The cochlear implant is considered one of the most successful neural prostheses to date, which was made possible by visionaries who continued to develop the cochlear implant through multiple technological and clinical challenges. However, patients without a functional auditory nerve or implantable cochlea cannot benefit from a cochlear implant. Together with academic, clinical and industry partners (listed below), we have been developing and testing a new type of central auditory prosthesis for this group of patients that is known as the auditory midbrain implant (AMI) and is designed for electrical stimulation within the inferior colliculus. Although the auditory brainstem implant (ABI) is available to this group of deaf patients, its performance has been generally much lower than the cochlear implant. Therefore, a better solution is needed for these patients.
Our AMI research has been performed over the past 18 years and has included physiology, behavioral/perceptual and safety studies in animals and humans as well as device and software development, allowing for translation of the AMI concept into human patients. The first AMI clinical study using a multi-site single-shank array was performed in 2006-2009. Although the single-shank AMI has achieved encouraging results in terms of safety and improvements in lip-reading capabilities and environmental awareness, it has not yet provided sufficient speech perception above what is possible with the current standard of care (i.e., ABI).
Since 2009, we performed further animal and human research, discovering that a two-shank AMI array can potentially improve hearing performance by targeting specific neurons of the inferior colliculus and minimizing unwanted suppressive effects induced by temporal stimulation patterns presented on individual electrodes. A new two-shank AMI device has been developed that is expected to improve hearing performance over the previous single-shank device and is currently being investigated in a clinical trial funded by the National Institutes of Health. The hope is that the two-shank AMI will serve as a better hearing alternative over the current ABI. We also envision that success with the AMI will open up new opportunities for central auditory prostheses to be more readily available to the general deaf patient population and provide a new generation of implantable devices that can achieve performance towards more natural hearing.
Further details of the AMI research and clinical trial are provided in these two review papers, NIH Reporter and clinicaltrials.gov listed below:
Lim HH, Shannon RV. "Two Laskers and Counting: Learning From the Past Enables Future Innovations With Central Neural Prostheses." Brain Stimulation, 8(3): 439-41, 2015. Invited Editorial Abstract
Lim HH, Lenarz T. "Auditory Midbrain Implant: Research and development towards a second clinical trial." Hearing Research 322: 212-223, 2015. Abstract
NIH Reporter - Link
Clinical Trial - Link
Funding: National Institutes of Health
Collaborators: Thomas Lenarz, MD, PhD (Chair of Otolaryngology Department, Hannover Medical School, Director of the German Hearing Center); Colette McKay, PhD (Professor, Bionics Institute, Australia); Amir Samii, MD (Vice-President and Deputy Medical Director, International Neuroscience Institute, Germany); Cochlear Limited (James Patrick, Chief Scientists - Emeritus); Hannover Clinical Trial Center (Heiko von der Leyen, Professor and Director)