang et al, 2006;
Darden et al, 1995; O’Hara and Marshall, 1997; Papavero and Caspar, 1993).
• Complete motor weakness resolution is reported in 78% of patients.
• Complete sensory deficit resolution is reported in 50% of patients.
• Excellent results are reported by 41% to 60% of patients.
• Good results are reported by 30% to 35% of patients.
• Unfavorable results are reported in 21.7% of patients.
Evidence
Chang SB, Lee SH, Ahn Y, Kim JM. Risk factor for unsatisfactory outcome after
lumbar foraminal and far lateral microdecompression. Spine 2006;31:1163-7.
Risk factors for unfavorable outcomes following surgical decompression of far
lateral disk herniation were analyzed. Age, gender, duration of symptoms,
degree of disk degeneration, presence of associated intracanalicular disk hernia,
and presence of instability were investigated. Unfavorable outcomes were
reported in 21.7% of patients (persistent or recurrent leg pain). This study
concluded that patients with double herniation were almost 3 times more likely
to have persistent or recurrent leg pain.
Darden 2nd BV, Wade JF, Alexander R, et al. Far lateral disc herniations treated by
microscopic fragment excision: techniques and results. Spine 1995;20:1500-5.
A series of patients who had been treated with microscopic facet-sparing
paraspinal muscle-splitting approach for far lateral disk herniation were
evaluated retrospectively using parameters such as history, physical examination,
pain questionnaires, visual analog scales, and plain radiographs. The overall
clinical results were encouraging, and no radiographic signs of instability were
noted. In addition, the paraspinal muscle-splitting approach is thought to
minimize manipulation of the dorsal root ganglion, which is responsible for
postoperative dysesthesia.
Fankhauser H, de Tribolet N. Extraforaminal approach for extreme lateral lumbar
disc herniation. In: Torrens MJ, RA Dickinson, editors. Operative Spinal Surgery
(Practice of Surgery Series). Edinburgh: Churchill Livingstone; 1991, p. 145-60.
Using the transmuscular approach for far lateral disk herniation, the authors
observed the posterior primary ramus of the spinal nerve during operative
dissection. However, its usefulness as an anatomic landmark has been argued
because of difficult identification of its branches and time consumption.
Jackson RP, Glah JJ. Foraminal and extraforaminal lumbar disc herniation:
diagnosis and treatment. Spine 1987;12:577-85.
In this study, 10% of patients undergoing lumbar diskectomy for herniated
nucleus pulposus were found to have far lateral foraminal or extraforaminal
disk herniation. Different diagnostic radiographic evaluations have been
proposed; however, diskography-enhanced computed tomography proved
accurate diagnosis in more than 90% of cases. In terms of surgical approach,
the authors opted for bilateral hemilaminectomy, with partial medial
facetectomy and partial internal foraminotomy as most effective for diskectomy
and nerve root decompression.
O’Brien MF, Peterson D, Crockard HA. A posterolateral microsurgical approach to
extreme-lateral lumbar disc herniation. J Neurosurg 1995;83:636-40.
O’Brien and colleagues have adopted the posterolateral approach of Watkins
for patients with a far lateral disk herniation. The authors recommend the
use of the lateral branch of the posterior primary ramus as a key anatomic
landmark to direct them to the spinal nerve and the intervertebral foramen.
O’Hara LJ, Marshall RW. Far lateral lumbar disc herniation: the key to the
intertransverse approach. J Bone Joint Surg Br 1997;79:943-7.
In a series of patients with far lateral lumbar disk herniation, an intertransverse
muscle-splitting approach has been adopted with encouraging outcomes. A
cadaver study describing the anatomic course of the posterior primary ramus
within the intertransverse membrane has also been reported. The authors
recommend the use of a muscle-splitting intertransverse approach to far lateral
herniation, referring to the posterior primary ramus as the anatomic key to safe
dissection.
