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Case 2: Percutaneous Instrumentation
C H A P T E R 4 5 Treatment of oracic Vertebral Fractures
285
An 84-year-old female presented 1 month after she was involved in a motor
vehicle accident in which she sustained a T9 Chance fracture (Figure
45-3A). oracic MRI performed hours after the accident showed a spinal epidural hematoma at the level of the fracture and an intact posterior
ligamentous complex. e patient underwent multilevel thoracic laminectomies and evacuation of the epidural hematoma. Subsequent MRI showed
no residual spinal cord compression; however, she had persistent spinal
cord injury and was unable to lift the lower extremities against gravity. She
also had severe back pain, which limited her mobility and rehabilitation.
We opted to perform percutaneous T6-12 instrumentation (Figure 45-3B).
Two months later, the patient was tolerating rehabilitation well, and her
lower extremity strength was markedly improved.
A B
F IG UR E 4 5- 3 A, Preoperative CT demonstrating T9 Chance fracture. Postoperative AP (B) and lateral (C) x-rays showing bilateral T6-8 and T10-12
pedicle screw and rod fixation.
C
Case 3: Pedicle Subtraction Osteotomy
A 57-year-old male presented with progressive myelopathy, including gait
disturbance due to spasticity progressing over a 5-year period. Bowel and
bladder control had been compromised, and the lower extremities were
diffusely weak to resistance. He reported severe paresthesias in his lower
extremities. Bilateral Babinski signs and bilateral ankle and knee clonus
were present. He also had a palpable nontender gibbus in the upper thoracic
spine.
MRI and CT scans revealed severe compression of the ventral spinal
cord due to a 30-degree focal kyphotic deformity at the level of T3-T4.
A T2 signal change was detected within the spinal cord at the same level,
consistent with advanced spinal cord injury (Figure 45-4A and B).
A posterior transpedicular osteotomy was performed using biplane
fluoroscopy, which guided the resection of a wedge of the superior T4
vertebra (Figure 45-5A-C). Rib osteotomies were completed at the level
of T4, and lateral wall osteotomies with preservation of the pleura were
accomplished. After a spontaneous partial reduction of the osteotomy, the
Mayfield head holder was elevated to reduce the gibbus and correct the
alignment of the upper thoracic spine. Longitudinal rods were contoured
and placed at the level of T1, T2, and T3 after reduction was completed
manually, with biplane fluoroscopy and intraoperative evoked potentials,
by closing the bony defect created by the vertebral osteotomy (Figure 45-5
C-D). e longitudinal rods were placed into a reduced position, achieving complete reduction of the kyphotic and sagittal plane deformity and
annihilating the gibbus deformity (Figure 45-5E). Biplane fluoroscopy
confirmed alignment of the sagittal and coronal plane at the instrumented
levels with complete resolution of the gibbus, and evoked potentials
remained unchanged (Figure 45-5E and F).
Two days after the surgery, the patient was transferred from the
intensive care unit to the floor, where he quickly recuperated his baseline
strength and was discharged home ambulating independently with the use
of a cane. Postoperative CT scans confirmed the established correction of
the sagittal plane deformity (Figure 45-6A and B).
286
P A R T V I Other Surgical Treatment Modalities: Thoracic Spine
H
30°
A B
F IG UR E 4 5 -4 A, T2-weighted MRI sequence sagittal view, showing the ventral spinal cord compression and
stretching resulting from the posttraumatic focal kyphosis at the level of T4. At the T4 level, the spinal cord is markedly
atrophied and shows a significantly increased signal consistent with spinal cord injury. B, Sagittal thoracic CT scan showing
a healed compression fracture at T4 the level with a resultant focal kyphosis of approximately 30 degrees.
T4
T4
A
T4
D
F IG UR E 4 5- 5 A, Intraoperative fluoroscopy showing placement of bilateral 5.5-mm and 6.5-mm pedicle screws from T1 to T10. The inferior part
of the spinous process and laminae of T3 are resected, as well as the inferior facets of T3 bilaterally. The superior facets of T4 and the pedicles of T4 are
resected, creating a giant foramen containing both T3 and T4 nerve roots. Rib heads at the level of T4 are osteomized along with the transverse processes.
B, Under fluoroscopic guidance, a wedge of the vertebral body of T4 is removed with different sizes of curettes and an electric drill. Rongeurs are used to
osteomize the lateral edges of the vertebral body. C, Placement of the contoured rods at T1, T2, and T3 allows manual reduction of the focal kyphosis at
the level of T3 with the guidance of biplane fluoroscopy and intraoperative evoked potentials (D) by closing the bony defect created by the vertebral osteotomy. E, The longitudinal rods were placed into a reduced position, where a complete reduction of the kyphotic and sagittal plane deformity was achieved,
annihilating the gibbus deformity and closing the bony wedge defect created by the PSO. F, Biplane fluoroscopy confirmed alignment of the coronal plane
at the instrumented levels.
