Doctor's Notes on Stroke
A stroke is an alteration, usually acute, of brain function due to injured or killed brain cells. Symptoms and signs of stroke include weakness in the arm or leg or both (usually on one side of the body), weakness of the muscles of the face, problems speaking, coordination problems, and dizziness and/or loss of consciousness. Some patients may develop vision problems and develop a severe headache. Although some patients may show some improvement in the signs and symptoms, a true stroke has some or all of the signs and symptoms still present after 24 hours. Some individuals may die during a stroke. Signs and symptoms of a stroke constitute a medical emergency and 911 should be called.
Some symptoms and signs described above can occur in individuals but resolve quickly and completely in less than 24 hours; these signs and symptoms are signs of a transient ischemic attack (mini stroke or TIA). TIA’s are signs and symptoms of the patient being at risk for a stroke.
The two main causes of strokes are ischemic or hemorrhagic problems with the brain’s blood vessels. Ischemic strokes (the cause of about 80 – 85% of strokes) are due to blood vessels that are blocked usually due to a clot while with a hemorrhagic stroke, the blood vessels in the brain actually burst or leak blood. That leakage allows blood to spill into the brain tissue causing a buildup of pressure on brain tissue and other brain blood vessels. Hemorrhagic strokes usually are more serious than ischemic strokes; death usually occurs in 30 to 50% of individuals with this stroke type. Both types of strokes produce similar symptoms that signal brain tissue injury and/or death due to lack of oxygen supplied by the blood, but their emergency treatments are different – call 911 as a stroke cause needs to be identified quickly in an emergency center, usually by a CT of the brain.
The symptoms of a stroke depend on what part of the brain and how much of the brain tissue is affected.
- Stroke symptoms usually come on suddenly -- in minutes to an hour.
- There is usually no pain associated with the symptoms.
- The symptoms may come and go, go away totally, or get worse over the course of several hours.
- If the symptoms go away completely in a short time (fewer than 24 hours), the episode is called a transient ischemic attack (TIA).
- One-third of all strokes occur during sleep, so people first notice the symptoms when they wake up; this situation makes it difficult to time when the stroke actually began.
Eight common symptoms of stroke are:
- Weakness in the arm or leg or both on the same side: This can range from total paralysis to a very mild weakness. Complete numbness or a pins-and-needles feeling may be present on one side of the body or part of one side of the body.
- Weakness in the muscles of the face: The face may droop or look lopsided. Speech may be slurred because the patient can't control the movement of their lips or tongue.
- Difficulty speaking: The patient can't speak, speech may be very slurred, or when the person speaks, the words sound fine but do not make sense.
- Coordination problems: The patient may seem uncoordinated and stumble or have difficulty walking or difficulty picking up objects.
- Dizziness: The patient may feel drunk or dizzy or have difficulty swallowing.
- Vision problems: The patient may develop difficulty with vision, such as double vision, loss of peripheral (side) vision, or blindness. (Blurred vision by itself is not usually a symptom of stroke.)
- Sudden headache: A sudden, severe headache may strike like "a bolt out of the blue."
- Loss of consciousness: The patient may become unconscious or hard to arouse and could die.
The two main causes of strokes are termed ischemic and hemorrhagic and involve blood vessels in the brain. Ischemic strokes comprise about 80% to 85% of all strokes. With an ischemic stroke, a blood vessel in the brain becomes clogged with a clot just like the clogged arteries in the heart. With a hemorrhagic stroke, a blood vessel in the brain actually bursts or leaks. Hemorrhagic strokes tend to be more serious. The distinction between these two types of stroke can be critical in determining the treatment used to help the patient. The "third" stroke type is considered by some investigators to be a subtype of ischemic strokes is a TIA or transient ischemic attack (also termed mini-stroke.
- Ischemic strokes occur when a blood vessel gets so narrow or clogged that not enough blood can get through to supply oxygen and keep the brain cells alive.
- Plaques (or buildup of cholesterol-containing fatty deposits called arteriosclerosis) in the blood vessel walls can narrow the blood vessels that supply the brain. These plaques build up until the center of the blood vessel is so narrow that little, if any, blood can get past. Many things including high cholesterol and high blood pressure cause plaques. The plaques may occur in small vessels that supply only a very tiny portion of the brain but may also occur in the big blood vessels in the neck (carotids) or in the large arteries to the brain (cerebral arteries).
- Ischemic strokes may also be caused by small blood clots or emboli that go through the bloodstream and then get clogged in an artery when the artery narrows. These clots can come from pieces of plaques in the bigger arteries that break off or from clots in the heart.
- Treatment is designed to break up or get rid of the blockage (see treatment section below).
- Hemorrhagic strokes occur when the wall of a blood vessel becomes weak and blood leaks out into the brain.
- In addition to having decreased blood flow past the leak, the blood in the brain damages brain cells as it decomposes. If a lot of blood leaks out, it can cause a buildup of pressure in the brain because the brain is enclosed in the skull. There is no room for brain tissue to expand, and so the leaked blood can compress and kill important areas of the brain.
- Hemorrhagic strokes tend to be more serious than ischemic strokes. Death occurs in 30% to 50% of people with this type of stroke.
- Treatment is designed to stop or prevent bleeding into brain tissue (see treatment section below).
Treating a hemorrhagic stroke with treatment designed for an ischemic stroke will likely cause worsening of the stroke or death.
When the brain’s blood supply is inadequate, a stroke results. Stroke symptoms (for example, loss of arm or leg function or slurred speech) signify a medical emergency because without treatment, blood-deprived brain cells quickly become damaged or die, resulting in brain injury, serious disability, or death. Call 9-1-1 if you notice stroke symptoms developing in someone.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.