Although most people with stroke still suffer functional brain damage, the new study's finding that at least one-third more people can be saved from permanent disability than with current practices amounts to the biggest improvement in stroke care ever. About 500,000 Americans suffer strokes each year.

The study involved 624 patients and tested the safety and usefulness of tissue plasminogen activator (t-PA), a clot-dissolving drug now used in the treatment of heart attacks. About 80 percent of strokes are caused by blood clots, which either form in a blood vessel in the brain or travel there from elsewhere in the body.

Twenty percent of patients who did not get t-PA had a full recovery from their stroke when evaluated by neurological examination three months later. Of those who got t-PA, 31 percent recovered. Three other measurements of daily functioning were also used and they showed a 30 to 50 percent greater likelihood of recovery in t-PA patients.