SKIP LAMINECTOMY FOR CERVICAL SPONDYLOTIC MYELOPATHY WITH MINIMAL INVASION OF THE POSTERIOR EXTENSOR MUSCLES

Abstract

In currently used expansive laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM), persistent axial pain, restriction of neck motion and loss of cervical l ordosis have been the significance postoperative problems. To prevent them, the author has developed skip laminectomy in which ordinary laminectomy at appropriate levels is combined with partial laminectomy of the cephalad half of laminae with preservation of the muscular attachments at adjacent levels. Since December 98, the author performed this procedure on 55 patients with CSM who required multilevel posterior decompressions. Twenty-one of these cases with follow-up period longer than 8 months, with an average of 12 months, were observed.

In skip laminectomy, a consecutive four-level decompression between C3/4 and C6/7 as an example is accomplished by removing alternate laminae (C4 and C6), the cephalad half of the C5 and C7 lamina and the ligamentum flava at those four levels. The laminae to be removed were selected after analysis of the pre- and postoperative radiological findings.

Intraoperative blood loss averaged 34 grams. The operation time averaged 128 minutes. The patients were allowed to sit up or walk on the first postoperative day without neck support of any kind. An average recovery rate according to the Japanese Orthopaedic Association score was 63%. None of these patients complained of residual axial pain. The postoperative ranges of neck motion on lateral X rays averaged 87% of the preoperative ranges. The spinal curvature index, according to Ishihara’s method, was reduced in only one of the 21 cases. Postoperative atrophy of the deep extensor muscles measured on T2 weighed axial MRI was minimal.

Skip laminectomy is less damaging to the posterior extensor muscles and its use reduces the postoperative problems commonly seen after ELAP.