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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6032_Библиотеки_им_академика_М_И_Перельмана
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Figure 3
emphasized the benefit of excellent visualization provided by the greater
lateral exposure and reported excellent neurologic improvement but a not
insignificant risk of pulmonary complications.
30
Schematic drawings showing thoracic disk removal from a
posterolateral transpedicular approach. A, The medial
facet, transverse process, and pedicle of the caudal level are
removed. B, The disk is entered laterally. C, The central disk space is
cleared using a pituitary rongeur. D, The herniated disk is pushed
anteriorly away from the spinal cord and into the cavity at the center of
the disk space, using a reverse-angled curet. (Reproduced from
Gebhauer G, Vaccaro A: Thoracic disk herniation and stenosis, in Rao
RD, Smuck M, eds: Orthopaedic Knowledge Update Spine 4.
Rosemont, IL, American Academy of Orthopaedic Surgeons, 2012, pp
324-328.)
Posterior minimally invasive techniques also have been described in the
thoracic spine. A tubular retractor system mounted to the operating table is
introduced with minimal soft-tissue retraction and docked in a paraspinal
location. Minimal bone resection of the lateral portion of the facet to expose
the exiting nerve root is performed. The disk space is accessed just caudal to
the nerve, which allows partial diskectomy with minimal dural retraction.
Effective, safe use has been reported in a small series of patients undergoing
minimally invasive thoracic diskectomy.
31
The role of adjunctive spine fusion with thoracic diskectomy is
controversial. When segmental instability exists, an instrumented fusion is
indicated if excessive kyphosis is anticipated or if bilateral facetectomies are
performed. In particular, fusion should be considered when substantial
facetectomies are performed in the more mobile regions of the lower thoracic
spine below the T8 level. Pedicle screw fixation has been performed in one
small series, and high rates of fusion and minimal complication rates were
reported.27 Although the need for concomitant fusion in patients undergoing
limited facet resections continues to be debated, adjunctive fusion appears to
be indicated when removal of the entire facet is necessary. Surgical exposure
should not be compromised by limited facet removal to avoid instability. An
analysis of 13,837 patients who underwent thoracic disk surgery from 2000
to 2010 reported a dramatic shift in surgical trends: almost one-half of
patients underwent accompanying instrumented fusion, compared with the
prior decade in which two-thirds of all procedures involved disk excision
only.32 Such a substantial shift in surgical practice may reflect greater
familiarity with the use of thoracic pedicle screw instrumentation as well as
the presumed collective belief among spine surgeons that stability is essential
for better clinical outcomes following thoracic diskectomies.32 To date, no
studies to compare thoracic disk surgery performed with and without fusion
have been published. Several small observational studies have reported that
instrumented fusion reduces postoperative instability and diminishes the
potential of axial back pain.
33,34
Specifically, interbody fusion has been
proposed to provide additional stability when bilateral facetectomies are
necessary to treat large central disk herniations.35 Transforaminal interbody
fusions with posterior instrumentation and either structural allograft or
autograft have been reported to be safe and effective, with high fusion rates
and minimal adverse neurologic events.
24,35,36
Comparative Studies
Because thoracic disk disease is relatively uncommon, no large prospective
or randomized studies have evaluated various surgical approaches or
techniques. Generally, the relevant literature consists of nonrandomized
outcome studies that compare distinct surgical approaches (anterior versus
posterior; open versus minimally invasive) or related techniques with various
modifications (transpedicular versus pedicle-sparing approach;
costotransversectomy versus LECA).
