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Measurement of the electrically evoked compound action potential in a child with an auditory brainstem implant
18 April 2018 (online)
In case of the treatment with a cochlear implant (CI) the measurement of the electrically evoked compound action potential (ECAP) is being done routinely intraoperatively and postoperatively, e.g. to proof integrity of the electrode-nerve interface, for the programming of the speech processor and to verify the proper location of the electrode array inside the cochlea. A measurement of the ECAP in patients with an auditory brainstem implant (ABI) is feasible, but so far rarely explored.
A boy was provided with an ABI at the age of 3 years. ECAP measurements have shown right from the beginning good responses on each of the 12 electrode contacts. The fitting of the speech processor has been done independently of the results of the measurement. Two contacts were left out due to side effects.
The slope of the ECAP amplitude growth function (AGF) was increasing over time on all electrode contacts.
From literature it is known, that the number of excitable neurons is correlated with the slope of the AGF. Electrical stimulation is regarded as a trophic factor for the spiral ganglion. The results presented in our work may reflect the natural growth of neuronal density or may give proof for electrical stimulation as a trophic factor.