Monitoring the Cochlea with Intracochlear Electrocochleography During Cochlear Implantation in Pediatric Patients: Setup, Electrocochleography Patterns and Intraoperative Findings

Background/Objectives: Intracochlear electrocochleography (ECochG) is increasingly used to monitor cochlear function during cochlear implantation, particularly in patients with residual hearing. However, optimal acquisition parameters and interpretation of intraoperative ECochG patterns remain unclear. To (1) establish optimal stimulation and acquisition parameters for intracochlear ECochG, (2) evaluate the feasibility of signal acquisition in pediatric patients, and (3) characterize intraoperative ECochG response patterns in relation to surgical events. Methods: The study consisted of two phases: an optimization phase (n = 50) and a clinical observational phase (n = 28). In the optimization phase, various stimulation frequencies (500–2000 Hz), recording configurations, and acquisition modes were tested. Based on these findings, a standardized ECochG protocol was developed and applied in the clinical cohort. Results: Optimal ECochG recordings were obtained using 500 Hz and 1500 Hz tone bursts at 100 dB nHL, recorded from the apical electrode contact (ICE22) in continuous mode. In the clinical cohort, ECochG responses were detected in 11/28 patients (39%). Cochlear microphonics were observed even in patients without preoperative evidence of residual hearing. Intraoperative signal fluctuations were temporally associated with specific surgical events, including electrode manipulation and suctioning. Conclusions: Intracochlear ECochG enables real-time monitoring of cochlear function during implantation. However, interpretation of signal changes remains complex and requires standardized protocols as well as careful consideration of the surgical context.