In a comprehensive evaluation of more than 25,000 patients from the
Nationwide Inpatient Sample, anterior approaches were associated with
longer hospitalization times, greater cost, and higher mortality rates
(primarily a result of pulmonary problems).37 One study evaluated four
techniques (transthoracic, lateral extracavitary, transpedicular, and transfacet
pedicle-sparing approaches) used to treat large calcified disk herniations and
noted equivalent symptomatic improvement and restoration of neurologic
function, but greater morbidity with the open transthoracic approach,
although this did not adversely affect the ultimate outcome.25 This study is
representative of most pertinent literature because it is retrospective, it
compares cohorts of wide-ranging numbers of patients, and the selection
criteria for the surgical techniques used are unclear. Although open
thoracotomy appears to have a predictably higher complication rate, less
invasive anterior techniques seem to mitigate this without compromising
efficacy. A 2014 study compared the use of mini-open transthoracic
diskectomy for large calcified central herniations with transpedicular
diskectomy for lateral herniations and found that duration of surgery, surgical
blood loss, incidence of complications, and length of hospital stay were
greater with the anterior approach, but both approaches had a similar
likelihood for successful clinical outcomes.20 A 2007 study compared minithoracotomy and thoracoscopic techniques for central disk herniations and
found no significant difference in surgical duration, perioperative
complication rate, or ultimate clinical outcome, although the thoracoscopic
technique was noted to have a higher learning curve.38 A 2005 study on giant
densely calcified herniations reported superior results and fewer neurologic
complications with open thoracotomy compared with thoracoscopy, because
of the ability to leverage large calcified fragments with an open approach that
would not have been safely possible thoracoscopically.9 The literature is
scarce in comparisons of the different posterolateral approaches. A
retrospective study of small, unequal cohorts who underwent a
costotransversectomy, LECA, transpedicular approach, or transfacet
approach noted no difference in clinical outcome, neurologic improvement,
or complication rate.34 When surgeons are inexperienced with an anterior
approach, posterolateral approaches are safe and effective. A 2012 study
compared the LECA with costotransversectomy and found longer surgical
times and greater blood loss with the more extensive ventral exposure of the
LECA, but no difference was noted in clinical outcome or frequency of
complications.29 Another study found that the reported rates of morbidity and
mortality associated with transpedicular approach, costotransversectomy, and
LECA are virtually identical.39 Given the array of techniques available, highquality prospective studies are needed to better evaluate the true efficacy and
best indications for each surgical approach.
Thoracic Spinal Stenosis
Thoracic spinal stenosis is much less common than either cervical or lumbar
stenosis. However, thoracic spinal stenosis can cause disabling symptoms and
severe neurologic dysfunction. Most frequently, stenosis results from
degenerative changes of the intervertebral disk and facet joints along with
ligamentum flavum hypertrophy. Ossification of the posterior longitudinal
ligament or ossification of the ligamentum flavum also can result in thoracic
spinal stenosis. Although rare, when ossifications of the posterior
longitudinal ligament and of the ligamentum flavum coexist, severe stenosis
and spinal cord compression result. Other conditions in which thoracic spinal
stenosis can manifest include Scheuermann kyphosis, Paget disease,
achondroplasia, and diffuse idiopathic skeletal hyperostosis. Thoracic spinal
stenosis affects men predominantly, especially after the sixth decade. As with
disk herniations, thoracic spinal stenosis occurs more frequently below the T8
level. Patients with symptomatic thoracic stenosis are more likely to have
concomitant cervical or lumbar stenosis.40 Such scenarios can create
diagnostic challenges, particularly when prominent symptoms of lumbar
radiculopathy or neurogenic claudication obscure more subtle features of
thoracic myelopathy.
As with thoracic disk herniation, the clinical presentation of thoracic
spinal stenosis varies and can consist of individual or combined features of
axial back pain, radiculopathy, or myelopathy. The diagnosis is made with
advanced imaging, either MRI or CT myelography. These advanced imaging
modalities should include the entire thoracic spine because spinal cord
compression can occur at multiple, potentially noncontiguous levels. Patients
with predominant symptoms of back pain or radiculopathy are best treated
nonsurgically with exercise, analgesic medications, and nerve-modifying
agents such as gabapentin or pregabalin. Epidural steroid injections should
not be considered if evidence of spinal cord compression exists. Patients with
mild, static myelopathy can be monitored with close clinical surveillance for
any neurologic deterioration. Patient education should be provided. For
advanced cases of myelopathy, surgery is the treatment of choice.
