Vestibular implications of noise-induced hearing loss.
An extensive vestibular examination was carried out in a group of 29 noise-exposed technicians. A spontaneous nystagmus was found in 18 persons, and 24 had a positional nystagmus exceeding a velocity of the slow phase of 5 degrees/s in three or more positions. In 17 subjects a cervical nystagmus could be provoked, while a nystagmus preponderance of more than 20% in the rotation test was found in seven persons. A difference in excitability between the labyrinths of more than 20% was shown by seven subjects. None of the subjects showed pathology in the tests for central vestibular disorders. The technicians were divided into four groups, according to the severity of their hearing loss. No correlation was found between the grade of the hearing loss and the vestibular function disturbance. This can be explained in terms of the adaptive properties of the vestibular system. All subjects showed pathology in one or more of the vestibular tests. The medico-legal aspects of vestibular involvement in noise-induced hearing loss can be of some importance. Hearing loss itself does not affect work capability directly; however, a vestibular disorder might well do so. In consequence, noise-exposed individuals could be disabled because of vertigo or balance disorder--an important and perhaps neglected aspect of noise-induced hearing damage.