VERTICAL PLANE SHORT AND MIDDLE LATENCY VESTIBULAR EVOKED-POTENTIALS IN HUMANS

In order to determine whether short and middle latency vestibular evok ed potentials (VsEPs) can be recorded in humans in response to angular acceleration stimuli in the vertical plane, a drum head-holder, and s tepper motor were designed to deliver upward acceleration impulses of 10,000 degrees/s(2) (1.8 degrees displacement) to the human head. Fore head and mastoid electrodes recorded electrical activity that was filt ered, differentially amplified, and averaged in Short (12.7 millisecon ds) and middle (63.5 milliseconds) latency time frames. Control record ings were used to eliminate various type of artifact. Recordings were conducted in 7 normal and in 4 control patients with congenital, profo und hearing loss and absence of caloric responses. Short and middle la tency VsEPs with high intrasubject and intersubject consistency were r ecorded in normal subjects and not in control patients. The middle lat ency responses were larger in amplitude than the short latency respons es. The effects of stimulus intensity and repetition rate on VsEP wave form, latency, and amplitude were studied. Experiments have shown that the responses are not electrical artifact, nor are they contaminated by auditory, somatosensory, or passive eye movement potentials.