Decompression laminectomy is the preferred surgery for symptomatic
thoracic spinal stenosis. All levels with substantial stenosis and spinal cord
compression should be treated. Because of the tenuous nature of the
compressed thoracic spinal cord, spinal cord monitoring is recommended,
and baseline signals should be obtained before the patient is positioned for
surgery. As with thoracic disk surgery, preoperative imaging of the thoracic
spine should include reference points such as the sacrum or cervicothoracic
junction to enable accurate intraoperative radiographic localization. Surgery
is performed with the patient in the prone position. A midline approach is
used with subperiosteal dissection of the levels intended for decompression.
If no fusion is planned, care should be taken to minimize disruption of the
facet joints during exposure. Laminectomy is performed with a high-speed
burr, creating a trough at the junction of the lamina and facet joint down to
the level of the ventral cortex. The laminectomy is completed with Kerrison
microrongeurs (1 or 2 mm), which also can be used to remove the
ligamentum flavum. The lamina can be elevated and removed en bloc. Great
care should be taken to avoid unnecessary tension on the dural sac or any
excessive manipulation of instruments within the spinal canal.
When ossification of the ligamentum flavum is present, particular
attention should be given to avoid forceful removal, which can result in
durotomies. Alternatively, if the calcified ligamentum is determined to be
completely incorporated with the dura, direct resection of that portion of the
ligamentum should be avoided. Adherent or incorporated areas of
ligamentum can be decompressed at the periphery in a circumferential
fashion and left as an island to float dorsally with the surrounding
decompressed dura.
Small series of patients undergoing laminectomy alone for thoracic spinal
stenosis with myelopathy have had generally good results: 80% to 90% of
patients noted some degree of symptomatic relief and neurologic
improvement.
41,42
Partial medial facetectomy may be necessary to allow
thorough posterior decompression, although this will result in increased
segmental motion by up to 30%.43 Resection of greater than 50% of the
surface area of the facet complex at a segment will markedly increase the
potential for instability and requires instrumented fusion. Adjunctive spinal
fusion is recommended when excessive resection of the facet joint complex is
necessary or when multiple-level laminectomies are performed in patients
with excessive kyphosis or preoperative instability. The stability provided by
instrumented fusion is theorized to provide neural protection by decreasing
the propensity for further kyphosis following laminectomy and the draping of
the spinal cord that would result. No prospective randomized studies have
compared laminectomy alone and laminectomy with fusion in the treatment
of thoracic stenosis; however, relief of axial back pain and favorable
neurologic outcomes have been reported following decompression
laminectomy and instrumented fusion.44 To provide additional interbody
support, transforaminal lumbar interbody fusion has been described in a small
series to achieve predictable positive outcomes and minimal morbidity,
despite the more extensive approach and the need to work ventral to the
spinal cord.45 Transforaminal lumbar interbody fusion has the potential for
better correction of kyphosis, greater stability, and increased likelihood of
solid arthrodesis.
The use of spinal monitoring accurately identifies adverse neurologic
events in thoracic stenosis surgery, especially when both somatosensoryevoked and motor-evoked potential monitoring are used.46 Cerebrospinal
fluid leaks are not infrequent, especially when ossified ligamentum flavum is
present. Small linear defects can be repaired primarily. The extent of the
durotomy must be accurately defined and the edges freed of any remaining
bone to allow accurate approximation and repair. When a large, complex
dural defect occurs, closure with a patch graft is indicated. A fascial
autograft, allograft, or synthetic patch can be used and secured with
interrupted sutures around the entire periphery. Adjunctive sealing with fibrin
glue can be used to supplement the repair. Diversion of cerebrospinal fluid
using an intrathecal drain can reduce the likelihood for recurrent leak, but is
associated with a small risk of infection.
