Most strokes starve the brain, not flood it
About eighty-seven percent of strokes are ischemic: a clot or blockage cuts blood to brain tissue. The rest are hemorrhagic, from bleeding into or around the brain. High blood pressure tops the risk list. In 2023, roughly 13.2 million people had a stroke worldwide.
A stroke is a cerebrovascular accident: blood flow to part of the brain falls or stops, and cells die. Ischemic strokes interrupt supply; hemorrhagic ones follow vessel rupture or abnormal vessels. Both leave affected regions unable to work properly. Signs can include facial droop, one-sided weakness or numbness, trouble speaking or understanding, dizziness, or vision loss on one side. Symptoms that clear within twenty-four hours are labelled a transient ischemic attack, or mini-stroke. Hemorrhagic events may bring a severe headache; deficits can last, and later complications include pneumonia and bladder-control loss.
High blood pressure is the leading risk factor; smoking, obesity, diabetes, high cholesterol, prior TIA, atrial fibrillation, and air pollution also raise odds. Ischemia usually means a blocked vessel—thrombosis forming locally, embolism from elsewhere, or systemic hypoperfusion in shock. Roughly thirty to forty percent of ischemic cases are cryptogenic, with no clear cause, and stimulant users such as those taking cocaine or methamphetamine face a high risk. Bleeding can also erupt inside an ischemic zone, called hemorrhagic transformation, and nobody knows how many bleeds begin that way. Hemorrhagic types include intracerebral bleeding into brain tissue or ventricles, and subarachnoid bleeding between arachnoid and pia. Epidural and subdural hematomas are intracranial bleeds but are not counted as hemorrhagic stroke.
The World Health Organization’s 1970s definition used a twenty-four-hour cutoff, chosen arbitrarily to separate stroke from TIA. With early clot-busting options for ischemic stroke within about three to four-and-a-half hours, many clinicians prefer urgent labels such as “brain attack.” Screening mnemonics like FAST (face, arm, speech, time) and BE FAST (adding balance and eyes) aim to speed recognition. In 2023 strokes were the second leading global cause of death; about 105 million survivors lived on, with roughly 3.2 million ischemic and 3.5 million hemorrhagic deaths, and about two-thirds of cases in people over sixty-five.
Source: Stroke
