YOUR HEALTH

DEAR DR. DONOHUE: What is the difference between a stroke caused by a bulge in an artery and a stroke caused by an aneurysm? Can a doctor ascertain the cause of such a stroke with a physical examination? Are Xrays or scans necessary? P.D.

ANSWER: A stroke is the sudden death of brain tissue due to deprivation of blood flow. The more common kind of stroke is ischemic (is-KEY-mick) stroke, a blockage of blood flow to a section of the brain. Ischemic strokes account for 85 percent of all strokes.

The second kind of stroke is a hemorrhagic stroke -a disruption of blood flow to the brain because of a broken, bleeding brain artery. One of the major causes

for brain-artery bleeding is the rupture of an artery aneurysm. An aneurysm is a bulge in the artery wall -a weak spot, often there since birth.

Sometimes people with an aneurysm have warning headaches due to small leakages of blood in the weeks prior to a major bursting of the aneurysm. When the aneurysm ruptures, people complain of the worst headache they have ever had, and then they usually lapse into unconsciousness. If they waken, they continue to complain of a terrible headache.

It is difficult to impossible to distinguish by physical exam between a stroke caused by a brain bleed and a stroke caused by an obstruction to blood flow. Scans are needed to make the distinction. Treatment differs radically for the two.

For a broken aneurysm, neurosurgeons place a clip on the broken vessel to prevent any rebleeding (something that often happens). Or a specially trained radiologist can deposit platinum coils into the broken vessel through a tube passed to the brain artery from an artery in the groin. The coils prompt clot formation, which seals the break and prevents rebleeding.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL32853-6475.