Stroke

Overview/Pathophysiology
Stroke is a sudden focal neurologic deficit, of vascular origin, lasting more than 24 hours. In other words, stroke is the sudden loss of blood flow to an area of the brain resulting in loss of brain function. Also called cerebrovascular accident or stroke syndrome, stroke is a nonspecific term encompassing a large number of different disease processes, including thrombosis (blood clot), embolism (clot from a different part of the body) and hemorrhage (bleeding) .

In the US, the incidence for first-time strokes is more than 400,000 per year and at current trends, the number is expected to jump to one million per year by the year 2050.
Stroke is the 3rd leading cause of death and the leading cause of disability in the United States

Key points:

1. Stroke is a medical emergency;

2. Stroke is also called cerebrovascular accident or stroke syndrome;

3. A stroke is a sudden loss of blood flow to an area of the brain resulting in a corresponding loss of neurologic function.

Causes of Stroke:
There are two main causes for a stroke.

The first is blockage of an artery;
The second is the rupture of an artery.

Blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain that is supplied by the clotted blood vessel is then deprived of blood and oxygen. The cells of that part of the brain die as a result. Typically, a clot forms in a small blood vessel within the brain that has been previously narrowed due to the long-term, damaging effects of high blood pressure (hypertension) or diabetes. The resulting strokes are called lacunar strokes because they look like little lakes. In other situations, usually because of hardening of the arteries (atherosclerosis), a blood clot can obstruct a larger vessel going to the brain, such as the carotid artery in the neck.

Another type of stroke occurs when a EMBOLISM =blood clot or a piece of atherosclerotic plaque (cholesterol and calcium deposits on the wall of the inside of the heart or artery) breaks loose, travels through open arteries, and lodges in an artery of the brain. When this happens, the flow of oxygen-rich blood to the brain is blocked and a stroke occurs. This type of stroke is referred to as an embolic stroke. For example, a blood clot might originally form in the heart chamber as a result of an irregular heart rhythm, such as atrial fibrillation. Usually, these clots remain attached to the inner lining of the heart; but occasionally they can break off, travel through the blood stream, form a plug (embolism) in a brain artery, and cause a stroke. An embolism can also originate in a large artery (for example, the carotid artery, a major artery in the neck that supplies blood to the brain) and then travel downstream to clog a small artery within the brain.

A cerebral hemorrhage occurs when a blood vessel in the brain bursts and bleeds into the surrounding brain tissue. A cerebral hemorrhage (bleeding in the brain) can cause a stroke by depriving blood and oxygen to parts of the brain. The accumulation of blood from a cerebral hemorrhage can also press on parts of the brain and cause damage. A subarachnoid hemorrhage is caused by the rupture of a blood vessel that is usually located between the outside of the brain and the inside of the skull. The blood vessel at the point of rupture is often previously abnormal (for example, from an aneurysm [an abnormal ballooning out of the wall of the vessel]). Subarachnoid hemorrhages usually cause a sudden, severe headache and are often complicated by further neurologic problems such as paralysis, coma, and even death.

Key points:

Causes of stroke include

1. Blockage of an artery;
2. Rupture of an artery.

Types of Stroke:

1. Ischemic stroke

In ischemic stroke, the most common type, the artery is blocked by a blood clot, which interrupts the brain's blood supply (ischemia means “to restrain blood” in Greek). This may be due to a cerebral thrombosis (sometimes called a thrombotic stroke) in which a blood clot forms in the main artery leading to the brain or due to a cerebral embolism (sometimes called an embolic stroke) in which a blood clot forms elsewhere in the body and is swept into the arteries serving the brain.

It may also be caused by a lacunar stroke, in which tiny blood vessels deep inside the brain become blocked. Lacunar strokes are usually less severe.

2. Hemorrhagic stroke

In this type of stroke, a blood vessel in or around the brain ruptures, causing bleeding or hemorrhage. The build-up of blood presses on the brain, damaging its delicate tissue, while other brain cells in the area are starved of blood and are damaged.

In an intra-cerebral hemorrhage, the bleeding occurs inside the brain itself. In a subarachnoid hemorrhage, the burst blood vessel bleeds into the subarachnoid space surrounding the brain.

Key points:

The two main types of stroke are

1. Ischemic stroke;
2. Hemorrhagic stroke.


Transient Ischemic Attack or TIA

A transient ischemic attack (TIA), often known as a mini-stroke, is when the blood supply to the brain is interrupted for a shorter period of time—any time from a symptoms last a few minutes up to 24 hours—followed by a complete recovery. In one in five people it can be a warning sign of a subsequent stroke.

#1: the two main types of stroke are ischemic and hemmorhaogic.
#2: TIA is known as a mini-stroke and is followed by complete recovery.

Risk Factors for Stroke:

1. Lifestyle factors

2. Medical factors:

Some other illnesses and medical conditions increase the risk of stroke. They include

3. Other factors:

Key points:

1. Risk factors for stroke include many modifiable factors (smoking, alcohol, inactivity, obesity) and some nonmodifiable factors (age, family history, sex).


Symptoms of stroke

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). A third of all strokes occur during sleep, so people first notice the symptoms when they awaken.

The common symptoms of stroke include

1. Weakness in the muscles of the face,

2. Difficulty speaking,

3. Coordination problems,

4. Dizziness,

5. Visual disturbances,

6. Sudden headache,

7. Loss of consciousness.

Key Points:

1: Stroke symptoms usually come on suddenly—in minutes to an hour; the symptoms may come and go, go away totally, or get worse over the course of several hours

What should be done if you suspect you or someone else is having a stroke?

