Our experience in management of cochlea basal turn ossification.

In far the most cases spiral canal ossification primarily affects the descending part of the basal turn. In this paper the method of atraumatic drilling of the ossified spiral canal is proposed. In the experimental procedure on 25 cadaveric temporal bones we revealed that the distance between round window membrane and basal turn curvature equals 8.0 mm; the width of labyrinthine capsule which borders spiral canal and internal auditory canal amounts to 0.36 mm and its width between spiral canal and internal carotid artery accounts for 0.77 mm. The original method, which is based on atraumatic drilling out of the ossification, was put forward. The drilling starts from the ossified round window membrane and proceeds till the basal turn curvature. Notable color difference between otic capsule and ossified tissue is observed: labyrinth capsule tends to look greyish and ossified tissue -- whitish. This enables gradual drilling out of the ossification along the descending part of the cochlea basal turn and preservation of modiolus. Taking into consideration close adjacency of the internal auditory canal and internal carotid artery lateral basal turn wall should always be kept in mind the landmark. The above-described surgical technique was applied in 62 patients with the ossification of the basal turn descending part. In 22 cases the length of the ossified spiral canal varied from 1 to 3 mm, in 40 patients it was in the interval of 4-6 mm and proceeded till the basal turn curvature. In all the 62 patients the proposed method enabled adequate approach to the cochlea spiral canal and full CONCERTO (MED-EL, Innsbruck, Austria) standard electrode insertion. In these cases only straight rigid electrode can be used to make its way through the drilled out spiral canal lumen. Postoperative audiological performance of the implanted patients correlated with the ones without ossification. [ABSTRACT FROM AUTHOR]