Recommendations for Measuring the Electrically Evoked Compound Action Potential in Children With Cochlear Nerve Deficiency.
Shuman He, Xiuhua Chao, Ruijie Wang and 9 others
PMID 31567301WHAT IT FOUND
In 25 children with cochlear nerve deficiency, adjusted cochlear implant test settings recorded nerve responses at 86.97% of electrodes, versus 37.50% with default settings.
This can guide testing, not set implant levels.
Key findings
01In the first 25 children tested with both settings, eCAP responses were recorded at 407 of 468 electrodes tested with the recommended parameters and at 92 of 245 electrodes with the default parameters.
02Among the 50 children, the eCAP was not recorded at any CI electrode in five patients; three showed only sound awareness, two showed no observable benefit, and none developed sufficient auditory skills for speech perception or spoken language.
03The slow probe rate needed for this method is not suitable for intraoperative eCAP recording and can triple or more the response collection time.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The paper is a perspective paper reporting a method developed from experience with 50 children, not a trial of communication outcomes. The method was developed only for Cochlear Nucleus Freedom or newer devices using Advanced NRT in Custom Sound EP, so it may not apply to other implant systems. The slow probe rate makes testing time long and unsuitable for intraoperative recording, and extended or repeated clinic visits may be needed. eCAP thresholds do not tell where behavioral audible or comfortable levels should be set, and behavioral testing remains the gold standard. Correctly identifying eCAP responses requires experience, and the automatic peak identification cannot be used because responses in these children often have atypical morphology. The polarity reversal method for artifact sometimes gives inconclusive results. It is unknown whether electrodes with absent or artifact-contaminated eCAPs should be used as functional channels in the programming map.
Declared interests
The article lists NIH extramural research support. One author, Holly F.B. Teagle, is a member of a Cochlear Corp. Audiology Advisory Board. The method uses Cochlear Nucleus devices and Cochlear Custom Sound EP software.
The easy way to misread this
Do not read the higher eCAP recording rate as proof that the child will hear better or that these settings replace behavioral testing. The method only helps identify nerve responses, and eCAP thresholds do not tell where audible and comfortable implant levels should be set.