SMART joysticks could soon be helping stroke victims regain control of their
limbs, say researchers in Massachusetts.
Over half a million Americans suffer strokes every year and nearly half of
them survive with some kind of disability, which means they need several months
of physiotherapy to help them recover some limb control. But the emphasis is
usually on teaching people to compensate for their disability, rather than
retraining a disabled limb. Retraining is more time-consuming and tiring for the
therapists, who have to detect tiny movements and move heavy limbs around in
response.
鈥淎 therapist cannot and doesn鈥檛 want to do this hundreds of times a day,鈥�
says Hermano Krebs of the Massachusetts Institute of Technology in Cambridge. So
he鈥檚 building intelligent joysticks and pedals that can move the patient鈥檚 limbs
for them. Krebs has combined pieces from industrial robots that produce very
specific rotations, and horizontal or vertical motions, with a springy sensor
connected to a feedback system that continually changes the joystick鈥檚
resistance, depending on how hard the user is pushing.
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Krebs has also created a range of specially designed computer games that
stroke patients can play with their disabled arms or legs. He鈥檚 presenting a
prototype this week at the Institute of Electrical and Electronics Engineers
conference on engineering in medicine and biology in Istanbul. Patients who鈥檝e
lost movement in their wrist, say, score points by moving icons towards targets
on a screen by manipulating the joystick. They鈥檙e only rewarded if they use
muscles affected by the stroke, so they can鈥檛 compensate by using other
muscles.
The joystick knows where the patient should be aiming and changes its
resistance as they get stronger. At first, a feeble twitch in any direction is
enough to move the icon, but in later sessions the patient has to make stronger
and more accurate movements.
鈥淲e鈥檙e not just having someone sit around and receive therapy,鈥� Krebs says,
explaining the approach. 鈥淭he person has to be actively engaged.鈥� He compared 76
stroke victims who used the joysticks every day at the Burke Rehabilitation
Hospital in White Plains, New York, with a similarly sized control group who
were allowed to move the joysticks with any muscles they wanted. Krebs found his
group regained twice as much control of their disabled muscles after three
months.
He鈥檚 also found his joysticks get better results than other robotic machines
that move the limb for the patient (快猫短视频, 18 June 1994, p 21).
While these do improve a patient鈥檚 range of motion, they don鈥檛 actually help
them regain limb control.
Steve Lehman, who works on voluntary muscle control at the University of
California, Berkeley, says the MIT team needs to assure patients that their
joystick can make a difference. It may be hard to get people to put hours per
day into playing computer games unless they are sure it鈥檚 going to help them, he
says.