title: Averaged electrode voltages: management of electrode failures in children, fluctuating threshold and comfort levels, and otosclerosis.
abstract: Implant-generated surface potentials, or averaged electrode voltages (AEVs), were collected by means of the electrode-by-electrode (E-E) mapping variable mode strategy. Three topics were investigated. 1) Eighteen children under the age of 7 were tested and the E-E map of 4 of them was found deviant; all 4 children were deaf owing to meningitis. Some electrodes marked as failing by E-E mapping did not cause problems during device fitting, and electrodes not usable in device fitting showed normal AEVs in 1 child. Overall, the AEVs agreed well with abnormalities in the behavioral threshold (T) and comfort (C) levels. The E-E maps provided useful clues for the audiologist in most cases. 2) Repeated E-E mapping in 2 children who displayed large fluctuations over time of T levels suggested a fluctuation in (neural) responsiveness in 1 child and new bone formation in the other. 3) Although massive phase reversals of AEVs in 2 patients deafened by otosclerosis seemed to indicate a very permeable cochlear bone, stimulation in the pseudomonopolar mode across the basal turn did not affect T levels, and affected pitch perception in only 1 patient. Deviant AEVs from abnormal cochleas should, therefore, not be interpreted too easily as an indication of an electrode failure, faulty electrode placement, or inadequate tonotopy.
authors.affiliation: Department of Otorhinolaryngology, University Hospital Nijmegen, The Netherlands.
authors.forename: L H
authors.initials: LH
authors.lastname: Mens
authors.forename: J P
authors.initials: JP
authors.lastname: Brokx
authors.forename: P
authors.initials: P
authors.lastname: van den Broek
mesh_terms: D002648:Child; D003054:Cochlear Implants; D003638:Deafness / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation; D004567:Electrodes, Implanted; D006801:Humans; D010040:Otosclerosis / Q000150:complications / Q000503:physiopathology*; D011475:Prosthesis Failure