Electrical stimulation of brain boosts stroke recovery
30 March 2006
Portland, Oregon USA. Sending tiny electric pulses to a part of the brain
controlling motor function helps ischemic stroke survivors regain partial
use of a weakened hand, according to a study by Oregon Health & Science
The study shows that combining cortical stimulation using a pulse
generator with aggressive rehabilitation is key to reversing the impairment.
"It's the coolest thing in stroke I've seen in a long time," said Helmi
Lutsep, M.D., associate professor of neurology and associate director of the
Oregon Stroke Center, OHSU School of Medicine.
In a study examining the safety of cortical stimulation therapy, Lutsep
and co-investigators found that stroke patients who received stimulation
with rehabilitation improved "significantly" better in hand mobility and
strength tests than people undergoing rehabilitation alone.
"Everybody improved to some degree, because even in the subjects who
received some rehabilitation, we did see improvement," Lutsep said. "What
the data suggested is those who received the (stimulation) implant improved
The study was published in the journal Neurosurgery. Lutsep's
co-investigators were Jeffrey A. Brown, M.D., of Wayne State University,
Detroit, Martin Weinand, M.D., of the University of Arizona, Tucson, and
Steven C. Cramer, M.D., of the University of California, Irvine.
Ischemic stroke occurs when a clot in a blood vessel blocks the flow of
oxygen-rich blood to the brain. The result can be major weakness on one side
of the body, a condition called hemiparesis, which is typically treated with
rehabilitation. According to the American Stroke Association, 88 percent of
the estimated 700,000 strokes that occur each year are ischemic.
In cortical stimulation, a pacemaker-like device called an external pulse
generator sends a low current through a wire to an electrode placed
surgically atop the dura, the fibrous membrane covering the brain. The
electrode rests above the motor cortex, the area in the brain corresponding
to hand function. Surgeons pinpoint the site using "neuronavigation"
techniques, including functional magnetic resonance imaging, or fMRI, then
remove a circular, 4-centimeter flap of the skull to access the dura.
The technique is similar to one used to treat Parkinson's disease called
deep brain stimulation, or DBS, which uses electrical impulses sent to two
electrodes surgically implanted in the brain to block the signials that
cause the disabling motor symptoms of the disease.
"It's like DBS, except that we don't go deep into the brain," Lutsep
emphasized. "It's considered generally safer, less invasive, but on the
other hand, we still have to go into the skull to place it."
Eight individuals ages 33 to 74 completed the Neurosurgery study. Each
had suffered motor deficits resulting from a stroke that occurred at least
four months before, and was randomly placed into one of two groups: An
active treatment group that received cortical stimulation with three weeks
of rehabilitation, and a control group that received rehabilitation alone.
In the active treatment group, the device was turned on only during
The study found that patients in the active treatment group "improved to
a significantly greater degree" than control patients, and they continued to
improve through the three-week treatment period and into a fourth week, when
a follow-up assessment takes place. Active treatment patients even
maintained their improvements through the 16th week of the study. In
comparison, control patients experienced "lesser" improvements within the
study's first two weeks, and the improvements decreased over time.
Researchers believe cortical stimulation induces neurons to rewire
themselves in response to the damage caused by stroke, a phenomenon known as
plasticity, and rehabilitation continues to encourage this rewiring
activity. "The idea is you induce plasticity in the brain and once it's
there, you can remove the hardware," Lutsep said.
One study participant, June Wallace, 77, of Portland, said stimulation
therapy helped her regain use of her right hand, which has remained weak
since suffering a stroke in May 2002.
"Before the study, I had been through just regular rehab and was in the
process of trying to shift everything I did to my left side. My right side
was pretty useless at that point," she recalled. "Since the study, I can
pretty well do everything I did. It wasn't immediate. It was just something
that happened. One day, it was like, 'Oh wow! Look what I can do!'"
OHSU is one of 16 sites around the country participating in a follow-up
study called EVEREST that will examine a larger group of stroke survivors -
174 people - to confirm the safety and effectiveness of cortical stimulation
therapy shown in the Neurosurgery study. Like that trial, the EVEREST trial
will focus on people age 21 years and older who have had an ischemic stroke
at least four months prior to screening and suffered weakness in one hand or