On a recent day, a determined grandmother sat in front of a television in Warwick, jabbing repeatedly at the screen with a loose fist.
The woman, a recovering stroke patient, was playing Nintendo’s Wii computer boxing game, as part of a clinical trial by a local medical device company that is using Nintendo’s virtual reality computer games to test its stoke rehabilitation technology.
Providence-based Afferent Corp. began the clinical trial in early August at Omega Medical Research in Warwick. The early-stage medical device company is still hoping to attract about 15 more subjects to the clinical trial whose use of an arm is limited as a result of a stroke, said Susan E. D’Andrea, Afferent’s director of clinical research.
Afferent’s core technology is a non-invasive device strapped to the arm or another body part affected by stroke that sends electrical signals to sensory motor control cells in the extremity, stimulating them to form new pathways of communication with the brain, said Jason D. Harry, Afferent’s executive vice president and chief technology officer.
Neuroscientists have recently learned that the brain can regain motor function lost as the result of a stroke much longer after the stroke occurred than originally thought. Motor function is regained if the brain can essentially remap itself, transferring functions to a different area of the brain unharmed by the stroke, he said.
Afferent’s device is specifically designed to stimulate mechanoreceptor cells, which exist in all soft tissue and are responsible for a complex physiological process that essentially tells the brain where each part of the body is located in space and what environmental stimulation the body part is receiving, Harry said.
“A very classic demonstration of mechanoreceptors is to close your eyes and wave your arms around in front of you and then slow down and stop and touch your fingertips together with your eyes still closed,” he said. “That’s something that’s incredibly complex from a motor control perspective, yet you’re able to accomplish it with a position accuracy of just a few millimeters, and generally you can touch your fingertips together if you concentrate on it with your eyes closed.”
Afferent’s fledgling technology has vast potential if successfully developed. Stroke is the No. 1 cause of adult disability and the third-leading cause of death in the United States, according to the American Stroke Foundation. The American Heart Association reports that there are about 5.7 million stroke survivors alive today.
At its clinical trial in Warwick, Afferent is having subjects exercise their stroke-weakened arms by playing modified versions of Nintendo’s Wii boxing and baseball video games while the company’s device is strapped to their arm. The device provides sub-sensory electrical and mechanical stimulation that cannot be felt by the subjects, D’Andrea said.
But the treatment is nonetheless expected to increase the speed and extent to which the subject regains use of the arm, she said.
“This is a randomized control study; all of the subjects wear the device, but half receive stimulation, and half don’t,” D’Andrea said. “We hypothesize that subjects who receive Afferent stimulation will get to a higher function level after therapy than those who don’t.”
Virtual-reality methods for doing stroke rehabilitation are being researched by a number of leading groups, but this is the first study to combine virtual-reality exercises with neurostimulation as a means to generate improved outcomes, Harry said.
“It’s sort of an everyday virtual-reality system,” D’Andrea said, describing Nintendo’s popular Wii brand of video games. “You have a little remote that you hold in your hand and there’s a sensor on system and the game on TV is controlled by the remote in your hand.”
“What we’re trying to encourage with these subjects is reaching motions, because that’s a lot of the deficits that stroke patients have, is in their ability to reach and grab,” she continued. “So the subjects come into Omega Medical Research, they are fitted with our devices … and then they play either boxing or baseball.”
An interesting aspect of Afferent’s clinical trial using Wii video games is its promise to test the hypothesis that stroke patients who enjoy physical therapy regain motor function faster and more completely than those who don’t enjoy the rehabilitation process, Harry said.
In a mysterious, almost metaphysical example of mind over (gray) matter, the brains of stroke patients who want to regain use of an affected arm (to play a video game, for example) remap the motor function away from the part of the brain destroyed by stroke more successfully than often occurs in the brains of patients who passively submit to the same level of physical therapy, he said.
“With the Wii, the subjects are really into it,” D’Andrea said. “The grandmas are bragging to their grandchildren that they get to go play video games in rehab.”
Afferent is also conducting a separate clinical trial that doesn’t involve virtual reality exercises at Spaulding Rehabilitation Hospital, a Harvard University-affiliated rehabilitation hospital. •
