If you believe that you or a loved one may be experiencing a stroke, call 9-1-1 immediately.
What is Stroke?
Stroke is caused by an interruption of blood flow to the brain or other parts of the nervous system. This interruption 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 an immediate, full evaluation, because patients with TIA are at risk for stroke. Stroke is the third-leading cause of death in the United States. It is estimated that 750,000 people have strokes every year, and approximately 160,000 of these strokes will be fatal. People who recover from stroke experience varying levels of disability.
Although anyone can have a stroke, the risk factors are highest for people with the following conditions:
Anyone who experiences stroke symptoms should call 911 and seek immediate medical assistance for this medical emergency.
The two most common types of stroke are ischemic stroke and hemorrhagic stroke, although a number of others also exist.
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 may weaken an artery and cause the stroke. 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 location of the hemorrhage determine recovery. Small superficial hemorrhages in the brain usually have a better prognosis than large, deep hemorrhages. Although most treatment options are not surgical, occasionally surgery to remove 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 and are thought to be related to changes in the blood flow from the blocked artery or 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 (e.g., 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 by deposits of cholesterol. Many patients with lacunar strokes have had other silent strokes in the deep part of the brain when they experienced 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 prognoses.
This refers to a hole, found in approximately 30 percent of the population, between the right side of heart and the left side of the heart. 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 to other organs.
An initial neurological consultation with the patient - and possibly family members and friends - is crucial. The time of symptoms' onset, sequence of events, and progression or fluctuation of symptoms are all 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 or CTA, MRI or MRA technologies.On occasion, a cerebral angiogram is required to clarify abnormalities in a blood vessel. Studies such as transcranial Doppler ultrasound and carotid ultrasound can be used to evaluate blood flow to the brain in cases where other blood flow studies cannot be performed. To aid in treatment, ultrasound on the heart (echocardiogram) is often done to evaluate the presence of abnormalities in the heart.There are two different types of echocardiograms:
To help rule out irregularities in the heartbeat that can lead to stroke, the patient may also undergo an electrocardiogram, and the heartbeat may be monitored for a prolonged period of time. When appropriate, blood tests for clotting disorders may also be performed.
Treatment for stroke will depend on many factors, including the type of stroke and location and extent of damage. Other factors that affect treatment include the patient's age, coexisting medical conditions and complications during hospitalization. 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 (a clot buster) for use in patients presenting within three hours of stroke onset. 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 major artery. In these cases, a catheter may be put into the artery to mechanically disrupt the clot, and a clot-busting drug is injected into the clot. Sometimes a stent is placed in the artery to keep it open.If the invasive intervention described above is not indicated, aspirin or aspirin-like medications are often recommended.Our stroke specialists include Kinan K. Hreib, MD, PhD; Matthew Tilem, MD; and a stroke fellow. Lahey's Department of Neurology also offers two stroke fellowship positions. This team of experts is actively engaged in a number of research studies on stroke and other cerebrovascular diseases.Lahey offers a Stroke Support Group, and additional Stroke resources are also available.
RESEARCH IN NEUROLOGY
The American Heart Association/American Stroke Association's Get With The Guidelines program has again awarded Lahey Clinic’s stroke service the Stroke Gold Performance Achievement Award.