AIDS and Hearing
The human immunodeficiency virus (HIV) has been identified as the virus that causes acquired immunodeficiency syndrome (AIDS). The terms HIV and AIDS, while familiar to most, are often mistakenly used interchangeably. HIV refers to the specific virus that infects a particular group of immune cells. Many HIV-infected individuals maintain normal immune cell counts and remain asymptomatic for long periods of time. These individuals do not meet the clinical definition of AIDS. In the event the virus infects more and more cells, the HIV-infected individual's immune cell counts decrease, resulting in the reduced ability to effectively fight off infection and disease. Once an infected individual's immune cell count declines to a certain level and/or the individual develops a specific disease condition (i.e. pneumonia), the individual meets the category of AIDS. In other words, HIV infected individuals do not necessarily have AIDS, however, a person with AIDS is always infected with HIV.
In terms of the auditory system, audiological changes may occur either as a direct or indirect consequence of HIV infection. HIV maintains a preferential affinity to the central nervous system. While the exact mechanisms for HIV infection is poorly understood, central pathology associated with abnormal auditory evoked potentials represents one of the few audiological manifestations directly attributable to HIV infection, particularly for those who have progressed to AIDS.
Indirectly, changes in hearing are mainly attributable to two factors: opportunistic infections and ototoxicity. Opportunistic infections (OI) originate from commonplace, ubiquitous organisms that do not cause infection in healthy individuals, but take the opportunity to infect individuals with weakened immune systems. The most common OIs associated with this patient population, including but not limited to cytomegalovirus, toxoplasmosis, and syphilis, are associated with the development of hearing loss, regardless of an individual's HIV status.
In the absence of a vaccine, the medical management of HIV relies on numerous pharmacological interventions including anti-retrovirals drugs designed to target HIV and a variety of other drugs designed to treat OIs. The potential for a drug-induced hearing loss for patients at any stage of HIV-infection is relatively high, particularly since many of the medications prescribed to treat OIs are known to be ototoxic.
For a comprehensive review of HIV/AIDS and the auditory system, the reader is referred to the special issue of Seminars in Hearing (1998), Volume 19, Number 2, Audiological Considerations of HIV and AIDS.