by: Brandon E. Cohen1, Anne Durstenfeld2 and Pamela C. Roehm3
Trends in Hearing Vol. 18 2014
A number of viral infections can cause hearing loss. Hearing loss induced by these viruses can be congenital or acquired, unilateral or bilateral. Certain viral infections can directly damage inner ear structures, others can induce inflammatory responses which then cause this damage, and still others can increase susceptibility or bacterial or fungal infection, leading to hearing loss. Typically, virus-induced hearing loss is sensorineural, although conductive and mixed hearing losses can be seen following infection with certain viruses. Occasionally, recovery of hearing after these infections can occur spontaneously. Most importantly, some of these viral infections can be prevented or treated. For many of these viruses, guidelines for their treatment or prevention have recently been revised. In this review, we outline many of the viruses that cause hearing loss, their epidemiology, course, prevention, and treatment.
Among the many causes of hearing loss, viruses often are ignored. Viral infections, in particular cytomegalovirus (CMV), cause up to 40% of all congenitally acquired hearing loss. Many viruses can be the cause of congenital or acquired hearing loss (Table 1). Typically, viruses cause sensorineural hearing loss (SNHL); however, a viral etiology has been proposed for otosclerosis. Infection with HIV can lead to conductive hearing loss (CHL) through bacterial and fungal infections, which become more frequent following the immunosuppression caused by that virus. Hearing loss caused by viruses can be mild or severe to profound, unilateral or bilateral. Mechanisms involved in the induction of hearing loss by different viruses vary greatly, ranging from direct damage to inner ear structures, including inner ear hair cells and organ of Corti (as seen in some of the classically described causes of viral hearing loss such as measles), to induction of host immune-mediated damage (Table 2). Following infections with certain viruses, hearing loss can be reversed or limited by appropriate antiviral therapy. Effective vaccines are available for many of the viruses that cause hearing loss, leading to substantial changes in the incidence of these infections and to their prevalence as causes of hearing loss. Although it may seem a daunting task, a working knowledge of the potential viral causes of hearing loss and their treatment is essential to the recognition of these entities and their appropriate management.
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