Effects of electrical stimulation on the acoustically evoked auditory-nerve response in guinea pigs with a high-frequency hearing loss.
Criteria for cochlear implantation keep expanding and people with substantial residual low-frequency hearing are considered candidates for implantation nowadays. Therefore, electro-acoustical stimulation in the same ear (EAS) is receiving increasing interest. We have investigated the effects of intracochlear electrical stimulation on acoustically evoked auditory-nerve activity, using a forward masking paradigm. The stimulation electrode was placed in the basal turn of the cochlea. Compound action potential (CAP) recordings were performed in guinea pigs with severe high-frequency hearing loss and in normal-hearing control animals. In normal-hearing animals, electrical stimulation generally suppressed CAPs, especially at high acoustic frequencies (8 and 16 kHz) and low sound levels. At low frequencies (0.5 and 1 kHz), suppression was observed only at high sound levels. In animals with a high-frequency hearing loss, suppression of CAPs at low frequencies was substantially less compared to control animals, even at high current levels and temporal overlap of acoustic and electric stimuli. Hence, effects of electrical stimulation substantially differed between normal-hearing animals and animals with a high-frequency hearing loss. These findings stress the need for a proper animal model when investigating EAS. We conclude that in case of high-frequency loss, the basal part of the cochlea can be stimulated electrically with little effect on responses to low-frequency acoustic stimuli.
Department of Otorhinolaryngology and Head & Neck Surgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands. h.stronk1@jhmi.edu
H Christiaan
HC
Stronks
Huib
H
Versnel
Vera F
VF
Prijs
Wilko
W
Grolman
Sjaak F L
SF
Klis
D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold; D003051:Cochlea / Q000294:innervation*; D019929:Cochlear Implantation; D003055:Cochlear Microphonic Potentials; D003056:Cochlear Nerve / Q000503:physiopathology*; D004195:Disease Models, Animal; D005260:Female; D005665:Furosemide; D006168:Guinea Pigs; D006316:Hearing Loss, High-Frequency / Q000139:chemically induced / Q000503:physiopathology / Q000628:therapy*; D007612:Kanamycin; D013997:Time Factors
D007612:Kanamycin; D005665:Furosemide