Detection and localization of brainstem lesions with auditory brainstem potentials

Abstract

From the very beginning research workers studying brainstem auditory evoked potentials have used simple clicks as their preferred stimuli. The practical compromise between an ideal rectangular acoustic click and a pure tone with long rise time is a tone pip, i.e. a tone burst with short rise and fall times and not more than one wave in the plateau1. This study uses such a tone pip to elicit the auditory evoked potentials. Brainstem potentials were recorded in a group of 10 normal subjects and in over 200 neurological patients. There is good evidence that the seven vertex-positive potentials (I–VII) relate to different levels in the auditory system2–4: Cochlea and acoustic nerve (I), medulla (II), caudal pons (III), rostral pons (IV), midbrain (V) and diencephalon (VI). The generators of VII are suspected to be the thalamus and the auditory radiation. Control values for the latency and amplitude of each component were obtained from neurologically and audiometrically normal persons. These values were then applied to the investigation of brainstem lesions.