(805) Accuracy Of OTOPLAN For Preoperative Cochlear Parameter Measurements And Electrode Visualization

Introduction: Preoperative measurements of cochlear parameters allow for individualized patient-specific surgical and cochlear implant electrode planning. When taking patient anatomy and residual hearing into consideration, the accuracy of preoperative estimates is more critical to optimal outcomes. The aim of the current study was to assess the accuracy of OTOPLAN for cochlear parameter measurements and preoperative electrode visualization for angular insertion depth estimation.

Methods: Thirty-one ears were implanted with MEDEL cochlear implants via the round window. Patients undergoing revision, those with congenital anomalies, and those with intracochlear ossification or fibrosis were excluded. OTOPLAN analysis was performed on all pre-operative scans to estimate cochlear duct lengths (CDL). Using these calculations, angular insertion depth (AID) was estimated for various electrode lengths. All patients underwent postoperative CT imaging with CDL estimates. Final electrode positioning was confirmed by postoperative CT and compared to preoperative estimates for implanted electrodes. The corresponding frequency for the apical-most contact was estimated at the spiral ganglion.

Results: All thirty-one ears were successfully implanted via round window insertions. There were no intraoperative or postsurgical complications. The mean preoperative CDL estimate was 32.0 mm (95% CI [ 31.2, 32.6]), and the mean postoperative CDL estimate was 32.4 mm (95% CI [ 31.6, 33.1]) (p=0.45). The mean preoperative angular insertion depth estimate based on the selected electrode was 614.6 degrees (95% CI [ 600.3, 629.0]), and the mean postoperative measured angular insertion depth was 600.0 degrees (95% CI [ 572.3, 626.1]). The mean absolute difference between preoperative AID estimates and postoperative electrode AID was 54.8 degrees (95% CI [40.9, 68.7]) (p=0.35). The mean frequency at the apical-most contact was 215 Hz.

Conclusions: Preoperative cochlear duct length and angular insertion depth estimates with OTOPLAN are accurate and can inform individualized, patient-centered surgical decision making.