A team of British researchers has devised a simple and useful way of estimating who is at imminent risk of having a stroke in the days after an episode of temporary symptoms known as a transient ischemic attack (TIA), or mini-stroke.
The estimate, which can be performed in a few minutes, will help physicians identify patients needing immediate treatment and may give people a clearer picture of what constellation of symptoms should be considered a medical emergency, even if it goes away.
The new study, published online yesterday by the Lancet because of its importance for clinical care, provides for TIAs a kind of risk-scoring system that many other diseases and syndromes have had for years. It provides a quick way of predicting the future -- at least to some extent -- and therefore provides doctors a chance to try to prevent impending disaster in some patients.
"This should have been done 50 years ago," said Peter M. Rothwell, a neurologist at the University of Oxford's Radcliffe Infirmary, who led the study. "It is really very straightforward research. It could have been a medical-student project." The usefulness of the information was immediately evident.
When the team looked at the experience of 206 people with TIAs referred to a hospital-based neurology clinic by their primary-care physicians, they found that 14 had suffered strokes before the appointment. The scoring system would have identified all of them as being at high risk of a stroke in the week after their TIA.
By identifying who is at highest risk -- and by estimating the magnitude of that risk, which is much higher than previously believed -- the British team hopes the study will open the door to more daring research in preventing strokes.
A large number of drugs have been shown to protect against experimentally induced strokes in animals. But nearly all have proved useless in human beings because they have always been given when the damage to the brain was underway or complete.
"We can now consider pre-treating these people, on the basis of the TIA, so that if they have a stroke they will be loaded with neuroprotective drugs beforehand," Rothwell said. This would have to be done as part of a research protocol at first, he added.
The British team calls its scoring system ABCD for "age, blood pressure, clinical features and duration of symptoms." While it may prove useful, an American expert on stroke, Jay P. Mohr of Columbia University, said it should not be viewed as foolproof.
"This scoring system should not take the place of a quick trip to the doctor to be sure your event is not a warning for a threatened stroke," even in the absence of a high score, he said.
Although stroke is the third-leading cause of death in the United States, it has been an orphan in the world of medical research, attracting far less money than heart disease, the leading cause of death, cancer, the second-leading cause, and infections such as AIDS. This is in part because of a pall of futility that for years hung over efforts to prevent or treat the disease. The pall has lifted to some extent in the past decade with success in preventing stroke by prescribing anticoagulants to people with atrial fibrillation, an abnormal heart rhythm, and with the more limited success in reversing strokes with clot-dissolving therapies given within an hour or two of first symptoms.
Strokes are the equivalent of heart attacks in the brain. They occur when something -- usually a clot -- slows or stops the flow of blood to a section of the brain. Deprived of oxygen for a long enough time, the brain tissue downstream eventually dies.
In 20 to 30 percent of strokes, a person experiences a brief episode of symptoms -- lasting from minutes to at most a few hours -- in the weeks or months before the event.
The researchers studied the experiences of people who suffered TIAs in the 1980s in a population of 100,000 people in Oxfordshire, a county in England. They looked at many variables and determined which ones were most potent in predicting a future stroke.
Their findings, and the score they assigned each, was as follows:
Age of 60 or older, one point; blood pressure of 140/90 or higher, one point; weakness in the face, arm or leg on one side of the body, two points; difficulty either speaking or understanding language but no muscle weakness, one point; and persistence of these symptoms for one hour or more, two points; persistence of symptoms for more than 10 minutes but less than one hour, one point.
When the researchers applied the scoring system to a different population, they found that people who had suffered a TIA and had a score of six had a 31 percent chance of having a stroke within a week.
People with very high scores should probably be hospitalized and observed, they said. They could then be treated with aspirin and possibly statin drugs and evaluated for a kind of preventive surgery called endarterectomy to unclog the major blood vessels to the brain.