Detection of Extracochlear Electrodes in Cochlear Implants with Electric Field Imaging/Transimpedance Measurements: A Human Cadaver Study.
Simone R de Rijk, Yu C Tam, Robert P Carlyon and 1 others
PMID 31923041WHAT IT FOUND
A new software analysis of cochlear implant voltage readings detected misplaced electrodes in cadavers with 100% accuracy, even when standard impedance tests failed.
It worked in a handful of live patients, but needs larger trials before replacing CT scans.
Key findings
01Automated analysis of transimpedance measurements detected extracochlear electrodes with 100% sensitivity and specificity in cadaveric heads for 2 to 5 misplaced electrodes.
02The method successfully identified misplaced electrodes in live patients even when contact impedances were normal, a condition where standard tests typically fail.
03The automated tool failed to detect or quantify cases with only one extracochlear electrode.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study was primarily conducted on cadaveric heads, which may not fully replicate the complex biological environment of a living patient. The sample size of live patients was extremely small (n=5), limiting the generalizability of the findings. The automated detection tool failed to identify cases with only one extracochlear electrode. The tool sometimes underestimated the number of misplaced electrodes by one. The cutoff values for detection were derived from a small number of full-insertion controls, requiring further validation in larger cohorts. The study only used Advanced Bionics implants; results may not apply to other manufacturers or electrode types.
Declared interests
One author is funded by a charitable fund. Another has previously received grants from cochlear implant manufacturers (Med-El, Advanced Bionics, Cochlear). A third has been employed as a consultant for Advanced Bionics, though the study itself was not funded by them.
The easy way to misread this
Do not replace CT scans with this method in clinical practice yet. The tool was only validated on eight cadavers and five live patients, and it failed to detect single-electrode migrations, meaning it is not ready for general diagnostic use.