B
T4
E
C
T4
F
C H A P T E R 4 5 Treatment of oracic Vertebral Fractures
30°
T4
T4
A B
F IG UR E 4 5 -6 A, Preoperative sagittal CT scan of the thoracic spine showing the wedge resection planning.
B, Postoperative sagittal CT scan of the thoracic spine showing the “closing” of the wedge resected by the PSO, and sub-
sequent “shortening” of the spine at T4.
287
provide structural support to the vertebral body. A smaller amount of
PMMA is then injected through the same channel around the PEEK construct, as compared to both vertebroplasty and kyphoplasty. The StaXx
kyphoplasty system potentially offers an advantage over kyphoplasty alone,
in which the space opened by the balloon may undergo some collapse before
the PMMA is injected. In vertebroplasty, the PMMA simply flows to the
spaces of least resistance, but does not offer height restoration.
Thoracic Stabilization
Surgical approaches for the treatment of unstable thoracic vertebral fractures
include anterior, posterior, and combined anterior and posterior stabilization
methods. Minimally invasive percutaneous pedicle screws may be placed if the
fracture involves mostly bony elements and the ligaments are intact. If ligamentous injury is present, pedicle screw placement with joint arthrodesis is advised.
Spinal Cord or Nerve Decompression
Thoracic vertebral fractures associated with cord or nerve compression
require decompression. Spinal cord decompression may be accomplished with
laminectomy alone (when the compressive pathology is dorsal to the cord),
although removal of a bone fragment ventral to the spinal cord may be necessary. This can be done from a posterior approach using a facet-sparing transpedicular approach or a far lateral approach. If the bone fragment compressing
the spinal cord is in a central and ventral location, an anterior approach may
then be required. Instrumentation and fusion are generally needed.
Deformity Correction
To treat spinal deformity (kyphosis and/or scoliosis), with or without
myelopathic symptoms, several surgical techniques may be used, including
pedicle subtraction osteotomy (PSO), Smith-Peterson osteotomy, pedicle
screw instrumentation, and arthrodesis. The use of PSO and SmithPeterson osteotomy in a posterior approach is a good alternative to a combined anterior and posterior approach.
The abnormal focal concavity, which results from the kyphotic deformity
caused by a compression fracture, stretches the spinal cord. The spinal cord
moves ventrally in an attempt to minimize the stretching effect. Myelopathic
deficits ensue once the ventral compression becomes significant, requiring
ventral compression of the bony elements and removal of the upper thoracic
concavity to reestablish the normal three-dimensional conformation of the
spinal cord. The distinct anatomy of the upper thoracic spine renders the
spinal cord more vulnerable to ventral compression.
Anterior approaches to treat a spinal deformity can also be performed.
However, any multisegment anterior fusion construct is subject to sustaining increased mechanical stress, which can thereby result in the failure of
the anterior spinal fusion.3 In addition, the upper thoracic spine is a difficult
region to access anteriorly due to the presence of major vascular elements as
well as vital structures ventral to the spine.
2
Moreover, Boockvar et al reported
that anterior reconstruction alone might not meet the biomechanical needs of
the upper thoracic spine. Recent advances in anesthesia, neural monitoring,
and posterior instrumentation have made a posterior approach to the upper
thoracic spine possible and treatment of the upper thoracic spine achievable.
In some cases, PSO may be safely used to correct abnormal severe focal
kyphotic deformities, which result in spinal cord stretching and ventral
compression, because it allows for significant correction through one spinal
segment by shortening the spinal column and reestablishing sagittal alignment. When PSO is performed, instrumented fusions are usually necessary,
and dural buckling needs to be ruled out with thoracic laminectomies at the
osteotomy sites.
CONCLUSIONS/DISCUSSION
The management of thoracic fractures is challenging because of the complex anatomic variations in this region. In addition, most spinal surgeons are
less comfortable with dealing with the thoracic area than with the cervical
vor lumbar regions. Nevertheless, with current technical and technologic
advances, the spinal surgeon is equipped with a wide variety of available
resources and methods to treat thoracic fractures according to severity, presenting symptoms, and impact on patient function.
References
1. K. Abumi, Y. Shono, M. Ito, H. Taneichi, Y. Kotani, K. Kaneda, Complications of pedicle
screw fixation in reconstructive surgery of the cervical spine, Spine 25 (2000) 962–969.
2. J.A. Boockvar, M.F. Philips, A.E. Telfeian, D.M. O’Rourke, P.J. Marcotte, Results and risk fac-
tors for anterior cervicothoracic junction surgery, J. Neurosurg. 94 (2001) 12–17.
3. H.F. Defino, A.E. Rodriquez-Fuentes, F.P. Piola, Surgical treatment of pathological kyphosis
[in Spanish], Acta Ortoped. Bras. 10 (2002) 10–16.
4. S.D. Gertzbein, Scoliosis Research Society: multicenter spine fracture study, Spine 17 (1992)
528.
