Bone-anchored hearing aid in unilateral inner ear deafness: electrophysiological results in patients following vestibular schwannoma removal.
CONCLUSIONS
The results show that the healthy cochlea perceives one auditory stimulus from two auditory signals: the first through normal air conduction and the second provided by the bone-anchored hearing aid (BAHA). This artificial acoustic difference could partly explain 'pseudo' binaural hearing. Functional cerebral imaging using the same experimental procedure is now necessary.


OBJECTIVE
The aim of this study was to evaluate electrophysiological phenomena induced by BAHA on brainstem and long-latency auditory evoked potentials (AEPs) to understand how patients recover a 'pseudo' binaural sensation with only one functional cochlea.


METHODS
This prospective study included 10 patients operated via the translabyrinthine approach and who received implants on the deaf side. Electrophysiological recordings were performed at least 2 months after BAHA use. Brainstem and long-latency (N1, P2, N2, P300) AEPs were studied in free field according to four conditions: 1, without BAHA; 2, with BAHA; 3, with BAHA and normal ear occluded; 4, without BAHA and normal ear occluded.


RESULTS
For brainstem AEPs, we found significantly longer latencies of waves III and V in condition 3 compared with condition 1. For long-latency AEPs, comparison between conditions showed no significant differences.
Tringali
Stephane
S
Service d'Oto-neurochirurgie, Hospices Civils de Lyon, Centre Hospitalier Lyon Sud, 69495 Pierre-Bénite Cedex, France. stephane.tringali@chu-lyon.fr
Marzin
Alexandre
A
Dubreuil
Christian
C
Ferber-Viart
Chantal
C
D000368:Aged; D001844:Bone Conduction; D005072:Evoked Potentials, Auditory; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006310:Hearing Aids; D046088:Hearing Loss, Unilateral / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*