Leg Compressions May Limit Stroke Damage
Compressing then releasing the legs several times with a five-minute break in between, while administering a clot-busting drug, may be a way to limit brain damage following a stroke.
This is the main finding of a US study published online in the journal Stroke on 21 August, whose senior author David Hess, is a stroke specialist and chair of the Medical College of Georgia Department of Neurology at Georgia Health Sciences University.
The study, was done on mice, so the technique now needs to be tested on humans. Conditioning Body to Survive Stroke Hess told the press this week that repeatedly compressing and releasing the leg in conjuction with giving the clot-busting drug tPA, could double the effectiveness of the drug.
The reason, says Hess, could be because the technique, called "remote ischemic perconditioning", which induces small periods of reduced blood flow, triggers natural mechanisms that have a protective effect:
"Much like preparation to run a marathon, you are getting yourself ready, you are conditioning your body to survive a stroke," he explains.
Hess says the technique is a potentially "very cheap, usable and safe" therapy for stroke, that involves only temporary discomfort. It could be used in an ambulance or at a small, rural hospital. Tools for Dealing with Stroke Are Limited There aren't many tools for dealing effectively with strokes, which occur when the blood supply to the brain becomes restricted, such as from a blood clot. The loss of blood supply leaves an area of surrounding tissue starved of oxygen and vital nutrients, and if not restored quickly, the tissue dies off, causing loss of brain function.
90% of strokes are due to blood clots, for which the clot-busting drug tPA, short for tissue plasminogen activator, is currently the only stroke therapy approved by the US Food and Drug Administration.
Also, tPA is only safe and effective if given within a small time window of a few hours from the start of the stroke (the window is even smaller in older patients).
While some new tools for improving stroke outcomes are being tested, for instance The Lancet recently reported a new generation tool that mechanically removes clots from blocked blood vessels, these tend to be sophisticated and can only be used by surgeons.
But emergency health professionals could apply remote ischemic perconditioning with a blood pressure cuff while the patient is being prepared to receive tPA, say the researchers. Mouse Study: Leg Compressions and Clot-Buster Reduced Stroke Size by 50% For their study, Hess and colleagues bred mice that developed a clot in the internal carotid artery, the most common cause of stroke in humans.
They found that applying remote ischemic perconditioning without tPA reduced stroke size in the mice by 25.7%, which is slightly better than tPA.
When they applied both together, the compressions and the clot-buster, the combination reduced stroke size by 50%.
Not only this, but applying compressions soon after stroke also extended the window during which tPA is safe and effective. Human Trials The researchers now want to look for biomarkers that will allow easy measurement of how effective the technique could be in humans.
One marker of technique effectiveness could be increased blood flow to the brain, something Hess and colleagues noticed in the mice.
Other markers might be found by analyzing the blood of healthy people before and after experiencing leg compressions.
Another option is to run more mouse trials to see whether applying leg compressions after tPA also works, or maybe works even better.
The team suggests the first human trial could involve applying a blood pressure cuff to the legs of a small group of stroke patients to see how well that works.
Stroke is the fourth leading cause of death in the United States, and is also a common cause of long-term disability.
Funds from the National Institutes of Health and Georgia Health Sciences University helped pay for the study.