Clot-busting corkscrew aids stroke patients
New technique may help reverse paralysis.
6 February 2004
HELEN R. PILCHER
Blood clots in the brain can kill if they aren't tackled within hours.
© SPL
A clot-busting corkscrew may help patients to recover after stroke. The device, which is guided through blood vessels to the brain, retrieves blobs of coagulated blood and can, in some cases, reverse paralysis.
The technique has worked for a small group of patients in a US clinical trial. Sidney Starkman from the University of California, Los Angeles and colleagues tested their method on 114 stroke patients. Sixty-one had their clots successfully removed, with 23 making a near-complete recovery.
One patient was paralysed down one side and couldn't speak, says Starkman. "We pulled out the clot and instantaneously he was back to normal," he says. The remaining 53 patients were either left paralysed, or died from their clot.
"It's difficult to judge how good a result this is," says stroke researcher Peter Rothwell of the Radcliffe Infirmary in Oxford, UK. Up to 30% of stroke patients recover spontaneously, without any treatment at all. "Some of these patients may have recovered anyway," he says.
Stroke is the main cause of disability in adults, and is the third-biggest cause of death in the United States. Those who survive often suffer from paralysis and have problems walking and talking.
The condition occurs when a blood vessel carrying oxygen and nutrients to the brain becomes blocked or bursts. Brain cells then start to suffocate and die.
Spring into action
The tiny corkscrew is made from a springy mixture of nickel and titanium. It can be pulled straight and stored inside a cylindrical casing, but springs back into shape when pushed free of its shell.
Patients begin their treatment with an X-ray that shows doctors where the clot is. Next, the corkscrew, which is attached to a long wire, is inserted into an artery in the groin. It's then guided through the body by remote control, until it reaches the brain.
You then twist the corkscrew into the clot and pull it out, explains Starkman: "It's like pulling out a cork from a wine bottle."
Similar techniques are already used to remove clots that cause heart attacks, says stroke clinician Tony Rudd from Guy's and St Thomas' Hospital, London. It's a complex and delicate procedure that requires a lot of skill, he says.
"Sometimes it's difficult to get the probe to the right place," agrees Starkman. The corkscrew may also be too soft to penetrate some blood clots, he says. The team is now working to refine their tools and techniques.
Better than drugs?
New clot-busting treatments are desperately needed. At present, there is only one licensed anti-stroke drug, called tissue plasminogen activator. But it must be given in the first three hours after a stroke, and only 3-5% of stroke patients reach hospital in time to receive it. Of those who make it in time, the blood clot dissolves in only 13% of patients.
Starkman tested his treatment on stroke victims who arrived at hospital too late for this drug to work. The patients received their corkscrew-based therapy up to 8 hours after the stroke. This shows that some patients benefit from treatment even after a long wait, says Starkman.
The study was presented this Thursday at the American Stroke Association's 29th International Stroke Conference in San Diego.
© Nature News Service / Macmillan Magazines Ltd 2004 |