262 Procedure 26 | Posterior Far Lateral Disk Herniation
Osborn AG, Hood RS, Sherry RG, Smoker WRK, Harnsberger HR. CT/MRI spectrum
of far lateral and anterior lumbosacral disc herniations. AJNR Am J Neuroradiol
1988;9:775-8.
A radiologic assessment of patients with extraforaminal disk herniations (EFDHs)
using CT and/or MRI reported that the most commonly affected level was L4-5;
however, 46% of EFDHs were overlooked and located at L2-3 or L3-4 levels.
EFDHs can be readily diagnosed on both CT and MRI if appropriate scans are
obtained from L2 through S1 and if the neural foramina and paravertebral
spaces are carefully examined. Overlooked EFDHs are an important preventable
cause of failed intraspinal diskectomy.
Papavero L, Caspar W. The lumbar microdiscectomy. Acta Orthop Scand Suppl
1993;64:34-7.
Pearson AM, Blood EA, Frymoyer JW, et al. SPORT lumbar intervertebral disc
herniation and back pain: does treatment, location, or morphology matter?
Spine 2008;33:428-35.
Patients with sciatica and low back pain secondary to HNP were enrolled in a
randomized and controlled cohort. The goal was to determine whether
diskectomy benefits low back pain and whether herniation location and
morphology affect treatment outcomes. The study concluded that leg pain
improves better than back pain, in both the surgery and nonoperative groups,
and they suggest that leg pain relief should be the primary aim of surgery.
Reulen HJ, Muller A, Ebeling U. Microsurgical anatomy of the lateral approach to
extraforaminal lumbar disc herniations. Neurosurgery 1996;39:345-50; discussion
350-1.
In lumbar spine specimens taken from human cadavers, the relevant distances
and proportions of the operative window were measured at the levels L1-2
to L5-S1. The anatomic findings led to important conclusions regarding the
microsurgical approach to extraforaminal lumbar disk herniations; at levels L1-2
to L3-4, the midline approach with lateral retraction of the paraspinal muscles
allows for efficient exposure of the lateral neural foramen and avoidance of
trauma to the facet joint. Often at level L4-5, and nearly always at level L5-S1, a
tangential route through a paramedian transmuscular approach offers many
advantages.
P R O C ED U R E 2 7
Lateral Extracavitary
Approach for
Vertebrectomy
Kene T. Ugokwe and Edward C. Benzel
I N D I CAT I O NS P I T F A L L S
• The degree of difficulty of the
operation requires experience, expertise,
and a working knowledge of
retroperitoneal surgical anatomy.
• It requires a moderate amount of
endurance. The operative procedure,
including placement of instrumentation
devices, may last from 4 to 6 hours.
• A unilateral approach does not allow
access beyond the contralateral pedicle.
• This approach does not allow direct
access to adjacent ventral intracavitary
structures (e.g., aorta and vena cava),
which may be involved with pathology
or may be inadvertently injured.
• The operation may be associated
with substantial blood loss and, as
such, autologous blood transfusion
techniques should be considered where
possible.
I N D I CAT I O NS
C O N T RO V E R S IE S
• It is a difficult and complex operation,
and the decision to subject a patient
with metastases to this operation
requires knowledge of the extent of
systemic disease and treatability of the
pathology.
Indications
n
The lateral extracavitary approach popularized by Larson and colleagues in 1976
allows access to the anterior vertebral bodies, as well as the posterior elements
of the spine, through a single incision, thereby providing a means of ventral
decompression and dorsal fixation of the spine during a single procedure. It is
a derivative of the lateral costotransversectomy, but it enlarges the scope of the
exposure because it entails the resection of a longer segment of rib and dissection of the intercostal neurovascular bundle.
n
This approach was developed for treating tuberculous spondylitis with neuro-
logic involvement (Alexander, 1946; Capener, 1954; Bohlman and Eismont,
1981).
n
Spinal cord decompression surgery has undergone many transformations in the
last 40 years (Schneider, 1962; Morgan et al, 1970; Wagner and Chehrazi, 1980;
Clark, 1981).
