Marked canal stenosis at the level of the atlas.

A 38-year-old man with severe canal stenosis at the level of the atlas is reported. The clinical manifestations were muscular weakness and wasting of the upper limbs and spastic paresis of the lower limbs, which all progressed slowly. The atlas was hypoplastic and its retrodental space was narrow. The spinal cord was markedly compressed between the odontoid process and the posterior arch of the atlas. The clinical manifestations improved after a posterior laminectomy of the atlas.