Auditory Evoked Brain-Stem Responses Induced by Bone-Conducted Sound in Conductive Hearing Loss

Abstract

The auditory evoked brain-stem responses induced by a bone-conducted sound were recorded in subjects with normal hearing and in those with conductive hearing losses including congenital aural atresia, secretory otitis media, discontinuity of the ossicular chain and otosclerosis.
In subjects with congenital aural atresia, secretory otitis media and otosclerosis, the wave I was clearly obtained by a bone-conducted sound delivered contralaterally as well as ipsilaterally, whereas the clear recording of wave I was limited to ipsilateral stimulation in case of the discontinued ossicular chain and the normal subjects. This contralaterally induced wave I disappeared after surgery for congenital aural atresia and secretory otitis media.
The generation mechanism of this phenomenon was not fully explained by the current theory of the bone conduction mechanism, i.e. compression and inertia. Further studies on this phenomenon will contribute to further clarification of the machanisms in the bone conduction as well as the sound transmission of the middle ear.