Investigation of the Effect of Tinnitus and Hearing Loss on Hippocampus Volume

Abstract

Objective: This study aims to compare hippocampal changes with a correlation of audiological testing results in patients suffering from tinnitus. Methods: Patients diagnosed with tinnitus in the university hospital between February 2021 and March 2022 were prospectively included in the study by performing magnetic resonance imaging. The volume was determined by manually tracing the hippocampus' margins on the images using the Vitrea2® workstation (Canon Medical Systems Vital Images, Minnesota, USA). Statistics were used to assess the correlation between the parameters of the hearing test. Results: The distribution of the patient group (21 males, 19 females) and control group (15 males, 15 females) was uniform, and the mean ages of the two groups were 50.23±12.09 and 32.30±7.97, respectively. Significant statistical differences existed in the mean ages of the groups (p<0.05). Bilateral hippocampal volumes, right bone, and air conduction all differed significantly (p<0.05). The median values in the patient group were as follows: right HC 2620 mm3 (range 1600-3610), left HC 2450 mm3 (range 1610-3990), right air conduction 20 dB (range 10-61), left air 21 dB (range 11-65), and right bone 13.5 dB (range 8-49). Age was positively correlated with bilateral measurements of air and bone hearing levels (p 0.05; right air r=0.513, right bone r=0.438, left air r=0.589, left bone r=0.487). Between the 30-39 and 60-69 age groups, there was a significant difference in bone and air conduction levels (p<0.05). Conclusion: In this study, it was found that the hippocampus volumes of healthy hearing people with tinnitus complaints were significantly higher in MRI examinations compared to the control group. In addition, in cases of tinnitus accompanied by bone conduction hearing loss, hippocampus volumes were found to be less than those of tinnitus alone, but not less than in the control group. It is suggested that chronic acoustic stimulation caused by tinnitus causes an increase in hippocampus volume and that problems in sensorineural integrity prevent this increase.