Cochlear Implantation of Slim Precurved Arrays Using Automatic Preoperative Insertion Plans.

Hypothesis: Preoperative cochlear implant (CI) electrode array (EL) insertion plans created by automated image analysis methods can improve positioning of slim precurved EL.

Background: This study represents the first evaluation of a system for patient-customized EL insertion planning for a slim precurved 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 postoperative imaging auto-segmentation techniques, allowing measurement of angular insertion depth (AID), mean modiolar distance (MMD), and scalar position.

Results: In the cadaveric temporal bones, three scalar translocations, including two 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 seven experimental temporal bone and the seven experimental clinical insertions. Among the nontranslocated 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 degrees 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 (0.07 versus 0.13 mm, p = 0.039) when the planned depth was achieved.