Preliminary results and technique for electrophysiological intra-operative monitoring of residual hearing during cochlear implantation.

AimsTo assess the feasibility of intra-operative monitoring of residual hearing using electrocochleography (ECOG) during cochlear implantation. We present our methods and preliminary results. MethodsWe attempted to monitor 21 consecutive paediatric and adult subjects during cochlear implantation. All subjects were implanted via a promontory cochleostomy with full electrode insertions of CochlearTM Nucleus® (Cochlear Nucleus, Cochlear Ltd, Australia) devices: 8 with straight electrodes and 13 with contoured electrodes. Baseline recordings were made after the completion of the posterior tympanotomy, and subsequently at stages of the cochleostomy and electrode insertion. ResultsWe were unable to obtain recordings on five patients because the ear-insert tubing kinked, which disrupted transmission of the stimulus. Five had insufficient cochlear function to be able to record a baseline ECOG. No subjects in whom we were able to obtain a satisfactory baseline ECOG (n = 11) had a reduction in ECOG action potential...