An experimental study on hyperbaric oxygen therapy for noise-induced hearing loss

LI Huan; LIU Chen; QIAO Yuehua; YU Ning

doi:10.3969/j.issn.1672-2922.2016.06.009

Abstract：Objective To study the timing and efficacy of hyperbaric oxygen therapy (HBOT) in treating noise-induced hearing loss, for potential translation to clinical applications. Methods Fifty healthy guinea pigs with normal ABR thresh-olds, weighing 250-300 g were used. Forty five guinea pigs were randomly divided into 3 groups, i.e. control, noise expo-sure, noise+hyperbaric oxygen therapy (2ATA, 10 days) groups. HBOT was given immediately, and at 7 and 14 days after noise exposure. The rest five guinea pigs were randomly selected as specimen donors immediately after noise exposure. Im-pulse noise (peak sound pressure 142 dB SPL, pulse width 0.25 ms) was given at 100 pulses in succession. Auditory brain-stem responses (ABRs) were measured before and immediately after exposure, and repeated after two, six and ten sessions of hyperbaric oxygen therapy. At the end of HBOT, changes in cochlear metabolism were measured by levels of inflammato-ry cytokines and oxygen free radicals. Results Compared with the noise exposure group, hyperbaric oxygen therapy imme-diately after noise exposure led to reduced ABR threshold shifts at 16 kHz (P<0.05). Thresholds of click ABRs and tone bursts ABRs at 4, 8, and 16 kHz were better in the hyperbaric oxygen therapy group on Day 7 (P<0.05) than those in the noise exposure only group. There was no significant difference at all tested frequencies between the noise exposure and the hyperbaric oxygen therapy groups on Day 14 day, with click and 4 kHz tone burst ABR thresholds in the hyperbaric oxygen therapy group being somewhat worse than those in the noise exposure group. Levels of 8-OHdG, TNF-αand IL-1βin the hy-perbaric oxygen treated group were lower than those in the noise only group (P<0.05). The level of HIF-1αin noise+hyper-baric oxygen treated group was also lower than that in the noise exposure group, but showing no statistical significance. Conclusion HBOT has a significant effect in treating noise-induced hearing loss, showing its best effects on Day 7 follow-ing exposure to noise. Its effects are not only poor on Day14 after exposure to noise, but show signs of adverse effects.