Neural response patterns in inner ear malformations: a scoping review of eABR findings

Abstract Purpose This scoping review aimed to synthesize current evidence on electrically evoked auditory brainstem responses (eABRs) in individuals with inner ear malformations (IEMs), with a focus on extraction rates, waveform characteristics, and clinical implications. Methods Following PRISMA-ScR and JBI guidelines, a systematic search was conducted in CINAHL, MEDLINE, EMBASE, and PubMed for studies published between January 2005 and June 2025. We included original research articles reporting eABR findings in participants with IEMs. Twenty-one studies met the eligibility criteria. Results eABRs were generally obtainable in children with IEMs, though higher thresholds and lower response detectability were frequently observed compared to peers with normal cochlear anatomy. Certain subtypes, such as common cavity and cochlear nerve canal stenosis, often exhibited elevated thresholds. Despite this, wave latency parameters often remained stable. Among patients with Incomplete Partition Type II (IP-II), eABR detectability varied considerably, indicating that cochlear size alone does not determine neural response strength. Factors such as stimulation site, electrode type, and timing of auditory input influenced eABR outcomes. Conclusion eABR is a useful tool for evaluating auditory pathway integrity in patients with IEMs. Elevated thresholds may reflect reduced neural synchrony, yet stable waveforms suggest retained function. Incorporating both anatomical and functional data may improve clinical interpretation and decision-making.