Long-term effects of zika virus infection on sound processing in the brain

The Zika virus is known to be neurotropic. While the effect of the Zika virus on the central nervous system (CNS) of children is well studied, the effects in adults are less well understood. New studies show that in adults the virus can affect cranial nerves as well as cause a meningoencephalitis. This suggests that the Zika virus could affect the auditory nerve and central auditory pathways as well as the cochlea. This is supported by case studies of hearing loss during acute Zika infection. At present, however, the long-term effects of Zika infection on either the peripheral and central hearing system are unknown. Previous work has shown that chronic viral infections involving the central nervous system can lead to persistent central auditory processing deficits. Interpreting speech in noise and detecting gaps in noise are demanding central nervous tasks involving multiple brain areas. Deficits in central auditory abilities can result from viral damage to the CNS. It has recently been demonstrated that patients with HIV often have signs of a central auditory deficit as evidenced by difficulty in understanding speech, and detecting gaps, presented in noise. Electrophysiological testing using the frequency following response (FFR) also shows changes consistent with difficulties with central auditory processing. These auditory deficits likely reflect the effect of HIV infection and/or treatment on the CNS because they correlate with performance on other tests of CNS function (e.g. neurocognitive screening tests). Also, these studies indicate that tests of central auditory processing can serve as a “window” into CNS function in HIV+ individuals. What is not known, however, is whether this might be true for Zika infection as well. The present study will use tests of both peripheral (audiometry, distortion product otoacoustic emissions) and central (speech-in-noise, triple-digit, gap detection, duration pattern, frequency-following response) hearing in a cohort of m