The nucleus double array cochlear implant: A new concept for the obliterated cochlea.

Aim: In order to increase the number of intracochlear electrodes to be inse rted into a totally obliterated cochlea a special implant has been develope d in collaboration with Cochlear Ltd. The implant features two separate ele ctrode carriers containing 11 and 10 active electrodes, respectively, and a reference electrode on the receiver stimulator package. The potential stim ulation modes include monopolar and bipolar stimulation as well as stimulat ion between both arrays. Surgical technique: A cochleostomy at the round wi ndow provides access to the scala tympani. Newly formed bone is removed as far as the anterior portion of the basal turn. Care is taken to identify an d preserve the osseous border of the cochlea. A second cochleostomy is perf ormed immediately caudal to the cochleariform process after removal of the incus. New tissue can be removed here in the same way. The two electrode ca rriers are then placed into the first and the second turn respectively. The remaining procedure corresponds to the procedure for cochlear implantation in cases in which the cochlea is not obliterated. Patients: For the purpos e of a clinical study n = 10 patients aged between 32-66 years with an obli terated cochlea were fitted with a double array cochlear implant. All patie nts showed signs of total obliteration of the basal turn either in preopera tive imaging or during surgery. Intraoperative inspection revealed that the second turn was not obliterated in 4 of 10 patients. postoperative results : Postoperatively, a standard test battery was used to determine auditory p erformance over a period of time. All patients achieved significantly bette r speech understanding due to the additional apical electrode array. No com plications occurred. Conclusion: In cases involving an obliterated cochlea, the number of intracochlear electrodes can be increased with the double ar ray implant. As a result, the patients achieve significantly better auditor y results.