The Results in Patients Implanted with the Nucleus Double Array Cochlear Implant: Pitch Discrimination and Auditory Performance Th. Lenarz, A. Büchner, C. Tasche, T. Cristofoli, A. Lesinski-Schiedat, E. v. Wallenberg, R.-D. Battmer, P. A. Busby, C. Frohne Objective: In patients with total or surgically inac- cessible cochlear obliteration, only a reduced num- ber of active electrodes can be inserted with stan- dard cochlear implants, resulting in below average auditory performance. Therefore, a special implant with two electrode arrays was developed on the basis of the Nucleus 22 cochlear implant, the so- called Double Array. One electrode array with 11 active electrodes is inserted into the basal turn of the cochlea, while the second array with 10 active electrodes is inserted into the second turn. The Double Array is now available on the basis of the more advanced Nucleus 24 with 11 active electrodes on each array and two reference electrodes, one at the case and the second one an additional ball electrode, which is placed under the temporalis muscle. For device description and surgical tech- nique see Lenarz et al. (2001). This paper presents psychophysical data on pitch discrimination and auditory performance of patients implanted with a Double Array on the basis of the Nucleus 22. Study Design: A prospective intra-individual study using a Latin square paradigm was performed in six adult patients with obliterated cochlea who re- ceived the Nucleus 22 Double Array. After appropri- ate fitting and loudness balancing, patients were tested either with the basal, the apical or both electrode arrays. Apart from auditory performance tests including numbers and monosyllable word tests, pitch discrimination was determined with a defined procedure. Results: When activating each array alone, auditory performance was better with the basal array than with the apical array. Both arrays together showed marked improvement compared with the basal ar- ray, indicating an additional effect of the second array. Pitch discrimination was significantly better for the electrodes in the basal turn than in the second turn, indicating differences in electrical ex- citation of the auditory nerve fibers. Pitch discrim- ination was positively correlated with auditory per- formance data. Conclusion: The additional apical array leads to significant improvement in auditory performance in patients with obliterated cochleae by increasing the number of intracochlear electrodes. Despite reduced pitch discrimination, the apical array pro- vides important information for speech recogni- tion. For this reason the Double Array provides a profound advantage for patients with obliterated or surgically inaccessible cochleae. (Ear & Hearing 2002;23;90S–99S) Cochlear implantation in adults and children has been established as the treatment of choice in patients with profound and severe sensorineural hearing loss. The auditory performance mainly depends on the duration of deafness, the age at implantation and the cause of deafness (Battmer, Gupta, Allum-Mecklen- burg, & Lenarz, 1995; Blamey et al., 1992). There is also a positive correlation between the number of activated intracochlear electrodes and speech recogni- tion (Hartrampf et al., 1995). In cases with total or surgically inaccessible cochlear obliteration only a re- duced number of electrodes (up to 11 of the standard Nucleus device) can be inserted after drill-out of the basal turn (Cohen & Waltzman, 1993; Dodds, Tyszk- iewicz, & Ramsden, 1997; Geier, Gilden, Luetje, & Maddox, 1993), which leads to below average auditory performance. Although total obliteration is rare (Green, Marion, & Hinojosa, 1991; Lenarz, 1998), a special solution is needed. Several approaches have been suggested to increase the number of intraco- chlear electrodes. Whereas Cohen and Waltzman (1993) proposed a drill-out technique of the basal turn, Gantz, McCabe, and Tyler (1987) suggested a com- plete drill-out of the first turn of the cochlea. However, postoperative side-effects, induced by stimulation of sensory nerve fibers in the middle ear, reduce the clinical use of this approach remarkably. Balkany, Luntz, Telische, and Hodges (1997) suggested a mod- ification of the Gantz approach, leaving the initial part of the basal turn intact. To overcome this problem of sensory nerve fibre stimulation and to increase the number of intracochlear electrodes significantly, sug- gestions for multiple electrode devices have been made Department of Otolaryngology (T.L., A.B., C.T., T.C., A.L.-S., R.-D.B., C.F.), Medical University of Hannover, Hannover, Ger- many; Cochlear AG (E.v.W.), Basel, Switzerland; and Depart- ment of Otolaryngology (P.A.B.), University of Melbourne, Victo- ria, Australia. 0196/0202/02/231S-0090S/0 • Ear & Hearing • Copyright © 2002 by Lippincott Williams & Wilkins • Printed in the U.S.A. 90S