Spinal cord compression caused by ossification of the transverse ligament of the atlas.

Although ossification of the posterior longitudinal ligament and ligamentum flavum are well known, ossification of the transverse ligament of the atlas is extremely rare. We present the case of a 79-year-old man who developed a gradually progressive spastic quadriparesis caused by upper cervical canal stenosis due to ossification of the transverse ligament of the atlas together with ligamentum flavum hypertrophy.