BreakThroughs - Medical Technology
from Discover - February, 1999 - page 25

Mind over Matter

Strokes and accidents that damage the brain or spinal cord sometimes leave
people fully conscious but unable to speak or move. Trapped in their own
bodies, the people who suffer from what is sometimes called locked-in
syndrome are lucky if they can communicate their needs with a blink or a
raised eyebrow. That may soon change. A team of neurologists has developed a
device that allows paralyzed people to communicate through a computer without
having to move a muscle. 

Philip Kennedy, a neurologist in private practice near Atlanta, has been
working on the implant - a millimeter-long electrode - for 12 yeras.
Implanted in the part of the brain that normally controls the hands, the
electrode, coated with growth factors that spur brain tissue to grow into it,
picks up electric signals sent back and forth by nreve cells. 

When a patient thinks about moving his hands, electrical activity near the
electrode increases. Through an amplifier and antennas positioned underneath
the scalp, those signals are transmitted to a computer, which uses them to
drive a cursor across a screen. By concentrating or relaxing, a patient can
control the firing  of his neurons and make the cursor stop on an icon with a
prepared message or on a letter of a keyboard display. The computer then
speaks or prints a letter or message. 

Kennedy and his partner Roy Bakay, a neurosurgeon at Emory University, have
tried the implant in two patients so far. The first, a woamn suffering from
amyotrophic laterial sclerosis, ot Lou Gehrig's disease, passed away due to
her illness 76 days after receiving the implant. Their second patient, a man
paralyzed from the top of the neck down after a stroke, has had his implant
for nearly a year. He hasn't quite mastered the keyboard, but he can position
the icon near prepared messages. "He's delighted," says Kennedy, "and when it
works for him, he has a big smile on his face."  

Kennedy and Bakay hope their implant will help people control prosthetic
devices as well as computer cursors. There are approximately 5 million people
in the world who are quadriplegic, paraplegic, or have locked-in syndrome.
With enough funding, says Kennedy, he could help these people in as little as
three to five years.