n
The lateral extracavitary approach may be used to address pathology anywhere
from T3 to S1. This pathology may include tumors, infections (Capener, 1954;
Larson et al, 1976), herniated disks, and fractures (Capener, 1954; Erickson
et al, 1977; Larson, 1980).
n
This approach does not involve entry into the abdominal or thoracic cavities. It
may also be used to approach the upper thoracic vertebrae without sternotomy
or thoracotomy. It does, however, require pleural retraction to provide adequate
visualization of the entire spinal canal.
n
The lateral extracavitary approach allows the surgeon to simultaneously decom-
press the ventral spinal cord and to place instrumentation devices dorsally
through the same incision and under the same anesthetic.
n
The approach may be performed on either the left or the right side, depending
on the location of the pathology.
n
In cases of complete spondylectomy, a bilateral approach may be considered.
Examination/Imaging
n
Spinal angiography can be used to identify and determine the course of the
artery of Adamkiewicz. Spinal tumors, depending on the region of the pathology,
can also be embolized 24 to 36 hours before resection.
n
In the preoperative planning stage for a lateral extracavitary approach, the
surgeon must have adequate radiographic imaging of the pathologic region.
n
Magnetic resonance imaging (MRI) with gadolinium is very helpful in assessing
the integrity of the thecal sac and spinal cord. It can also be used to delineate
the extent of tumor spread and areas of infection. The T2-weighted sequence
on MRI is also useful in determining soft tissue and ligamentous injury.
264 Procedure 27 | Lateral Extracavitary Approach for Vertebrectomy
n
T R E A T M E N T OP T I O N S
• Alternative approaches to the ventral
thoracic and thoracolumbar spine
include the retropleural and transpleural
thoracotomy.
• Anterolateral transthoracic approach
• Posterolateral costotransversectomy
• Staged transthoracic and dorsal
combined approach
P O S I TI O N I N G PE A R L S
• Placing the “up arm” on an adjustable
Mayo stand facilitates its lowering after
exposure, thereby allowing the scapula
to be rotated out of the field of view
for high thoracic approaches (T3-5).
• The patient must be properly secured to
the operating table with tape to allow
rotation of the table.
• The lateral extracavitary approach can
also be performed with the patient in
the prone position on a table that
allows the abdomen to hang free.
Computed tomography (CT) scans are also very useful in elucidating bony
anatomy.
n
Plain radiographs in combination with CT scans can also help to determine bone
quality and the ability of the spine to accommodate an implant.
n
Imaging should also be adequate to look at the position of adjacent ventral
structures in relation to the pathology (e.g., “Is the tumor exophytic and encasing the aorta?”).
Surgical Anatomy
n
The posterior musculature of the thoracic spine, which may be encountered
during this operation, depending on the level of the incision, is grouped into
the superficial, intermediate, and deep layers.
n
Superficial muscles include the trapezius, latissimus dorsi, and rhomboids.
n
Intermediate muscles are the serratus posterior superior and inferior.
n
The deep layer includes the erector spinae muscles and the transversospinalis
muscles.
n
The thoracic segmental vessels are located at the waist of the thoracic vertebral
body and divide laterally into a dorsal and ventral division.
n
The thoracic nerve root exits the neural foramen beneath the pedicle and divides
into a dorsal and ventral ramus. The dorsal ramus runs into the erector spinae
muscles and is accompanied by the dorsal branches of the posterior intercostal
vessels. These should be ligated to prevent bleeding.
n
The sympathetic trunk should be identified and protected.
P O S I TI O N I N G PI T FA L L S
• Positioning the patient prone on a
table that causes compression of the
abdomen can lead to increased blood
loss during the operation.
• Placing the patient in a knee–chest
position could lead to the development
of flat back syndrome when lumbar
spine fusion is performed.
P O S I TI O N I N G EQ U I P M EN T
• If the patient is placed in the prone
position, the Jackson frame may be
used, which allows the table to be
rotated away from the surgeon to
facilitate visualization.
