IT IS THE purpose of this paper to present briefly the underlying neuropathophysiological basis for the signs and symptoms of the acoustic neurinoma. Far too frequently diagnoses are made simply by memory of a set symptom complex and laboratory data without cognizance of the fundamental physiological basis for the diagnosis. Since, in the majority of cases, patients with eighth nerve tumor consult first the otolaryngologist, he should be capable of localizing the lesion and determining the extent of the lesion and the probable operability. The following review of the normal neurophysiology of the vestibular mechanism and associated neuropathways affected by acoustic neurinomas should aid one in understanding more readily the reasoning in making the diagnosis.
The cerebellopontine angle is located on the lateral aspect of the brain stem at the junction of the pons and the medulla and is bounded above by the biventral lobule of the cerebellum. The cranial