Costotransversectomy and Lateral Extracavitary Approach

Illustrative Case

A 47-year-old woman with metastatic breast cancer presenting with severe thoracic back pain and myelopathy (Figures 15-1 and 15-2).

Figure 15-1 ▪ Sagittal computed tomography image, demonstrating lytic destructive lesion of the T2 and T3 vertebral bodies with segmental kyphosis.

Figure 15-2 ▪ Sagittal T2-weighted magnetic resonance image, demonstrating destructive lesion of the T2 and T3 vertebral bodies with dorsal extension into the spinal canal and focal kyphosis resulting in ventral cord compression.

Radiologic Assessment

Carefully assess preoperative imaging for sites of pathology to confirm adequacy of working channel and visualization via posterior-only approach
Measure approximate lengths and sizes of planned instrumentation
Review preoperative plain films carefully to establish vertebral level nomenclature for intraoperative localization
Assess bone stock available for fixation and/or reconstruction
- Pedicles available for screw fixation
- Endplate involvement if planning anterior column reconstruction
Consider preoperative angiography to assess for vascularity of lesion and presence of artery of Adamkiewicz within planned surgical field. Preoperative embolization may be used in the setting of suspected highly vascular lesions. If Adamkiewicz arises from the involved segment, we avoid any surgical approach that might injure it in order to avoid incurring cord ischemia.

Positioning

May position prone with Mayfield head holder if crossing cervicothoracic junction, or on the prone Jackson table for thoracolumbar exposure.
- If planning to use polymethylmethacrylate (PMMA) cement for vertebral body augmentation, ensure that patient is positioned such that operative level(s) are horizontal for level cement distribution.
Ensure posterior iliac crest is prepped and draped if harvesting autograft

Anesthesia/Neuromonitoring Concerns

Mean arterial pressure goal >80 mm Hg in setting of myelopathy or during planned deformity correction
Total intravenous anesthesia in setting of motor-evoked potential monitoring

Localization of Incision

Midline incision centered over spinous processes
- Extend skin incision cranially and caudally approximately three levels to allow for lateral retraction and visualization
Ensure same counting nomenclature is used between preoperative and intraoperative imaging for localization of thoracic levels. This is clearly of greater importance when treating lesions that are not obvious on plain x-ray.

Approach

Standard posterior thoracolumbar approach with midline incision out to the transverse processes
- Greater lateral dissection is needed than for a typical thoracolumbar fusion in order to gain posterolateral access to the vertebral body, disks, and ventral aspect of the spinal canal. This is facilitated by a longer incision and further lateral dissection out to the rib(s) of the level(s) undergoing corpectomy.
- Ensure that interspinous ligaments and facet capsules remain intact between and cranial-adjacent level to lower risk of proximal junction kyphosis.

Extent of lateral soft-tissue dissection varies depending on planned bony resection and working corridor needed (Figure 15-3).

Figure 15-3 ▪ A, B, Costotransversectomy and the lateral extracavitary approach are similar. The lateral extracavitary surgical approach requires further lateral dissection, which in turn, allows for greater access to the contralateral vertebral body. The line of sight is therefore more oblique, allowing for greater visualization of the vertebral body and ventral aspect of the canal.

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