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

Objective: To increase the number of intracochlear electrodes that may be i nserted into a totally obliterated cochlea, a special implant has been deve loped in collaboration with Cochlear Limited. This implant features two sep arate electrode carriers containing 11 and 10 active electrodes, respective ly, as well as a reference electrode located on the receiver-stimulator pac kage. The potential stimulation modes available with this device therefore include monopolar and bipolar stimulation, and stimulation between both arr ays. Surgical Technique: A cochleostomy anterior to the round window provides ac cess to the basal turn (both the scala tympani and the scala vestibuli), an d new built connective tissue and bone can be removed until the anterior wa ll of the basal turn is approached. A second cochleostomy is performed at t he second turn caudal of the cochleariform process and 2 mm anterior of the oval window after removal of the incus. New tissue should also be removed if necessary. The two electrode carriers are then placed into the scala tym pani of the basal and the scala vestibuli of the second turn, respectively. The remaining surgical procedure is identical with that used for cochlear implantation in patients without obliterated cochleas. Patients: In this clinical study, 10 patients aged 32 to 66 years with an o bliterated cochlea each received a double array cochlear implant. All patie nts had total obliteration of the basal turn either on preoperative imaging or during surgery. Intraoperatively, the second turn was not obliterated i n only 4 of 10 patients. Postoperatively, a standard audiologic test battery was used to determine a uditory improvement over time. Postoperative Results: All patients achieved significantly improved speech understanding when the additional apical ele ctrode array was used, compared with the use of each electrode array indepe ndently. No complications occurred. Conclusion: In patients with a totally obliterated cochlea, the number of i ntracochlear electrodes can be increased by use of the Nucleus double array implant. As a result, patients achieve significantly better auditory resul ts.