The transpedicular or posterolateral spinal approach is indicated for broad, ventral compressive etiologies of the thoracic spinal cord, discitis with epidural abscess, calcified or non-calcified degenerative disk disease, metastatic epidural spinal cord compression, nerve sheath tumors, meningiomas, traumatic burst fractures, and less commonly, primary bone tumors.
Many of the lesions requiring circumferential spinal cord decompression present with either the slow or gradual onset of thoracic myelopathy. In the case of lesions causing direct compression without bony involvement, the decline tends to be more gradual, although in a compressive pyogenic abscess without bony involvement, a rapid decline can be observed. In lesions causing bony destruction such as osteodiscitis, or neoplasms involving bone in the thoracic spine, the abrupt onset of significant motor and sensory deficits preceded by a long period of axial and mechanical back pain is not altogether uncommon.
A standard motor and sensory examination to assess the neurologic level of injury is called for, as well as an assessment of myelopathic findings.
CT and MRI are the mainstays for evaluation. A CT is vital in planning the corridors of approach and assessment of the bone quality for stabilization, as well as for planning ventral column support after resection. An MRI is important for determining levels of central canal and neural foraminal compromise.
Alternative corridors for circumferential spinal cord decompression can be provided via a posterior laminectomy followed by ventral decompression with a lateral transthoracic approach. Not all patients are able to medically tolerate the morbidity of a lateral transthoracic surgery, especially those with pre-existing pulmonary diseases. For those, a posterolateral approach, either with transpedicular, costotransversectomy, or lateral extracavity, retropleural serve as a means to provide decompression and stabilization simultaneously.
Total intravenous anesthesia is commonly utilized with the use of a short-acting intravenous narcotic as well as a short-acting hypnotic (diprivan).This facilitates the use of neuromonitoring throughout the case with motor evoked potentials, somatosensory evoked potentials, and stimulus-evoked electromyography.
Expected postoperative stay will total approximately a week and significantly varies depending on the neurologic status and comorbidities.
Damage to the great vessels is the most feared of all complications when providing circumferential decompression, prompting urgent cardiothoracic surgery consultation. Thoracic fixation should be measured with the consideration that malpositioned screws could potentially injure a vessel and cause fatal neurologic injury. Similarly, transgression of the neural foramina or spinal canal with a screw can cause neurologic deficit or persistent radiculopathy.
In the case of infection or neoplasm, the parietal pleura can lose its plane and provide a risk for pneumothorax or hemothorax. Repeated passing of surgical instruments through a narrow injury by the spinal cord and exiting thoracic nerve root make direct injury to the spinal cord one of the more common and feared complications, as they carry the potential for paralysis. Furthermore, durotomy may occur, even without neurologic injury. In this case, these dural injuries can be managed with a primary repair with or without lumbar drain placement.
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