Clinical Utility of Intraoperative Electrocochleography (ECochG) During Cochlear Implantation: A Systematic Review and Quantitative Analysis

Objective: To evaluate the utility of intraoperative electrocochleography (ECochG) as a predictive tool for preservation of residual acoustic hearing after cochlear implantation. Data Sources: A systematic review employing a multi-database search strategy (Ovid MEDLINE, Embase, EBM Cochrane, and Scopus) was conducted from inception to August 1, 2019. English language studies in humans were included. Study Selection: All articles were independently reviewed by two authors according to Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) guidelines. Studies without intraoperative ECochG obtained during cochlear implantation were excluded. Data Extraction: Extracted variables included number of patients, ECochG recording technique, success rate of obtaining ECochG potentials, intraoperative changes in ECochG signal, and postoperative hearing preservation outcomes. Data Synthesis: Among 537 eligible articles, 22 met inclusion criteria encompassing 498 unique patients. Ten studies featured extracochlear measurements, eight featured intracochlear measurements, and four featured both. Extracochlear ECochG had an average (SD) recording success rate of 94.9% (12.7%) while intracochlear ECochG had an average (SD) recording success rate of 91.8% (9.8%). One hundred forty five unique patients from six studies had complete intraoperative ECochG data with postoperative behavioral audiometry. After accounting for study-specific definitions of ECochG signal disturbance, worsening changes in intraoperative ECochG signal predicted postoperative hearing loss with limited sensitivity and specificity and notable heterogeneity across studies. Conclusions: Intraoperative ECochG recordings can be obtained in over 90% of patients, but accuracy in predicting postoperative hearing loss remains limited. Standardization of intraoperative ECochG monitoring technique and data interpretation are necessary to more robustly investigate outcomes and refine technique.