Cochlear Implantation of Slim Pre-curved Arrays using Automatic Pre-operative Insertion Plans

TL;DR

This study evaluates a novel automated pre-operative planning system for cochlear implant electrode insertion, showing trends toward improved positioning and reduced variability in electrode placement within the cochlea.

Contribution

First evaluation of a patient-specific automated insertion planning system for slim pre-curved cochlear implant electrodes, demonstrating potential improvements in electrode positioning.

Findings

No scalar translocations or folds in experimental insertions with planning

Reduced variability in mean modiolar distance when planned insertion depth was achieved

Trend toward better electrode positioning within scala tympani with planning

Abstract

Hypothesis: Pre-operative cochlear implant (CI) electrode array (EL) insertion plans created by automated image analysis methods can improve positioning of slim pre-curved EL. Background: This study represents the first evaluation of a system for patient-customized EL insertion planning for a slim pre-curved EL. Methods: Twenty-one temporal bone specimens were divided into experimental and control groups and underwent cochlear implantation. For the control group, the surgeon performed a traditional insertion without an insertion plan. For the experimental group, customized insertion plans guided entry site, trajectory, curl direction, and base insertion depth. An additional 35 clinical insertions from the same surgeon were analyzed, 7 of which were conducted using the insertion plans. EL positioning was analyzed using post-operative imaging auto-segmentation techniques, allowing measurement of angular insertion depth (AID), mean modiolar distance (MMD), and scalar position. Results: In the cadaveric temporal bones, 3 scalar translocations, including 2 foldovers, occurred in 14 control group insertions. In the clinical insertions, translocations occurred in 2 of 28 control cases. No translocations or folds occurred in the 7 experimental temporal bone and the 7 experimental clinical insertions. Among the non-translocated cases, overall AID and MMD were 401(41) degrees and 0.34(0.13) mm for the control insertions. AID and MMD for the experimental insertions were 424(43) degrees and 0.34(0.09) mm overall and were 432(19) and 0.30(0.07) mm for cases where the planned insertion depth was achieved. Conclusions: Trends toward improved EL positioning within scala tympani were observed when EL insertion plans are used. Variability in MMD was significantly reduced (0.07mm vs 0.13 mm, p=0.039) when the planned depth was achieved.