Cochlear implantation using thin-film array electrodes

Objective. Current limitations in language perception may stem from an inability to provide high-resolution sound input. Thin-film array technology allows for a greater density of stimulating sites within the limited diameter of the scala tympani. This study examines the use of a flexible carrier to achieve adequate depth of insertion. Study Design. A prospective human cadaveric temporal bone insertion analysis. Setting. Academic otolaryngology department and school of electrical and computer engineering collaboration. Methods. A prototype thin-film array electrode coupled with an insertion test device (ITD) was manufactured and inserted into 10 human cadaveric temporal bones. As controls, 2 additional temporal bones were implanted with the ITD only and 2 were unimplanted. Radiologic and histologic data were collected. Results. Ten thin-film array electrodes were successfully implanted into 10 individual temporal bones via round window (5) and cochleostomy (5) approaches. Seventeen millimeters of insertion was noted for each device, with an average angular insertion depth of 292° by radiographic measurements and 392° by histologic sectioning. Electrode distance to the modiolus averaged 0.88 mm by computed tomography and 0.67 mm by histologic measurements. Average percentage trauma was 26% for the ITD-backed arrays compared with 15% and 29% for ITD only and unimplanted temporal bones, respectively. Conclusion. Thin-film array electrodes coupled with an ITD were successfully inserted into the human cochlea with limited trauma. With continued development and testing of this electrode design, the thin-film array may improve the language perception achieved through cochlear implantation.