Summary
Thoracic disk herniation and thoracic spinal stenosis are relatively
uncommon, largely because of the relative stability of the thoracic spinal
column. However, both herniation and spinal stenosis can cause severe
symptoms and neurologic dysfunction. A high degree of clinical suspicion
often is necessary because pain may not be an obvious symptom and
myelopathic features can progress slowly. In addition, symptoms related to
coexistent lumbar or cervical stenosis can obscure those related to thoracic
pathology. The presence of thoracic back pain and any objective or subjective
features of myelopathy warrant advanced imaging. Surgical intervention is
indicated for most cases of myelopathy and when radiculopathy and back
pain have not improved with nonsurgical management. With the appropriate
surgical approach, careful correlation of preoperative and intraoperative
imaging for accurate localization, and skillful technique, surgery can be
predictably safe and effective. For disk herniation, the size, location, and
presence of any calcification determines which approach is most suitable,
along with the patient’s general health, particularly any pulmonary
compromise that would make an anterior approach less favorable. Both
anterior and posterior minimally invasive techniques provide the potential
benefit of less soft-tissue compromise and more rapid recovery, although no
prospective comparative studies exist. For stenosis, a decompression
laminectomy is appropriate, and instrumented fusion may be indicated.
Key Study Points
Thoracic disk herniations and spinal stenosis are relatively uncommon
compared with degenerative disease in the cervical and thoracic spine.
The inherent stability of the thoracic spine is largely provided by
articulation with the rib cage; this results in substantially less clinically
relevant neural compression than elsewhere in the spinal column.
A high index of suspicion is necessary to diagnose thoracic pathology
because coexistent neural compression in the cervical or lumbar spine
often exists.
Careful preoperative planning and meticulous technique are essential to
ensure successful surgical outcomes and minimize adverse events.
Various surgical techniques can be used effectively. The appropriate
surgical strategy is based on the location of the neural compression, the
patient’s clinical presentation, and the surgeon’s experience.
Annotated References
1. Bajwa NS, Toy JO, Ahn NU: Establishment of parameters for congenital thoracic
stenosis: A study of 700 postmortem specimens. Clin Orthop Relat Res
2012;470(11):3195-3201.
In this study, 700 cadaver spines were evaluated. Congenital thoracic stenosis was
defined as a sagittal plane diameter less than 15 mm or an interpedicle distance less than
18.5 mm.
2. Bajwa NS, Toy JO, Ahn NU: Is lumbar stenosis associated with thoracic stenosis? A
study of 1,072 human cadaveric specimens. Spine J 2012;12(12):1142-1146.
Of 1,072 cadaver spines that were evaluated, concurrent lumbar and thoracic stenosis
had a prevalence of 1.42%.
3. Wood KB, Blair JM, Aepple DM, et al: The natural history of asymptomatic thoracic
disc herniations. Spine (Phila Pa 1976) 1997;22(5):525-529, discussion 529-530.
4. Arce CA, Dohrmann GJ: Herniated thoracic disks. Neurol Clin 1985;3(2):383-392.
5. Stillerman CB, Weiss MH: Management of thoracic disc disease. Clin Neurosurg
1992;38:325-352.
6. Brown CW, Deffer PA Jr, Akmakjian J, Donaldson DH, Brugman JL: The natural
history of thoracic disc herniation. Spine (Phila Pa 1976) 1992;17(6suppl):S97-S102.
7. Ayhan S, Nelson C, Gok B, et al: Transthoracic surgical treatment for centrally located
thoracic disc herniations presenting with myelopathy: A 5-year institutional experience.
J Spinal Disord Tech 2010;23(2):79-88.
8. Bohlman HH, Zdeblick TA: Anterior excision of herniated thoracic discs. J Bone Joint
Surg Am 1988;70(7):1038-1047.
