Syringobulbia: a surgical review.

Syringobulbia is a term which is applied to brain stem symptoms or signs in patients with syringomyelia or hindbrain herniation. Syringobulbia clefts due to a dissection of the CSF under pressure from the fourth ventricle should be differentiated from the ascending syringobulbia which may occur from upward impulsive fluid movements in a syringomyelia. Clinical analysis suggests that the commonest correlation of bulbar features is with neither of the above mechanisms but with pressure differences acting downward upon the hindbrain with distortion of the cerebellum and stem, traction on the cranial nerves or indentation of the brain stem by vascular loops. A review of patients with bulbar symptoms in a neurosurgical practice with an interest in hindbrain herniation in the Midland Centre for Neurosurgery and Neurology (M.C.N.N.) is presented.