http://www.jneuroengrehab.com/content/10/1/39/abstract
Abstract (provisional)
Background
Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery,
motivate patients to practice, and allow therapists to deliver semi-autonomous training.
However, because such devices are often complex and actively apply forces, they have
not achieved widespread use in rehabilitation clinics or at home. This paper describes
the design and pilot testing of a simple, mechanically passive device that provides
robot-like assistance for active arm training using the principle of mechanical resonance.
Methods
The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim
of a wheelchair, a forearm support, and an elastic band that stores energy. Patients
push and pull on the lever to roll the wheelchair back and forth by about 20 cm around
a neutral position. We performed two separate pilot studies of the device. In the
first, we tested whether the predicted resonant properties of RAE amplified a user's
arm mobility by comparing his or her active range of motion (AROM) in the device achieved
during a single, sustained push and pull to the AROM achieved during rocking. In a
second pilot study designed to test the therapeutic potential of the device, eight
participants with chronic stroke (35 +/- 24 months since injury) and a mean, stable,
initial upper extremity Fugl-Meyer (FM) score of 17 +/- 8 / 66 exercised with RAE
for eight 45 minute sessions over three weeks. The primary outcome measure was the
average AROM measured with a tilt sensor during a one minute test, and the secondary
outcome measures were the FM score and the visual analog scale for arm pain.
Results
In the first pilot study, we found people with a severe motor impairment after stroke
intuitively found the resonant frequency of the chair, and the mechanical resonance
of RAE amplified their arm AROM by a factor of about 2. In the second pilot study,
AROM increased by 66% +/- 20% (p = 0.003). The mean FM score increase was 8.5 +/-
4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with
rocking. Improvements were sustained at three months.
Conclusions
These results demonstrate that a simple mechanical device that snaps onto a manual
wheelchair can use resonance to assist arm training, and that such training shows
potential for safely increasing arm movement ability for people with severe chronic
hemiparetic stroke.
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