Idiopathic sudden deafness, generally unilateral and always sensorineural, is more common than generally recognized. The site of the lesion producing deafness may be either cochlear or neural (retrocochlear), and it is important to attempt to try to distinguish, by means of audiometric examination, one locus from the other.

The causes generally are believed to be either vascular or viral. Recently there is evidence to suggest that the two causes need not be separate or mutually exclusive but, in fact, a viral etiology may cause certain vascular changes that result in a reduced blood flow to the cochlea.

There is no consensus concerning proper treatment for sudden deafness and about one-third of the otolaryngologists replying to a questionnaire said they were not certain that any treatment helps; but because the only alternative is no treatment, most physicians will want to offer treatment. A brief plan is given using the site of the lesion as a prognostic and therapeutic guide.