Cervical myelopathy due to ossification of the posterior longitudinal ligament.

Ossification of the posterior longitudinal ligament in the cervical spine may be a cause of cervical myelopathy. This ossification has often been encountered in Japan, but only sporadically among the Caucasian races. It is therefore probable that racial factors are relevant to the pathology. During the past four years, due to the routine use of computerised axial tomography (CAT) in the pre-operative study of cervical myelopathy, we were able to show that in 13 cases stenosis of the vertebral canal was due to ossification of the posterior longitudinal ligament. This was visible in the standard radiographs in only two out of these 13 cases. The clinical data, diagnostic criteria and results of treatment are reported. This is the largest series yet reported outside Japan.