Thoracic disc herniation and acute myelopathy: clinical presentation, neuroimaging findings, surgical considerations, and outcome.

OBJECT: Thoracic disc herniations (TDHs) may occasionally present with an acute myelopathy, defined as a variable degree of motor, sensory, and sphincter disturbances developing in less than 24 hours, and resulting in a Frankel Grade C or worse. Confronted with such a patient, the surgeon has to decide whether to perform an emergency operation and whether to use an anterior or posterior approach. The authors analyze their own experience and the pertinent literature, focusing on clinical presentation, imaging findings, surgical timing, technique, and outcome.
METHODS: Among 250 patients who underwent surgery for symptomatic TDH, 209 had at least 1 year of follow-up at the time of writing, including 8 patients who presented with an acute myelopathy. They were surgically treated using standard thoracoscopic microdiscectomy, careful blood pressure monitoring, and intravenous methylprednisolone. The authors analyzed pre- and postoperative neuroimaging, and Frankel scores preoperatively, at discharge, and 1 year postoperatively.
RESULTS: Although 5 patients had multiple TDHs, the symptomatic TDH was invariably situated between T9-10 and T11-12. Seven TDHs were giant, 6 were calcified, 6 were accompanied by myelomalacia, and 4 were accompanied by segmental stenosis. Although sudden dorsalgia was the initial symptom in 6, a precipitating event was noted in only 1. All patients had severe neurological deficits by the time they underwent surgery. Frankel grades improved from B to D in 2 patients, from C to E in 4, and from C to D and B to E in 1 patient each. All patients regained continence and ambulation. Transient complications were CSF leak (in 2 patients), and intraoperative blood loss greater than 1000 ml, reversible ischemic neurological deficit, and subileus (in 1 patient each).
CONCLUSIONS: Approximately 4% of TDHs present with an acute myelopathy. They are often situated between T9-10 and T11-12, large or giant, and even calcified. They almost invariably cause important cord compression (sometimes aggravated by an associated segmental stenosis) and myelomalacia. Their clinical presentation may be misleading, and diagnosis may be delayed until other causes (especially vascular) have been excluded and the clinical picture has become more complete. Interestingly, whereas a precipitating event or trauma is rarely present, dorsalgia frequently precedes profound myelopathy and may help to make an early diagnosis. Remarkable recovery is possible even with profound neurological deficit, a delay of several days, in the elderly, and in the presence of myelomalacia, provided the spinal cord is adequately decompressed and intraoperative hypotension is strictly avoided. Although alternative approaches more familiar to most neurosurgeons may be used, the anterior transthoracic approach has the advantage of reaching the TDH in front of the compromised spinal cord, avoiding any manipulation. In experienced hands, thoracoscopic microdiscectomy combines the advantage and versatility of an anterior approach with minimal postoperative discomfort. The authors conclude that TDH-related acute myelopathy may have a favorable outcome when managed correctly, and they strongly recommend that every single patient should undergo surgical treatment.