Idiopathic sudden sensorineural hearing loss (ISSNHL) is defined as an unexplainable decline in hearing that occurs within a short period of time (12–72 hours in most studies). The incidence of ISSNHL is estimated at five to 20 cases per 100,000 persons per year. In the vast majority of the cases ISSNHL is unilateral, and the prognosis for hearing recovery is good (spontaneous recovery rate 45 to 65 percent). Due to the rare nature of the disease, clinical trials measuring the effectiveness of treatments often have difficulty recruiting sufficient numbers of patients to yield significant results.
Explore this issue:September 2012
Multiple etiologies for ISSNHL have been proposed, including inner ear membrane rupture, obstruction of cochlear vasculature and new onset or reactivation of viral infection. Hypotheses suggesting a viral etiology are supported by the observation that many patients have had recent upper respiratory tract infections within two weeks of the onset of ISSNHL, although some authors have noted that this rate is not higher than the general population. Some have shown that many patients with ISSNHL have significant levels of antiviral antibodies.
The appropriate treatment for ISSNHL is still debated despite numerous trials. Many treatment modalities have been used for patients with ISSNHL including vasodilators, hyperbaric oxygen, intravenous contrast agents, antihistamines, corticosteroids and antiherpetic medications (antivirals, including acyclovir and valacyclovir). Currently, steroid therapy started within 10 days of onset of hearing loss is considered the best supported therapy for ISSNHL. Many investigators have suggested that the use of antiviral medications in addition to high-dose steroids might improve patient hearing outcomes by stopping viral replication. We examine the evidence regarding the addition of antiherpetic medications to high-dose steroid therapy in the treatment of ISSNHL.