Idiopathic sudden hearing loss.

Idiopathic sudden hearing loss is an otologic emergency with an obscure cause. It is the acute onset of hearing loss of 30 cB in three contiguous frequencies, which may occur instantaneously or progressively over several days. Suspect etiologies include viral infections, cochlear artery occlusion, rupture of the intracochlear membranes, and biochemical alterations in the metabolism maintaining the endocochlear membrane potentials. Histopathology of the temporal bone most commonly reveals atrophy of the organ of Corti and striae vascularis. Treatments proposed include close observation for spontaneous recovery, steroid theray, and combination regimens of vasodilators, steroids, diuretics, and intravenous iodinated radiocontrast material. Prognosis and recovery are related to the audiometric pattern of the hearing loss and associated symptoms. The absence of vertigo at th clinical onset and low tone hearing loss are associated with better hearing recovery.