Surgical treatment of thoracic ossification of the posterior longitudinal ligament: Intraoperative spinal cord monitoring

Abstract

Introduction Myelopathy caused by Ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine cannot be treated adequately by conservative therapy and therefore demands surgical intervention. However, surgical outcomes reported to date have not been satisfactory [1-12], and effective surgical procedures for this disease have still to be established. One reason for the poor surgical outcomes is the presence of physiological kyphosis in the thoracic spine, which does not exist in the cervical or lumbar spine and which may compromise the effects of spinal cord decompression via a posterior approach. In addition, anterior approaches are technically challenging because: (1) adhesion of the dura mater to ossifi ed ligaments may hamper surgical manipulations; (2) median sternotomy is required for an approach to the upper thoracic spine, in which visualization of the surgical fi eld [3-7] is limited; and (3) mid or lower thoracic spinal surgery requires an anterolateral approach involving rib resection [9,12]. We have recently reported four cases of neurological deterioration after an operation for thoracic OPLL, all of which exhibited a sharply protruding, segmental form of Ossification [1,2]. When severe spinal cord compression is present as a result of adhesion of the ossifi ed yellow ligament to the dura mater or Ossification of the dura mater itself, laminectomy can easily compromise the vulnerable spinal cord. Laminectomy may also augment thoracic kyphosis, which causes spinal cord injury. This report describes a method of intraoperative spinal cord monitoring during posterior decompression surgery for thoracic OPLL performed to avoid spinal cord injury, the most serious complication associated with these surgical procedures for thoracic OPLL. © Springer 2006.