RACHEL MARTIN, HOST:
The Food and Drug Administration has authorized a device that can help stroke patients regain the use of a disabled hand. The device uses signals from the uninjured side of a patient's brain. NPR's Jon Hamilton has more.
JON HAMILTON, BYLINE: On a winter night in 2015, Mark Forrest started feeling bad. He thought it was his blood sugar. His wife, Patti, realized he was having a stroke.
MARK FORREST: So we called 911, and off to the hospital I went. And by the time I got there, most of my right side was paralyzed.
HAMILTON: Including his right hand. And more than six months after his stroke, Forrest was still struggling to pull on his socks and button his shirts. What he missed the most, though, was fishing for bass in the rivers and lakes near St. Louis.
M FORREST: I mean, I'm a die-hard fisherman, so that really hurt for me not to be able to do that.
HAMILTON: Forrest even tried cutting down a fishing pole so he could hold it with his left hand, but his right hand wouldn't reel in the line. So he kept working with a physical therapist, month after month, until he got really frustrated.
M FORREST: I said, how much more am I going to improve? She says, I don't think you're going to improve hardly at all.
PATTI FORREST: That was tough.
M FORREST: And that was hard for me to take.
HAMILTON: Around that time, Forrest started talking to Dr. Eric Leuthardt, a brain surgeon at Washington University in St. Louis. For many years, Leuthardt had been puzzled by something he often heard from patients.
ERIC LEUTHARDT: If you talk to a stroke patient, they can imagine moving their hand, they can try to move their hand, but they just can't actually move it.
HAMILTON: So Leuthardt had been looking for the source of those thoughts and he found them in a surprising place - the side of the brain that had not been injured by the stroke.
LEUTHARDT: So now we're starting to look at signals being generated on the opposite side of the brain, where there's still kind of the intent to move and it's present.
HAMILTON: Leuthardt and his team were able to build a device that used those signals to control a robotic exoskeleton. The device could open and close a patient's disabled hand for them. But a mechanical hand wasn't Leuthardt's ultimate goal. He wanted to help his patients regain the ability to move their own hand, and that meant answering a question.
LEUTHARDT: If somebody can generate a brain signal that's associated with their desire to move, and the exoskeleton moves it so they're getting feedback, can we use this device that controls their affected limb to essentially encourage the brain to rewire?
HAMILTON: Early experiments suggested the approach worked. Leuthardt says video of one man showed him initially trying and failing to grasp a marble and place it on a shelf.
LEUTHARDT: Then, after six weeks of training, you see his hand - it's not perfect, but he's more dexterous. He can pick up that marble and he can move it on top of the shelf.
HAMILTON: Leuthardt had founded a company called Neurolutions to develop the technology. Its CEO is Leo Petrossian, a brain scientist with a business degree.
LEO PETROSSIAN: I got involved specifically to help take something that was great in clinical studies and figure out how we can now bring this out to the million-plus people in the United States living with disability post-stroke.
HAMILTON: Petrossian says the conventional wisdom is that most recovery from a stroke takes place in the first 90 days or so.
PETROSSIAN: So if it's day 100 and a person can't move their arm very well, that's how their arm's going to be for the rest of their life.
HAMILTON: The company began developing a system to challenge that sort of thinking. It included a headset that analyzes brain signals, a tablet computer and a robotic exoskeleton worn over the patient's wrist and hand. Petrossian says they began trying prototypes on patients who got better.
PETROSSIAN: If you spend an hour a day doing this exercise of thinking and visualizing opening and closing a hand, five days a week for 12 weeks, you retrain a different part of the brain to drive that previously disabled appendage.
HAMILTON: Mark Forrest, the die-hard fisherman, tested several different versions of the device called IpsiHand. He often spent several hours a day working to open and close his hand with the exoskeleton's help. His wife, Patti Forrest, says by this time, more than a year had passed since the stroke and other therapies had stopped helping.
P FORREST: But with this, he was making great strides. Like, all of a sudden, he could touch his index finger with his thumb and he would be like, whoa. And so it was much bigger gains in a shorter period of time.
HAMILTON: Mark Forrest decided to test his new dexterity by building a fishing boat. Dealing with the tiny screws was still a challenge, and his friends kept joking that the homemade boat was going to sink.
M FORREST: It didn't. I built a really nice one; it's got wheels on the bottom of it, so it rolls in and out of the water.
HAMILTON: Forrest put the boat in the water for the first time in March, and he discovered that he had regained the ability to reel in a fishing line with his right hand.
M FORREST: We sat and fished for five hours on that boat and probably every cast, every other cast, we were catching fish.
HAMILTON: In April, the FDA OK'd the IpsiHand for people recovering from a stroke, even if it occurred years earlier. Neurolutions is gearing up to manufacture the device and expects it to be on the market in a matter of months.
Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
