Stroke and TIA

A stroke is an interruption of the blood supply to any part of the brain, resulting in damaged brain tissue. A transient ischemic attack (TIA) results from a temporary interruption of blood supply. It is a minor stroke that has symptoms such as temporary loss of speech, or paralysis of an arm or leg - but the symptoms resolve within 24 hours, and usually within 1-2 hours. TIA. If the symptoms persist beyond this time, the event is considered to be a completed stroke.

Stroke is the third leading cause of death in most developed countries, and the leading cause of serious long-term disability in adults. Stroke accounts for about 10% of all deaths in most developed countries. More than 30% of stroke victims die within 1 year of stroke onset. Based on direct costs alone stroke is among the most expensive illnesses in the USA.

After cessation of blood supply following occlusion or hypoperfusion of the tissue, neuronal cell death occurs in the core of the infarcted area within a few minutes. The area surrounding the core, known as the ischaemic penumbra, contains functionally impaired but still viable brain tissue supplied with blood from collateral vessels. This area may be transformed into infarction as a result of secondary neuronal damage induced by deleterious biochemical cascades resulting in cytotoxic and exitotoxic effects.

The risk factors for stroke fall into three categories: non-modifiable factors, such as age, gender, race and heredity, medical conditions, which may be modifiable, and lifestyle or behavioural factors that can be modified. The medical conditions that increase stroke risk include hypertension, cardiac disease, atrial fibrillation, hyperlipidaemia, diabetes mellitus, carotid stenosis, prior TIA or stroke and elevated homocysteine levels.