SBIR-STTR Award

The long-range goal of this project is to be able to treat effectively plegic stroke victims using a novel therapeutic regimen and robotic device called "AMES," an acronym for Assisted Movement with Enhanced Sensation. In AMES, the patient assists the motion of the robotic device using biofeedback of voluntary joint torque, while the sensation of motion is enhanced by tendon vibration. In a pre-clinical trial, we showed AMES to be effective at restoring functional movement in both upper and lower extremities in a majority of profoundly disabled chronic stroke patients (>2 yr event). At enrollment, these subjects ranked <30th percentile of normal limb strength. Despite our success at treating profoundly disabled stroke victims, AMES treatment did not restore functional movement at joints (e.g., fingers, wrist, and ankle) rendered completely plegic by the stroke. Using EMG recordings, however, we found that most plegic stroke patients retain the ability to activate voluntarily the 'plegic' muscles. Because the activity is so weak and it competes with antagonistic spasticity and co-contraction, these individuals are unable to move the joint in one or the other direction. The goal of the proposed project is to incorporate EMG biofeedback into the AMES treatment, as an alternative for torque biofeedback, in order to treat effectively profoundly plegic stroke patients. There are 2 specific aims proposed in this Phase I application. The first specific aim is to convert EMG signals into useful biofeedback on a graphics display. Two tasks must be accomplished: (1) to develop and test software to low-pass filter the EMG signals so the bandwidth (~0-2 Hz) is matched to that of the patient's efforts and (2) to present on a graphics display the activity from 2 agonist and 2 antagonist muscles in a way that it is intuitive to the patients how to correct their dyssynergia. The second specific aim is necessitated by the proposed EMG acquisition in the presence of tendon vibration-mechanical and electrical interference produced by the vibrators must be reduced in the EMG recording to levels where it does not reduce the information content of the biofeedback. Specific Aim 2 is to reduce this interference down to =2% of the overall signal amplitude. We propose to explore a number of alternative solutions to the mechanical artifact and electrical artifact problems and to implement solutions that are effective while minimizing cost. Once we have implemented useful EMG biofeedback with the AMES device, Phase II of this project will test the methodology in a controlled clinical trial. This project addresses a sub-group of chronic stroke patients with complete plegia at one or more joints, but who retain some ability to activate voluntarily the 'plegic' muscles. Our preliminary studies indicate that a sizable proportion of the 5 million chronic stroke patients in the US are plegic at one or more joints while retaining some voluntary activation of the 'plegic' muscles. The proposed technology is designed to permit the reversal of dyssynergia at plegic joints and, with further therapy, to restore functional movement. A separate pre-clinical trial indicates that AMES treatment is effective at restoring functional movement in individuals who chronically disabled by traumatic brain injury (TBI). There are current about 1 million chronically disabled TBI patients in the US

The long-range goal of this project is to restore functional movement to low-functioning stroke patients using a novel therapeutic regimen and robotic device called "AMES," an acronym for Assisted Movement with Enhanced Sensation. In AMES-as it is currently used-the patient's affected limb is moved cyclically with the AMES robotic device while the sensation of motion is enhanced by an AMES muscle vibrator applied to the antagonist muscle(s). The patient simultaneously assists with the imposed movement using biofeedback of voluntary joint torque. In a Phase I clinical trial (Cordo 2008), AMES was determined to be effective at restoring functional movement in both upper and lower extremities of low-functioning chronic stroke subjects (>1 yr post-stroke), several of which were plegic. At enrollment, most of these subjects had no more than 30% of normal strength in the affected arm or leg. Despite this success at treating these highly disabled stroke subjects, AMES treatment usually did not restore functional movement at the fingers, wrist, or ankle if the joint was plegic. EMG recordings were taken of these subjects during AMES therapy, and all retained the ability to activate voluntarily their 'plegic' muscles. However, because this muscle activity was so weak, and because it competed with antagonistic co-contraction, these individuals were unable to counteract the opposing forces in order to move the joint. The goal of this proposed project is to incorporate EMG biofeedback into the AMES device and regimen for plegic stroke patients, as an alternative to joint torque biofeedback when no joint torque can be produced. Phase I of this project focused on eliminating electrical and mechanical noise in EMG recordings caused by the tendon vibrators, and on prototyping software to test the feasibility of combining the AMES regimen with EMG biofeedback. The goal of Phase II is to further develop the hardware and software associated with EMG biofeedback and muscle vibration, and to test the efficacy of AMES with EMG biofeedback on stroke patients with hand extensor plegia. There are 3 specific aims proposed in this Phase II application. Specific Aim 1 is to develop further the presentation of EMG biofeedback on the AMES device by designing and integrating a 2-channel EMG amplifier into the device and making the biofeedback more engaging to patients. Specific Aim 2 is to develop new, more reliable and user-friendly technology for muscle vibration, including the vibrator itself and its positioning mechanism. Specific Aim 3 is to test the efficacy of AMES with EMG biofeedback at 3 sites (Emory University School of Medicine, Oregon Health & Sciences University, and the Rehabilitation Institute of Chicago) in a randomized, controlled clinical study of 64 chronic plegic stroke patients.

Public Health Relevance:
This project addresses a sub-group of chronic stroke patients with hand plegia in extension, but who retain some ability to activate voluntarily the 'plegic' muscles. Our earlier studies suggest that as many as a third of the approximately 4 million stroke victims in the US with chronic motor disabilities have hand and/or foot plegia. The proposed technology is designed to reverse co-contraction at plegic joints and to restore functional movement. This Phase II project will test the efficacy of using biofeedback to retrain muscles in conjunction with a new therapeutic regimen called "AMES," and to bring the AMES therapy device to the threshold of commercialization.

Public Health Relevance:
This Public Health Relevance is not available.

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