Cerebrovascular disease or stroke is the loss or alteration of body functions that results from an insufficient supply of blood to some parts of the brain. For human brain to function at peak levels, blood must flow through its many vessels. If the blood flow is obstructed for more than several minutes, injury to the brain cells becomes permanent and tissue dies in the affected region.
Stroke is one of the leading causes of disability. It can lead to weakness or paralysis usually of one side of the body. Often, the person has slurring of speech or even inability to talk (aphasia). Of course, if stroke is massive and severe, death becomes inevitable.
If we consider an isolated blood vessel, blood flow to the brain tissue can be hampered in two ways: 1.) the vessel clogs within (ischemic stroke); and 2.) the vessel ruptures, causing blood to leak into the brain (hemorrhagic stroke).
Ischemic strokes accounts for about 85% of all cases. It occurs as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls. This condition is called atherosclerosis. These fatty deposits can cause two types of obstruction - cerebral thrombosis and cerebral embolism.
- Cerebral thrombosis refers to a thrombus (blood clot) that develops at the clogged part of the vessel. This is usually seen in older people and may occur in a person at rest.
- Cerebral embolism refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain's blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain. The onset of cerebral embolism is usually sudden.
On the other hand, hemorrhagic stroke accounts for 15% of all cases. It results from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. It may either cause intracerebral hemorrhage or subarachnoid hemorrhage.
Hemorrhagic stroke occurs when a weakened blood vessel ruptures. The two types of weakened blood vessels that usually cause hemorrhagic stroke are aneurysms and arteriovenous malformations (AVMs).
An aneurysm is a ballooning of a weakened region of a blood vessel. If left untreated, the aneurysm continues to weaken until it ruptures and bleeds into the brain. Meanwhile, an arteriovenous malformation (AVM) is a cluster of abnormally formed blood vessels. Any one of these vessels can rupture, also causing bleeding into the brain.
Another important condition is the transient ischemic attacks or TIAs, which are considered minor or warning strokes. In a TIA, conditions indicative of an ischemic stroke are present and the typical stroke warning signs develop. However, the obstruction (blood clot) occurs for a short time and tends to resolve itself through normal mechanisms.
Even though the symptoms disappear after a short time, TIAs are strong indicators of a possible major stroke. Steps should be taken immediately to prevent a stroke.
Warning Signs of Stroke
- sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- sudden confusion, trouble speaking or understanding
- sudden trouble seeing in one or both eyes
- sudden trouble walking, dizziness, loss of balance or coordination; and
- sudden, severe headache with no known cause
Risk Factors of Stroke
Several risk factors have been identified for stroke, some cannot be controlled like age and family health history, but the others can be modified through lifestyle change like smoking and hypertension. The more risk factors a person has, the greater the chance he or she will have a stroke.
- Increasing age. The chance of having a stroke more than doubles for each decade of life after age 55. While stroke is common among the elderly, including Tiya Dely, many people under 65 also have strokes.
- Sex. Overall, the incidence and prevalence of stroke are about equal for men and women. However, at all ages, more women than men die of stroke.
- Heredity (family history). The chance of stroke is greater in people who have a family history of stroke.
- Hypertension. High blood pressure is the most important risk factor for stroke. In fact, stroke risk varies directly with blood pressure.
- Cigarette smoking. In recent years, studies have shown cigarette smoking to be an important risk factor for stroke. The nicotine and carbon monoxide in cigarette smoke damages the cardiovascular system in many ways. The use of oral contraceptives combined with cigarette smoking greatly increases stroke risk.
- Diabetes mellitus. Diabetes is an independent risk factor for stroke and is strongly correlated with high blood pressure. While diabetes is treatable, having it increases a person's risk of stroke. People with diabetes often also have high cholesterol and are overweight, increasing their risk even more.
- Heart disease. People with heart problems have more than twice the risk of stroke as those whose hearts work normally. Atrial fibrillation (the rapid uncoordinated beating of the heart's upper chambers) in particular, raises the risk for stroke. Heart attack is also the major cause of death among stroke survivors.
- High red blood cell count. A moderate or marked increase in the red blood cell count is a risk factor for stroke. The reason is that more red blood cells thicken the blood and make clots more likely. This is present in persons with chronic heart and lung diseases.
- Season and climate. Stroke deaths occur more often during periods of extremely hot or cold temperatures.
- Socioeconomic factors. There is some evidence that people of lower income and educational levels have a higher risk for stroke.
- Excessive alcohol intake. Excessive drinking (more than one drink per day for women and more than two drinks per day for men) and binge drinking can raise blood pressure, contribute to obesity, high triglycerides, cancer and other diseases, cause heart failure and lead to stroke.
- Certain kinds of drug abuse. Intravenous (injecting) drug abuse carries a high risk of stroke from cerebral emboli. Cocaine use has been closely related to strokes, heart attacks and a variety of cardiovascular complications. Some of them have been fatal even for first- time cocaine users.
Prevention of Stroke
The following are key areas for the prevention of stroke:
- Treatment and control of hypertension. Many people believe that effective treatment of high blood pressure is a key reason for the rapid decline in the death rates for stroke.
- Smoking cessation and promoting a smoke-free environment.
- Preventing thrombus formation in rheumatic heart disease and arrhythmias with appropriate medications. These medications are usually taken on a daily basis. Heath providers need to remind these people to take their medications as prescribed.
- Limiting alcohol consumption for women to not more than one drink per day and for men to not more than two drinks per day.
- Avoiding intravenous drug abuse and cocaine.
- Health Beat Magazine Issue no. 50. Department of Health of the Philippines. (Accessed on May 31, 2010).