Advanced Bionics Thin Lateral and Helix II Electrodes: A Temporal Bone Study

Abstract

Both electrodes performed favorably in our human temporal bone trials, and both arrays appear promising for clinical use, especially in patients with residual hearing in whom atraumatic insertion is an important objective.

Cochlear Implants: System Design, Integration, and Evaluation

“…When fully inserted in temporal bones the HiFocus 1J electrode was positioned with a mean distance of 1.23 mm (electrode n=4) from the modiolus [120]. Although there have been no quantitative studies of the Combi array published to date it is reasonable to assume that the position of this electrode would be similar and published images of this electrode in place confirm their location near the spiral ligament.…”

“…To access lower frequency components of the speech spectra (200-1200 Hz), it is necessary to insert the electrode array to an approximate depth of 1.5 cochlear turns or 540° degrees measured from the round window. Recent studies have shown that in most cases the current generation of electrodes can be inserted to a depth of less than 400° and that deeper insertion results in higher rates of intracochlear damage and misplaced electrodes [119,120 ]. Thus, significant advances in electrode design will be required to reliably achieve optimum insertion depth with minimal trauma.…”

“…Although there have been no quantitative studies of the Combi array published to date it is reasonable to assume that the position of this electrode would be similar and published images of this electrode in place confirm their location near the spiral ligament. This position compares with a mean in situ distance from the electrode to the modiolus of 0.16 mm (electrode n=3) for the earlier HiFocus II electrode array with positioner [128], 0.65 mm (electrode n=4) for the HiFocus Helix array [120] and 0.33 mm (n=3) for the Cochlear Contour electrode [128]. Although the straighter electrodes are located laterally, it should be noted that the location of the perimodiolar arrays is highly variable and that this variability may affect threshold and channel interaction in highly idiosyncratic ways along the length of an array in an individual subject and across subjects throughout the patient population.…”

“…At present, there is a large variation in distance from the array to the modiolus in current perimodiolar designs [120,161 ]. Refinement will be needed to consistently locate stimulating contacts close to the spiral ganglion.…”

Micro-CT scan, electron microscopy and optical microscopy study of insertional traumas of cochlear implants

“…Wright [25] embedded the specimens in a medium, subjected to EDTA decalcification, before drilling the upper portion of the osseous labyrinth to visualize the electrode array across the osseous spiral lamina and basilar membrane to evaluate their integrity. Adunka [1] embedded the implanted cochleae in polymethacrylate subsequent to infusion with physiological serum via the oval window and took sequential sections spaced 100 microns apart.…”