Microsurgery for Spinal Stenosis

Abstract & Commentary

Source: Guiot BH, et al. Spine. 2002;27:432-438.

Can microsurgery satisfactorily address lumbar spinal stenosis? Microendoscopic decompressive laminotomy (MEDL) was compared to standard procedures in this cadaver study to determine if MEDL provides comparable and adequate decompression.

Laminae 1 through 4 of 4 cadavers were subjected to 4 surgical procedures, totaling 16 operations. Each level underwent each procedure. These included a) unilateral MEDL, with angulation of the endoscope to achieve contralateral decompression; b) bilateral MEDL, with 2 separate paramedian incisions; c) unilateral open laminotomy, ipsilateral medial facetectomy, and foraminotomy, with a midline incision for bilateral decompression; and d) bilateral open laminotomy, similar to (c) but with bilateral laminotomy. Computerized tomographic imaging of the spine was performed before and after each procedure and measurements of midsagittal diameters, interpedicular distances, and decompression diameters were taken for comparison. Student’s t test and 2 ´ 2 analysis of variance provided statistical analysis.

All 4 procedures were comparable in achieving satisfactory decompression and all techniques visualized exiting nerve roots equally well. Complications included ipsilateral facet complex disruption (n = 2) and dural tear (n = 1) and were independent of the approach used. Although technically demanding for the surgeon, MEDL appears promising and clinical trials are required (and underway) to determine its true benefit.

Commentary

Rarely, spinal stenosis may involve the thoracic spine. Among 28 such consecutive cases seen over 10 years, most (86%) presented with paraparesis and most (61%) were of insidious onset (Chang UK, et al. Spinal Cord. 2001;39:362-369). Lower thoracic segments (T9-T12) were most often involved (54%), followed by middle (25%) and upper (21%) segments. Ligamentum flavum ossification (64%), facet hypertrophy (46%), posterior longitudinal ligament hypertrophy (22%), and ventral spur or disc protrusion (14%) were causative. Surgery, either anterior or posterior decompression, or both, was beneficial in 79%. Two patients with longstanding deficits did not change, with 4 patients deteriorating following surgery. Thoracic spinal stenosis with myelopathy responds to decompression, with results conditional on symptom duration, adequate decompression, and presence of additional proximal stenosis. Microendoscopic decompressive laminotomy may be applicable to this situation as well. —Michael Rubin

Dr. Rubin, Professor of Clinical Neurology, New York Presbyterian Hospital-Cornell Campus, is Assistant Editor of Neurology Alert.