September 27, 2008

Positivity: Bionic breakthrough as prosthetic lets woman ‘feel’ her missing hand

Filed under: Positivity — Tom @ 7:01 am

From Chicago, and Maryland (HT Good News Blog):

Last updated at 3:11 PM on 10th September 2008

A bizarre discovery by the woman fitted with the world’s most advanced bionic arm could pave the way for hi-tech limbs that feel as well as move.

When surgeons fitted Claudia Mitchell’s £2million prosthetic, they hot-wired it to her brain via her original shoulder nerves so she could control the mechanical arm by thought alone.

But now she can also ‘feel’ sensations in her missing hand.

Miss Mitchell, a former US marine, lost her left arm at the shoulder in a motorcycle accident in 2004.

Because her real arm had been severed almost at the shoulder, she had lost the use of the nerves that ought to have been able to control a conventional prosthetic.

But in a new surgical technique called ‘targeted reinnervation’, her dormant shoulder nerves were implanted in her chest, away from the damaged area.

Now when Miss Mitchell wants to move her arm, her brain sends a signal to the chest muscle rather than to her useless shoulder.

‘We have rewired her,’ said Dr Todd Kuiken, the American who devised the technique.

Electrical pulses from her chest muscle are transmitted to the bionic limb where a computer decodes them and turns them into arm movements.

By thought alone, Miss Mitchell, of Ellicott City, Maryland, can bend her wrist back, move her thumb and clench her fingers.

‘I have what I call my “eureka moments,”‘ she said. ‘There are a lot of daily tasks that people don’t even think about being able to do that I can do now.’

But the twist came four months after her 2006 operation as Miss Mitchell was taking a shower.

When the hot water hit her chest, she felt it on her missing left hand.

She found that touching her chest or applying heat and cold to it would give her the sensation of pressure, warmth or coolness in her lost arm.

This was because doctors had moved not only her motor nerves but also her sensation nerves.

‘Claudia was the first person that we did this on. We purposely directed her hand sensation nerves onto some chest skin, and it worked,’ Dr Kuiken, of Chicago’s Rehabilitation Institute, told ABC News.

Paul Marasco, a touch specialist at the institute, has since charted the way Miss Mitchell’s hand sensations correspond with locations on her chest.

Depending on her chest is touched, he said, ‘She has the distinct sense of her joints being bent back in particular ways, and she has feelings of her skin being stretched.’

Researchers hope Miss Mitchell’s experiences – bizarre as they are – will open up major improvements in prosthetic technology.

She has become an honorary member of the research team, even spending her holidays testing out new equipment.

Go here for the rest of the story.


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