People at risk and partners or caretakers of people at risk for stroke should be aware of the general symptoms, and the stroke victim should get to the hospital as soon as possible after these warning signs appear. It is particularly important for people with migraines or frequent severe headaches to understand how to distinguish between their usual headaches and symptoms of stroke.

Transient Ischemic Attacks (TIAs)

TIAs are mini-ischemic strokes, usually caused by tiny emboli that lodge in an artery and then quickly break up and dissolve. There is no residual damage.

One of two major arteries is usually involved in a transient ischemic attack, either the carotid or basilar arteries. The carotid arteries are the more commonly involved sites; they start at the aorta and lead up through the neck around the windpipe and on into the brain. (The pulse of a carotid artery can be felt by placing fingertips gently against either side of the neck right under the jaw.) When TIAs occur here, the retina of the eye or the cerebral hemisphere (the large top part of the brain) can be affected. When oxygen to the eye is reduced, people describe the visual effect as a shade being pulled down. People may develop poor night vision. When the cerebral hemisphere is affected by a TIA, a person can experience problems with speech and partial and temporary paralysis, tingling, and numbness -- usually on one side of the body.

The other major site of trouble, the basilar artery, is formed at the base of the skull from the vertebral arteries, which run up along the spine. When TIAs occur here, both hemispheres of the brain may be effected so that symptoms occur on both sides of the body. Vision in both eyes can become temporarily dim, gray, blurry, or lost. The mouth, cheeks or gums may tingle. Other symptoms may include headache in the back of the head, dizziness, nausea and vomiting, difficulty swallowing, inability to speak clearly, numbness around the mouth, and weakness in the arms and legs, sometimes causing a sudden fall.

Another warning sign of potential trouble is a series of very tiny ischemic strokes called lacunar infarcts, which cause clumsiness, weakness, and emotional variability.

Symptoms of Major Ischemic Stroke

If a major ischemic stroke is caused by a large embolus that has traveled to and lodged in an artery in the brain, the onset is sudden. Headache and seizures can occur within seconds of the blockage. When thrombosis -- a blood clot that has formed in a narrowed artery -- causes the stroke, the onset usually occurs more gradually -- over minutes to hours; on rare occasions it progresses over days to weeks. The symptoms for an ischemic stroke are extremely variable. They can be identical to those of a transient ischemic attack, since, in both cases, the clot can produce a blockage in a branch of the carotid or basilar arteries. (In the case of a TIA, however, the symptoms resolve.) The blood clot usually affects the opposite side of the body from its location in the brain, with possible loss of feeling on one side of the face, in an arm or leg, or blindness in one eye. The person may have difficulty swallowing. Speech problems can occur if the left hemisphere of the brain is involved. (In some people, mostly those who are left-handed, speech can be affected by a clot on the right side of the brain.) The stroke victim may be unable to express thoughts verbally or to understand spoken words. Other symptoms include dizziness, vomiting, loss of muscle tone, major seizures, and possibly coma.

Symptoms of Hemorrhagic Stroke

Symptoms of a cerebral, or parenchymal, hemorrhage typically begin very suddenly and evolve over several hours and include headache, nausea and vomiting, and altered mental states. When the hemorrhage is a subarachnoid type, warning signs (abrupt headaches, nausea and vomiting, sensitivity to light, and various neurologic abnormalities) can occur from the leaky blood vessel a few days to a month before the aneurysm fully develops and ruptures. When the aneurysm ruptures, the stroke victim may experience a terrible headache, neck stiffness, vomiting, confusion, and altered states of consciousness. The eyes may become fixed in one direction or lose vision. Stupor, rigidity, and coma can result.

Silent Brain Infarctions

As many as 31% of the elderly experience silent brain infarctions, which are small strokes that cause no apparent symptoms but are major contributors to mental impairment in the elderly. Smokers and people with hypertension are at particular risk.