Fireworks are a sure sign it's the fourth of July.

A sudden severe headache, blurry vision and numbness are often sure signs of a stroke. But not everybody gets those fireworks kind of warnings.

In fact, new research suggests as many as ten percent of healthy people have suffered the brain damaging event and don't even know it!

James Amos is known for his wit... and for his touch of flair.

So it doesn't seem surprising that when this hardworking hospital program director suffered a stroke in 2007, it came with a theme song.

But not every brain episode comes with such an obvious warning

Boston University researchers scanned the brains of just over 2,000 healthy people around age 60, finding 10% had suffered a stroke, and never knew it.

Duke University's Dr. Larry Goldstein says these silent strokes set the stage for future trouble.

Alarming, yes, but not reason for healthy people to get a brain scan, says Goldstein.

The same risk factors for stroke - smoking, high blood pressure, high cholesterol, diabetes, and a common heart rhythm condition called Atrial Fibrillation - were also common among the silent stroke sufferers.

A message James Amos hears loud and clear, he's keeping a close eye on his high blood pressure, and is trying to adopt a new theme song - slowing down!

Still with a touch of flair!