Anomaly of the axis causing cervical myelopathy. Case report.

Although the craniovertebral junction is one of the most common sites at which anomalies develop, spina bifida occulta of the axis (C-2) associated with cervical myelopathy is extremely rare. The authors present the case of a 46-year-old man who developed progressive tetraparesis caused by a cervical canal stenosis at the level of the axis. The spinal cord was compressed by an invaginated bifid lamina of the axis. The patient made a remarkable recovery after undergoing decompressive laminectomy of C-3 and removal of the bifid posterior arch of the axis.