Prediction accuracy of cochlear implant electrode insertion depth using a software program

Introduction

The conservative insertion of the cochlear implant (CI) electrode array is important today, not only in hearing preserving approaches. The planning of the insertion depth and subsequently the choice of the appropriate electrode array length is important. To facilitate this, a preoperative measurement of the cochlea is available. The aim of this retrospective study is to evaluate whether the OTOPLAN software can be used to reliably predict the postoperative electrode position.

Method

To date, 8 patients who received a Cochlearimplant from 2018 until today and for whom DICOM preoperative computed tomography (CT) and postoperative digital volume tomography (DVT) datasets were available were included. The preoperative electrode insertion angle of electrodes 1, 6, and 12 was determined using OTOPLAN (Cascination Company) and compared with the angle value measured on the postoperative DVT.

Results

The predicted values for electrode contacts 1, 6, and 12 differed on average by 54° (min:22°; max:161°), 23° (min:1°; max:90°), and 30° (min:18°; max: 39°) from those measured postoperatively, which corresponded to a length of 2.0mm (min:0.1mm; max:3.7mm), 0.8mm (min:0.3mm; max:1.4mm), and 2.1mm (min:1.2mm; max:2.9mm), respectively. The corresponding intracochlear assigned frequency for the three electrode points varied by 100Hz, 269Hz and 3355Hz, respectively.

Discussion

Prediction of electrode array insertion depth is possible with the help of the software used, so preoperative electrode selection can succeed based on CT-Dicom data. Future studies must show whether the predicted frequency-specific allocation, e.g. concerning hearing preservation, can also be audiologically proven.

Publication History

Article published online:
24 May 2022