Optimizing stimulation parameters to record electrically evoked cortical auditory potentials in cochlear implant users.

Objectives: To measure the effect of burst duration, stimulated electrode position, and stimulation level on the P1-N1-P2 electrically evoked cortical auditory potentials (eCAEPs) elicited via the direct stimulation of selected electrode contacts on a cochlear implant (CI) electrode array.Methods: Prospective observational study of 20 adult cochlear implant users with a MED-EL CI system. eCAEPs were recorded simultaneously with the Eclipse (Interacoustics) and the Neuropack S1 MEB-9400 (Nihon Kohden) recording systems. Tone bursts with durations of 50, 100, and 150 ms were used for stimulation at the maximum comfortable loudness level (MCL) and MCL minus 50% dynamic range (DR) at selected apical, medial, and basal intracochlear electrodes.Results: Individual P1-N1 and N1-P2 amplitudes were significantly higher at the MCL level of stimulation than at the MCL minus 50% DR. Burst length and stimulated electrode position did not affect the eCAEP responses. Residual noise was lower in the Neuropack S1 MEB-9400 system.Conclusions: This study shows the feasibility of eCAEP recording using the MAESTRO software. The eCAEP morphology was independent of the burst duration and the stimulated electrode position. This allows a large flexibility in using direct cochlear stimulation to elicit eCAEPs.