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Last Updated: Saturday, 7 February, 2004, 00:45 GMT
'Corkscrew' repairs stroke damage
The device removes blood clots from the brain
Scientists have developed a 'corkscrew' which can capture and remove blood clots in the brains of stroke patients.

Doctors from the University of California were able to reverse the disabling effects of a stroke in patients using the device.

It is inserted via an artery in the groin and guided through the body to the brain, where it 'remembers' to form into a corkscrew around the clot.

The device is then removed, taking the clot with it and unblocking the artery.

The researchers studied patients who had suffered ischemic stroke.

These are caused by a blood clot that blocks the blood supply to the brain and are the most common kind of strokes.

Doctors can give patients clot-busting drugs to dissolve the blockage - but these are only effective if they are given within three hours of a stroke.

'Capturing' clots

The corkscrew device - or Concentric Merci Retrieval System - is made from nickel and titanium.

This alloy has the ability to 'remember' to form a particular shape at certain temperatures.

It is fed into the artery in the groin, and up to the brain, inside a catheter.

Once it is released inside the blocked artery, the body's temperature prompts the metal to form into the corkscrew shape.

The blood clot is then "captured", and the device can be withdrawn from the artery.

As the clot is removed, a tiny balloon attached to the catheter is briefly inflated, stopping the blood flow so the clots can be safely removed.

Researchers from the University of California Los Angeles tested the device on 114 patients who had been severely affected by a stroke.

They were able to restore blood flow through the artery in 61 patients.

Of these, 23 were left with no lasting effects from the stroke, or with relatively minor disabilities, such as difficulties with writing.

'Devastating effects'

Sidney Starkman, a professor of emergency medicine who developed the device, said: "We have had patients completely paralysed on one side of their body, who were made normal almost instantaneously when the clot was retrieved."

He added: "Thus far, we have seen that the Merci Retrieval System is quite safe and we believe it holds great promise, but more research is needed to refine the device and study its effectiveness."

A spokeswoman for the UK's Stroke Association told BBC News Online: "We would welcome any treatment that would help to prevent the devastating effects of strokes, especially in those who are at high risk.

"This is a potentially exciting development for stroke patients; however, it is at an early stage. We will be watching its progress, and the results of further clinical trials, with interest."

The researchers presented their work to the American Stroke Association's International Stroke Conference in San Diego,

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