9. Hott JS, Feiz-Erfan I, Kenny K, Dickman CA: Surgical management of giant herniated
thoracic discs: Analysis of 20 cases. J Neurosurg Spine 2005;3(3):191-197.
thoracic disc herniations: Considerations and treatment strategies. Eur Spine J
2014;23(suppl 1):S76-S83.
In this study, 13 patients with giant calcified thoracic disk herniations underwent
transthoracic diskectomy (6 of whom also underwent interbody fusion): 77% improved
at least one Frankel grade and there were 4 complications (3 durotomies and 1 recurrent
herniation). Level of evidence: IV.
treatment of calcified giant herniated thoracic discs. Eur Spine J 2013;22(11):2466-
2473.
In this study, 15 patients with central or lateral thoracic disk herniations underwent
transthoracic decompression and interbody fusion. All patients reported symptomatic
improvement, 12 had neurologic improvement, and a low rate of complications was
noted. Level of evidence: IV.
for the treatment of giant thoracic disc herniation. Spine (Phila Pa 1976)
2012;37(17):E1079-E1084.
In this study, 17 patients with myelopathy underwent mini-open retropleural
transthoracic diskectomy without rib resection. Of these, 13 had neurologic
improvement of one or more Frankel grade, 3 had no neurologic improvement, and 1
patient died postoperatively of pneumonia.
symptomatic thoracic disc herniation: Initial multicenter clinical experience. J
Neurosurg Spine 2012;16(3):264-279.
In this study, 60 patients in five different centers underwent a mini-open lateral
approach in which a blade retractor was introduced in a retropleural fashion and docked
to the spine: 80% had an excellent result, with relief of myelopathy, radiculopathy, axial
back pain, and bowel and/or bladder dysfunction. Major complications occurred in
6.7% of cases.
transthoracic transpleural approach: A novel technique for thoracic disc herniation. A
review of the literature, description of a new surgical technique and experience with
first 12 consecutive patients. J Spinal Disord Tech 2011;24(5):E40-E48.
In this study, 12 patients underwent successful single-level anterior thoracic diskectomy
and instrumented fusion with a minimally invasive tubular system. Approach-related
morbidity was limited. Level of evidence: IV.
discussion 262-263.
The authors present a critique of mini-open lateral thoracic diskectomy with a blade
retraction system, with comments about increasing the surgical distance and limiting the
working angles when using a tubular system in the thoracic spine.
discectomy. J Clin Neurosci 2015;22(11):1708-1713.
This meta-analysis reviewed 545 surgical patients from 12 articles on thoracoscopic
diskectomy. Complete resolution of symptoms occurred in 79%, partial improvement in
10%, no change in 10%, and worsening in 1%. The overall complication rate was 24%.
Clinical presentation, neuroimaging findings, surgical considerations, and outcome. J
Neurosurg Spine 2011;14(4):520-528.
In this study, eight patients with acute myelopathy resulting from thoracic disk
herniation underwent thoracoscopic microdiskectomy. Each patient improved at least
one Frankel grade and all regained both continence and the ability to ambulate; four
transient, mild complications occurred. Level of evidence: IV.
herniated thoracic discs: Clinical results in 121 patients. Spine (Phila Pa 1976)
2012;37(1):35-40.
In this study, 121 patients underwent thoracoscopically assisted thoracic diskectomy
during a 15-year period. Improvement or resolution of myelopathy, radiculopathy, and
axial back pain improved at rates of 91%, 97%, 86%, respectively; 97% of patients
were willing to undergo surgery again. Complication rates were low and acceptable.
Level of evidence: IV.
thoracoscopic spine surgery: The second generation. Neurosurg Focus 2014;36(3):E8.
Video-assisted thoracoscopic surgery was used in conjunction with image-guided
surgical techniques to effectively treat eight patients with thoracic disk herniations.
Level of evidence: IV.
comparative cohort of mini-transthoracic versus transpedicular discectomies. Spine J
2014;14(8):1654-1662.
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