Impact of modulating phase duration on electrically evoked auditory brainstem responses obtained during cochlear implantation

AbstractObjectiveTo investigate the effect of increasing phase duration (pulse width, T-pulse) using a biphasic pulse composed of an initial anodic active phase followed by a balancing cathodic phase on the electrically evoked auditory brainstem responses (eABRs) recorded at the time of cochlear implantation.DesigneABRs recorded during 188 surgeries for cochlear implantation from 1999 to 2006 in a single center were retrospectively reviewed by two independent observers. All patients were fitted with a NEURELEC cochlear implant (CI) device, initially DIGISONIC® then DIGISONIC SP® (2004–2006).ResultImmediately following cochlear implantation, stimulation by the CI resulted in reliable wave III and V eABR waveforms (mean wave III latency 2.23 ± 0.38 ms SD and wave V latency 4.28 ± 0.42 ms SD). Latencies followed an apical to basal gradient (0.32 ms increase in mean eV latency and 0.12 ms for eIII latency). With increasing phase duration, wave III and wave V latencies significantly decreased in association wi...