Localisation by Impedance

Area of Science:

• Otorhinolaryngology
• Neurosurgery
• Biomedical Engineering

Background:

• Accurate intracochlear electrode placement is crucial for successful cochlear implantation (CI) outcomes.
• Radiographic imaging is the standard for postoperative evaluation, but lacks real-time intraoperative feedback.
• Transimpedance Matrix (TIM) measurements offer a novel approach for real-time intraoperative assessment.

Purpose of the Study:

• To evaluate the accuracy and reliability of Transimpedance Matrix (TIM) measurements for intraoperative assessment of electrode array positioning during cochlear implantation.
• To compare TIM data with radiographic imaging for detecting electrode placement anomalies.
• To investigate the utility of TIM in identifying specific configurations like tip fold-over (TFO).

Main Methods:

• Retrospective observational study of 15 patients (24 ears) undergoing CI with CI532® and CI632® electrode arrays.
• Intraoperative TIM data were collected and compared with intraoperative and immediate postoperative radiographic imaging.
• TIM heatmaps were analyzed for voltage gradient distribution and TFO detection.

Main Results:

• 96% of cochlear implantations showed regular TIM voltage distribution, indicating proper modiolar placement.
• A single instance of tip fold-over (TFO) was accurately identified intraoperatively using TIM and confirmed radiographically.
• TIM findings were concordant with radiological assessments in all other cases, demonstrating high reliability.

Conclusions:

• Transimpedance Matrix (TIM) measurements are a reliable intraoperative tool for cochlear implantation with Slim Modiolar electrode arrays.
• TIM accurately detects electrode placement deviations, enhancing surgical precision and potentially reducing radiation exposure and postoperative imaging.
• Further prospective studies are needed to validate TIM for clinical implementation and establish standardized protocols.