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

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.