Nerve Surgery Leaves Woman With Feeling in an Arm That Isn't There

Sept. 8, 2008— -- Claudia Mitchell may look like your average 20-something college student. She is anything but.

As a result of an experimental surgery, Mitchell has become the first real "Bionic Woman": part human, part computer.

Mitchell's bionic life began in 2004 with a ride on a friend's motorcycle. The bike suddenly spun out of control, and Mitchell's left arm was severed by a highway divider. After her doctor's attempts to reattach the arm proved unsuccessful, she was outfitted with a standard prosthetic arm.

Mitchell thought that her new prosthesis would make her life return to normal. But it didn't work. Her amputation was almost at her shoulder, which made the prosthetic arm all but impossible for her to control.

"It just sat on the shelf. It didn't do anything," Mitchell said.

Ready to Try Anything

She grew depressed, thinking she would have to spend the rest of her life with one arm, unable to perform even the most basic tasks. What saved her was a tiny article about an experimental nerve surgery.

The "targeted reinnervation" surgery was developed by Dr. Todd Kuiken of the Rehabilitation Institute of Chicago. It was a radical idea: a robotic arm controlled not by a patient's stump or shoulder, but by a patient's thoughts.

Mitchell, a U.S. Marine, was ready to try anything to have a second functioning arm. She volunteered for the surgery.

During the six-hour procedure in 2006, doctors took the severed and dormant nerves in Mitchell's shoulder, nerves that are used to control the movement of her arm, and put them under the muscle in her chest.

They wanted the nerves to reawaken and work her chest muscle. The doctors eventually used the electrical nerve signals from that chest muscle to power a new bionic arm.

'We Have Rewired Her'

Now, when Mitchell wants to move her arm, she thinks "move." The signal travels from her brain to the muscle in her chest. According to Kuiken, Mitchell's chest muscle then contracts and "lets tiny bits of electricity out."

There are tiny antennas built into the robotic arm, which pick up these electrical signals. The signals then go to an internal computer that decodes them and tells the artificial arm what to do. It's almost instantaneous.

"We have rewired her," Kuiken said.

For Mitchell, living with her new arm has meant constant discovery.

"I have what I call my 'eureka moments,'" Mitchell said. "My stunned 'I can't believe I just did that' moments."

Now she can do the simple things that most people take for granted, like folding a shirt, slicing vegetables or even opening a wine bottle.

"There are a lot of daily tasks that people don't even think about being able to do that I can [do] now," she said.

Familiar Sensations

But four months after Mitchell's surgery, things started to get a bit bizarre. While Mitchell was in the shower, hot water hit her chest -- and she could suddenly feel hot water on her left hand, the one that was missing.

It got even more strange: When she touched her chest, she could feel all sorts of other sensations in her missing hand. She could suddenly feel hot and cold, pressure and touch. All of this, just from touching particular spots on her chest.

It turns out that during Mitchell's surgery her doctors had moved not only Mitchell's motor nerves, the nerves that control movement, but her severed sensation nerves as well.

"Claudia was the first person that we did this on. We purposely directed her hand sensation nerves onto some chest skin, and it worked," said Kuiken of the Rehabilitation Institute.

Now when somebody touches Mitchell's chest, she feels the sensations in her missing hand.

"Claudia's brain doesn't know where her hand is living right now," Kuiken said.

Paul Marasco, a touch specialist and research scientist with the Rehabilitation Institute of Chicago, was brought in to study the hand sensations that Mitchell feels in her chest. He put together a detailed map, connecting what Mitchell's missing hand feels with the corresponding locations on her chest.

Depending on where you touch her chest, "she has the distinct sense of her joints being bent back in particular ways, and she has feelings of her skin being stretched," Marasco said.

And Mitchell feels the exact same sensation in the exact same spot, every single time.

"She is like clockwork," Marasco said. "Her sensations are very well established."

The Next Frontier

Doctors hope that Mitchell's new sensations will give them greater insight into how the brain deals with injury, and they also hope that it will help pave the way for future prosthetic technology. The next frontier is designing a prosthetic arm that will not only be able to touch but also to feel.

"When you touch something with this prosthetic hand, it will feel like your hand. When you touch your hot cup of coffee, you'll know it's warm," Kuiken said.

Mitchell is committed to the research, even spending most of her vacations at Kuiken's lab, test-driving the latest prosthetic equipment. Mitchell said that although she knows that she is a patient, she now feels that she is also part of the research team.

As for being called the "real life Bionic Woman," Mitchell finds it funny. She said she has never seen the 1970s show that starred Lindsay Wagner, but she is asked by children if she can do cool things with her bionic arm, like lift cars.

Mitchell doesn't want to be superhuman. She just wants what she has now -- a second chance at a normal life.

For more information about targeted reinnvervation surgery, click here.