Hearing complaints in HIV infection originate in the brain not the ear.

Abstract

Evidence suggests damage to brain auditory pathways, rather than inner ear damage, underlies the hearing difficulties HIV+ individuals report. But, antiretroviral therapy (ART) may affect the hearing system and also lead to hearing complaints. Longitudinal study of HIV+ and HIV- individuals in Dar es Salaam Tanzania. A subset of this cohort started ART while in the study allowing the effects of ART to be studied directly. The ability to hear quiet sounds (pure-tone audiometry), cochlear outer hair cell function [distortion-product otoacoustic emissions (DPOAEs)], and gaps-in-noise detection thresholds (a central auditory processing test) were assessed at each visit. Visits were scheduled for 6-month intervals, but the number and spacing of visits varied. In the group that started ART while in the study, 107 HIV+ individuals had audiometric thresholds, 98 had DPOAEs, and 98 had gap measurements suitable for analysis. Data were analyzed using a linear mixed model with time and starting ART as fixed effects and individual participant repeated measures as random effects. Starting ART did not affect audiometric or gap detection thresholds. The slope of the DPOAE amplitude vs. time relationship was more negative after starting ART but did not differ from the HIV- group. Gap thresholds were higher in the HIV+ group. ART did not affect audiometric thresholds significantly suggesting common ART drugs are not major ototoxins. The gap detection results from the study show effects on central auditory processing in HIV+ individuals, supporting the origin of HIV-related hearing complaints in the central auditory system.