Few Americans know the major warning signs of stroke, new survey findings indicate, and few would call 911 immediately if they thought someone was having a stroke.

“A lot of people are afraid to do that,” Dr. Janet Croft told Reuters Health in an interview. “They don’t feel they have the medical knowledge.”

She encouraged everyone to learn the signs of stroke and to be willing to call 911 if they think someone is having a stroke. “This is an opportunity for every person in the U.S. to be a hero,” said Croft, a senior epidemiologist at the Centers for Disease Control and Prevention in Atlanta.

There is no time to waste when someone is having a stroke, Croft said. The CDC researcher noted that 50 percent of stroke deaths occur before an ambulance arrives. While stroke symptoms sometimes begin suddenly, some people may die because their symptoms were not recognized soon enough, Croft said.

Croft noted that one type of treatment for the most common type of stroke, an ischemic stroke, is most effective when given within 3 hours of the first symptoms.

An ischemic stroke occurs when a clot or blocked artery cuts off blood flowing to the brain. Stroke may also occur when a blood vessel ruptures in the brain.

According to the CDC, the five major warning signs for stroke are sudden confusion or trouble speaking or understanding; sudden numbness or weakness, particularly on one side of the body; sudden vision trouble; dizziness or trouble walking; and sudden severe headache with no apparent cause.

Croft and her colleagues at the CDC tested the stroke knowledge of more than 61,000 adults in 17 states and the U.S. Virgin Islands.

Although most people could recognize some warning signs of stroke, only 17 percent knew all warning signs and said that they would call 911 if they thought someone was having a heart attack or stroke.

The results of the study appear in this week’s issue of the CDC publication Morbidity and Mortality Weekly Report. May is National Stroke Awareness Month.

“The fact that only 17 percent of those surveyed both recognized all five of the major warning signs and indicated they would first call 911 shows that we still have a long way to go in educating the public about stroke,” Dr. Larry B. Goldstein, the chairman of the American Stroke Association’s advisory committee, said in a press release.

“People must then call for emergency assistance when stroke symptoms occur. Time lost is brain lost,” said Goldstein, who is at Duke University Medical Center in Durham, North Carolina.

To prevent stroke deaths and damage, people have to be willing to call 911 as soon as they think someone is having a stroke, according to Croft. She encouraged people to put themselves in the shoes of a stroke victim.

“You are not able to call for help. You may be paralyzed. You may be losing your sight. You may not be able to hold a telephone in your hand,” she said. “You would want someone to call 911 for you if you were in that situation,” she said.

Croft noted that a person may not experience all five major stroke symptoms, so it is important to call 911 even if someone has just one symptom.

SOURCE: Morbidity and Mortality Weekly Report, May 7, 2004.