Clarion 1.2 standard electrode array with partial space-filling positioner: radiological and histological evaluation in human temporal bones

The purpose of this study was to evaluate whether use of a positioner for situating the Clarion 1.29 standard electrode array in close proximity to the modiolus, causes damage to fine intra-cochlear structures, and to provide a comparison with results obtained for insertions of the array performed without a positioner. The study was performed in seven freshly frozen human temporal bones. Electrode location and intra-cochlear trauma was analysed using cross-sectional imaging and histological analysis. Insertion of the Clarion array did not reveal major trauma. The devices inserted with the positioner showed a consistently closer location of the electron array towards the modiolus, however, insertion resulted in significant displacement of both the electrode array and the positioner resulting in severe destruction of the basilar membrane and osseous spiral lamina along the length of the basal and middle turns. The devices inserted with the positioner resulted in major trauma to the basilar membrane and osseous spiral lamina. Therefore, systematic safety studies in larger samples of human temporal bones should be performed and the results carefully evaluated before implantation can be recommended unreservedly.