Ischemic Stroke

Stroke, or brain attacks as they are often called in the United States, are a major cause of death and permanent disability. There are two main types of stroke: ischemic and hemorrhagic.

What is an ischemic stroke? Ischemic strokes are caused by blockage in an artery that supplies blood to the brain, resulting in a deficiency in blood flow (ischemia) to the brain. Approximately 80% of all strokes are ischemic. The brain requires fresh blood from the heart and lungs to bring it oxygen and nutrients and to take away carbon dioxide and cellular waste. If an artery is clogged, brain cells will quickly stop working. If the artery remains blocked, the cells will eventually die. Early medical intervention can halt this process and reduce the risk of irreversible complications, making immediate medical treatment absolutely essential.

Ischemic strokes can be subdivided into two basic types: thrombotic strokes and embolic strokes.

Thrombotic Strokes

A thrombotic stroke occurs when cerebral arteries become blocked by the development of a blood clot within the brain. Known clinically as cerebral thrombosis or cerebral infarction, this type of occurrence is the cause of almost half of all strokes. Cerebral thrombosis can be subdivided further into two additional categories defined by where blockage occurs in the brain. Large-vessel thrombosis is the term used for a blockage in a large artery like the carotid or middle cerebral. When the thrombosis involves one (or more) of the brain's smaller arteries found deep within the brain, it is known as a small vessel thrombosis, sometimes also referred to as a lacuner stroke.

Embolic Strokes

An embolic stroke occurs when the clot forms in an artery outside the brain, frequently in the heart itself. The emboli will travel until it becomes lodged and can move no further, resulting in restricted blood flow to the brain and almost immediate physical and neurological deficiencies.

Signs and Symptoms

As strokes are often not accompanied by severe pain, patients sometimes delay seeking treatment, resulting in extensive brain tissue damage. Symptoms of stroke can include the following:

• Difficulty speaking or understanding speech (aphasia)
• Difficulty walking
• Dizziness or lightheadedness (vertigo)
• Numbness, paralysis, or weakness, usually on one side of the body
• Seizure (relatively rare)
• Severe headache with no known cause
• Sudden confusion
• Sudden decrease in the level of consciousness
• Sudden loss of balance or coordination
• Sudden vision problems (e.g., blurry vision, blindness in one eye)
• Vomiting

Complications

Complications resulting from an ischemic stroke are almost immediate and part of a process referred to clinically as an ischemic cascade: a biochemical series of events where one event triggers another. Complications arising with 72 hours of a stroke include the following:

• Cerebral swelling (edema)
• Increased intracranial pressure (ICP)
• Intracerebral hemorrhage
• Seizures
• Paralysis on one side of the body (hemiparesis)
• Speech problems

Complications that may develop gradually as a result of immobility include the following:

• Bedsores
• Blood clots
• Fibrosis of connective tissue resulting in decreased mobility
• Malnutrition
• Pneumonia
• Urinary tract infections if a catheter is required

More than 30% of stroke patients require assistance with daily living and approximately 15% require care in an assisted-living facility (e.g., nursing home, rehabilitation center). Approximately 20% of stroke patients require help walking (e.g., cane, walker,) and as many as 33% suffer from depression. Treatment for stroke usually involves rehabilitation.

Risk Factors

There are several factors that increase the likelihood of an ischemic stroke. Not all risk factors can be eliminated, but some can. Reducing or eliminating a risk factor will, of course, reduce the likelihood of having a stroke.

Major risk factors are:

• Age is a significant factor in determining who has a stroke. The chance of stroke doubles every ten years after an individual reaches age 55..
• Heredity is an important factor. If a family is prone to hypertension and arteriosclerosis, the chances for a stroke are higher.
• A previous stroke or transient ischemic attack (TIA) greatly increases the chance of another stroke.
• High blood pressure (hypertension) is a factor in almost 70% of all cases of stroke.
• High levels of ‘bad’ cholesterol and triglycerides are a major cause of stroke as they lead to arteriosclerosis.
• High blood sugar (diabetes) or uncontrolled diabetes contributes to atherosclerosis, which in turn increases the risk for developing stroke.
• Obesity leads to hypertension and atherosclerosis, both major stroke causing factors
• Existing heart disease or a prior heart attack is a major risk factor. Arterial fibrillation, or arrhythmia, is also a major contributing factor.
• Smoking has been shown to be a significant factor in increasing the chance for stroke. Cessation for 2-5 years will significantly reduce the risk for stroke.

If you suspect a stroke has occurred, prompt, accurate diagnosis and treatment is necessary to minimize brain tissue damage. Diagnosis includes obtaining a medical history, a physical and neurological examination and a series of diagnostic tests that fall into three basic categories.

• Imaging Procedures. Computed tomography (CT scan) is performed as soon as possible after a suspected stroke. CT scans produce x-ray images of the brain and provides valuable information about the cause of a stroke and the location and extent of an injury to the brain. Another imaging technique, magnetic resonance imaging (MRI) uses a magnetic field to produce detailed images of brain tissue and arteries in the neck and brain. The image produced by an MRI is sharper and more detailed than a CT scan and is often used to diagnose small, deep injuries.s.
• Electrical Activity Tests. There are two basic tests available to analyze the brain’s electrical activity. In an EEG (electroencephalogram), electrodes are placed on the head to pick up electrical impulses. The signals are then printed out as brain waves and examined. Another common test evaluates the patient’s evoked response by measuring the time it takes for the brain to respond to various stimuli, such as hearing and vision.

How to help prevent stroke. The following measures may help prevent stroke:

• Controlling hypertensionion
• Lowering cholesterol and saturated fat intake
• Quitting smoking
• Controlling diabetes
• Regular exercise
• Maintaining body weight within an ideal range
• Drinking alcohol in moderation, avoiding binge drinking

For more information, please contactt
Bangkok Neuroscience Center
Tel. (662) 310 3011, (662) 755 1011
Email : info@bangkokhospital.com