PP1006 - Auditory Brainstem Response in Young Adults Post-COVID-19 Infection

Abstract:
Audiologic symptoms of COVID-19 suggest damage to the auditory system. The present study evaluated the effects of COVID-19 on younger adults (21-41 years) with typical hearing. Single channel (Cz-M1/M2) Auditory Brainstem Response (ABR) was acquired in thirteen participants using an alternating, 75 dB nHL click stimulus, at two rates (27.7/s; 81.1/s) with filters from 30-1500 Hz, repeated and summed for ≥2000 sweeps per condition. Preliminary results revealed interaural morphological differences for fast rate, supporting possible early functional differences. Descriptive and analytical statistics will compare ABR latency, amplitude, and waveform morphology to normative values for clinical implications.

Summary
Rationale:
In 2019, SARS-CoV-2 (COVID-19) was declared a public health emergency. Clinical symptoms typically included cough, fatigue, and loss of taste and smell. Audiologic symptoms include tinnitus, aural fullness, and hearing loss, suggesting damage to the auditory system. Early case reports about central auditory effects of COVID-19 in adults included Auditory Brainstem Response (ABR) results that were different from normative values. Fewer studies have focused on younger adults with typical hearing pre-COVID to assess any potential changes in ABR latency, amplitude, and waveform morphology.

Purpose:
The current study examined the effect of COVID-19 on the central auditory system using the ABR of young adults with normal hearing sensitivity. Research questions explored whether ABR measures in participants who had COVID-19 were different from respective normative values for:1) ABR acquired with two stimulus rates, 2) Absolute/interpeak latencies of waves I, III and V, 3) the V/I amplitude ratio, and 4) ABR waveform morphology.

Design:
A cohort study of 13 participants, mean age 25.2 years (8 female, 5 male) who reported a previous positive COVID-19 test were evaluated. ABRs were compared to normative values from healthy adults. All participants completed a survey detailing previous COVID-19 experiences, medical diagnoses, current medications, and hearing/communication difficulties, and passed a pure tone air conduction screening test at 20 dB HL at .5, 1, 2, 4 kHz using headphones. Single channel (Cz-M1/M2) ABR was acquired using the Intelligent Hearing Systems (IHS) Smart EP unit inside a sound-treated booth. Monaural ABR acquisition utilized an alternating click stimulus at 75 dB nHL at two stimulus rates (27.7/s; 81.1/s). Stimuli were presented in counterbalanced order using 1,000 sweeps through amplifiers set to filter activity between high pass (30 Hz) and low pass (1500 Hz) settings. Waveforms were repeated to determine reliability, then summed for ≥2000 sweeps per condition, yielding 4 total waveforms per participant.

Data management included waveform analysis (absolute and interpeak I, III, V latencies, I/V amplitude ratio, and morphology) using IHS SmartEP software. Expected latency ranges were used for reference when identifying peaks; alternative rules were applied if morphology was unclear. Statistically significant differences will be determined using T-tests and ANOVA.

Results:
Data analysis is underway. Waveform analysis from all conditions reflects interesting differences. Notable interaural morphological differences for the fast stimulus rate (81.1/s) suggest unexpected neurophysiological changes in the central auditory system of young adults who had COVID-19 without affecting peripheral hearing ability. Preliminary results support possible early functional differences in the auditory pathways. Additional results will be reported for complete descriptive and analytical statistics, including T-tests and ANOVA for latency and amplitude ratio differences. Clinical implications will be highlighted.

Conclusion:
Differences are present in the ABR morphology of young, typically hearing individuals who had COVID-19. Ongoing analysis will determine statistically significant differences compared to individuals without COVID-19 history. Clinical implications will be discussed including recommendations for ABR interpretation and possible long-term effects of COVID-19 diagnosis.

Brief Summary of Clinical Takeaways:
The clinical takeaway for this session includes recommendations for ABR interpretation in patients with previous COVID-19 diagnosis and normal hearing.

Assumptions:
Attendees should have an understanding of typical ABR responses for young adults with normal hearing. In addition, knowledge of ABR waveform morphology and latency, and amplitude norms would assist in understanding the current study findings.