The Effect of Pulse Polarity on Neural Response of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency and Children With Normal-Sized Cochlear Nerves.
Lei Xu, Jeffrey Skidmore, Jianfen Luo and 4 others
PMID 32141933WHAT IT FOUND
Anodic-leading cochlear implant stimulus produced larger nerve responses, lower thresholds and shorter response times than cathodic-leading stimulus in children with cochlear nerve deficiency and children with normal nerves, but polarity difference did not confirm a useful marker of cochlear nerve health.
Key findings
01Changing from cathodic-leading to anodic-leading stimulus produced larger nerve responses, lower thresholds and shorter response times in both groups.
02Children with cochlear nerve deficiency had smaller nerve responses, higher thresholds, flatter growth slopes and longer response times than children with normal-sized nerves.
03The size of the polarity effect differed between groups only for the growth slope of the nerve response, not for amplitude, threshold or response time.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study used only symmetric biphasic pulses, so results may not apply to other pulse configurations. The polarity effect on response amplitude and N1 latency was tested only at the maximum comfortable level for the anodic-leading stimulus, so behavior at lower levels is unknown. Children with cochlear nerve deficiency did not confirm the polarity effect as a practical indicator of local cochlear nerve health. The study measured nerve responses, not behavioral listening, speech or language outcomes. Previous work showed inconsistent polarity effects across devices, etiologies, neural survival patterns and cognitive function, so the findings may not generalize to all implant users.
Declared interests
No funding and no conflicts of interest were declared.
The easy way to misread this
Do not conclude that anodic-leading stimulation will improve a child's hearing or speech. The study measured nerve responses, not behavioral listening or speech outcomes, and the polarity effect did not confirm a useful marker of cochlear nerve health.