Scientists are testing a
new thought-controlled device that may one day help people move limbs again
after they've been paralyzed by a stroke.
The device combines a high-tech
brain-computer interface with electrical stimulation of the damaged muscles to
help patients relearn how to move frozen limbs.
So far, eight patients who
had lost movement in one hand have been through six weeks of therapy with the
device. They reported improvements in their ability to complete daily tasks.
"Things like combing
their hair and buttoning their shirt," explained study author Dr Vivek
Prabhakaran, director of functional Neuroimaging in radiology at the University
Picking up brain signals
"These are patients
who are months and years out from their strokes," Prabhakaran said.
"Early studies suggested that there was no real room for change for these patients
that they had plateaued in the recovery. We're showing there is still room for
change. There is plasticity we can harness."
To use the new tool,
patients wear a cap of electrodes that picks up brain signals. Those signals
are decoded by a computer. The computer, in turn, sends tiny jolts of
electricity through wires to sticky pads placed on the muscles of a patient's
paralyzed arm. The jolts act like nerve impulses, telling the muscles to move.
A simple video game on the
computer screen prompts patients to try to hit a target by moving a ball with
their affected arm. Patients practice with the game for about two hours at a
time, every other day.
Researchers also scanned
the patients' brains before, during and a month after they finished 15 sessions
with the device.
The more patients
practiced, the more they were able to train their brains, the researchers
The findings were scheduled
for presentation at the annual meeting of the Radiological Society of
North America, in Chicago.
Strokes occur when blood
flow to the brain stops. This happens because a blood clot blocks a blood vessel
in the brain or a blood vessel breaks in the brain. Strokes often cause
problems with movement and language.
Though it's an early look
at evidence supporting the therapy, one expert who was not involved with the
research said the results looked promising.
"Stroke is the largest
cause of disability in the country," said Dr Rafael Ortiz, director of
neuro-endovascular surgery and stroke at Lenox Hill Hospital in New York City.
"50% of stroke patients end up with severe disability, and that's out of
800 000 strokes that happen a year," he said. Better kinds of
rehabilitation for stroke patients are desperately needed, he added.
"Using therapies like
this, we can offer hope to patients, even six or twelve months after their
stroke," he said.
The brain has two sides, or
hemispheres. Researchers say that what seems to be happening is that the side
of the brain that wasn't damaged by the stroke learns to take over many of the
functions lost on the affected side.
And the more patients are
able to recruit the unaffected side, the better their progress, Prabhakaran
Some, but not all, of the
positive brain changes remained even a month after patients had finished
therapy. Researchers think maintenance sessions may be necessary to help people
keep their gains.
Patients with mild to
moderate damage seem to get the most help from the device, he added. Patients
with milder impairments were able to increase their speed on a task that
required them to move pegs on a board. Patients with moderate damage were able
to recover movement and strength.
The study is still in its
early stages. Researchers said they won't know for sure how well it works or
how useful it may be until they've tested it on more patients. Prabhakaran said
he hoped to recruit 44 in total.
Data and conclusions
presented at meetings are typically considered preliminary until published in a
peer-reviewed medical journal.
For more on stroke
rehabilitation, see the National Institute of Neurologic Disorders and Stroke.