A new treatment in which drugs are injected into the brain while a stroke occurs has prevented serious disability in 70 percent of patients tested, researchers say.

The treatment is one of several new techniques that allow researchers to insert medical instruments into the brain to treat ailing blood vessels, said Dr. Jacques Theron, who conducted the study.He has treated 54 patients with clot-dissolving drugs to eliminate blockages that deprive parts of the brain of blood, causing strokes, he said Thursday at the American Heart Association's annual stroke meeting.

Strokes are the third leading cause of death in the United States and the leading cause of disability, the heart association says.

The clot-dissolving drugs are delivered through a narrow tube called a catheter, inserted into the groin and threaded through blood vessels to the brain, Theron said.

His 70 percent success rate opens a new field of research, said Dr. Linda Sternau, a neurosurgeon at the University of Miami.

"Being able to introduce a catheter right to where the injury is and take care of it is going to revolutionize treatment of stroke," Sternau said.

"We've been able to get inside the brain only very recently," within the past four years, said Dr. L. Nick Hopkins, a neurosurgeon at the State University of New York in Buffalo.

"Until recently the only thing we could do was open the head in a major operative procedure," he said.

The new techniques reduce the risk and the complications associated with trying to treat blood vessel disorders in the brain, he said.

Another researcher said a drug found in commonly used cough medicines may be effective for treating strokes.

Tests on rabbits indicate the substance, dextromethorphan, may protect against brain damage from strokes, said Dr. Gary Steinberg of Stanford University in California.

About 500,000 Americans suffer from strokes each year, the heart association says, and 150,000 die.

Of the 3 million Americans who have survived strokes, 31 percent are so disabled they cannot care for themselves without help.