Changes in Inner Ear Structure and Function after Drill - Induced Acoustic Trauma

Abstract

Background: drilling on the intact ossicular chain produce acoustic trauma resulting in inner ear structure damage, these changes occurred in organ of corti with disruption of cytoarchitecture and cellular degeneration. Objective: To evaluate the changes in inner ear structure and function after drill - induced acoustic trauma in guinea pigs by Scanning Electron Microscope (SEM) and Otoacoustic emission (OAE). Methods and Material: An experimental study conducted on healthy pigmented guinea pigs in Otolaryngology-Head and neck Surgery Department at Jazan University, Kingdom of Saudi Arabia. Results: Thirty guinea pigs were divided into a control group (N) to document the baseline Distortion Product Otoacoustic Emissions (DPOAEs) and the normal scanning electron microscopic (SEM) morphology of the inner ear, Drill induced acoustic trauma group (D) to evaluate the effect of induced sensorineural hearing loss using micromotor drill (20,000rpm) maximum speed against the body of incus and 2weeks postoperative group (2W) to evaluate to the effect of spontaneous recovery after 2 weeks from induced sensorineural hearing loss which showed spontaneous although incomplete recovery of the DPOAEs amplitudes and SEM morphology with scar tissue replacing the damaged outer hair cells. Conclusion: Avoid touching ossicular chain when using high speed drill during ear surgery as this may cause structural and functional damage to the inner ear. Spontaneous recovery could be occurs after acoustic trauma but incomplete recovery with permanent scar formation in outer hair cells may occur.