Direct recording of electrically-evoked auditory brainstem responses (CI-eABR) using Advanced Bionics cochlear implants: a feasibility study

Electrically-evoked auditory brainstem responses (eABRs) provide an objective measure of auditory pathway function, reflecting neural activity in the auditory nerve and brainstem. To date, eABRs have been predominantly acquired using conventional electrophysiological (EP) systems with far-field scalp electrodes, which require separate recording hardware and may limit clinical applicability. An integrated framework enabling direct recording through the cochlear implant (CI) system could overcome these limitations and support streamlined objective assessment. This study evaluates the clinical feasibility of direct cochlear implant–based eABR recording (CI-eABR) using the Advanced Bionics system. A prototype interface was developed to acquire eABRs via intracochlear electrodes using implant-based back telemetry, enabling synchronized bilateral recordings with stimulation from a single implant. Recordings were obtained from engineering test bench, and from CI users with a subset compared to conventional scalp recordings. Bench testing demonstrated stable acquisition, effective artifact rejection, and reliable waveform extraction. In human participants, measurable ipsilateral responses were observed at comfortable levels, with peak latencies within expected ranges. In subjects with scalp recordings, strong agreement in waveform morphology and latency was observed, with CI-eABR showing larger amplitudes consistent with near-field recording. These findings support the feasibility of direct implant-based eABR recording and represent a step toward rapid, clinically applicable objective auditory assessment.