5. J.Y. Lee, A.R. Vacarro, M.R. Lim, et al., Thoracolumbar injury classification and severity score:
a new paradigm for the treatment of thoracolumbar spine trauma, J. Orthop. Sci. 10 (2005)
671–675.
6. I.H. Lieberman, S. Dudeney, M.K. Reinhardt, et al., Initial outcome and efficacy of “kypho-
plasty” in the treatment of painful osteoporotic vertebral compression fractures, Spine 26
(2001) 1631–1638.
7. F. Magerl, M. Aebi, S.D. Gertzbein, et al., A comprehensive classificaton of thoracic and lum-
bar injuries,, Eur. Spine J. 3 (1994) 184–201.
8. J.B. Martin, B. Jean, K. Sugui, et al., Vertebroplasty: clinical experience and follow-up results,
Bone 25 (1999) 11S–15S.
9. M.M. Panjabi, K. Takata, V. Goal, et al., Thoracic human vertebrae: quantitative three-
dimensional anatomy, Spine 26 (1991) 888–901.
1
Tumors of the Thoracic Spine
Timothy F. Witham, Vivek A. Mehta, and Ziya L. Gokaslan
46
k e y p o i n t s
Surgical decompression followed by radiotherapy has replaced radiotherapy
alone as the gold standard for treatment of spinal cord compression caused
by metastatic cancer.
Tumor histology, location, and anterior column compromise should dictate
the surgical approach.
Anterior, posterior, combined, or en bloc approaches should be considered
in a disease-directed fashion for the treatment of thoracic spinal column
neoplasms.
Instability must be considered, particularly when there is anterior column
compromise.
e clinical goals of surgical intervention should be local disease control,
preservation or restoration of neurological function, stabilization of the spinal
column, and pain control.
INTRODUCTION
Nearly 1.4 million new cases of cancer are diagnosed in the United States
1
per year.
per year, patients ultimately succumb to complications related to metastatic
disease. Approximately 30% to 90% of cancer patients will have evidence
of metastases to the spinal column at autopsy, and 5% to 10% of cancer
patients develop symptomatic metastatic epidural spinal cord compression
(MESCC), an oncologic emergency.
of symptomatic MESCC in the united states each year.
is the most common site of metastatic disease involvement in the vertebral
column and the most common site of primary vertebral column tumors.
Because symptomatic degenerative disease is less common in the thoracic
spine relative to the cervical or lumbar spine, thoracic region pain in a
middle-aged or elderly patient should be considered a red flag symptom.
Imaging should be considered expeditiously, particularly if the patient has
a history of primary cancer. Nonetheless, delay in the diagnosis of thoracic
region tumors is common. Surgical intervention for thoracic spinal cord
and spinal column neoplasms continues to present significant challenges.
Lesions in the thoracic spine can be subdivided into four major categories:
metastatic disease, intradural extramedullary tumors, intramedullary spinal
cord tumors, and primary neoplasms involving skeletal elements.
In a majority of the approximately 724,000 cancer-related deaths
1
There are approximately 25,000 cases
1
The thoracic spine
Metastatic Tumors
Approximately 70% of metastatic disease to the vertebral column involves
the thoracic spine, making it the most common site of spinal metastases.
As increased survival due to improved treatment strategies for primary
neoplasms becomes a trend, the incidence of bone metastases to the spine
will also increase. The unique venous drainage of visceral organs through
the Batson plexus is one explanation for this anatomical phenomenon, along
with the close proximity of the thoracic spine to thoracic and abdominal
2
viscera.
Eighty percent of metastases involve the vertebral body, while 20%
involve the posterior elements.
2
Of the four subtypes of tumors of the tho-
288
racic spine, metastatic tumors are by far the most common. Cancers that
have a propensity to spread to the thoracic spine include breast, lung, leukemia/lymphoma, prostate, and renal cell.
consideration of the need for decompression of the neural elements, for restoration of spinal stability, and for pain relief. With tumors of breast, prostate, or renal origin, aggressive resection is indicated, as this has been shown
to have a favorable impact on ambulatory function and may have a favorable
impact on survival.
3
2
Surgical management requires
Intradural Extramedullary Tumors
Intradural extramedullary (IDEM) tumors account for two thirds of intradural spinal tumors.
spine are meningiomas, neurofibromas and schwannomas, which account
for over 80% of tumors in this location.
noid cap cells; 75% of spinal meningiomas are contained within the thoracic
spine, and they show a strong predilection for women (80%).
have a benign biological behavior in the spinal column and management
should be directed toward gross total resection to achieve a cure. This may
not be feasible with anteriorly situated, calcified tumors, and the risk of neurological injury must be weighed against the indolent growth rates usually
observed after subtotal resection. Radiotherapy is thus reserved for recurrent tumors that cannot be completely resected.
Schwannomas arise from Schwann cells of the posterior nerve roots and
are most common in the thoracic and upper lumbar spine. The location, in
13% of cases, may be both extradural and intradural. Spinal schwannomas
have an increased frequency in certain genetic disorders, such as neurofibromatosis type 2 (NF2).