Positioning
n
The lateral extracavitary approach can be performed in the three-quarter prone
position or in the true prone position. Both positions facilitate freeing of the
abdomen from compression. The following is a description of the positioning
when the operation is performed in a three-quarter prone position.
n
When general anesthesia is induced, the patient is placed in the three-quarter
prone position.
n
It is important to note that the patient is intubated and prepared for surgery
while on his or her bed in the supine position. After all lines and tubes are
secured, the patient is slid to the edge of the bed and rolled to the lateral
decubitus position on the operating table.
n
Four or five assistants help move the patient, which minimizes the chance for
inadvertent spinal manipulation that might cause neural injury.
n
A generous axillary roll is placed with the “down arm” extended laterally in a
position of 10 degrees above the perpendicular axis of the patient’s body. The
patient is then rolled further into a three-quarter prone position and secured
P O S I TI O N I N G
C O N T RO V E R S IE S
• Spinal cord monitoring, including
somatosensory evoked potentials,
motor evoked potentials, and
electromyography, may be used. Spinal
cord monitoring may, however, be
helpful during surgery for severe
deformity correction.
in this position with 3-inch adhesive tape and rolls formed from sheets and
blankets (Figure 27-1).
n
The patient’s abdomen is freed of all compression. The upper arm may be placed
on a well-padded Mayo stand or pillow. The operative table can be tilted from
side to side to facilitate the view of the operative site by both the operating
surgeon and the assistant.
Portals/Exposures
n
An intraoperative radiograph after positioning and before draping also is helpful
in localization, because the skin incision should be centered over the lesion. It
is important to prepare and drape a wide area to allow for maximal exposure.
n
The approach may be performed on either the left or the right side, depending
on the location of the pathology. However, in cases of complete spondylectomy,
a bilateral approach may be considered.
FIGURE 27-1
Procedure 27 | Lateral Extracavitary Approach for Vertebrectomy 265
FIGURE 27-2
n
A hockey stick–shaped incision is generally used, with the lateral limb curving
off 8 to 10 cm toward the side of the pathology and the vertical limb running
along the midline (Figure 27-2). A gentle angle should be used to prevent
ischemic injury to the skin flap. In certain cases, an L-shaped incision may be
used, but this may lead to necrosis of a devascularized corner.
n
The vertical limb of the incision can be taken down through the subcutaneous
tissue and the thoracodorsal fascia to the spinous processes with monopolar
cauterization.
n
The thoracodorsal fascia is incised in the shape of a T. A subperiosteal dissec-
tion, using a Cobb dissector or periosteal elevator, also helps decrease bleeding
and thermal injury to the muscle.
266 Procedure 27 | Lateral Extracavitary Approach for Vertebrectomy
A
S T E P 1 P EA R L S
• It is important to obtain intraoperative
imaging to confirm accurate operative
level.
• Use of a self-retaining retractor system
(e.g., the Omni retractor) to retract the
lung will aid in visualization.
S T E P 1 P IT FA L L S
• Failure to identify and preserve the
neurovascular bundle after rib resection
can lead to unwanted morbidity in the
lumbar spine.
B
FIGURE 27-3, A-D
Procedure
Step 1
n
After incision of the thoracic fascia (Figure 27-3, A), the myocutaneous flap is
retracted laterally to expose the erector spinae muscles (Figure 27-3, B), which
are retracted medially (Figure 27-3, C ). Retraction of the erector spinae muscles
medially (Figure 27-3, D ) and resection of the appropriate ribs allows access to
the dorsolateral aspect of the spinal column by an extrapleural approach.
n
A Doyen rib dissector is used to remove the soft tissue on the undersurface or
ventral aspect of the ribs. The ribs are dissected out to the costovertebral joints.
n
The next step involves resecting the rib using a rib cutter. Approximately 8 to
10 cm of rib is resected from the costovertebral joint for tumor surgery, and this
is also adequate for vertebrectomy. For disk surgery, a rib resection of 3 cm is
adequate. The resected rib should be saved to use as a bone graft for fusion.
