Brainstem Auditory Evoked Potential in HIV-Positive Adults

Mild hearing loss in C57BL6/J mice after exposure to antiretroviral compounds during gestation and nursing

OBJECTIVE

There is evidence of ototoxicity from antiretrovirals (ARVs), and ARV therapy in pregnant/nursing mothers can expose offspring to these compounds. The current work modelled whether exposure to ARVs in utero and during nursing altered the functioning of the auditory system in offspring mice.

DESIGN

The females of seven breeding pairs of C57BL6/J mice were given daily doses of ARVs lamivudine and tenofovir disoproxil fumarate by oral gavage during gestation and nursing. Three breeder females were given equivalent volumes of water as controls. At wean age (3 weeks after birth), the offspring mice were tested with auditory brainstem responses (ABRs). At the conclusion of the experiment, the offspring mice's cochleae were examined for hair cell counts.

STUDY SAMPLE

Ten breeder female C57BL6/J mice and 69 offspring mice.

RESULTS

The offspring mice exposed to ARVs during development showed higher ABR thresholds than the control offspring. No differences were found in supra-threshold ABRs. There was no evidence of missing hair cells.

CONCLUSIONS

Hearing impairment may be a possible consequence of exposure to ARVs during gestation and development. Because the threshold differences were not large, if they are occurring in humans, it is unlikely they would be identified in any hearing screening tests.

Auditory Brainstem Response Test at Different Stimulus Rates in Normal-Hearing Adults Living With HIV

Purpose The study investigated whether the auditory brainstem response (ABR) at a baseline and at higher repetition rates can detect if neurodegeneration has occurred in adults living with HIV who present with normal behavioral pure-tone thresholds. Method An exploratory research design was used. Forty adults with HIV (80 ears, 57.5% female; M _age = 26.3 years, SD = 3.68) and 20 adults without HIV participated. Phase 1 compared ABR absolute and interwave latencies at a baseline rate. Phase 2 examined the effect of HIV status and category of immunodeficiency on ABR absolute Wave V latency and Wave V latency shift at increased stimulus rates. Analysis included a two-way analysis of variance of the interaction between stimulus rate and HIV status and between CD4+ category and rate, and multiple regression analysis. Results In adults living with HIV, the baseline ABR yielded prolonged Wave III and V absolute latencies and interpeak prolongations in 22.5%. Interaural Wave V latency differences were present in 15% of participants. An additional 15% of ears presented with abnormal Wave V at increased rates. No significant interaction between HIV status and rate in either ear or between CD4+ category and rate was found in either ear (p > .05). Although rate and gender contributed significantly to the prediction of Wave V latency of the rate study (left and right, p < .001), HIV status did not (left and right, p > .05). Conclusions Although the interaction of HIV status and CD4+ with rate was not significant, more ears were identified with abnormal results at increased stimulus rates than with the baseline ABR alone. The ABR at increased rates may therefore be a valuable addition for the identification of individuals living with HIV with auditory neural deficiencies.

Oxidative Stress as a Risk Factor for Hearing Changes in HIV-positive Normal Listeners

OBJECTIVES

Human immunodeficiency virus-positive (HIV+) individuals can experience a decrease in antioxidants. Such deficiency can make inner ear cells and synapses more vulnerable to oxidative stress, resulting in auditory alterations, even in the presence of normal thresholds. This study aims to compare the audiological findings of HIV+ patients (with and without exposure to anti-retroviral treatment) to those of healthy individuals.

METHODS

This was a cross-sectional observational study, comprising 42 normal-hearing adults divided into the Control Group (CG), without HIV; Group I (GI), HIV+, without exposure to the highly active anti-retroviral therapy (HAART); Group II (GII), HIV+, with exposure to HAART. All participants underwent conventional audiometry (0.25-8 kHz), high-frequency audiometry (9-20 kHz), transient evoked otoacoustic emissions (TEOAEs), efferent auditory pathway's inhibitory effect assessment, brainstem auditory evoked potentials (BAEPs), and cognitive potential (P300).

RESULTS

In the comparison of the hearing thresholds between the groups, there was a statistically significant difference for most of the frequencies assessed (GII presented hearing thresholds significantly poor when compared with other groups). The presence of TEOAE and the inhibitory effect was also verified in a significantly higher number of individuals in the CG than in the other groups. As for the BAEP, there was a statistically significant difference for the interpeak intervals I-V (GII showed higher values when compared with CG). For P300, there were no statistically significant differences.

CONCLUSION

Normal-hearing HIV+ individuals (with and without exposure to HAART) presented with poor performance in the audiological procedures, suggesting the presence of auditory alterations even in the presence of normal-hearing thresholds.