Thursday, November 10, 2005

Saftey of Cochlear Implants: some products are better than others

Reliability of Cochlear Implants.
Maurer J, Marangos N, Ziegler E:
Otolaryngol Head Neck Surg; 2005; 132 (May): 746-750

Background: Cochlear implantation, especially in children, involves the placement of the device, which is designed to remain functional throughout the entire life of the patient. Therefore, seeking long-term data in terms of reliability is often first and foremost on the minds of patients and physicians. A 91.7% implant survival rate has been calculated, but often data reflecting true survival rates and reliability of implants are lacking. Objective: To provide data from a center with a large cohort of patients on successes and failures with cochlear implants. Methods/Participants: The implant center in Koblenz, Germany retrospectively reviewed 192 cochlear implants from different manufacturers both in adults (n=58) and in children (n=134). Results: The overall survival rate was approximately 91.7% over 11 years. The authors noted that the main reasons for failures were typically product design errors coupled with consequences of trauma to the implant site, especially in children. These various traumatic incidents often result in breakage of the implant body and/or the electrode array. Conclusions: To improve the knowledge about reliability of cochlear implants, it is important to very carefully examine the problems that arise in present day implants. Improvements in design that are learned from these reports will often result in improved long-term reliability. Children are receiving implants earlier and earlier, increasing the lifespan of implants. Therefore, implant reliability must be guaranteed by improving mechanical, electrical, and medical designs. Cochlear implant reliability data germane to individual manufacturers should be considered when choosing an implant for a specific patient. Reviewer's Comments: The authors describe their experience with 3 different devices, including Med-EL, Nucleus, and MXM. Clearly, their experience was most robust using the Med-EL implant, but complication rates in children approached 15% with the Med-EL (15 of 102) as opposed to zero with the Nucleus (0 of 32). The authors suspect this may be due to the form and/or material that is used in the Med-EL device, that being a ceramic encasing, and other potential design errors, which are in the process of being corrected. (Reviewer–Cliff A. Megerian, MD, FACS).

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