A new pre-curved electrode array benefits as measured by initial psychophysics [Abstract]
AuthorSaunders, Elaine; Cohen, Lawrence T.; Treaba, Claudiu; Pyman, Brian C.; Clark, Graeme M.
Source TitleAbstracts & Program 7th Symposium Cochlear Implants in Children
Document TypeConference Item
CitationsSaunders, E., Cohen, L. T., Treaba, C., Pyman, B. C., & Clark, G. M. (1998). A new pre-curved electrode array benefits as measured by initial psychophysics [Abstract]. In Abstracts & Program 7th Symposium Cochlear Implants in Children, Iowa City, Iowa.
Access StatusOpen Access
Theory suggests that an electrode which lies close to the modiolus should provide a more efficient interface with the auditory nerve, although it is important to ensure that stimulating fields are not so intense as to risk neural damage. A pre-curved, banded 22-electrode array has been developed which, following evaluation for ease of insertion and comprehensive safety studies, has been inserted in three patients. Detailed X-ray analyses, in which the positions of the electrode bands are specified, have been carried out. This has enabled comparative detailed, psychophysical studies to be carried out, within each subject, between electrodes which lie at differing distances from the modiolus. These studies have shown that, as the as electrode distance from the modiolus decreased, threshold currents decreased and dynamic ranges increased. Thresholds are lower than in a comparison group of subjects fitted with straight arrays which had been similarly position specified. Extensive forward masking studies have shown that current spread was more focused at the electrodes closer to the modiolus. Electrode discrimination studies were carried out and in the loudness jittered condition, which is more representative of the dynamic speech signal, discrimination was better at the electrodes closer to the modiolus. Just Noticeable Differences for loudness, expressed as a function of dynamic range, also decreased in this condition. Thus, a preliminary psychophysical profile of the parameters of interest, for an improved implant design, indicate that an array which lies closer to the modiolus can result in lower current requirements and a more localised pattern of neural excitation.
Keywordsotolaryngology; modiolus; neural excitation; thresholds
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- Graeme Clark Collection