Long-term follow-up study of anterior surgery for cervical spondylotic myelopathy with special reference to the magnetic resonance imaging findings in 52 cases.

A series of 151 patients with cervical spondylotic myelopathy (CSM) were surgically treated through an anterior approach in the period from 1960 to 1987. Particular attention was given to the results of the 52 patients who were operated on more than 12 years ago. Satisfactory short-term results were obtained in all but the few who had incomplete decompression. In these patients, function deteriorated within five years. A disturbing incidence of progression of myelopathy was noted ten years after surgery. Magnetic resonance imaging identified many of the causes (e.g., newly developed intervertebral disk herniation and progression of spondylosis associated with spinal malalignment in both cephalad and caudal directions). Other adverse changes were hypertrophy of the yellow ligament and ossification of the posterior longitudinal ligament. The new and improved techniques consist of decompression to a width of 16 mm or more with intraoperative ultrasonography in addition to extirpation of the posterior longitudinal ligament. This new measure may reduce the incidence of late neurologic deterioration.