Nucleus double electrode array: a new approach for ossified cochleae

The ossified cochlea is still a special surgical issue that requires a special surgical procedure. The current cochlear implants only have one electrode lead, which can be placed only partially in the drilled out basal turn. The small number of used active electrodes leads to worse performance as compared with patients with full insertion.

To overcome this limitation, a special electrode was developed consisting of two arrays. One array with 11 active electrode rings is placed in the drilled out basal turn, the second array with 10 active electrodes in the opened second turn. The number of inserted electrodes can be significantly increased. The surgery is similar to that in nonossified cochleae. After the posterior tympanotomy, the bridge is removed and the incus is located. A cochleostomy is performed at the basal turn and the new-built tissue removed. A second cochleostomy is placed below the cochleariform process. In most cases, the second turn is not obliterated and the second electrode array can be fully inserted.

The surgical procedure was in all nine cases uneventful. Intraoperative stapedius reflex could be recorded with elevated thresholds. The wide variety of stimulation modes and sites allows an individual fitting to maximize the performance. All patients show a gap in the pitch scale between the apical and the basal array. The pitch variation is much smaller in the apical array. All patients have some benefit from the additional apical array and an improved performance.

The nucleus double electrode array is an advanced treatment option for patients with ossified cochleae. The receiver/stimulator is a regular nucleus cochlear implant.