Procedure 27 | Lateral Extracavitary Approach for Vertebrectomy 267
C
S T E P 2 P EA R L S
• Complete exposure of the vertebral
elements above and below the
pathologic level ensures adequate
ventral exposure.
• Meticulous hemostasis during the initial
exposure will help reduce blood loss.
• Dural tears should be repaired primarily
when possible. Another option is
patching the dura with a substitute,
such as bovine pericardium or other
dural substitutes.
D
FIGURE 27-3, cont'd
FIGURE 27-4
Step 2
n
When the neurovascular bundle is identified, it may be followed into the
foramen. The neural foramina above and below the vertebrectomy site are
enlarged, and an intraoperative radiograph may again be helpful for localization
if the pathology is not clearly evident.
n
The disk space immediately superior and inferior to the vertebrectomy site
should be removed with a scalpel. The vertebral body can be removed with
either a high-speed drill or a rongeur under direct visualization (Figure 27-4).
The dura can be further exposed using a high-speed burr, rongeurs, and curettes.
268 Procedure 27 | Lateral Extracavitary Approach for Vertebrectomy
n
S T E P 2 P IT FA L L S
• Failure to identify and preserve the
neurovascular bundle after rib resection
can lead to unwanted morbidity in the
lumbar spine canal.
• Nerve root damage during
decompression must be avoided.
• Preoperative angiography to identify
the artery of Adamkiewicz will help
determine which segmentals may be
ligated.
• Unrecognized pneumothorax from
pleural violation can occur.
The vertebral body resection should be carried out to the distal pedicle. It is
imperative to completely decompress the spinal canal. This may be difficult,
however, because visualization of all bony fragments is not always possible. The
superior disk space should be explored for any bony fragments. The posterior
longitudinal ligament may also be opened to explore the epidural space.
Step 3
n
It is important after a vertebrectomy to maintain the integrity of the spinal
column by reconstructing it. A midline subperiosteal exposure is performed
along the spinous processes and laminae over the appropriate levels for placement of dorsal instrumentation. Freedom of movement at the level of the
involved disk interspaces, which is gained by the vertebrectomy, allows optimal
spine reduction.
n
Following placement of the dorsal instrumentation, the original operative site
S T E P 3 P EA R L S
• In the upper thoracic spine, the parietal
pleura should be inspected for leaks.
Small leaks may be repaired primarily,
and larger leaks may require chest tube
placement.
is reexposed.
n
An appropriately fashioned rib or iliac crest graft or interbody cage may be
positioned with an impactor and a hammer. The iliac crest can be exposed
through the lower lateral aspect of the operative field, in the lumbar and low
thoracic approaches, to harvest tricortical iliac bone. In the thoracic and thoracolumbar region, appropriately fashioned rib segments may be used as strut
grafts.
n
Tibial allograft struts or titanium cages packed with bone from resected rib or
S T E P 3 P IT FA L L S
• Certain patients suffer significant
morbidity from iliac crest graft harvest,
and this should be avoided if possible.
• Placement of grafts too close to the
spinal cord can lead to graft migration
and spinal cord injury.
• Unrecognized pneumothorax from
pleural violation can occur.
vertebral body may also be used for a fusion (Figure 27-5).
n
When an interbody bone graft is to be placed, curettes are used to make troughs
in the vertebral body above and below the decompressed area. Ventral plating
followed by dorsal instrumentation may be inserted as deemed appropriate.
n
The wound is closed in layers, and a surgical drain may be placed adjacent to
the surgical site.
S T E P 3 C ON T R O V ER S I E S
• Some surgeons are hesitant to place
a surgical drain in the presence of a
cerebrospinal fluid leak. If a drain is
placed in this situation, it is important
to ensure that the leak is repaired first
and that the drain output is monitored
closely.
FIGURE 27-5