Long-term follow-up of the progression of ossification of the posterior longitudinal ligament.

The authors report the case of a man with cervical ossification of the posterior longitudinal ligament (OPLL) who was observed for more than 26 years. Initial symptoms consisted of subtle numbness of the hands, and initial radiography showed small, segmental-type OPLL in the cervical spine. Lateral radiography of the cervical spine was performed every few years. Ossification accelerated for about 4 years during the follow-up. Segmental-type OPLL developed into mixed-type extensive OPLL. This case shows an accelerating maturation process of OPLL over the course of a few years. Segmental-type OPLL appears to represent an initial stage of extensive OPLL.