CORRELATION BETWEEN PATHOLOGICALLY CONFIRMED SITES OF NEUROLOGICAL LESIONS AND ABNORMALITIES OF FAR-FIELD AUDITORY BRAINSTEM RESPONSES.

Abstract

AMERICAN ASSOCIATION OF NEUROPATHOLOGISTS 159 CORRELAnON BEIWEEN PAntOLOCICALLY CONFIRMED SITES OF NEUROLOGICAL LESIONS AND ABNORMALITIES OF FAR-FIELD AUDITORY BRAINSTEM RESPONSES. A. Starr and A.E. Hamilton*. University of C4lifornia, Irvine, C4lifornia College of Medicine, Irvine, California. Far-field auditory brainstelll responses were recorded in nine patients in whom the distribution of the pathology was defined at autopsy in order to correlate the loss of the electrical components of the auditory res- ponse to the anatomic components of the auditory tract. lbe normal res- ponse consists of seven wave components in the initial ten miliseconds following click signals. A schwanoma of the eighth nerve resulted in the loss of the components after Wave I. Two patients with midbrain tumors had intact Waves I, II, and III, abnormal Waves IV and V, and absent Waves V and VI. A patient with a brainstem glioma which completely obliterated the midbrain and pons, a patient vbose pons and medulla vere completely infarcted. and a drug overdose patient with patchy brainstem encepbalomalacia and three patients with diffuse severe anoxic brainstem changes had clearly detectable Wave I's. The subsequent components were either absent or significantly altered in latency or amplibide. We con- clude that Wave I reflects the activity, Waves II and III reflect activity of the cochlear nucleus, trapezoid body and superior olive and Waves IV and V reflect the activity of the lateral lemniscus and inferior colliculus. The anatomic sources of Waves VI and VII vere not elucidated. (Supported in part by Grant PBS NS 11876 from the USPHS.)