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Updated: Oct 26, 2026
Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation
Published on: August 4, 2023
Incidence and Clinical Course of Intraoperative Impedance Abnormalities in Cochlear Implantation
Yoshinori Fujiwara1, Nozomu Matsumoto, Noritaka Komune
1Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Objective:
To investigate the incidence, characteristics, and postoperative course of intraoperative impedance abnormalities during cochlear implant (CI) surgery, with particular attention to features associated with persistent abnormalities.
Study Design:
Retrospective observational study.
Setting:
Tertiary referral university hospital.
Patients:
A total of 324 cochlear implantations were performed between March 2000 and March 2025 with available intraoperative and postoperative impedance measurements.
Interventions:
Cochlear implantation with intraoperative and postoperative electrode impedance measurements.
Main Outcome Measures:
Incidence of intraoperative impedance abnormalities, time to normalization, postoperative persistence, and device-related differences.
Results:
Intraoperative impedance abnormalities were detected in 27 of 324 devices (8.3%), involving 102 of 7128 electrode contacts (1.4%). OCs were identified in 25 devices involving 98 electrode contacts, whereas SCs were identified in 2 devices involving 4 electrode contacts. All 12 devices with complete intraoperative resolution had OCs, and all 83 contacts with documented intraoperative normalization were OCs. Among these 83 OC contacts, 80 (96%) were first recorded as normal within 11 minutes. Among the 25 devices with OCs, persistent abnormalities were more frequent in devices with ≤2 affected contacts (66.7%) than in those with ≥3 affected contacts (14.3%) (OR: 12.0; 95% CI: 1.16-123.7; P=0.030). The incidence of abnormalities was higher in the slim modiolar electrode (SME) arrays (8.1%) than in the non-SME arrays (2.8%) (OR: 3.04; 95% CI: 1.05-8.79; P=0.048).
Conclusion:
Most OCs that normalized intraoperatively were first recorded as normal within 11 minutes. OCs persisting beyond this interval may persist postoperatively. Careful monitoring is warranted for SME devices, while decisions regarding device verification or replacement should be made cautiously and require further validation.
