PP508 - Auditory Brainstem Response Findings in Tinnitus Perception During Silence

Abstract:
This study examined the emergence of temporary tinnitus perceptions during exposure to a brief period of silence in 60 normal-hearing female participants and the presence of any concomitant subclinical changes in the auditory system associated with these perceptions using auditory brainstem response (ABR). Results revealed that 55% of the participants in the current study perceived tinnitus sounds within the first five minutes of silence exposure in the absence of directed auditory attention. No statistically significant differences in ABR I, III, and V absolute and interpeak latencies, and amplitude were observed between tinnitus and non-tinnitus perceiving groups.

Summary:

Rationale:
Silent environments have been recognized as a significant trigger for the emergence of transient tinnitus perceptions in individuals without prior tinnitus-related complaints (Del Bo et al., 2008; Heller & Bergman, 1953; Knobel & Sanchez, 2008; Tucker et al., 2005; Abdrabbou & Tucker, 2021). Brief periods of auditory deprivation can be induced by circumstances such as earplug use or staying in a sound booth for a short time. Such situations have been shown to influence the Central Auditory Nervous System (CANS) in a manner akin to the effects observed in hearing loss, resulting in temporary tinnitus (Møller et al., 2011; Schaette et al., 2012). Interestingly, tinnitus perception during silence has been associated with increased subcortical neural activity, as evidenced by Larger Auditory Middle-Latency Response (AMLR) waveform amplitude, both before and after exposure to silence (Abdrabbou & Tucker, 2021). This increased spontaneous neural activity among individuals experiencing tinnitus could signify decreased input from the peripheral auditory system before exposure to silence, aligning with the central gain hypothesis (Jastreboff, 1990). In light of these observations, the ABR emerges as a valuable tool for evaluating the function and integrity of the auditory nerve and auditory brainstem functions. This study aims to examine ABR waveforms in normal hearing subjects with and without tinnitus perception during silence.

Design:
This study examined ABR waveforms in 60 female participants aged 18- 40 years categorizing them based on whether they experienced tinnitus or not during silence. Inclusion criteria required normal hearing sensitivity (air conduction thresholds < 25 dB from 250 to 8,000 Hz); normal tympanogram (peaks within -100 and +100 dapa); no history of chronic tinnitus; and no history of head trauma, neurologic disease, or ear surgery. ABR recordings were obtained from the right ear before a ten-minute silence exposure and ANOVA analysis was utilized to examine baseline ABR waveform latency and amplitude to tinnitus and non-tinnitus perceiving groups before silence exposure.

Results:
Results revealed that 55% of the participants perceived tinnitus sounds within the first five minutes of silence exposure. ANOVA statistical analysis revealed no statistically significant differences in the baseline ABR wave I, III, and V absolute latencies, interpeak latencies (I-III, III-V, and I-V) between tinnitus and non-tinnitus perceiving groups (0.33, 𝜌 = 0.85). Additionally, there were no statistically significant differences in ABR wave I, V, or V/1 amplitude ratio between the two groups (0.41, 𝜌 = 0.75).

Conclusion:
This present study further documents the connection between silence and the emergence of tinnitus in normal-hearing individuals after exposure to silence. This study revealed that the self-perceived presence or absence of tinnitus before silence exposure was not associated with discernible differences in ABR measures. This suggests that the underlying auditory nerve and brainstem functions, as captured by these ABR parameters, do not seem to be the primary factors contributing to the perception of tinnitus during silence. Further research is necessary to further enhance our understanding of the mechanisms responsible for this intriguing phenomenon.