August 30, 2005

Robotic arm can improve motor control after stroke

NEW YORK (Reuters Health) - A computerized robotic arm
trainer appears to be more effective than electrical
stimulation in improving motor control and strength in stroke
patients who are left with severe arm paralysis, German
investigators report.

The effectiveness of the Bi-Manu-Track robotic arm trainer
(Reha-Stim Company, Berlin), which helps the arm muscles to
contract and flex, was compared with electric stimulation,
which applies electrical pulses to the affected limb.

Dr. Stefan Hesse, from Klinic Berlin, and associates
recruited patients 4 to 8 weeks after stroke causing severe arm
paralysis. Twenty-one patients were randomly assigned to the
arm trainer group and 22 to electrical stimulation group.

In addition to regular physical therapy, all of the
patients received 20 minutes of the intervention therapy every
work day for 6 weeks, according to the report in the medical
journal Stroke. Patients in the arm trainer group performed 800
repetitions per session, while those in the electrical
stimulation group performed 60 to 80 wrist extensions per

At the end of the 6-week trial, the average motor function
score was 24.6 in the arm trainer group and 10.4 in the
electrical stimulation group. After 3 months, those in the arm
trainer group still had higher motor scores (30.0 versus 16.6).

Average scores for upper limb muscle strength were also
higher in the arm trainer group -- 21.8 versus 6.8,
respectively, at week 6, and 22.6 versus 6.9 at week 18. Muscle
tone did not differ between groups.

The greater improvement achieved with the arm trainer "is
probably attributable to the greater number of repetitions and
the bilateral approach," Hesse's group concludes. They
recommend confirmation of these findings in a larger,
multicenter clinical trial.

SOURCE: Stroke, September 2005.