Incidence and prognosis of acute profound deafness in Japan.

The Acute Profound Deafness Investigation and Research Group of the Japanese Ministry of Health and Welfare conducted nation-wide studies on idiopathic sudden deafness, mumps deafness, and deafness accompanied by perilymphatic leak. In the epidemiological study, data were accumulated from 11 institutions on the incidence and prognosis of patients with idiopathic sudden deafness, especially involving total deafness or near-total deafness; mumps deafness; and deafness accompanied by perilymphatic leak. Out of 1,331 patients with sudden deafness, total deafness was found in 8.6% of the patients, and near-total deafness was found in 10.7% of the patients, with prognosis being less favorable in the former than in the latter. Perilymphatic leak was found in 10(0.7%) of the patients with idiopathic sudden deafness. Among the patients with deafness accompanied by perilymphatic leak, hearing recovery was rated as cured or markedly recovered in 41% of the patients. Hearing recovery was not observed in all the patients with mumps deafness showing total deafness.