Neural Response Telemetry in Pediatric Cochlear Implantation

Abstract

Objective: 1) Evaluate the neural response telemetry (NRT) of patients with inner ear anomalies, and determine correlations between NRT and postoperative speech recognition thresholds (SRT). 2) Determine if higher incidence of negative intraoperative NRT exists in pediatric patients with inner ear anomalies, namely enlarged vestibular aqueduct syndrome (EVAS). Method: Retrospective chart review of pediatric patients who underwent cochlear implantation at a tertiary care pediatric referral center from 2001 to present. Patients with inner ear anomalies were age matched to controls without anomalies. Associations between abnormal NRT and perilymphatic gusher and correlations between NRT and audiometry were assessed. Results: Twenty-seven subjects with radiographic evidence of EVAS were evaluated; 35 ears implanted. Median age of implantation was 77.5 months. NRT was normal in 69%, abnormal 11%, marginal 6%, missing 4%. Intraoperative data revealed a perilymphatic gusher in 8 patients (23%); of which 50% had abnormal NRT compared to 8% among patients without gusher ( P = .03). Postoperative audiometric data were available for 8 out of 35 ears. No significant correlations between intraoperative and postoperative NRT with postoperative SRT at 1 kHz, 2 kHz, 4 kHz ( P > .2). There appeared to be a correlation between intraoperative NRT and postoperative SRT at 500 kHz (ρ = 0.68, P = .14); this was not statistically significant. Conclusion: The presence of perilymphatic gusher at the time of cochlear implantation in patients with enlarged vestibular aqueduct syndrome (EVAS) seems to be related to abnormal NRT. There is no significant correlation between intraoperative and postoperative NRT and speech recognition thresholds (SRT) at 1 kHZ, 2 kHz, and 4 kHz in patients with EVAS.