MULTICHANNEL COCHLEAR IMPLANT "SUPERIORITY" TO SINGLE-CHANNEL DEVICES

MULTICHANNEL COCHLEAR IMPLANT "SUPERIORITY" TO SINGLE-CHANNEL DEVICES is observed by Noel Cohen, MD, New York University School of Medicine, New York City, et. al, in a prospective, randomized study published in the Jan. 28 New England Journal of Medicine. Commenting on the results of their 80-patient clinical trial, the authors state: "This study demonstrates the superiority of multichannel implants" to single-channel implants, "especially in their ability to allow patients to understand speech without lip reading." According to the authors, the trial is the first randomized, prospective study to compare different cochlear implants. Multichannel implants currently are the standard of care, and only one multichannel device has FDA approval -- Cochlear Corp.'s Nucleus. Of the 80 patients in the study, 30 were randomized to receive Smith and Nephew's investigational Ineraid multichannel device, 30 were assigned to receive Cochlear's Nucleus multichannel implant, and 20 were assigned to 3M's Vienna single-chamber implant. The study explains that the distribution is uneven because the Vienna was "withdrawn by its manufacturer" before additional patients could be assigned to that group. Efficacy of the implants was assessed through 24 hearing tests. The tests were grouped into five categories according to the type of parameters they measured, and "a weighted composite index was developed to provide a single numerical indicator of the overall auditory response" seen in the tests. The tests were given before implantation of the devices and 12 and 24 months after implantation. After the two-year testing period, 24 patients with the Nucleus device also received a new speech processor (the Mini- Speech Processor), which was expected to have improved performance over Cochlear's older Wearable Speech Processor. Patients who had the speech processor replaced were tested at the time of initial stimulation with the new processor and three months later. At the two year testing period, 60% of the Ineraid patients, 63% of the Nucleus patients and 5% of the Vienna patients "were able to distinguish some words and sentences." The scores for the composite index "were similar" for patients with the Ineraid and Nucleus implants, "and were higher in both these groups than in patients who received" the Vienna, with statistical significance at the p = 0.02 level. The 24 Nucleus patients who received the Mini Speech Processor improved further after the older Wearable Speech Processor was replaced. The composite index score for the patients "increased significantly within three months (p < 0.001)" and "was also significantly higher (p = 0.04) than the score of the patients with [Ineraid] at 24 months," the study states. Discussing their results, the authors comment that "the superiority of both multi-channel implants...was most evident in open-set speech recognition and in the patients' ability to understand some everyday conversation without lip reading." Implant recipients "who can understand some speech without lip reading can perform the activities of daily living more effectively," the authors assert. Cohen et al. also believe that the study results show "that these devices can be implanted with a high degree of safety." There were "very few surgical or medical problems related to the cochlear implants. Notably, no patient had a facial-nerve injury, major flap necrosis, or compression or misplacement of the electrodes, all of which have been reported in other series of cochlear-implant recipients." Noting that "it has been of ongoing concern that the development of new devices may render current implants obsolete," Cohen et al. point out that it is "impossible to anticipate whether a patient will do better if given an implant with another design." This study, "has clearly demonstrated, however, that changing the external hardware and speech-processing strategy of an existing implant can have a substantial effect on open-set speech understanding in an individual patient." In an editorial published in the same NEJM issue, Thomas Balkany, MD, University of Miami School of Medicine, identifies the results relating to the new processor as being "of great interest." The "improved processor significantly enhanced understanding of speech, demonstrating that future improvements may be possible without the need to replace implanted hardware," he says.