FNI

Nerve cuff implementation in the upper extremity

Principal Investigator: Dustin Tyler, Ph.D.

Staff/Students : Katie Polasek, Ph.D., Natalie Brill, Daniel Tan

Description: The purpose of this project is to improve the function of neuroprostheses and decrease the complexity of the implant surgery by replacing some or all of the muscle-based electrodes with nerve-based electrodes. Potential benefits of nerve electrodes compared to electrodes implanted within, or on the surface of muscles are: 1) All axons in the nerve can be stimulated together to completely activate broad muscles that are difficult to stimulate using a single muscle-based electrode. 2) Since nerve electrodes are in direct contact with the nerve, less current is required than when using muscle-based electrodes. Lower stimulating currents would reduce the power required and extend the life of an implanted battery. 3) Several contacts within one cuff can activate different portions of the nerve, potentially activating different functions and/or muscles independently. In a neuroprosthesis application, this would reduce the number of implant sites needed and could decrease the length and complexity of the implant surgery.

To date, we have implanted eleven spiral nerve cuff electrodes in two human subjects for the restoration of shoulder and arm function.  The initial electrodes have been implanted for over 2 years with no known adverse physiological effects.  Selective activation of at least a single muscle from each nerve has been shown and this was improved with the use of multi-contact stimulation. 

One goal of this project is to implement a neuroprosthesis made up of only nerve electrodes for the restoration of hand function. Selective activation of a single muscle is sufficient in some applications but ideally, each muscle innervated by the nerve could be controlled individually.  In order to accomplish this, the Flat Interface Nerve Electrode is being evaluated in human subjects.  Initially, fascicular anatomy and neural models will be used to predict the electrode performance and help to specify the electrode design.  Following design and manufacture of the electrodes, intraoperative trials will provide invaluable clinical data and direct future efforts.