1998 年 12 巻 2 号 p. 177-186
Patients with lumbar canal stenosis have usually been treated by conventional bilateral laminectomy. Using high resolution computed tomographic myelography, in patients with lumbar canal stenosis, it can be shown that the cross sectional areas (CSA) of the stenotic dural sac [0.62±0.22(cm)^2 (mean±SD)] and the hypertrophic ligamentum flava (1.52±0.76(cm)^2) are wider than that of the normal dural sac (1.32±0.28(cm)^2). Based on this result, during the last two years, patients with lumbar canal stenosis due to hypertrophic ligamentum flavum have been treated by unilateral laminectomy and bilateral ligamentectomy. Furthermore, patients with hypertrophic ligamentum flavum combined with lumbar disc herniation or spondylolisthesis have also been treated by this procedure. Decompression of the nerve root in the opposite lateral recess can be more easily achieved than by using the approach side, where the facet joint has to be destroyed to some extent. This approach is undesirable in cases with contralateral nerve root compression peripheral to lateral recess. Because, compared with other techniques, this procedure is less invasive of the paraspinal muscles, the facet joint and the supra-and interspinous ligament, rapid recovery even in elderly patients can be achieved and the incidence of delayed lumbar instability may be decreased. In cases requiring a pedicle screw, this procedure is very useful for saving the grafting area on the opposite side. The early results were good in all cases, but restenosis occurred in two cases. The restenosis was caused by dense scar formation. Meticulous hemostasis especially of contralateral epidural venous bleeding may be important to prevent scar formation and re-stenosis.