Auditory steady-state responses to low-level stimuli in children with auditory neuropathy: case series and...

To present a pattern of low-level auditory steady-state response (ASSR) findings that are discordant with auditory brainstem response (ABR) findings, in children with auditory neuropathy (AN), and discuss the potential origins hereof.

This case series presents four examples of AN with ASSRs elicited by low-level stimuli (<50 dB HL uncorrected).

Four children diagnosed with AN, aged 3 weeks to 33 months of age.

In one case, the cochlear nerve was absent, and in another, equivalent latency calculations identified the ASSR's origin as pre-neural. By systematic elimination and review of empirical evidence, the summating potential (SP) is postulated to be the source of the ASSRs. In AN cases without functional neural input, the SP is particularly dominant. The SP's ability to track temporal stimulus changes likely generates periodic electrical responses that are identified by ASSR objective response detection algorithms.

Albeit rare, these findings underscore the necessity of incorporating ABR as foundational in AEP threshold estimation. Predicting hearing thresholds in individuals with AN based on ASSR findings is unreliable. ASSR thresholds may be elevated, or alternatively, as our case series shows, ASSR may detect pre-neural cochlear activity at stimulus levels unrelated to actual behavioural hearing thresholds.