STROKE can be defined as a sudden interruption of blood flow to the brain due to blockage or rupture of the brain arteries resulting in partial or complete paralysis of one half of the body accompanied by speech disturbances and impairment of memory or level of consciousness. Three types of stroke are commonly encountered; they are: Thrombotic, Haemorrhagic and Embolic. Both the thrombotic and the embolic involve clot formation within the arteries of the brain or from the left side of the circulation such as the heart, aorta or its main branches. In thrombotic stroke, complete occlusion of an artery within the brain occurs. In the embolic variety, blood clot formed outside the brain (e.g. in the heart, legs, etc) is carried to the brain where it blocks an artery in the brain. In the haemorrhagic stroke, tiny tears occur in worn-out blood vessels with leakage of blood into the tissue.
Thrombotic stroke is frequently heralded by brief transient neurological complaints (such as weakness in the legs or arms) in the days, weeks, or months preceding the onset of the fixed neurological damage. These brief early warnings tend to be similar. The fixed neurological disability usually develops in a step-wise fashion over a period ranging from minutes to hours (a stroke in evolution). Once the thrombosis is secure, the neurological damage stabilizes (a completed stroke).
This type of stroke in adults may occur at any time, but a disproportionately large number seem to appear at night during sleep or soon after waking. The reason for this is unknown. The clinical features, including the warning symptoms include the following: headache, transient weakness of limbs or speech, bizarre behaviour, poor memory, forgetfulness, intellectual deterioration; numbness of one half of the body, epileptic attacks, partial blindness in one eye or both, dizziness, giddy turns, double vision, hand tremors and vomiting.