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Assessing the Significance of Abnormal Inserted Perimodiolar Slim Electrodes: Perception and Management Strategies
Phoebe Helena Ramos1,2,3, Aaron Collins4, Jean-Marc Gerard4,5
1Department of Otolaryngology of the University of Melbourne, Melbourne, Victoria, Australia, phoeberamos@gmail.com.
Audiology & Neuro-Otology
|October 31, 2025
Summary
Abnormal slim perimodiolar electrode (PSE) placement in cochlear implants is rare but linked to worse speech perception. Surgeons should check electrode shape during surgery to improve hearing outcomes.
Area of Science:
- Otolaryngology
- Neurosurgery
- Medical Imaging
Background:
- Slim perimodiolar electrodes (PSEs) aim for optimal cochlear proximity.
- Deviations in PSE placement can negatively impact speech perception outcomes.
- This study evaluates the incidence, imaging characteristics, and hearing results of abnormally positioned PSEs.
Purpose of the Study:
- To determine the prevalence and radiologic features of abnormal PSE positioning.
- To assess the impact of abnormal PSE positioning on speech perception.
- To propose intraoperative strategies for managing PSE placement.
Main Methods:
- Retrospective review of 239 adult cochlear implant patients with PSEs.
- Analysis of postoperative CT scans to identify electrode position using metrics like angular insertion depth (AID), intracochlear position index (ICPI), and wrapping factor (WF).
- Comparison of speech perception scores at 3 and 12 months with a reference cohort.
Main Results:
- Abnormal PSE positioning was found in 3% of cases, characterized by shallower insertions, increased lateralization, and higher WF.
- Patients with abnormal PSE positioning showed significantly lower speech perception scores at 3 and 12 months compared to controls.
- Intraoperative X-rays failed to detect these abnormal electrode positions.
Conclusions:
- While uncommon, abnormal PSE placement significantly impairs speech perception.
- Intraoperative assessment of electrode configuration and potential reinsertion are crucial.
- Postoperative CT scans are vital for quality control, and intraoperative strategies are needed to prevent lateralization and enhance outcomes.
