An Implanted Upper Extremity Neuroprosthesis Utilizing Myoelectric Control

Abstract

Neuroprostheses use electrical stimulation of paralyzed muscles to produce controlled limb movement. A first generation implanted neuroprosthesis for upper extremity function underwent a successful multi-center clinical trial and received FDA approval in 1997. We have now developed a family of second generation implanted neuroprosthetic systems. These systems provide control of grasp-release, forearm pronation, and elbow extension for individuals with cervical level spinal cord injury. The key feature of the advanced system is the capability to transmit data out of the body, allowing the use of implanted control sensors, thus minimizing the required external components. Clinical studies have been initiated with a second generation neuroprosthesis that consists of twelve stimulating electrodes, two myoelectric signal recording electrodes, an implanted stimulator-telemeter device and an external control unit and transmit/receive coil. This system has now been implemented in three C5/C6 spinal cord injured individuals, including one subject with bilateral implants. The results from these three subjects demonstrate that myoelectric signals can be recorded from voluntary muscles in the presence of electrical stimulation of nearby muscles. Myoelectric signals can be used for both discrete and proportional control signals. The results to date are promising, and all subjects have demonstrated improved function using the implanted neuroprosthesis