A Comparison of ECochG With the Subjective Sound Perception During Cochlear Implantation Under Local Anesthesia-A Case Series Study

Objective: Intraoperative electrocochleography (ECochG) has been proposed for cochlear monitoring to minimize trauma during the insertion of the electrode of a cochlear implant (CI). CI surgery is normally performed under general anesthesia, which is why intraoperative ECochG measurements have never been validated against the patient's subjective sound perception. The main objectives of this study were to investigate the feasibility of cochlear monitoring based on the patients hearing and to validate it against intraoperative ECochG measurements during CI surgery under local anesthesia. Study Design: Prospective case series study. Setting: Tertiary referral center. Patients: Patients eligible for cochlear implantation with residual hearing (pure-tone threshold averages [PTA] 2501000 Hz <= 75 dB HL). Additionally, patients should be able to hear ECochG stimuli at 250, 500, or 1000 Hz at less than or equal to 100 dB (HL). Interventions: Cochlear implantation under local anesthesia without conscious sedation. Intraoperative ECochG monitoring. Main Outcome Measures: The development of ECochG amplitudes and the patients' subjective perception to the sound stimuli. Results: In all patients, monitoring based on their subjective sound perception was feasible, whereas, reliable ECochG responses could be measured in seven patients. Sixty percent of the registered declines in ECochG amplitude were associated with a concomitant attenuation of the subjectively perceived sound. Conclusions: The developments in the ECochG responses matched well with the changes of the sound stimulus perceived by the patients, which supports the applicability of ECochG for preventing insertion trauma. Monitoring of the patients subjective hearing appears to be more reliable than ECochG but requires surgery under local anesthesia without conscious sedation.