An EABR paradigm for assessing inner ear malformations in cochlear implantation

BACKGROUND: Children with prelingual profound sensorineural hearing loss (SNHL) and inner ear malformations (IEM), including cochleovestibular nerve anomalies, present complex and challenging cases during cochlear implantation. Intraoperative objective assessments, such as the electric auditory brainstem response (eABR), provide crucial information on auditory pathway integrity during surgery. AIMS/OBJECTIVES: To evaluate a novel intraoperative eABR paradigm in children with IEM and compare the findings with those from children with normal inner ear anatomy. MATERIAL AND METHODS: Nineteen cochlear implant candidates (11 with IEM, 8 with normal anatomy) underwent implantation following comprehensive preoperative imaging and audiological evaluation. Under general anesthesia, intraoperative eABR was recorded using three stimulation paradigms, namely: external promontory (ePEABR), internal promontory (iPEABR), and intracochlear (iEABR). The presence, latency, amplitude, and threshold of Waves III and V were analyzed. RESULTS: ePEABR responses were observed in 45.5% of IEM and 37.5% of normal cases, with elevated thresholds and frequent artifacts. iPEABR responses were detected in all patients, showing consistent latency patterns. iEABR elicited robust responses in all pateints. Latencies shortened and amplitudes increased as stimulation approached the cochlear nerve. CONCLUSIONS AND SIGNIFICANCE: Intraoperative iPEABR is feasible and provides valuable objective information on auditory pathway function in children with IEM, supporting surgical decision-making during cochlear implantation.