Stroke is caused by an interruption of blood flow to the brain or other parts of the nervous system. This deprives the brain of oxygen and vital nutrients, and within minutes, brain cells begin to die. Generally, if symptoms resolve completely within the first hour, the event is referred to as a TIA, or transient ischemic attack. This terminology does not mean that the process is benign, but rather that the process has caused no deficits. Even brief symptoms will require a full evaluation. It is estimated that 750,000 people have strokes every year in the United States; approximately 160,000 of these strokes will be fatal. People who recover from stroke experience varying levels of disability. Stroke is the third leading cause of death in the United States.
The symptoms of stroke include:
Anyone who experiences any symptom of stroke should get immediate medical assistance for this medical emergency.
Treatment for stroke will depend on many factors, including the type of stroke, and the location and extent of the damage. Other factors that affect treatment include the age of the patient, coexisting medical conditions and complications during hospitalization. Although anyone can have a stroke, the risk factors are highest for people with the following conditions:
The two most common types of stroke are ischemic stroke and hemorrhagic stroke.
An ischemic stroke is caused by a blood clot that blocks or plugs a blood vessel or artery in the brain. About 80 percent of all strokes are ischemic. People with atherosclerosis (plaque buildup in the arteries) are at high risk for developing this type of stroke.
Hemorrhagic stroke accounts for approximately 15 to 20 percent of all strokes. These strokes are caused by a spillage of blood inside the brain. Uncontrolled high blood pressure or infiltration of the blood vessel by abnormal proteins, such as amyloid, may weaken an artery and cause the bleeding. Most of the hemorrhages occur in older patients, but some occur in the younger population. In younger patients, the hemorrhage may be related to bleeding abnormalities or certain types of drugs, such as cocaine. The size and the location of the hemorrhage determine recovery. Small superficial hemorrhages in the brain usually have a better prognosis than large and deep hemorrhages. Although most treatment options are not surgical, occasionally, surgery to evacuate the blood can be helpful.
Embolic strokes are caused by clots, cholesterol, or other elements that travel to the brain from the heart, or blood vessels outside or inside the brain, and then block blood flow in an artery. These types of strokes occur suddenly, but symptoms can fluctuate over hours or days. Such fluctuations are thought to be related to changes in the blood flow from the blocked artery or from nearby arteries. Symptoms may worsen due to swelling in the area of the stroke or from other complications related to the stroke, such as bleeding or concurrent medical conditions, such as an infection.
This type of stroke is related to a disruption of blood flow to small blood vessels deep in the brain. Unlike embolic strokes, the majority of lacunar strokes are believed to result from thickening of the blood vessel wall to the point where blood flow is compromised. This thickening is believed to be caused by hypertension and possibly deposits of cholesterol. Many patients with lacunar strokes have had other silent strokes in the deep part of the brain when they experience an initial symptomatic stroke. Like most strokes, the location dictates the amount of deficit and eventual recovery. For example, a stroke involving the motor pathways will cause a significant deficit even if the stroke is relatively small. Fortunately, these strokes generally have good prognosis.
This refers to a hole between the right side of heart and the left side of the heart, and is found in approximately 30 percent of the population. However, only in a small percentage of people does the hole become the source of a clot-causing stroke. In this case, clots in the vein can find their way to the left side of the heart through the hole, and proceed to travel through the arteries to the brain or other organs.
An initial neurological consultation with the patient and possibly family members and friends is crucial. The time of symptoms onset and the sequence of events, and progression or fluctuation of symptoms are important factors in determining the type of stroke. Once the clinical evaluation is completed, imaging of the brain is obtained, often using a CT scan, CTA, MRI or MRA technologies. On occasion, a cerebral angiogram is required to clarify abnormalities in a blood vessel. An ultrasound of the arteries in the neck and the brain can be done in cases where other blood flow studies cannot be done. Ultrasound on the heart (echocardiogram) is often done to evaluate the presence of abnormalities in the heart that can help in the treatment. There are two different types of echocardiograms:
The patient will also undergo an electrocardiogram and the heartbeat may be monitored for a prolonged period of time to help rule out irregularities in the beat that can lead to stroke. When appropriate, blood tests for clotting disorders may also be done.
At this time there is no single treatment known to prevent all types of strokes. In approximately 40 percent of patients, no specific cause can be determined. The window of opportunity to treat an ischemic stroke is extremely brief. Some ischemic strokes are treatable with medications called 'clot busters.' The Food and Drug Administration has approved the use of t-PA (clot buster) for use in patients presenting within three hours of symptoms. However, because of the potential for bleeding, the drug is given selectively even in those patients arriving within the first three hours. Occasionally, patients presenting after three hours are treated with a clot buster. Usually those patients have a large clot blocking flow in a large artery. In these cases, a catheter may be put into the artery, the clot is mechanically disrupted, and a clot-busting drug is given into the clot. Sometimes a stent is placed in the artery to keep it open. If surgical intervention is not known to be beneficial, the use of aspirin or aspirin-like medications is often recommended.