An Implanted Myoelectrically-Controlled Neuroprosthesis for Upper Extremity Function in Spinal Cord Injury

Abstract

A second generation implantable neuroprosthesis has been developed which provides improved control of grasp-release, forearm pronation, and elbow extension for individuals with cervical level spinal cord injury. In addition to the capacity to stimulate twelve muscles, the key technological feature of the advanced system is the capability to transmit data out of the body. This allows the use of myoelectric signal recording via implanted electrodes, 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 nine arms in seven C5/C6 spinal cord injured individuals. The results from these subjects demonstrate that myoelectric signals can be recorded from voluntary muscles in the presence of electrical stimulation of nearby muscles. The functional results show that the neuroprosthesis provides significantly increased pinch force and grasp function for each subject. All subjects have demonstrated increased independence and improved function in activities of daily living. We believe that these results indicate that implanted myoelectric control is a desirable option for neuroprostheses.