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Updated: Feb 18, 2026
Author Spotlight: Advancements in Impedance Monitoring for Cochlear Implant Surgery
Published on: August 4, 2023
Electrode Impedance Fluctuations as a Biomarker for Inner Ear Pathology After Cochlear Implantation
June Choi1, Matthew R Payne, Luke J Campbell
1*Department of Otolaryngology †Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ‡Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea §The HEARing CRC, Carlton, Australia.
Objectives/Hypothesis:
Cochlear implant surgery now aims to preserve residual low frequency hearing. The current research explores whether fluctuations in the electrical impedance of cochlear implant electrodes may act as a biomarker for pathological changes that lead to the delayed loss of residual hearing.
Study Design:
Secondary analysis of a double-blinded randomized trial, where methylprednisolone was administered intravenously before cochlear implantation with a view to preserving residual hearing.
Methods:
Seventy-four patients with residual hearing after cochlear implant surgery were investigated for an impedance "spike," defined as a median rise of ≥4 kΩ across all electrodes from the baseline measurements. Spikes were related to objective and subjective hearing loss, dizziness, and tinnitus.
Results:
An impedance spike occurred in 14% (10/74) of enrolled patients. Three months after surgery, five patients exhibited spikes and three of these patients had a total loss of their residual hearing. 4.3% of the 69 patients without spikes lost residual hearing. At 1 year, 9 of 10 patients who exhibited spikes had lost all their residual hearing. 8.1% of the 37 patients who did not experience a spike lost their residual hearing. Seventy percent of patients exhibiting a spike also experienced vertigo. The administration of steroids at the time of surgery did not influence the occurrence of spikes.
Conclusion:
Our results suggest that there is a relationship between a spike and the loss of residual hearing. It seems that rises in impedance can reflect pathology within the inner ear and predict the future loss of residual hearing.
