Abstract
Objective: Determine if intraoperative electrocochleography (ECoG) during cochlear implant (CI) surgery provides online feedback to the surgeon to modify surgery and reduce trauma for increasing preservation of residual hearing.
Method: Seventeen adult patients undergoing CI who had measurable auditory thresholds preoperatively in the low- to mid-frequencies were enrolled. Eight subjects had intraoperative compound action potentials (CAPs) measured to assess cochlear function during surgery. In those patients, surgery was modified according to ECoG feedback. Nine subjects performed CI without ECoG feedback.
Results: The average preoperative PTA thresholds (0.25-2 KHz) were 76 ± 9 and 84 ± 12 dBHL in the unmonitored and monitored cohorts, respectively (P > .05). CAPs recording showed latency shift (0.5-1.5msec) and normalized amplitude deterioration (10%-50%) during surgery. All these changes reverted to normal after electrode insertion in all but one subject. The average postoperative PTA threshold shifts (0.25-2 KHz) were 4 ± 2 and 23 ± 11 dBHL in the monitored and unmonitored cohorts, respectively (P = .0022). Complete hearing preservation (loss of ≤10 dB) at 6 months was achieved in 88% (7/8) of subjects who had ECoG feedback and in 33% (3/9) of unmonitored patients.
Conclusion: Monitoring cochlear function with ECoG provides real-time feedback to the surgeon during CI surgery providing objective data to modify his or her surgical technique in ways that can improve the rate of hearing preservation.
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