A method to visualize orientation-independent forces in real-time during cochlear implant electrode array insertion

Introduction 

As cochlear implants are increasingly used for patients with residual hearing, atraumatic insertion of the electrode array (EA) is essential. Insertion forces are considered a risk factor for intracochlear trauma, but their evaluation is limited by the surgeon’s abilities of force perception at the fingertips. We recently developed a hand-held tool to enable measurement of insertion forces. Herein, we describe a solution how to process and visualize the measured data to the surgeon in real-time.

Materials and Methods 

The insertion tool was designed around a small 1D force sensor and equipped with an inertial measurement unit (IMU) in order to remove an orientation-dependent error from the force signal caused by the weight of the electrode holder, the sensor, and the EA. A custom-made software was developed and implemented to process and visualize measured data. To enable real-time performance, the programming language C+ + was used in combination with the framework Qt.

Results 

The developed algorithm fuses the force and IMU signal and calculates a corrected force which is almost fully freed from orientation-dependent errors. The corrected force is visualized as a continuously updated graph over the last 8 seconds. This graph is displayed on an external monitor with a frequency of 50 Hz.

Conclusion 

The presented software and hardware will enable intraoperative monitoring of the applied insertion forces during the EA insertion. To provide user-friendly feedback, visualization of the measured forces directly inside the surgeon’s field of view is intended. The visualization with Qt allows cross-platform development and is also suitable for embedded devices.

German Federal Ministry of Education and Research – Project: OtoTrak, Grant no.: 13GW0367B

Publication History

Article published online:
24 May 2022