Extratympanic electrocochleographic changes on noise-induced temporary threshold shift.
OBJECTIVE
Electrocochleography (ECoG) is a sensitive evoked-response test for evaluating changes in cochlear function. We investigated the extratympanic ECoG in a noise-induced temporary threshold shift (TTS) to evaluate the usefulness of ECoG in the early detection of noise-induced hearing loss (NIHL).


METHODS
In a prospective analysis, 15 healthy ears were exposed to 90.3- to 105.0-dB noise for 3 hours in the same computer-game arcade. Pure-tone audiometry and ECoG were performed before, immediately after, and 24 hours after the exposure.


RESULTS
Before the exposure, the average hearing level was 5.8 +/- 2.7 dB, which increased significantly to 12.8 +/- 2.8 dB immediately after exposure. A marked increment in the SP/AP (summating potential/action potential) ratio was observed with the TTS. The mean ratio was 0.22 +/- 0.11 before the exposure, 0.46 +/- 0.18 in the TTS phase, and 0.20 +/- 0.11 after resolution.


CONCLUSIONS
The results of this study suggest that the SP/AP ratio is useful for the early detection and monitoring of NIHL.
Nam
Eui-Cheol
EC
Department of Otolaryngology, Kangwon National University Hospital, Chunchon, Kangwon, Korea. birdynec@kangwon.ac.kr
Won
Jun Yeon
JY
D000200:Action Potentials; D000328:Adult; D001300:Audiometry, Evoked Response; D001309:Auditory Threshold; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013997:Time Factors; D018910:Video Games