Intramedullary syndrome due to an extradural neurinoma near the foramen magnum.

A case of right sided extradural neurinoma at the level of the foramen magnum is reported which presented as an intramedullary spinal cord syndrome. Ischemia of the anterior spinal artery or of the vertebral artery was considered to be an important pathogenic factor in the production of the neurological syndrome. The outer part of the spinothalamic tract, where sensory fibers carrying pain and thermal sensibility from the sacral segments are situated, escaped ischemia as that part is supplied by penetrating branches of the pial arterial plexus. The discrepancy between the level of neurological deficit (C5) and site of the tumor (C1-2) was due to distant ischemia. The lack of a history of root pain and the rapid recovery following removal of the tumor also favor a vascular origin for the neurological deficit.