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Monday, November 05, 2012
FLEX Electrodes: Design Matters for Atraumaticity and Hearing Preservation
By Darla Franz
 
The US Food and Drug Administration approved new FLEX24 and FLEX28 electrode arrays from worldwide hearing implant manufacturer MED-EL earlier this year for use with its MAESTRO Cochlear Implant System. The first US patients began taking advantage of this new technology in July. Does electrode length really matter when it comes to cochlear implants? And does electrode design make a difference when it comes to atraumaticity and preservation of residual hearing? Research tells us they do.
 
The FLEX28 array is 28 mm in length and enables implantation in 96 percent of all typical cochlear anatomies, allowing for complete cochlear coverage. The FLEX24 electrode incorporates the same design criteria with a 24-mm insertion length for situations where a FLEX28 electrode insertion might not be achieved or desired.
 
The FLEX electrode is designed to be soft for surgical insertion into the cochlea with minimal trauma or damage to the delicate structures and tiny hair cells of the inner ear. The new FLEX arrays incorporate FLEX-Tip technology, with the apical portion of the array thinner and more flexible than before to reduce implantation and explanation trauma. The thin diameter and flexibility was achieved in part by changing the electrode contacts in that portion of the array. 
 
The device still offers the same number of channels as previous designs, and the first seven most basal channels continue to be represented by paired contacts, but the five most apical channels now utilize single contacts, reducing the diameter of that portion of the array significantly. This design improvement creates an electrode that is narrower, tapered, and more flexible on the apical end to better match the shape of most cochleae. The same electrode can be used for either ear.
The FLEX options are new and all of MED-EL’s electrode arrays feature exclusive flexible, wave-shaped wires designed to reduce rigidity significantly in comparison with a straight wire design. MED-EL will also continue to offer the standard, medium, and compressed electrode arrays to enable surgeons to tailor the best electrode option to each patient and his unique anatomy.
 
Protecting the patient’s residual hearing was a key factor when designing the new electrodes. Cochlear implant technology continues to evolve, with tremendous potential for new hearing loss treatments still untapped. Children being implanted today have life expectancies into their 80s and beyond, so it is possible that they will receive more than one implant in their lifetime. Atraumaticity is also important when thinking about accessing future innovations that are being researched. Treatment possibilities, such as stem cells or genes, might be delivered through the electrode and likely will benefit from intact cell structures. We want to do all we can to help preserve that potential for our patients while still providing an opportunity to take advantage of all that current cochlear implant technology has to offer. 
 
What is next in cochlear implant R&D? We continue to move well beyond the original goal of cochlear implants, which was to see if electrical stimulation could trigger the brain to recognize the presence of sound. We have taken patients from the early days, where they might have been able to detect noise but not understand specific sounds or speech, to more than 40 years later where patients often understand a great deal of speech, even in complex environments.
 
We are now able to offer a variety of different pulse patterns to trigger different kinds of hearing perceptions. Our research is even helping us learn how to generate specific types of pulse patterns for a person to be able to understand and appreciate music. We are currently focused on refining perception for complex sound inputs like music and noise and creating smaller and more power efficient devices that maximize battery life. MED-EL‘s mission is to come closer to eliminating deafness as a barrier to a better quality of life.
 
Ms. Franz is a cochlear implant audiologist and a senior director of education for MED-EL Corporation, USA, with more than 20 years of experience working with CI users.
About the Author

Michelle Hogan, Editor
Editor, The Hearing Journal

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