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

Objective To 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. Design eABRs 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).