A stroke (sometimes called an acute cerebrovascular
attack) is the rapidly developing loss of brain function(s) due to
disturbance in the blood supply to
the brain. This can be due to ischemia (lack of glucose & oxygen
caused by thrombosis or embolism or due to a hemorrhage.
As a result, the affected area of the brain is unable to function,
leading to inability to move one or more limbs on one side of the body,
inability to understand or formulate speech, or inability to see one
side of the visual field.
A stroke is a medical emergency and can cause permanent neurological
damage, complications, and death. It is the leading cause of adult
disability in the United States and Europe. It is the number two cause
of death worldwide and may soon become the leading cause of death
factors for stroke include advanced age, hypertension (high blood
pressure), previous stroke or transient ischemic attack (TIA), diabetes,
high cholesterol, cigarette smoking and atrial fibrillation.
High blood pressure is the most important modifiable risk factor of
The traditional definition of stroke, devised by the World Health
Organization in the 1970s,
is a "neurological deficit of cerebrovascular cause that persists
beyond 24 hours or is interrupted by death within 24 hours". This
definition was supposed to reflect the reversibility of tissue damage
and was devised for the purpose, with the time frame of 24 hours being
chosen arbitrarily. The 24-hour limit divides stroke from transient
ischemic attack, which is a related syndrome of stroke symptoms that
resolve completely within 24 hours.
With the availability of treatments that, when given early, can reduce
stroke severity, many now prefer alternative concepts, such as brain
attack and acute ischemic cerebrovascular syndrome (modeled
after heart attack and acute coronary syndrome respectively), that
reflect the urgency of stroke symptoms and the need to act swiftly.
A stroke is occasionally treated with thrombolysis ("clot buster"),
but usually with supportive care (speech and
language therapy, physiotherapy
and occupational therapy) in a "stroke unit" and secondary prevention
with antiplatelet drugs (aspirin and
often dipyridamole), blood pressure control, statins, and in selected
patients with carotid endarterectomy and anticoagulation.