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Robot Therapy Helps Stroke Patients Regain Motor Function


doi: 10.1097/01.NT.0000349800.15864.8f
News From the International Stroke Conference
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In a small study, 15 chronic stroke patients with weakness of the distal right arm and hand were all able to grasp and release objects more easily after treatment with a robotic device that cradled the lower arms and hands.

SAN DIEGO—Robotic therapy helped patients with chronic moderate-to-severe motor deficits after stroke to regain modest motor function, a small study shows.

Fifteen chronic stroke patients with weakness of the distal right arm and hand were all able to grasp and release objects more easily after treatment with a robotic device that cradled the lower arms and hands, Steven C. Cramer, MD, director of the Stroke Center at the University of California-Irvine, reported here in February at the American Stroke Association International Stroke Conference. The patients had had strokes four months to 10 years before starting the two-week course of therapy.

The better the baseline motor skills, the greater the recovery, Dr. Cramer said.

The new study expands previous work in which the hand-wrist robot had favorable effects on hand and arm function in 13 patients with chronic stroke, reported in 2008 in Brain.

The Hand-Wrist Assisting Robotic Device — nicknamed HOWARD — wraps around the hand and, in concert with a computer program, directs the thumb and fingers through a physical therapy session, said Dr. Cramer, who was also a co-investigator on the 2008 study.





Users initiate hand movements on their own; HOWARD monitors the movement, helps train the hands into the positions it needs to be in to perform various tasks, and provides assistance to complete each activity, he said.

The therapy was built upon principles of motor learning including use of intense, active repetitive movement and sensorimotor integration, he said.

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The new study involved 15 patients, average age 61, with a right hemiparesis. Their strokes occurred an average 2.6 years before therapy commenced. Seven patients were randomized to the same motor therapy used in the first study. Eight others received a more complex robotic approach called premotor therapy, which was identical in all ways to motor therapy except for the manner of cueing, Dr. Cramer said.

For motor therapy, cueing consisted of a repeating cycle to open, then close, and then rest the hand — in an unchanging order. For premotor therapy, each command was presented in random order, and was coded by a set of color-based cues that changed every 2.75 min., he said.

“This therapy mimicked normal function of the premotor cortex, in that subjects processed external cues to select the next action,” Dr. Cramer said.

In both types of therapy, the computer completed the movement for the patients only if they incompletely squeezed or relaxed their hands.

“In response to one of three color cues, patients try to open, then close, then rest, the weak hand. After they do the best they can, the robot completes the movement to the extent the patient could not,” Dr. Cramer said.

The reason the computer kicks in at that point, he said, is because “sensory feedback is a normal part of motor performance. We completed the movement in these instances so the brain could experience the signals of a completed correct movement. That helps the brain recall what to do the next time,” he said.

Robot treatment sessions consisted of two 25 min. sets of grasp-release exercises, 35 min. of robotic assessments, and two 30 min. sets of virtual reality games. Ten-minute rest periods were given between exercises.

Physical recovery was measured with three tools that assess arm motor function: The standard arm-motor Fugl-Meyer scale, in which 66 points is normal; the Action Research Arm Test (ARAT), which measures the ability to perform real-world tasks such as grasping an object or gripping a drinking glass, in which 57 points is normal; and the Box-and-Blocks Test, which assesses manual dexterity in terms of the number of blocks one can move from one side of a box to another in one minute.

At baseline, the patients' average Fugl-Meyer score was 35 points and their average ARAT score was 25 points. On the Box-and-Blocks Test, patients could move an average of 12 blocks from one side of the box to the other.

Gains from baseline to one month post-therapy did not significantly differ according to treatment assignment, for any of the three measures evaluated. However, a suggestion that the two forms of therapy had different effects was found when the data were analyzed according to the patients' baseline motor status.

Among the six patients with higher baseline Fugl-Meyer scores (average 54 points), for example, premotor therapy produced significantly greater gains in Fugl-Meyer score than did standard therapy at one month post-treatment.

“No such difference was seen among nine patients with an average baseline Fugl-Meyer score of 23 points,” Dr. Cramer said. The researchers also looked at whether the effect of type of therapy varied as a function of injury to the premotor/motor system. They found that in patients with greater ischemic destruction of these tracts, as seen on functional MRI, the effects of motor and premotor therapy were similar.

In patients with less injury, however, premotor therapy produced significantly greater gains than motor therapy did, Dr. Cramer said. “The results suggest that to restore motor function after stroke, different treatment strategies may be needed in relation to differences in clinical status and in relation to extent of stroke-related injury,” he said.

Dr. Cramer said robotic therapy remains at an early stage but has great potential, perhaps in use with other experimental treatments, including drugs, electro-stimulation, and cell transplants. “It offers the ability to provide therapy without fatigue for long time periods, in a consistent and precise manner, and can be automated for many functions. Most importantly, it enables telemedicine rehabilitation so we can help more patients who now miss out on therapy because they live too far away [from a rehab facility],” he said.



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Edward J. Mendelsohn, MD, staff physiatrist at Manhattan Rehabilitation Services and attending physiatrist at St. Vincent's Medical Center in NY, said that it is noteworthy that patients experienced gains in motor function even though they didn't have the treatment for months or years after the stroke.

“Usually most return of function occurs within the first three months, or even out to one year,” Dr. Mendelsohn said. “But using [robots, video games, and relaxation exercises], we're now seeing improvements in range of motion and in function in patients who had strokes five or six years earlier. Seeing any improvement at all years after the stroke is significant,” he said.

Larry B. Goldstein, MD, director of the Duke Center for Cerebrovascular Disease at Duke University Medical Center in Durham, NC, agreed. “The findings are consistent with the idea that we can get some gains, even late after stroke. “Robotic therapy is a way of giving intensive, repetitive training of paretic limbs. But some caution is warranted, as it did not help all patients, only those who were doing better to begin with,” he said. •

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Takahashi CD, Der-Yeghaian L, Le V, et al. Robot-based hand motor therapy after stroke. Brain 2008; 131:425–437.
    ©2009 American Academy of Neurology