Developmental lumbar spinal stenosis. Pathology and surgical treatment.

The purpose of this presentation is to outline the extent of surgical resection necessary for complete decompression of the neural elements in spinal stenosis and to introduce a system for the evaluation of disability in patients with spinal stenosis. Sixteen patients with the confirmed diagnosis of lumbar spinal stenosis were evaluated by the system. Ten cases were treated surgically. Indications for operative treatment were 1) intolerable pain in average daily living, 2) progressively worsening or significant degree of motor weakness, and 3) sphincter dysfunction. Satisfactory results from operative treatment were expected only after adequate and thorough decompression. The extent of surgical decompression was determined by clinical evaluation, myelographic examination, and by the type of disease process exhibited. The most common cause of unsatisfactory results was inadequate decompression of spinal contents. The extent of adequate decompression is described according to three different variations of pathologic anatomy of spinal stenosis: a) concentric contraction of the spinal canal, b) sagittal flattening of the spinal canal, and c) stenosis caused by anomalous articular process(es). No excellent results were obtained even after thorough and adequate decompression of spinal contents.