Development of a system for intraoperative real-time monitoring of the insertion progress during cochlear implantation by measuring facial nerve stimulation

The insertion of the electrode array of a cochlear implant (CI) represents a "black box". There are approaches to measure the progress of insertion by means of continuous measurement of impedances, eCAPs or by ECochG . The spatial resolution of these methods is not very high, they are rather used to check implant function or residual hearing. The aim of the study was to use intracochlear facial nerve stimulation to demonstrate the progress of insertion

For this purpose, a system was developed to stimulate the facial nerve during the insertion process intracochlearly in an electrode-specific manner. The system was evaluated intraoperatively in 20 subjects during cochlear implantation. During insertion, stimulation was performed on the most apical contact of the electrode array. After successful insertion, a profile of all contacts was generated. The electromyogram (EMG) was recorded using needle electrodes.

During the insertion procedure, an increase in the EMG and a decrease in its further course could be shown, which can be explained by the approximation and distancing of the stimulating contact from the facial nerve. The profile showed a peak in the area of the contacts that showed the greatest proximity to the facial nerve in postoperative radiological imaging.

By means of intracochlear measurement of intracochlear facial nerve stimulation, a system was developed to display the insertion progress with high spatial resolution. Further investigations are necessary to determine the ideal stimulation intensity, which can then further increase the accuracy of the measurements. In addition, the system can be combined with a preoperative determination of the electrode contact, which should be located closest to the facial nerve and be used as a steering instrument.

Poster-PDF A-1138.pdf

Publication History

Article published online:
13 May 2021