Cochlear implant research at Mayo encompasses several areas:
Mayo Clinic's Cochlear Implant Facility in Rochester, Minn., was one of the first programs to use cochlear implants to treat children with auditory neuropathy spectrum disorder (ANSD), also referred to as auditory neuropathy/dyssynchrony. Approximately 10 percent of children with congenital sensorineural hearing loss have ANSD.
Hearing aids benefit some, but not all, children with ANSD; Mayo Clinic's cochlear implant team has successfully treated a large number of children with ANSD who did not benefit from hearing aids. These children have been followed and studied closely over time, and Mayo researchers continue to compare their abilities with those of other children who have been implanted for different etiologies of hearing loss. Several papers have been published on Mayo's pediatric ANSD patient population, and Mayo is continuing its efforts to better understand ANSD and cochlear implants.
An additional area of research relates to measures used to determine cochlear implant candidacy for children. These tests are often limited in the number of available randomizations, making it difficult to test a child using hearing aids for each ear separately and together. Mayo has studied the possibility of using more adult tests, which have a greater number of randomizations. Findings have been positive, and Mayo is now routinely using the more advanced tests.
Finally, the children's cochlear implant team at Mayo is studying speech perception in noise for children with cochlear implants, as well as the availability of binaural cues for children with cochlear implants. These studies are very important, as children spend most of their waking hours in noisy environments.
Mayo has completed cochlear implants on many patients of advanced age. In a recent review of Mayo's experience with implanting adults more than 80 years old, researchers found that older patients experience substantial improvements from cochlear implant surgery — nearly identical to younger adult patients. Mayo researchers also found that surgery was very well tolerated by all age groups, with most patients leaving the same or next day.
Mayo has a long history of participating in multicenter investigations and clinical trials involving innovations of hardware and software used in cochlear implantation and programming. One such ongoing trial is the Nucleus Hybrid L24 clinical trial, in which people seen in Mayo Clinic's Cochlear Implant Facility may be eligible to participate. The L24 is a shorter electrode array designed to help preserve low-frequency hearing during surgery. The speech processor uses both electric and acoustic stimulation to maximize speech-perception abilities.
Other recent technology-related studies at Mayo have been looking at electrode insertion length for preservation of hearing. Short-, medium- and full-insertion electrodes have been studied in an attempt to minimize damage to the delicate inner ear structures. A surgical technique has been developed at Mayo that allows surgeons to minimize loss of residual hearing with a fully inserted electrode array.
Cochlear implants are very successful at providing access to the sound that is necessary for communication, but some individuals have difficulty learning to use this new sound. Rehabilitation is an important aspect of overall success. Traditional auditory training is expensive and not reimbursed well by third party payers, so Mayo is studying innovative, cost-effective ways to provide rehabilitation. Currently, Mayo patients have access to a variety of computer-based rehabilitation programs, which can be taken home and used on a personal computer or accessed in Mayo's patient education computer lab.
Objective measures for implant programming
Mayo Clinic's cochlear implant team has studied objective measures for programming cochlear implants. This includes measuring neural responses to electric stimulation in order to predict valuable programming information for individuals who are unable to give reliable information, such as very young children and adults with cognitive concerns. Currently, staff is comparing intraoperative neural responses to electric stimulation with postoperative speech-perception test results, which may lead to a predictive measure for positive cochlear implant outcomes.