Neoplasms of spinal origin involving the foramen magnum. Neurodiagnostic considerations on 36 cases.

: The radiological problems concerning the diagnosis of neoplasms of spinal origin involving the foramen magnum are discussed on the basis of 36 cases studied. The high number of apparently normal neurodiagnostic examinations are investigated and accordingly explained. Some anatomical features of the area involved are examined in relation to the misleading results. As a result of the studies conducted, opaque myelography is recommended as the best neurodiagnostic procedure particularly in cases of poor clinical conditions. Of the 22% of apparently normal myelographies, 8% appears to be related either to technical features or 14% to incorrect clinical information with regard to the tumor level. Our data stress the importance of following the clinical course of the development of these neoplasms, hardly distinguishable from other degenerative processes. Our findings indicate that a normal myelogram alone does not justify the diagnosis of a non-surgical entity. Therefore repeated neuroradiological investigations are advisable.