Indications
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Costotransversectomy provides a posterolaterally directed corridor of access to the costovertebral joints, lateral spinal canal, and neural foramina and to a portion of the posterolateral vertebral body located from T1-12.
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Lateral or paracentral soft disk herniations
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Epidural or bony tumor debulking or removal
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Thoracic sympathectomy
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Osteomyelitis or diskitis with or without abscess
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Canal decompression for trauma
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Epidural metastasis in which palliation rather than en bloc resection is the goal
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Intractable costovertebral joint pain associated with ankylosing spondylitis
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Need for a thoracic approach with a relatively low rate of pulmonary and vascular morbidities
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Contraindications
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Anatomically, access to the midline anterior dura, epidural space, and vertebral body is most constrained; however, soft or suckable pathologies near the midline may be more readily resected in some cases, even with indirect visualization.
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Midline disk herniations (or traumatic bone fragments) via this approach—for calcified disks, including paracentral locations, an alternative approach is mandated for similar reasons.
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When spondylectomy or en bloc resection are required based on the pathology, imaging, and clinical picture.
Planning and positioning
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Planning begins with a thorough review of the patient’s presenting neurologic symptoms, medical comorbidities, and imaging. Axial views on magnetic resonance imaging (MRI) or computed tomography (CT) are especially informative in selecting among alternative operative approaches. Myelography is particularly helpful in defining osteophytes from soft disks. For tumors, T2-weighted, fat-suppressed short tau inversion recovery (STIR) and contrasted T1 MRI sequences are useful for identifying bony infiltration. CT can additionally differentiate sclerotic from lytic lesions. Sagittal and coronal alignment of the spine can be assessed with plain x-rays.
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The key issue determining selection of an approach is the ability to visualize the lesion of interest without retraction on the already deformed spinal cord. Increased neurologic deterioration or paraplegia can occur from additional traction on an already compromised spinal cord. Preoperative imaging requires careful review, paying particular attention to the lesion of interest and its relationship to the midline, dura, disk space, pedicle, and nerve roots.
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Various patient positions accommodating numerous modifications have been described for the costotransversectomy procedure. Generally, we favor the prone position over semiprone or lateral decubitus alternatives. With the patient tightly secured to the frame, bed rotation in combination with the degree of freedom provided by the operating microscope can typically provide adequate posterolateral visualization. The patient may be secured on a Wilson frame or gel rolls, but we typically prefer a rotating Jackson table with the arms extended upward to facilitate ease of fluoroscopy or navigation-based instrumentation. Attention to the padding of bony prominences and sites of potential neurovascular compression is essential.
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Baseline prepositioning, postpositioning, and intraoperative somatosensory and motor evoked potential monitoring is recommended in all cases.
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A common pitfall for thoracic surgery is accurate localization, and this requires careful attention to anatomy and fluoroscopic technique. Intraoperative localization usually employs fluoroscopy to count up from L5 or the last rib (assuming this is T12). This strategy can result in error. A preoperative x-ray of the whole spine should be reviewed to identify the last visualized rib and as a reference during surgery. Intraoperative confirmation of the operative level by multiple techniques in anteroposterior and lateral planes is recommended. Anatomically numbered ribs articulate with the disk space above the correspondingly numbered vertebral body. In the lowest segments of the thoracic spine, rib articulations can be found below the level of the corresponding disk space. Preoperative localization in radiology using fluoroscopy or CT can limit the chance of operating on the wrong level. We have asked the radiologist to place a localization coil or small amount of cement in the pedicle caudal to the targeted disk space.
Figure 66-1:
Axial views of typical thoracic vertebral body. Shaded areas correspond to approach-specific zones of bony decompression and surgical access. Arrows delineate the angle of approach but not location of the skin incision. Correlation with preoperative axial MRI and CT is necessary for preoperative planning. A, Laminectomy. Access to the vertebral body and anterior dura is precluded by excessive cord manipulation. B, Transpedicular or lateral gutter approach. Bony removal of the facet and pedicle to the level of the posterior vertebral body cortex facilitates the most limited access to the lateral disk, canal, and vertebral body pathology. C, Costotransversectomy. Disarticulation and removal of the proximal 3 to 5 cm of ribs allows greater visualization of the lateral vertebral body, disk space, and neural foramen. Anterior decompression is limited to the midline. D, Lateral extracavitary approach. Additional 5 to 7 cm of lateral rib removal and downward pleural retraction allows for greater exposure and a more lateral angle of entry, which translates into improved anterior decompression across the midline. E, Transthoracic approach. The greatest degree of access to the vertebral body is afforded through the thoracic cavity, providing access to decompress the entire anterior canal if needed. Posterior elements cannot be addressed from this approach.
Figure 66-2:
Posterolateral anatomic ( A ) and anteroposterior and lateral radiographic ( B ) views of mid-thoracic spine. The anatomic view depicts the relationship of the numbered rib head to corresponding disk space. Note the relationships of the sympathetic chain, rib head, transverse process, nerve root, and pedicle. The rib head and disk space are outlined and numbered again on radiographic views. Proper adjustment of fluoroscope to align the pedicles and end-plates is necessary to avoid errors in localization because of parallax.
