Surgical treatment of lumbar stenosis in achondroplasia

Object. The authors conducted a study to evaluate the results of a unique surgical procedure for treating primary lumbar stenosis in patients with achondroplasia, based on its distorted anatomical dimensions. Methods. A consecutive single-center series of 36 achondroplastic dwarfs with symptomatic lumbar stenosis underwent dynamic lumbar myelography to determine the most stenotic lumbar segment. This level was surgically decompressed by selective widening of the lumbar interapophyseolaminar diameter; laminectomy was not performed. The L2-3 level was decompressed in 97% of the cases and the L1-2 and L3-4 levels in 58 and 61%, respectively. Lower lumbar levels were rarely affected by stenosis. Stenosis typically did not occur at the level of the lamina, where the pseudoscalloping of the vertebral body compensates for the spinal narrowing, obviating the need for laminectomy. Complete relief of symptoms was demonstrated in 25 (71.4%) of 35 patients. Tolerable disease remained in eight patients (22.9%) postoperatively. In two cases (5.7%) surgery resulted in no benefit. One case was lost to follow up. The presence of a lumbar epidural hematoma complicated one procedure. Conclusions. In this series the interapophyseolaminar decompression was demonstrated to be an effective and safe procedure for the treatment of symptomatic stenosis in achondroplasia. The upper lumbar segments, particularly the L2-3 level. were most frequently involved. Dynamic lumbar myelography proved mandatory in demonstrating the symptomatic level.