Cervical myelopathy caused by invagination of anomalous lamina of the axis.

The authors report a case of cervical myelopathy caused by invagination of the bilaterally separated lamina of the axis. They also present a literature review. The patient was a previously healthy 68-year-old man with a 1-year history of slowly progressive gait disturbance, right-hand clumsiness, and right dominant sensory disturbance in his trunk and extremities. Both MRI and CT showed that the spinal cord was markedly compressed at the C2-3 level, on the right side, by a deeply invaginated anomalous lamina of the axis. A bilaterally separated lamina was also visible. The patient underwent removal of the anomalous invaginated fragment of the separated lamina and the spinous process of the axis. One year after surgery, his myelopathic symptoms had almost completely resolved. Here, the authors present the case of a patient with an extremely rare anomaly of the lamina of the axis. The underlying pathogenesis of this anomaly could be the failure of the 2 chondrification centers on either side to fuse into a single ossification center. Surgical removal of the anomalous invaginated lamina produced a satisfactory outcome.