Protective effect of isoflurane anesthesia on noise-induced hearing loss in mice.

Abstract

HYPOTHESIS/OBJECTIVES: To examine the protective effect of general anesthesia with isoflurane against noise-induced hearing loss in mice. STUDY DESIGN: Animal study using noise stimulation and measurement of hearing in BALB/c mice. METHODS: Mice were exposed to 122 dB peak equivalent sound pressure level click noise for 3 hours per day for 3 consecutive days with or without anesthesia using isoflurane. Hearing levels were measured and hair cell survival ratio was observed. RESULTS: In mice without anesthesia, hearing threshold increased after noise stimulation (73.7 dB hearing level [HL]) and persisted for at least 1 month. However, in mice exposed to noise under anesthesia, hearing loss was less severe (44.1 dB HL) and had recovered more (26.5 dB HL) by one month. Histological examination showed hair cell survival was higher in anesthetized compared to non-anesthetized mice. CONCLUSION: These data indicate isoflurane general anesthesia protects against noise-induced hearing loss and tissue damage in mice.