The Nucleus Contour electrode array: A radiological and histological study

Objectives: To evaluate the handling and insertion trauma of the recently d eveloped Nucleus perimodiolar Contour electrode array (Cochlear Ltd., Pty, Lane Cove, New South Wales, Australia) in human temporal bones compared wit h the Nucleus standard straight electrode array. Study Design: Experimental control group, Methods: Twenty-nine fresh-frozen bones were implanted with different electrode arrays by an experienced cochlear implant surgeon, and evaluated both radiologically and histologically. Results: Intracochlear i nsertion of the standard Nucleus straight electrode array was found to be a traumatic, confirming previous findings in the literature. Insertion of the Nucleus Contour electrode array resulted in instances of localized basilar membrane penetration causing the electrode array to move from the scala ty mpani into the scala vestibuli. However, this trauma did not result in any observable damage to the osseous spiral lamina or the modiolus, Basilar mem brane penetration was observed in six of eight cochlear bones when a standa rd cochleostomy size (approximately 0.8 mm) and site (anterior and superior to the round window) were used, However, when the surgical technique was m odified to use a slightly larger cochleostomy (approximately 1.8 mm) situat ed closer to the round window and employ a partial stylet withdrawal techni que during electrode insertion, the frequency of penetrations was restricte d to two of seven bones. This trauma rate is comparable to that observed wi th other cochlear implants designs, Conclusions: Following our results, the design of the Nucleus Contour electrode appears to fulfill the safety requ irements for an intracochlear electrode array,provided that the surgical in sertion technique is modified in the manner outlined.