HOWARD the robot lends a hand after stroke
Abstract P145
(This is also the subject of a video news release)
SAN FRANCISCO, Feb. 7 – A robotic therapy device may help people regain strength and normal use of affected hands long after a stroke, researchers reported today at the American Stroke Association’s International Stroke Conference 2007.
“Most spontaneous improvement in function occurs in the first three months after a stroke and after that things tend to plateau,” said Steven C. Cramer, M.D., lead author of the study and associate professor in neurology, anatomy and neurobiology at the University of California, Irvine. “Robot-assisted therapy may help rewire the brain and make weak limbs move better long afterwards.”
Robots may offer particular advantages in long-term therapy that requires intense, repetitive movement practice.
“Robots can consistently and precisely perform the same task without getting tired, record and adjust to the patient’s responses, and provide feedback and virtual reality games that keep people interested and motivated,” Cramer said.
Robots also have a high potential for tele-rehabilitation. “With the robot, a therapist could theoretically run 10 therapy sessions at once, or use a webcam to provide therapy from a distance at home,” he said.
Previously, robotic devices have improved post-stroke shoulder and leg function. Cramer said this study is one of the first attempts to specifically aid hand function.
Researchers developed a Hand-Wrist Assisting Robotic Device (HOWARD) that monitors and aids patients as they grasp and release common objects. Seven women and six men, average age 63, participated in the pilot study using HOWARD. More than three months after a stroke, each patient had at least moderate residual weakness and reduced function of the right hand, although the affected hands were not totally paralyzed nor unable to feel.
Each patient received 15 two-hour therapy sessions, spread over three weeks, designed to improve their ability to grasp and release objects. All worked with HOWARD for the 15 sessions. For seven, HOWARD shaped and helped complete movements across all sessions, while six had complete support from HOWARD for only the second half of the sessions.
“The therapy isn’t passive; the brain has to jumpstart the program and initiate the motor command,” Cramer said. “But if the hand is weak and can only budge one-tenth of an inch, the robot helps to complete the task so the brain relearns what it’s like to make the full movement.”
At the end of three weeks, all patients had improved in their ability to grasp and release objects. Their average score on the Action Research Arm Test improved 4.2 points, from 33.5 to 37.3 points. The test measures, on a scale from 0 to 57, the ability to perform such real-world tasks as grasping a block, gripping a drinking glass, pinching to pick up a small marble or ball bearing, and putting your hand on your head. The average score on the Box-and-Blocks Test, which assesses manual dexterity as one moves blocks from one side of a box to another in one minute, also rose 4.2 points, from 19.7 to 23.9.
Patients also developed a significantly greater range of motion in their hands and wrists and were rated as less disabled on a standard occupational therapy assessment tool called the Fugl-Meyer score, which rose an average of 7.6 on the 66-point scale.
“Assessing changes in before-and-after scores within each subject, these were highly significant gains after three weeks of therapy,” Cramer said.
The average gain in function after therapy was more striking in patients who received robotic assistance during all sessions vs. half:
- 5.3 vs. 2.8 on Action Research Arm Test;
- 5.3 vs. 3.0 on Box-and-Blocks;
- 9.1 vs. 5.8 on Fugl-Meyer.
“There were significant differences even though the groups got the same therapy, with the same content, for the same number of minutes," Cramer said. "The only difference was that during the first half of the sessions, the robot did not move the hand and wrist for six of the subjects.”
The team is using what they learned from study participants to create a “son of HOWARD,” with improved hand-robot connections and more software options to individualize therapy and keep patients interested.
“There is more ability to rebuild the brain than we realized in the past," Cramer said. "Scientists are investigating the impact of using these things one at a time, but ultimately they will not be used in isolation. I can imagine the power of using several of them together, with robots as one component, to make weak limbs move better in parallel with a restorative drug or growth factor.”
Stroke is a major cause of long-term disability in the United States, with more than 1.1 million adults in 1999 reporting difficulty performing everyday activities because of stroke, according to the American Heart Association.
Co-authors are Lucy Der-Yeghiaian, M.A., OTR/L; Jill See, M.P.T.; Vu Lee, M.S.; and Craig D. Takahashi, Ph.D. The study was partly funded by a National Institutes of Health Institutional Training Grant.
Statements and conclusions of abstract authors presented at American Heart Association/American Stroke Association scientific meetings are solely those of the abstract authors and do not necessarily reflect association policy or position. The associations make no representation or warranty as to their accuracy or reliability.
NR07-1106 (ISC07/ Cramer)
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Note: Presentation time is 5:30 p.m., PST, Wednesday, Feb. 7, 2007