Neurofibromas of spinal nerve root origin may be seen sporadically or in
patients with neurofibromatosis. These tumors will have an extradural component in 30% of cases.
mas and neurofibromas is complete surgical resection. If the tumor cannot
be separated from the nerve root of origin, then sacrifice of that root may be
necessary. Fortunately, this is usually of little consequence in the thoracic spine.
IDEM tumors of the thoracic spine most often manifest with long tract
signs, and the corticospinal tracts are particularly vulnerable. Stiffness and
muscle fatigue are often primary signs with spasticity frequently occurring
secondarily. In patients presenting with myelopathy, surgical indications are
straightforward. It is the incidentally found meningioma or nerve sheath
tumor that may present a dilemma. Patient age, medical comorbidities, and
tumor growth observed with serial imaging help direct the necessity and
timing of surgical intervention.
Intramedullary Spinal Cord Tumors
2
Intramedullary spinal cord tumors (IMSCTs) make up 2% to 8.5% of all central nervous system(CNS) tumors and approximately one third of primary
spinal column tumors.
types observed in the thoracic spine are astrocytomas and ependymomas,
which are seen with almost equal frequency in adults. Hemangioblastomas,
which are less commonly observed, may be sporadic or a part of von HippelLindau syndrome. Astrocytomas are most often seen at the cervicothoracic
4
The most common IDEM tumors of the thoracic
5
Meningiomas arise from arach-
5
Meningiomas
5
The surgical goal in the treatment of thoracic schwanno-
6
Approximately 90% are of glial origin.4 The major
C H A P T E R 4 6 Tumors of the oracic Spine
289
junction and in the lower thoracic spinal cord. In adults, ependymomas are
the most common IMSCT. However, the majority of these occur in the cervical spine or arise from the filum terminale (myxopapillary ependymoma).
Treatment of ependymomas is focused on gross total resection. Patients who
have incompletely-removed tumors should be considered for re-resection or
followed closely with serial imaging and considered for reoperation if growth is
documented. Radiation therapy is often reserved for incomplete resection after
reoperation. Astrocytomas in adults tend to be infiltrative and blend imperceptibly with the spinal cord at the margins of the tumor. For this reason, total
removal may not be possible. Most commonly, infiltrative tumors treated with
subtotal resection will undergo radiation therapy. For high-grade infiltrative
lesions, biopsy or subtotal resection is also often followed by radiation therapy.
For some low-grade lesions treated with subtotal resection, postoperative radiation therapy remains controversial.
6
Pain is the most common presentation of IMSCT in the thoracic spine;
it usually localizes to the level of the tumor and is either regional back pain
or radicular.
4
Up to one third of patients may also experience sensory or
motor complaints and spasticity. The most common sign of an IMSCT
within the thoracic spine is a mild scoliosis with spasticity and sensory disturbance.
6
Until recently, it was believed that posterior decompression and
radiation therapy were the limits of therapy, but aggressive gross total resection, with the aid of microsurgical tools and intraoperative monitoring, has
been shown to be safe and to improve functional recovery and reduce tumor
recurrence.
Primary Vertebral Column Tumors
Primary tumors of the vertebral column are rare, making up less than 10% of
all tumors involving the spinal column.
patients present with a vertebral column mass in the absence of impending
neurological compromise, minimally invasive, image-guided biopsy should be
performed prior to definitive treatment planning. Many of the primary neoplasms of the thoracic spinal column are best treated via radical en bloc surgical resection. These types of surgical approaches require careful and detailed
preoperative surgical planning by an experienced surgical team. Therefore,
knowing the tumor histology up front is critical to the surgical plan.
Primary osseous tumors can be divided into three categories: benign,
benign but locally aggressive, and malignant. Benign tumors include hemangiomas, osteoid osteomas/osteoblastomas, chondroma/osteochondromas, aneurysmal bone cysts, and eosinophilic granulomas. Hemangiomas
are the most common primary neoplasm affecting the thoracic spine and
have been seen in approximately 11% of all postmortem examinations.
Infrequently, hemangiomas can behave in an atypical or locally aggressive
fashion and can cause spinal cord compression. In this situation, aggressive
surgical resection is advocated. Giant cell tumors have a variable biological
behavior and may act in a locally aggressive fashion. Because of this, the
authors often recommend radical en bloc excision of tumors exhibiting this
pathology and will strongly consider adjuvant radiation therapy postoperatively. Chordomas occurring in the thoracic spine are almost uniformly
locally aggressive and recurrences are common after intralesional resection,
including gross total resection. Similarly, we recommend radical en bloc
resection techniques for thoracic chordomas. Chemotherapy protocols for
chordomas have not been promising to date, nor have conventional radiation therapy modalities. Proton beam irradiation therapy has been shown
to be the most promising radiation modality and patients are evaluated
postoperatively for this modality on an individual basis. However, it is our
belief that the most effective treatment modality for achieving long term
local disease control is aggressive en bloc resection with negative margins,
including resection of the biopsy tract if possible. Proton beam irradiation should not be relied on for cases where gross total resection cannot be
achieved. However, it may be employed even in cases of en bloc resection
with negative margins.
