Effects of noise on the vestibular system of normal-hearing workers

Abstract

BACKGROUND: Studies in noise-exposed animals have shown changes in vestibular structures. Likewise, studies in humans have been suggesting that noise can damage the vestibular system, even with normal assessment results. OBJECTIVE: To assess the vestibular system of workers exposed to noise and to compare with individuals not exposed. METHODS: Twenty normal-hearing male adults were divided in the study group (SG), exposed to occupational noise, and control group (CG). We conducted the following procedures: medical history, Dizziness Handicap Inventory (DHI), Dix-Hallpike maneuver, and electronystagmography (eye and caloric tests). RESULTS: The DHI score did not differ between groups. The Dix-Hallpike maneuver was normal for both groups. All individuals had normal responses in the eye tests. 50% of the SG had hyperreflexia in the caloric tests, with a significant difference between the groups. There was a trend towards a statistical significance in the absolute values of angular speed of the slow component in the cold-air test, which were higher in the SG. There was a significant difference between the groups in the relative values of labyrinthine preponderance, which were higher in the SG. CONCLUSION: Our findings showed that 70% of the workers exposed to occupational noise had vestibular alterations identified with electronystagmography, whereas 100% of the individuals in the CG had normal results in the vestibular assessment. Moreover, only 20% of the sample in both groups had vestibular complaints, indicating the presence of subclinical vestibular changes in 50% of the individuals exposed to occupational noise.