Radiological diagnosis of mass lesions within and adjacent to the foramen magnum.

Masses within or adjacent to the foramen magnum may present difficult clinical problems. They may sometimes be misdiagnosed as degenerative disease of the central nervous system, cervical spondylosis, or even cervical disk disease. In most cases, roentgenographyis necessary for proper diagnosis. The anatomy of the region of the foramen magnum is reviewed and 13 cases representing various diseases are presented. Alterations in the regional arterial and venous anatomy are emphasized.