Abstract
In currently used expansive laminoplasties (ELAP) of the cervical spine, axial symptoms and loss of lordotic curvature have been significant postoperative problems. Recent papers have suggested that intraoperative injury to the paravertebral muscles is one of the major factors causing these problems. To prevent them, the author developed skip laminectomy and interlaminar decompression. Twenty-four patients of cervical spondylotic myelopathy (CSM) underwent one of either of these procedures. In skip laminectomy, consecutive four-level decompression between C3-4 and C6-7 is accomplished by removing every other laminae (C4 and C6), the cephalad half of the C5 and C7 laminae and the ligamenta flava at those four levels. The laminae and the spinous processes of C3, C5 and C7 as well as the attaching bilateral semi-spinalis cervicis and multifidus muscles are preserved. The lamina to be removed was selected by the preoperative radiological findings, bearing in mind the need to minimize damage to the posterior extensor mechanism including the deep extensor muscles. Instead of laminectomy, interlaminar decompression was performed at the level where anterior spinal cord compression was less significant. Interlaminar decompression is accomplished by removing the cephalad half of the lamina and the ligamentum flavum at the interlaminar space, leaving the spinous processes and the attaching muscles completely undisturbed. The amount of intraoperative blood loss averaged 37 grams. The operation time averaged 133 minutes. A soft collar was used postoperatively by 20 patients for an average period of 3.5 days. Five patients did not use one at all. The follow-up period averaged 8.5 months. The average recovery rate according to JOA scores was 64.3%. None of the patients complained of axial symptoms. Spinal curvature index calculated by Ishihara's method was reduced postoperatively in one of 24 patients. Skip laminectomy and interlaminar decompression are less invasive to the deep extensor muscles than ELAP.