If any of the symptoms mentioned above suddenly appear, emergency medical attention should be sought. The sooner treatment is started, the better the eventual outcome will be. Therefore, the first action should be to call 911 (or whatever number activates the emergency medical response in your area). The family doctor and/or neurologist should also be contacted. However, the first priority is ensuring that the ambulance arrives as soon as possible. The affected person should lie flat to promote an optimal blood flow to the brain. If drowsiness, unresponsiveness, or nausea is present, the person should lie on one side to prevent choking on his/her vomit. Although aspirin plays a major role in stroke prevention (see below), once the symptoms of a stroke begin, it is generally recommended that additional aspirin not be taken until the patient receives medical attention. If stroke is of the bleeding type, aspirin could theoretically make matters worse.

Key points:

1. At the first onset of stroke symptoms, seek emergency attention.

Diagnosis of Stroke

A stroke is a medical emergency and anyone suspected of having a stroke must be taken to a medical facility IMMEDIATELY. Just because a person has slurred speech or weakness on one side of the body does not necessarily signal the occurrence of a stroke. There are other possibilities that can be responsible for these symptoms. Other conditions that can mimic a stroke include brain tumors, a brain abscess (a collection of pus in the brain caused by bacteria or a fungus), and subdural hematomas.

A subdural hematoma is a collection of, mostly, clotted blood that accumulates between the brain and the skull. This produces a mass that can enlarge and press against the brain. In contrast, in a subarachnoid hemorrhage, blood spills out into the space between the brain and the skull and causes more sudden and catastrophic effects. Viral encephalitis can also produce symptoms similar to those of a stroke, as can an overdose of certain medications. An imbalance of sodium, calcium, or glucose in the body can also cause changes in the nervous system that can mimic a stroke.

First of all, the doctor takes a medical history from the person who may have had a stroke. Then, a complete physical examination will be performed, which will include blood pressure and pulse rate, examination of the heart and lungs, as well as a neurologic examination.

Other tests performed include: (LIST ALL ON SCREEN ONE BY ONE)

1. Blood tests—Blood tests (such as a sedimentation rate) are done to look for signs of inflammation that can suggest inflamed arteries. Certain blood proteins that can increase the chance of stroke by thickening the blood are measured. Cholesterol tests may be done. These tests are performed to identify treatable causes of a stroke or to help prevent further injury.

2. CT Scan—To help determine the cause of a suspected stroke, a special x-ray test called a CAT scan (also called a CT scan), of the brain is often performed. A CAT scan can show bleeding into the brain, which is treated differently than a stroke that is caused by blockage of the blood supply. A CAT scan also rules out many of the other causes of neurologic conditions mentioned above that can mimic a stroke.

3. MRI—A newer method of viewing the brain is Magnetic Resonance Imaging (MRI), which uses harmless magnetic waves rather than x-rays. The major advantage of an MRI is that the pictures it takes of the brain are much more detailed than with CAT scans.

4. EKG—to look for atrial fibrillation or signs of a heart attack which can accompany a stroke

5. Carotid Doppler—to assess blockage of the carotid arteries.


Key Points:

1. The diagnosis of a stroke is based on taking a medical history, physical examination, neurologic examination and tests which may include: Blood Tests, CT Scan, MRI, EKG and Carotid Doppler.

Treatment of Stroke

A stroke is a medical emergency, regardless of whether it is a major stroke or a short-lasting TIA. A person suffering a stroke should be taken immediately to a hospital emergency department. Brain cells begin to die within 4 minutes of the beginning of a stroke. The key to survival is prompt medical attention.

The initial treatment for stroke is supportive care which includes

1. IV fluid (Intravenous Fluid),

2. Oxygen,

3. May or may not be given aspirin,

4. No eating and no drinking

Key points:

1. The treatment of an individual suffering from stroke should be immediate since a stroke is a medical emergency.
2. The key to survival is prompt medical attention.
3. Treatment modalities include IV fluids, oxygen administration, possible aspirin therapy,

Medications for Stroke Therapy

Medications for the management of ischemic stroke can be distributed into the following categories:

(1) reperfusion (thrombolytics); e.g., tissue plasminogen activators (TPA drugs),

(2) antiplatelet, (like plavix )

(3) anticoagulation, (like aspirin)

(4) neuroprotective.


Currently, only one drug is approved by the FDA for the treatment of stroke. It is the clot-busting medication called tissue plasminogen activator (TPA). Other treatments in this category are being tested. A major side-effect of this medication is bleeding into the tissues. Careful monitoring is required.

Key points:

1. The one medication now approved for the acute treatment of stroke is Tissue Plasminogen Activator (TPA).

Stroke Prevention

1. Get your blood pressure checked and treated if it is high.

2. Treat high cholesterol with diet and exercise and then medication to reduce the risk of stroke.

3. With certain irregular heart rhythms, such as atrial fibrillation, the use of blood thinners such as warfarin (Coumadin) has been shown to reduce the risk of stroke.

4. Control diabetes.

5. Stop smoking or never smoke.

6. Reduce alcohol intake.

7. Maintain normal weight.

8. Exercise regularly.

9. Take a baby aspirin every day if you have risk factors for a stroke and your doctor says it is OK .

Key Points:

1. Knowledge of the risk factors associated with stroke and the avoidance or management of them can help in preventing strokes.


Copyright 2007, MD Kiosk