Currently, in the United States alone, there are more than 10 million people whose movement is profoundly limited by diseases of and injuries to the brain and spinal cord. About half of these people are so disabled that currently available therapies are not effective in restoring normal movement. Recent rehabilitation research suggests that at least some of these severely disabled people can recover functional movement if the therapy that they receive focuses on the fundamental problems that prevent movement.

Fig. 1 – The AMES Rehabilitation Device as used in research.
That’s the inspiration behind a device created by Paul J. Cordo, PhD, a professor of biomedical engineering at the Oregon Health & Science University, Portland, whose research in movement, motor control, and kinesiology led to the design and development of a rehabilitation device to help stroke victims regain movement.

His research involved applying muscle vibration to the receptors in the muscle tendon at the same time as the joint is being moved. This is thought to result in an exaggerated perception of movement of the extremity, at the time movement is made. The central nervous system monitors the sensory output of the muscles and when a signal is detected, the brain senses that movement, thereby helping guide the motion.

Preliminary findings indicated that individuals who have experienced a stroke, and whose muscle weakness has stabilized can benefit from a three-part approach to rehabilitation. In addition to range-of-motion and exercise, patients receive sensory stimulation.

In order to provide those three parts in a way that can be measured and verified, Cordo created a device that is capable of delivering combination therapy through a series of programmed treatment regimens controlled via computer software. (See Figure 1)

The technology is called assisted movement with enhanced sensation (AMES). It is completely noninvasive, involving computer- controlled devices that assist stroke patients who have suffered loss of movement in their arms or legs.

How It Works

During a therapy session, the device helps a patient move the impaired limb while vibrating the tendons of the limb to stimulate sensory receptors in the muscles. The machines were placed in the homes of the subjects to allow computerized exercises for the wrist, fingers, and ankle. The subject puts his arm or leg into a sleeve or boot that delivers vibration to the limb. The vibration stimulates sensory pathways to invigorate the motor pathways in the brain that control movement. Subjects were to exercise with the device for 30 minutes per day. Periodically during the 6-month duration of the clinical testing, a technician visited the patients’ homes to download data from the computer. The AMES rehabilitation device uses robotic technology to assist a patient in moving the affected limb while vibrating the muscle receptors at the same time. During use, the patient’s input effort and other parameters important in therapy are measured and recorded by the device and displayed to the patient as real-time visual biofeedback. The AMES Device can also perform several diagnostic tests each time a patient is treated by the device to track progress.

Preclinical studies of 22 stroke patients with these devices showed that, in 80 percent of cases, significant arm or leg function was regained over a six-month period of self-applied treatment in the home. While the device cannot regain movement for certain types of central nervous system injuries and diseases, such as where the spinal cord is completely severed, the device can assist in regaining some movement in a large number of patients, Cordo said.

Where It Stands

AMES Technology, Inc., was spun off from the Oregon Health & Science University in 2004, and established to transform Cordo’s OHSU research findings into a rehabilitation medical device for use in hospitals and clinics. The AMES device is patented technology and is exclusively licensed worldwide to AMES. Both OHSU and Dr. Cordo have a significant financial interest in AMES Technology, Inc.

“For many of these patients, this means that they are able to once again perform daily tasks such as brushing their hair and teeth—actions that many of us take for granted. In other cases, patients regained the ability to walk,” said Cordo, who serves as founder and chief technology officer of AMES Technology.

At the end of May, the FDA granted 510(k) clearance to the AMES rehabilitation medical device, which allows AMES to market and sell the device. AMES anticipates delivering the device to hospitals and clinics in early 2014.

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