Ossification of the posterior longitudinal ligament.

Two non-Japanese patients with ossification of the cervical posterior longitudinal ligament were described. This abnormality is very common in Japan, but rare in non-Japanese people. The reason is unknown. Although the disease appears to be generally asymptomatic, it can cause a myelopathy. The clinical picture, the diagnostic important X-ray examinations and the histopathological findings are revealed. The similarity to the vascular pattern in the lumbar spine in cases of intermittent neurogenic claudication is noted.