Malignant types include plasmacytomas, chondrosarcomas, and osteosarcomas. Plasmacytomas make up nearly 30% of all primary tumors and
have a propensity to occur in the thoracic spine.
radiation-sensitive lesions, surgery may be necessary for failure of radiation
therapy, acute neurological decline from spinal cord compression, and overt
instability of the spinal column. Sarcomas present a specific treatment challenge. Biopsy is recommended to assess the specific histology and grade.
7
It should be emphasized that when
8
While these tumors are
Systemic workup for metastases is important prior to embarking on treatment. High-grade lesions that are large or those tumors associated with
metastatic disease may be treated with neoadjuvant chemotherapy protocols
to shrink the local disease and address metatstatic disease prior to surgical
resection. En bloc resection is the technique that gives the patient the best
opportunity for a longer-term survival with these tumor types, particularly
when metastatic disease is not present.
Thoracic spinal column neoplasms present a host of treatment challenges. Knowing the tumor histology through a biopsy is ideal prior to
embarking on a formal surgical plan. In the setting of impending neurological decline, a biopsy may not be possible and urgent decompression may
be necessary. However, surgical planning is best determined when the histology, systemic disease status, patient age, and medical comorbidities are
known.
BASIC SCIENCE
Research related to the molecular biology and genetics of specific tumor types
that affect the spinal column either as primary or metastatic lesions is beyond
the scope of this text. However, several animal models of spinal column
neoplasia and the translational research related to these animal models are
worth discussion. Recently, animal models for metastatic disease to the spine
and intramedullary spinal cord gliomas have been developed that will allow
for more rigorous preclinical analysis of novel therapies. Mantha et al have
established a reproducible model of metastatic breast adenocarcinoma to the
vertebral column in rats.
9
The establishment of this model represents the
first of its kind and has allowed for the study of multiple treatment modalities focused on treating spinal metastatic disease, including surgery, radiation
therapy, and the novel use of locally delivered chemotherapeutic agents.
Using the metastatic model developed by Mantha et al, Bagley et al have
shown that radiation reliably delays paraparesis and death in this model, as
does local delivery of paclitaxel.
10,11
The combination of these two modalities
has been shown to be more effective than either treatment alone.
ally, Gok et al. have shown that the combination of decompressive surgery,
local chemotherapy, and radiation has the most profound results in terms of
preservation of neurological function and prolongation of survival in this animal model with of metastatic epidural spinal cord compression.
is that this experimental data may translate into useful clinical trials designed
to improve neurological morbidity and, potentially, survival in patients with
MESCC due to metastatic breast cancer and other tumor histologies.
7
Pennant et al. have examined the efficacy of microsurgical excision in a rat
model of intramedullary spinal cord tumor. The established model mimics the
behavior of IMSCTS, both functionally and histopathologically.
tumor implantation, animals were randomized into a treatment group (microsurgical resection) or to no treatment. The animals that underwent resection
had a significant delay in the onset of functional paraplegia as compared to the
controls and these results were highly reproducible. This new model allows
for the study of new treatment options for high-grade intramedullary tumors.
Schuster et al have developed a novel model of spine metastasis using
human osteoblasts implanted in immune incompetent (SCID) mice that has
shown to be highly reproducible.
14
This model allows for the study of bonetumor interaction in metastatic disease, as well as the basic biology of bone
metastases. Chordoma models have been difficult to establish, but through
human cell culture, nude animal models have been conceptualized. Laboratory study of this extremely aggressive local tumor is much needed given the
limited options for treatment outside of aggressive radical resection.
CLINICAL PRACTICE GUIDELINES
Surgical intervention has a clear and proven role in the treatment of patients
with metastatic disease involving the thoracic spine that results in spinal
cord compression. Surgical treatment, followed by radiation therapy, not
only extends ambulatory status but also results in a trend toward longer
survival and reduces the need for steroids and pain medications.
The indications for surgical intervention include the need to establish a diagnosis, the treatment of spinal instability, and the restoration or
preservation of neurological function in the setting of epidural spinal cord
compression. Additional indications include the treatment of radioresistant
tumors, and the treatment of tumor recurrence following radiation therapy
11
Addition-
12
The hope
13
Following
3
290
P A R T V I Other Surgical Treatment Modalities: Thoracic Spine
or the treatment of neurological decline during radiation therapy. A systemic approach for treatment of thoracic metastases has been developed
and may aid in designing the optimal surgical strategy.
15
The mnemonic
“MAPS” stands for (1) method of resection; (2) anatomy of spinal disease;
(3) patient’s level of fitness; and (4) stabilization.
Surgical approaches to the spine can be generally categorized as either
anterior, posterior, or combined. Posterior approaches may include laminectomy alone, or laminectomy combined with transpedicular, costotransversectomy, or lateral extracavitary resection techniques and stabilization.
