Introduction:
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.
Case Report:
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.
Discussion:
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.
