Audiological Neural Response Telemetry (NRT) role in detection of electrode migration in Cochlear Implantation and assessment of Implant Performance.

This study aimed to detect incidence of electrode migration and effect of this migration on device performance. The study was conducted on one hundred and twenty patients collected from CI program of Wadi EL Neel hospital underwent the operation from 2008 and were in their routine follow up.

The implant device was inserted in a bony bed and the electrode was implanted intra-cochlear through round window approach without any fixation method and covered by fat.

All study patients were subjected to sequence audiological Neural Response Telemetry (NRT) and impedance to each electrode channel and compared with results that were recorded intraoperative. Also all patients were subjected to 2D and 3D reconstruction CT scan to detect the implant device and electrode position

The result showed that five patients (4.1%) were found having a partially migrated basal electrode array on HRCT that were not detected by NRT. Three of them were implanted with the Cochlear Straight array, one patient was implanted with Med-El Standard array and one patient was implanted with Advance Bionics Hifocus 1J array. The number of electrodes outside the cochlea varied from one to three basal electrodes for the Straight array, one basal electrode (No 12) for the Med-El array and one basal electrode (No 16) for the Advance Bionics with no significant affection on device performance.

Conclusion NRT can be useful in follow up detection of electrode stability and alarming for possibility of electrode migration. It could give a general view about mapping of functioning contacts and need for radiological assessment or re-implantation surgery. However, it could not be the only indicator for electrode migration as their results could be inflicted with nonfunctioning contacts of the electrode.

Publication History

Article published online:
24 May 2022