Anterior approaches in the upper thoracic spine include cervicothoracic
and trap door exposure. Anterior access to the lower thoracic spine can be
accomplished by a thoracotomy or thoracoabdominal approach.
The vascular anatomy is particularly important when designing an
anterior approach as well as the tumor laterality. For example, above T6 or
T7 a right-sided thoracotomy is preferred, because the aortic arch often
complicates a left-sided approach to the mid/upper thoracic spine. Similarly, tumors situated between T1 and T4 are a unique challenge from
the perspective of an anterior approach. With metastatic lesions in the
upper thoracic spine, the authors will often consider a posterior approach.
If anterior column resection or reconstruction is necessary, it is often
done with a transpedicular, costotransversectomy, or lateral extracavitary
technique.
The method of resection may be en bloc (wide or marginal) or intralesional resection of various degrees ranging from open biopsy to gross
total resection. En bloc resection may be considered with a solitary spinal
metastatic lesion, in the absence of visceral metastatic disease and with a
favorable histological tumor type (breast, prostate, renal cell carcinoma,
thyroid carcinoma). In addition, the feasibility of such an approach should
be considered with respect to surgical staging and medical fitness of the
patient. En bloc spondylectomy in the thoracic spine may be performed
through an all-posterior approach or a combined posterior approach first
and a second staged anterior approach. En bloc spondylectomy through a
posterior-only approach requires laminectomy above and below the vertebral segment of interest. Then while protecting the spinal cord and nerve
roots, the pedicles are cut at the junction with the vertebral body using a
chisel or saw. This allows the posterior elements to be removed in one piece
after the facets are disrupted on each side. A wide costotransversectomy is
performed on each side to allow for dissection around the entire vertebral
body, so that the aorta and venous structures may be dissected off of the
spinal column. Radical discectomies are performed above and below the
segment of interest to mobilize the entire vertebral body. With the pleura
completely exposed, the vertebral body may be rotated, carefully translated
posteriorly around the side of the spinal cord, and resected in one piece.
Staged posterior followed by anterior en bloc spondylectomy is similar, but
after the radical discectomies, a Silastic sheath is placed between the posterior vertebral body and the anterior dura. Subsequent staged thoracotomy
is performed to remove the mobilized vertebral segment in one piece. Special care is taken not to injure the anterior vasculature. The spinal cord
is relatively protected with this technique because the Silastic sheath was
placed during the first stage to clearly identify the plane between the spinal
cord dura and the vertebral body.
The majority of metastases within the thoracic spinal column will
affect the vertebral body, which favors an anterior approach. A diseasedirected approach to the thoracic spine provides the most direct access for
resection of tumors contained within the vertebral body and allows for the
most effective reconstruction of the anterior aspects of the weight-bearing
spine. A consideration of patient fitness is essential in the choice of surgical approach. Previously irradiated tissue increases the risk of wound
dehiscence and thus may favor an anterior approach. Additionally, the
possibility of high intraoperative blood loss, nutritional depletion, corticosteroid use, advanced age, comorbidity, and paraparesis are significant risk
factors that should be considered.
Though the thoracic spine is well supported by the rib cage, additional stabilization should be considered in the case of significant disease
or removal of the vertebral bodies, facet joints or pedicles. Anterior stabilization is always indicated following vertebrectomy, and the need for
additional posterior stabilization should be considered. Supplementary
posterior stabilization following vertebrectomy and vertebral body reconstruction might be considered in a variety of situations, including the
case of a posterolateral approach, in patients with a significant kyphosis
or deformity, in patients with junctional zone disease, significant adjacent
chest wall reconstruction, a greater than two-level corpectomy, spondylectomy, or in the case of poor bone quality. The authors do not recommend
laminectomy alone for the treatment of thoracic tumors, except in the setting of IMSCTs. Often laminoplasty is an attractive option for IMSCTs.
Typically with posterior reconstruction for metastatic tumors, we will place
pedicle screws two to three levels above and two or three levels below the
area of the laminectomy, particularly if a posterior approach is used for
anterior column reconstruction.
Finally, metastatic spread from lymphomas, multiple myeloma, and small
cell lung carcinoma represent tumors that are particularly radiosensitive;
therefore radiation modalities may be considered as a first-line treatment
and the need for surgery may be obviated or withheld until radiotherapy has
been implemented and failed.
CLINICAL CASE EXAMPLES
Case 1: Posterolateral Approach for Metastatic Spine Disease
PATIENT PRESENTATION
A 70-year-old female with a history of diabetes and osteoarthritis of the
hips presented to an outside emergency department with shortness of
breath and dyspnea. Work-up included a chest CT scan and an incidental
lesion was found in the T3 vertebral body. Formal imaging of the spine was
done via a dedicated MRI and CT scan. Initially the lesion was thought to
represent metastatic disease. e patient initially had no neurological symptoms and the lesion was felt to be incidentally found. A systemic metastatic
work-up was negative. Given the lack of neurological symptoms despite evidence of epidural spinal cord compression on the MRI scan, CT-guided
biopsy was recommended. e results were nondiagnostic on two occasions
despite thorough review by an experienced neuropathologist. e pathology
sample did show rare plasma cells, but serum protein electrophoresis and
urine protein electrophoresis were negative. e patient was referred to our
institution for further care when she began to develop mild lower extremity
weakness, subtle gait difficulty, lower extremity paresthesias, and long tract
findings on exam.
