Sound-evoked myogenic potentials and responses with 3-ms latency in auditory brainstem response.

Abstract

The vestibular-evoked myogenic potential (VEMP) has shed new light on vestibular testing. A large negative deflection with a 3-ms latency within the auditory brainstem response (ABR) has been reported in some patients with deafness. This negative deflection has been termed the N3 potential and it is assumed to be a vestibular-evoked potential. This study investigated the relationship between the VEMP and the N3 potential. Prospective evaluation of the VEMP and the N3 potential in 21 patients. The oto-neurological tests, including caloric test, hearing sensitivity test, VEMP, and ABR, were performed and data were analyzed. The average hearing threshold ranged from 65 to above 110 dB, which includes 9 (37.5%) totally deaf ears. The N3 potentials were recorded in 10 (41.7%) ears. A normal VEMP was detected in 16 (66.7%) ears. Canal paresis was observed in 11 (45.8%) ears. Both the VEMP and the N3 potential appear to originate from the sacculus, but because the characteristics of these two responses are not identical, additional factors might be involved in the generation of the N3 potential.