Averaged Electrode Voltages in Users of the Clarion Cochlear Implant Device

• Published in: Annals of otology, rhinology & laryngology Vol. 111; no. 4; pp. 370 - 375
• Main Authors: Mens, Lucas H. M., Mulder, Jef J. S.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.04.2002; Annals Publishing Compagny; SAGE PUBLICATIONS, INC
• Subjects: Adult; Biological and medical sciences; Cochlear Implants - standards; Deafness - etiology; Electric Impedance; Electrodes; Equipment Failure; Head and neck surgery. Maxillofacial surgery. Dental surgery. Orthodontics; Humans; Medical sciences; Osteogenesis Imperfecta - complications; Otosclerosis - complications; Surface Properties; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the ear, the auditive nerve and the facial nerve; Technology. Biomaterials. Equipments; Telemetry; Time Factors; cochlear implant; device failure; integrity testing; averaged electrode voltages; Human; Implant; Internal ear disease; Auditory disorder; Average; Exploration; Electrodes; Treatment; Equipment; Surgical implantation; Surgery; Voltage; Cochlea; ENT disease; Perception hearing loss; Sensory hearing loss; Integrity
• ISSN: 0003-4894; 1943-572X
• DOI: 10.1177/000348940211100415

Averaged electrode voltages (AEVs) are of secondary importance for integrity testing of cochlear implant devices featuring back-telemetry. However, AEVs are device-independent and may show intermittent failures and deviant stimulation patterns unnoticed by telemetry. We collected AEVs from 18 users of the Clarion 1.2 system and 6 users of the HiFocus system in order to establish norms for evaluating AEVs in difficult cases. The stimuli were presented with the standard clinical software. Monopolar stimulation at about 16 μA showed large AEVs (mean, 173 μV) suitable for integrity testing. No electrode failures were found. The AEV amplitudes from neighboring electrodes differed by less than 30% (2 SD). The AEVs from subjects with the Clarion HiFocus electrode and/or the Clarion electrode positioner were within the normal range. The AEV amplitudes from bipolar stimulation were much more variable. Inversion of phases between electrodes was found in patients with an altered state of the cochlea (otosclerosis and osteogenesis imperfecta) and in a patient with a curled electrode tip. There was no correlation across subjects between AEVs and electrode impedances. Therefore, impedances are dominated by the electrode-tissue interface, in contrast to AEVs, which are determined by the volume conduction in the body.