Evaluation of Effect of Vitamin B12 on Noise-Induced Hearing Loss by Distortion Product Otoacoustic Emission (Dpoae) and Scanning Electron Microscopy

microscopy (SEM) and Distortion Product Otoacoustic Emission (DPOAE). Materials and Methods: In this study, eight adult albino guinea pigs were used as the study group (n = 4) and control group (n = 4). DPOAE measurements of both groups were performed before the procedure. 2 hours before administration of the noise, 0.9% NaCl solution was intraperitoneally injected to control group and vitamin B12 to study group once a day for 5 days. 105 dB SPL 4 KHz frequency-based narrow-band noise was administered to both groups 2 hours per day for 5 days. DPOAE measurements were performed again at 6th day and cochleae were dissected and examined by SEM at 7th day. Results: Regarding results of DPOAE, noise induced hearing loss (NIHL) was observed in both groups at 6th day. Loss, flattening and fusion, which are findings of permanent hearing loss, were determined in stereocilias of inner and outer hair cells by SEM. These findings were evaluated as signs of permanent threshold shift. When DPOAE measurements and SEM results were evaluated in Vitamin B12 study group, no significant difference was observed in NIHL compared to control group (p> 0.05). Conclusion: In our study, it was observed that simultaneously administration of vitamin B12 during noise had no protective effect on permanent threshold shift. However, new studies on noise and long-term use of vitamin B12 can be performed.