The effects of noise on the vestibular system

Purpose: Subjects with noise-induced hearing loss sometimes also complain a bout balance disorders, but reports of clinical series that give contradict ory results are highly controversial. This study was designed to evaluate t he effects of intense noise on the vestibular labyrinth, both in subjects w ith symmetrical hearing loss and in subjects with asymmetrical loss, and to examine the correlation between the subjects' complaints and the results o f the vestibular function tests. Methods: A total of 258 male military personnel, heavily exposed to various intense noises, were included in the study. They were divided into 2 group s according to their hearing; 134 had a symmetrical high-tone hearing loss, and 124 had asymmetrical losses. Each group was divided into 2 subgroups a ccording to the presence or absence of vestibular complaints. All of the su bjects underwent a complete audiological and electronystagmographic evaluat ion. Results: We found that vestibular damage caused by intense noise exposure m ight be expressed clinically in subjects with asymmetrical hearing loss. Th ere was a strong correlation between the subjects' complaints and the resul ts of the vestibular function tests. There was no correlation between the s everity of the hearing loss and the vestibular symptomatology and pathology . Conclusions: Subjects exposed to intense noise may have evidence of vestibu lar pathology only when there is an asymmetrical hearing loss. Whenever hea ring loss is symmetrical, an equal damage to the vestibular system of both ears is most probably responsible for the absence of abnormal findings on t he vestibular function tests. The results of this study have important medi colegal implications for individuals exposed to intense noises. (Am J Otola ryngol 2001;22:190-196. Copyright (C) 2001 by W.B. Saunders Company).