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. The focus of the paper is to review the development and translation of 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. The rationale and results for the first AMI clinical study using a multi-site single-shank array will be presented initially. Although the 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. Animal and human data will then be presented to show that a two-shank AMI array can potentially improve hearing performance by targeting specific neurons of the inferior colliculus. Anew two-shank array, stimulation strategy, and surgical approach are planned for the AMI that are expected to improve hearing performance in the patients who will be implanted in an upcoming clinical trial funded by the National Institutes of Health. Positive outcomes from this clinical trial will motivate new efforts and developments toward improving central auditory prostheses for those who cannot sufficiently benefit from cochlear implants.This article is part of a Special Issue entitled <Lasker Award>.
Bibliographical noteFunding Information:
Minoo Lenarz from University of Berlin-Charité (Germany) and James Patrick from Cochlear Limited (Australia) both played a critical part in the initiation and progress of the AMI research and clinical study. David Anderson from University of Michigan (USA) played a critical role in the initiation and progress of the AMI animal research. Gert Joseph, Urte Rost, Joerg Pesch, Nicole Neben, Thilo Rode, and Rolf-Dieter Battmer contributed to the fitting and testing of the AMI patients at Hannover Medical School (Germany). Thilo Rode, Roger Calixto, Anke Neuheiser, Tanja Hartmann, Günter Reuter, Uta Reich, Gerrit Paasche, Verena Scheper, and Andrej Kral contributed to the AMI animal studies at Hannover Medical School, while Malgorzata Straka and Sarah Offutt performed AMI animal studies at University of Minnesota (USA). The AMI surgeries were performed together with Madjid Samii and Amir Samii at the International Neuroscience Institute (Germany). The improved surgical approach in cadaver studies was developed together with Amir Samii, Omid Majdani, Markus Pietsch, Peter Erfurt, and Sven Balster at Hannover Medical School. The engineers and scientists at Cochlear Limited including James Patrick, Frank Risi, Godofredo (JR) Timbol, Shahram Manoucherhi, Adrian Cryer, Peter Gibson, Brett Swanson, and Jason Leavens developed the AMI devices and software. Colette McKay from Bionics Institute (Australia) and Robert Shannon from University of Southern California (USA) helped with AMI and ABI psychophysical studies. Ray Meddis (University of Essex, UK) as well as Christian Sumner and Mark Steadman (Nottingham University, UK) provided and helped with the code for the DRNL model. Funding was provided by Cochlear Limited, German Research Foundation ( SFB 599 , Cluster of Excellence Hearing4All), Germany Ministry of Research and Education ( 01GQ0816 ), funds from University of Minnesota , and National Institutes of Health ( P41EB2030 , R03DC011589 , U01DC013030 ).
The second AMI clinical trial is currently underway and is funded by the National Institutes of Health (Grant Number U01DC013030). The clinical trial will be performed at Hannover Medical School in collaboration with Cochlear Limited and University of Minnesota for implanting the two-shank AMI device in five adult NF2 patients who cannot sufficiently benefit from a CI or ABI. The clinical study is occurring from April 2014 to March 2019. The primary objectives of this study are to demonstrate the safety and reliability of the new two-shank AMI array and the ability to consistently position the array into the ICC across patients. The secondary objectives are to show that the two-shank AMI can achieve hearing performance greater than what is typically achievable with the single-shank AMI and ABI devices used in NF2 deaf patients. Success with these initial patients will open up opportunities for expanding the use of the AMI to a larger patient population and in clinics within different countries including the United States.
© 2015 Elsevier B.V.