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Bionic Arm Links Body, Mind

Jesse Sullivan, 59, is the first amputee with a prosthetic forelimb controlled by thoughts, a device that may one day help injured troops.

September 17, 2006|Bill Poovey | Associated Press Writer

DAYTON, Tenn. — Jesse Sullivan has two prosthetic arms, but he can climb a ladder at his house and apply a fresh coat of paint. He's also good with a weed-whacker, bending his elbow and rotating his forearm to guide the machine. He has even mastered a more sensitive maneuver -- hugging his grandchildren.

The motions are coordinated and smooth because his left arm is a bionic device controlled by his brain. He thinks, "Close hand," and electrical signals sent through surgically rerouted nerves make it happen.

Doctors describe Sullivan as the first amputee with a thought-controlled artificial arm.

Researchers encouraged Sullivan, who became an amputee in an industrial accident, not to go easy on his experimental limb.

"When I left, they said, 'Don't bring it back looking new,' " Sullivan, 59, said with a grin. At times he has been so rough with the bionic arm that it has broken, including once when he pulled the end off starting a lawnmower.

That prompted researchers to make improvements, part of a U.S. government initiative to refine artificial limbs that connect body and mind. The National Institutes of Health has supported the research, joined more recently by the military's research-and-development wing, the Defense Advanced Research Projects Agency. Some 411 U.S. troops in Iraq and 37 in Afghanistan have had wounds that cost them at least one limb, the Army Medical Command says.

Although work that created Sullivan's arm preceded the research by DARPA, he said he was proud to test a type of bionic arm that soldiers could someday use. "Those guys are heroes in my book," he said, "and they should have the best there is."

"We're excited about collaborating with the military," said the developer of Sullivan's arm, Dr. Todd Kuiken, director of the Neural Engineering Center for Artificial Limbs at the Rehabilitation Institute of Chicago, one of 35 partners now in a DARPA project to develop a state-of-the-art arm.

Sullivan's bionic arm represents an advance over typical artificial arms, like the right-arm prosthesis he uses, which has a hook and operates with sequential motions. There is no perceivable delay in the motions of Sullivan's flesh-colored, plastic-like left arm. Until now, it has been nearly impossible to re-create the subtle and complex motion of a human arm.

"It is not as smooth as a normal arm, but it works much smoother than a normal prosthesis," Kuiken said.

Sullivan lost his arms in May 2001 working as a utility lineman. He suffered electrical burns so severe that doctors amputated both his arms at the shoulder.

Seven weeks later, he was headed to meet the Chicago researchers.

Sullivan says his bionic arm isn't much like the one test pilot Steve Austin got in the '70s TV series "The Six Million Dollar Man." "I don't really feel superhuman or anything," he said.

"It's not magic," added his 4-year-old grandson, Luke Westlake, as he placed a nut in Sullivan's grip and challenged Paw-Paw to crack it open.

Not magic but high-tech science makes the bionic arm work. A procedure called "muscle reinnervation," developed by Kuiken and used on five additional patients so far, is the key.

For Sullivan, it involved grafting shoulder nerves, which used to go to his arms, to his pectoral muscle. The grafts receive thought-generated impulses, and the muscle activity is picked up by electrodes; these relay the signals to the arm's computer, which causes motors to move the elbow and hand, mimicking a normal arm.

"The nerves grow into the chest muscles, so when the patient thinks, 'Close hand,' a portion of the chest muscle contracts," according to an institute fact sheet.

Kuiken added: "Basically it is connecting the dots. Finding the nerves. We have to free the nerves and see how far they reach" and connect to muscles.

About three months after the surgery, Sullivan first noticed voluntary twitches in his pectoral muscle when he tried to bend his missing elbow, the institute said. By five months, he could activate four different areas of his major pectoral muscle.

Trying to flex his missing elbow would cause a strong contraction of the muscle area just beneath the clavicle. When he mentally closed his missing hand, a signal could be detected on the pectoral region below the clavicle, and when he tried to open his hand there was a separate signal. Extending his elbow and hand caused a contraction of the lower pectoral muscle.

When Sullivan's chest was touched he "had a sensation of touch to different parts of his hand and arm," the institute said. "The patient had substituted sensation of touch, graded pressure, sharp-dull and thermal sensation."

Sullivan said of the thought-controlled arm: "When I use the new prosthesis I just do things. I don't have to think about it."

Kuiken describes the procedure on Sullivan as the first time such a graft has been used to control an artificial limb.

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