Abstract

BACKGROUND: The effect of division of the stapedial tendon on susceptibility to noise-induced inner ear damage has not been previously studied. This study aimed to evaluate the effects of noise exposure following division of the stapedial tendon in guinea pigs.

MATERIAL AND METHODS: Ten adult albino guinea pigs were used. The stapedial tendon of each right ear was cut. The stapedial tendon in each left ear was left intact and these ears served as a control group. DPOAEs and ABR tests were performed before and 10 days after noise exposure. The animals were exposed to a 110-dB noise stimulus for 6 h in a silent room a week after surgery. Cochleas of the animals were removed, and inner and outer hair cells were examined under a light microscope.

RESULTS: We found that noise exposure adversely affected DPOAE measurements at all frequencies except 2 KHz in experimental ears. Noise exposure also produced significantly elevated ABR thresholds in experimental ears at 2, 4, 8, and 16 KHz. On histopathological examination, we found a significantly greater prevalence of apoptotic cells in the experimental ears.

CONCLUSIONS: Based on these findings, we can conclude that after division of the stapedial tendon, noise exposure may cause damage to the inner ear. This is the first study in the English literature that demonstrates the potential protective effect of the stapedial tendon against acoustic damage.

Keywords: Guinea Pigs, Ear, Inner - physiopathology, Hair Cells, Auditory - pathology, Hearing Loss, Noise-Induced - physiopathology, In Situ Nick-End Labeling, Ligaments - physiopathology, Otoacoustic Emissions, Spontaneous, Stapedius - physiopathology, Tendons - physiopathology