Acute spiral ganglion cell degeneration following acoustic overstimulation: an experimental study.

Abstract

BACKGROUND: To evaluate acoustic overstimulation-induced spiral ganglion cell (SGC) degeneration, and determine the relationship between the duration of acoustic overstimulation and rate of SGC degeneration. METHODS: Fifteen guinea pigs were randomized equally to 4 experimental groups, which were exposed to different durations (7.5, 15, 30 and 60 min) of acoustic overstimulation (120 dB at 4 kHz), and a control group. Every bulla was examined histopathologically and immunohistochemically. A quantitative and statistical analysis of acidophilic and TUNEL-positive SGCs was performed. RESULTS: In the control group, 2.1% of SGCs were acidophilic and no TUNEL-positive SGC was detected. In contrast, a statistically significant number of acidophilic (p = 0.000) and TUNEL-positive SGCs (p = 0.002) was determined in the experimental groups. Moreover, a positive correlation between the duration of acoustic overstimulation and acidophilic SGCs (p = 0.000), and a statistically significant relationship between the duration of acoustic overstimulation and TUNEL-positive SGCs (p = 0.000) were demonstrated. CONCLUSION: Acoustic overstimulation may induce acute SGC degeneration. A positive correlation was determined between the duration of acoustic overstimulation and rate of degenerated SGCs.