MRI of the thoracic spine and CT scan of the thoracic spine are shown
in Figure 46-1. We felt that despite the negative biopsy, the imaging was
most characteristic of an atypical vertebral hemangioma with epidural
spinal cord compression. Imaging features that support this diagnosis
include the appearance of vascular channels on the MRI and the “polkadot” appearance with vascular channels also present on the CT scan.
Also included in the differential diagnosis was plasmacytoma/multiple
myeloma.
Because of impending neurological deterioration and the lack of a diagnosis, a surgical approach was recommended. Given the possibility of a
highly vascular lesion such as a vertebral hemangioma, preoperative embolization by an interventional neuroradiologist was recommended and successfully carried out through glue embolization via the right T3 intercostal
artery feeding an arteriovenous fistula to the T3 vertebral body and tumor
blush. e following day the patient was taken to surgery.
Approaches to this lesion were discussed, with several considerations in
mind. First, the epidural compression was noted to occur from an anterolateral direction at one segment, making an anterior approach appealing.
However, at the T3 level, anterior approaches are more complicated and
involve splitting the sternum to gain access to this location and working
around the great vessels. We recommended a posterolateral approach to
allow for decompression, resection of tumor, and both anterior column and
posterior reconstruction.
C H A P T E R 4 6 Tumors of the oracic Spine
291
A
C
F I G UR E 4 6- 1 A, Sagittal and B, Axial T2-weighted MRI of the thoracic spine demonstrating a T3 lesion with epidural
spinal cord compression. Also of note is a lesion at T7 consistent with a typical hemangioma on all sequences. C, Coronal and
CT scan of the thoracic spine demonstrated a “polka-dot” type lesion at T3 with the appearance of vascular channels. This
lesion was felt to be consistent with an atypical hemangioma.
B
D
intralesional resection of the tumor were performed. Reconstruction
was achieved with an expandable cage placed from T2 to T4 and supplemented with pedicle screw instrumentation extending from T1 to T9. An
intraoperative photo is shown in Figure 46-2. We elected to extend the
construct multiple levels below the site of tumor resection because we did
not want to stop our instrumentation just above or at the site of the apex
of the thoracic kyphosis for fear of inferior construct failure. Bone grafting was performed with allograft and demineralized bone matrix. In the
setting of potential malignant disease affecting the bone marrow and with
spinal tumor surgery in general, we tend to avoid the use of autograft bone
or BMP.
F IG UR E 4 6 -2 Intraoperative photograph demonstrating T2-T4 lami-
nectomies and posterior spinal instrumentation extending from T1-T9.
SURGICAL TECHNIQUE
With the patient in a prone position on the Jackson table with neurological monitoring, T2-T4 laminectomies, T3 costotransversectomy, transpedicular decompression of the spinal canal, and T3 corpectomy with
POSTOPERATIVE COURSE
e patient tolerated the procedure well and spent one night in the neuro
intensive care unit. e patient had no new neurological deficits. Postoperative CT scan demonstrating the cage reconstruction and pedicle
screw instrumentation is shown in Figure 46-3. Pathological analysis
confirmed the tumor to be a hemangioma. e patient was discharged
to rehab and is being followed with serial imaging and clinical evaluation to assess for tumor recurrence. However, given the benign nature of
the histopathology despite aggressive local behavior, it is suspected that
the patient is cured of her disease, and adjuvant therapy has not been
recommended.
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P A R T V I Other Surgical Treatment Modalities: Thoracic Spine
F IG UR E 4 6 -3 Postoperative sagittal CT
scan and lateral scout view showing cage reconstruction of T3 and pedicle screw instrumentation
construct.
Case 2: Anterior Approach
PATIENT PRESENTATION
A 61-year-old male with a history of pheochromocytoma presented with
progressive midthoracic pain. Nineteen years prior to presentation the patient
was diagnosed with a pheochromocytoma and was treated successfully with
left adrenalectomy. Six years prior to presentation the patient developed midthoracic region pain and was treated conservatively with physical therapy and
NSAIDs. e patient developed myelopathic signs and symptoms to include
lower extremity weakness and gait dysfunction. And an MRI of the thoracic
spine disclosed a lesion at T5 with significant epidural spinal cord compression. He was then treated with radiation therapy and his pain and neurological dysfunction improved. Several years following the radiation therapy, the
patient developed worsening and severe midthoracic pain that had a mechanical component to it. Associated symptoms included bilateral thoracic radicular pain and subjective lower extremity weakness. He described dragging his
feet, but denied sphincter dysfunction. On exam he had 4/5 strength of the
iliopsoas and dorsiflexors bilaterally. He was also noted to be hyperreflexic in
his lower extremities. MRI of the thoracic spine (Figure 46-4) showed partial
collapse of the T5 vertebral body with kyphosis and epidural spinal cord compression. T2 signal change was noted in the spinal cord at this level, consistent with myelomalacia. Surgery was recommended, given evidence of spinal
cord compression, clinical myelopathy, anterior vertebral column compromise
and kyphosis. An all-posterior approach with transpedicular corpectomy and
reconstruction of the anterior column was considered. However, it was felt
that an anterior approach would be the best approach to resect the anterior
compressive tumor, correct the kyphosis, and reconstruct the anterior column
without having to perform a multilevel instrumented fusion that would be
required with an all-posterior approach.
