Minimally invasive thoracic microendoscopic diskectomy: a tool for all surgeons?

One of the most common pathologic conditions encountered by spine surgeons is a herniated nucleus pulposus. The incidence of symptomatic thoracic disk herniations is <1%. The relative mobility and range of motion about the ventrally located instantaneous axis of rotation partially accounts for the frequency of herniations in the lumbar and cervical spine. The thoracic spine is comparatively immobile with the sternum and rib cage providing substantial structural support, with a commensurate restriction of motion. Paraspinal muscles also contribute to diminished mobility, whereas the natural kyphosis of the thoracic spine limits the incidence of dorsal disk and annulus bulging. The structures that provide such immobilization making herniated nucleus pulposus less common in the thoracic region also serve as a barrier, of sorts, to the surgeon for surgical intervention. The transthoracic, transthoracic extrapleural, costotransversectomy, and dorsal approaches all are associated with significant drawbacks from an exposure and technical perspective. None of these approaches can be universally employed, and each is associated with approach-specific obstacles. The location, laterality, and characteristics of a disk herniation play a key role in the surgical decision-making process. A central calcified disk is better addressed through a ventral or far lateral approach, whereas a soft lateral disk herniation may be better managed via a dorsolateral approach. Patient presentation may vary, depending on the location and magnitude of the herniation. For far lateral disk herniations, radicular pain may be the presenting complaint. An acute central disk herniation may cause rapid onset of myelopathy. Upper thoracic to midthoracic disk herniations may cause a deep chest pain that can be mistaken for cardiac pain. Midthoracic to lower thoracic disk herniations may masquerade as renal colic or gastrointestinal pain. The ultimate key to the decision-making process is careful physical examination in conjunction with obtaining appropriate imaging studies.