The epidemiology of sudden deafness

Sudden deafness, more specifically sudden sensorineural hearing loss, is defined as 30 decibels (dB) hearing loss in 3 consecutive frequencies occurring within 72 hours. It is considered an otologic emergency and treatment should be initiated immediately. However, it is uncertain if treatment has any effect. Approximately 98% of cases are unilateral, and the condition is frequently associated with vertigo and/or tinnitus. The incidence is estimated to 10-20 cases per 100 000, with an incidence peak at age 50-60 years, but individuals of all ages may be affected. Due to the lack of large epidemiological studies and the possibility of spontaneous recovery, the true incidence is unknown. Furthermore, in most cases the cause is unknown. Several proposed causes exist, such as: infections conditions, traumatic injuries, neoplastic disease, neurological disorders, autoimmune diseases, vascular impairment or specific otologic diseases. The objectives of this project are to investigate hearing recovery, possible etiologies, and prognostic factors of sudden deafness.