SURGICAL TECHNIQUE
Given the history of pheochromocytoma, the patient was seen by endocrinology and anesthesia preoperatively and was premedicated with phenoxybenzaprine for alpha blockade. Pheochromocytomas are highly vascular
tumors and preoperative embolization was also recommended. e right
and left T5 intercostal vessels were entered and the tumor was successfully
embolized with embospheres. A right-sided, high posterolateral thoracotomy approach was selected to allow for access to the anterolateral vertebral
column, because of the prominence of the aortic arch on the left side. e
high posterolateral thoracotomy requires mobilization of the scapula, and
in this case, partial resection of the right 5th rib. A T5 corpectomy was
performed with opening of the posterior longitudinal ligament for complete
decompression of the spinal cord (Figure 46-5). Reconstruction of the anterior column was achieved with a distractible cage and plate. Bone grafting
was performed using allograft bone. Autograft bone was avoided to limit the
rest of metastatic spread of tumor potentially present in the bone marrow
of the adjacent rib.
POSTOPERATIVE COURSE
e patient was observed in the neuro intensive care unit overnight. A chest
tube was placed at the time of surgery and removed 72 hours postoperatively. He remained at his baseline neurological exam. He was discharged
to home, fully ambulatory, on postoperative day number 8. Postoperative
x-rays demonstrated excellent position of the cage and plate (Figure 46-6).
At 1-year follow-up the patient had excellent pain control and stable postoperative imaging.
C H A P T E R 4 6 Tumors of the oracic Spine
T7
293
A
B
F IG U R E 4 6- 4 A, Sagittal and B, Axial MRI of the thoracic spine demonstrating T5 pheochromocytoma with partial
anterior column collapse and epidural spinal cord compression with T2 signal change in the spinal cord.
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P A R T V I Other Surgical Treatment Modalities: Thoracic Spine
F IG UR E 4 6- 5 Intraoperative photograph demonstrating right thoracotomy
approach, T5 corpectomy with decompression of the spinal cord, and reconstruction with
expandable cage and plating from T4-T6.
A
F IG UR E 4 6- 6 Postoperative AP and lateral thoracic spine x-rays demonstrating stable position of the cage and plate.
Case 3: Anterior/-Posterior Combined Approach
PATIENT PRESENTATION
A 52-year-old male with a history of hypertension presented with a 1-year
history of progressive right-sided abdominal and flank region pain. His
pain subsequently progressed to include axial back pain that was most
severe at night when recumbent in bed. A CT scan (Figure 46-7) of the
thoracic spine revealed a lytic/destructive lesion at T9-T10 with associated large paraspinal posterior pleural-based mass on the right side. MRI
(Figure 46-8) disclosed significant epidural extension and spinal cord compression. e patient denied lower extremity sensory changes, weakness,
or bowel or bladder dysfunction. He had no history of systemic cancer.
Neurological exam was significant for 5/5 strength in his lower extremities, and a normal sensory exam except for dermatomal sensory loss in
the right T9-T10 location. He was also noted to have hyperreflexia in his
lower extremities and two to three beats of bilateral ankle clonus. Given
the prolonged history, it was felt that this lesion might represent a relatively slow-growing histopathological entity. Considerations were sarcoma,
B
plasmacytoma/multiple myeloma, and possibly metastatic carcinoma.
Given his preserved motor function, an expedited CT-guided biopsy of
the lesion was recommended. e pathology proved the lesion to be a plasmacytoma/multiple myeloma. Further staging disclosed this to be stage
1A IgG kappa multiple myeloma. Despite the lytic appearance of this
tumor, the patient initially did not have mechanical pain and the anterior
column height was preserved without pathological fracture or deformity.
Given the high radiation sensitivity of multiple myeloma, radiation therapy
was recommended with close follow-up. e patient failed to respond to
radiation therapy and developed mild gait dysfunction. Surgical resection
was recommended. e lack of response to radiation called into question
the diagnosis of multiple myeloma. Concomitant thoracotomy and posterior approach was planned. In any situation when an anterior approach
is planned and a greater than 1 level corpectomy is performed, we recommend supplemental posterior stabilization. In this case, we felt as well that
a combined posterior approach would also assist with the tumor resection
and decompression.