Monitoring of the Inner Ear Function During and After Cochlear Implant Insertion Using Electrocochleography.
Sabine Haumann, Marina Imsiecke, Günther Bauernfeind and 4 others
PMID 30909815WHAT IT FOUND
In 10 CI users, intracochlear electrocochleography matched hearing thresholds well post-surgery but failed to predict delayed hearing loss.
Extracochlear recordings were faster for intraoperative use but correlated poorly with final outcomes, meaning neither method reliably forecasts residual hearing preservation.
Key findings
01Intracochlear electrocochleography thresholds correlated strongly with pure tone audiometry when measured at the same postoperative appointment, suggesting potential for objective hearing estimation during fitting.
02Neither extracochlear nor intracochlear intraoperative recordings predicted the deterioration of residual hearing that occurred after surgery.
03Extracochlear recordings were faster and suitable for intraoperative monitoring, but correlations with postoperative hearing outcomes were weak or non-existent.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study included only 10 subjects, making it a very small pilot with limited generalizability. The study was not designed to test a specific intervention for hearing preservation, but rather to evaluate monitoring tools. Intraoperative EC recordings were kept short (10 averages) to save anesthesia time, which may have reduced signal quality compared to postoperative recordings (100 averages). The study did not find a reliable way to predict post-operative hearing loss, which remains a major clinical challenge.
Declared interests
Funding was provided by the Deutsche Forschungsgemeinschaft. The authors used MED-EL implants and research tools, but no direct corporate funding or conflicts of interest involving MED-EL were explicitly declared in the provided text beyond the use of their equipment.
The easy way to misread this
Do not assume that normal intraoperative ECochG responses guarantee preserved hearing. The study found that hearing often deteriorated after surgery despite good intraoperative signals, meaning these tools currently cannot predict final outcomes.