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Medicine | IN THE LAB

Rapid stroke treatment, delivered by paramedics

November 03, 2003|Shari Roan | Times Staff Writer

Doctors have known for at least 10 years that stroke should be treated as an emergency. But that knowledge doesn't always translate into practice.

Beginning early next year, however, some stroke patients in Los Angeles County will receive an experimental stroke treatment as soon as humanly possible -- in an ambulance.

A new federal study, based at UCLA Medical Center, will attempt to determine whether rapid treatment with magnesium sulfate can limit brain damage in stroke patients. About 330 fire stations and 80 hospitals with emergency rooms are expected to participate.

The study, funded by the National Institutes of Health, was prompted by doctors' frustration with efforts to bring brain-sparing treatment to stroke patients sooner. Many drugs have been shown to limit brain damage when given to laboratory animals, but the therapies have often proved useless when given to stroke patients in the emergency room.

"Time lost is brain lost in acute stroke," says Dr. Jeffrey Saver, a co-investigator of the study and a professor of neurology at the David Geffen School of Medicine at UCLA.

Strokes typically occur when a blood clot limits blood flow to the brain. Without the oxygen-rich blood, brain cells can die, creating permanent damage. (About 20% of strokes, known as hemorrhagic strokes, are caused by bleeding in the brain.)

Most drugs are given to patients six to 24 hours after stroke symptoms begin, Saver says, but by that time, much of the neurological damage has occurred.

"If we're going to find a benefit from neuro-protective drugs, we need to get it to patients early," he says. "Paramedics are uniquely positioned to accelerate conventional stroke care and deliver brain-protective drugs."

Magnesium sulfate is considered a prime candidate for stroke treatment delivered in the field. The drug has been used for various ailments other than stroke -- such as to treat eclampsia, a dangerous condition in pregnancy -- for about 75 years and carries few risks or side effects. Doctors believe that magnesium sulfate can help stroke patients in two ways: by dilating blood vessels to increase blood flow to the brain and by blocking calcium that overloads cells in the brain when blood flow is reduced. The therapy is primarily intended for ischemic stroke, strokes caused by blood clots, but may help people with hemorrhagic stroke too.

Magnesium sulfate won't harm patients who appear to be having a stroke but are actually having a seizure, migraine headache or are suffering from a rapid change in blood sugar.

Still, it's likely paramedics won't often be mistaken. In a pilot study conducted from 2000 to 2002 in Los Angeles, paramedics gave magnesium sulfate to 20 patients following a stroke screening process. The screening includes observation (such as whether the patient has weakness in facial muscles and in the arms and hands), four questions, and a blood glucose test.

In all 20 cases, the patients were confirmed to have had a stroke, Saver says.

The new study, which is awaiting final approval by the state Emergency Medical Services Authority before it begins, probably in January, will determine how effective early drug treatment is in reducing brain damage. Paramedics will ask patients whether they want to participate. If so, the patient will be connected to a doctor, via cellphone from the ambulance, who will explain the study. If the patient cannot give consent, a family member can, Saver says.

Paramedics are looking forward to the challenge, says Dr. Marc Eckstein, medical director of the Los Angeles Fire Department and a co-investigator for the study.

"While it requires more work on their part, as long as there is a potential benefit for the patient, they'll buy into it," he says.

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For now, only one drug treats acute stroke

When it comes to limiting brain damage from an acute ischemic stroke (a stroke caused by a blood clot), doctors have only one drug in their arsenal.

Tissue plasminogen activator, or TPA, was approved in 1996 and works by breaking up the clot. The drug, however, has to be administered within three hours of the first symptoms. Because TPA can be dangerous if given to patients whose strokes are caused by bleeding, known as hemorrhagic strokes, the patient must first be transported to a hospital and given an imaging test to confirm the blood clot.

Only about 1% to 2% of stroke patients receive TPA, says Dr. Jeffrey Saver, a professor of neurology at the David Geffen School of Medicine at UCLA. Many patients don't get to the hospital soon enough.

"We are desperately in need of more and better treatments for acute stroke," he says. "Acute stroke is, in some ways, an untreatable condition."

People who think they may be having a stroke should call 911, according to the American Stroke Assn. The most obvious sign of stroke is weakness on one side of the body.

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