Stroke is an acute injury to the brain caused by obstruction of its blood supply or by bleeding within or around it. Reduced circulation deprives brain tissue of oxygen and nutrients, while bleeding can directly damage tissue and produce swelling. The resulting neurological impairment may be temporary or permanent. Stroke is a medical emergency because injury can develop rapidly, and treatment effectiveness often depends on how soon care begins. (ninds.nih.gov)
Types and mechanisms
Ischemic stroke results from inadequate blood flow, usually because an artery becomes blocked. The obstruction may arise from thrombosis, in which a clot forms locally, or embolism, in which material travels from elsewhere, often the heart. Severe narrowing of an artery supplying the brain can also impair circulation. Ischemic stroke is the most common major stroke type. (ninds.nih.gov)
Hemorrhagic stroke occurs when a blood vessel ruptures. Intracerebral hemorrhage involves bleeding into brain tissue; subarachnoid hemorrhage involves bleeding into the space surrounding the brain. Causes include longstanding high blood pressure, rupture of a cerebral aneurysm, and abnormal vascular connections. Bleeding may also obstruct the circulation of cerebrospinal fluid, increasing pressure within the skull. (ninds.nih.gov)
A transient ischemic attack (TIA) is a related episode of temporary neurological dysfunction caused by briefly interrupted circulation. Symptoms commonly resolve within minutes, but their disappearance does not establish that the underlying vascular problem has resolved. TIA is an important warning of possible subsequent stroke. (ninds.nih.gov)
Clinical manifestations
Stroke symptoms characteristically begin suddenly. Common manifestations include weakness or numbness of the face, arm, or leg, particularly on one side; difficulty speaking or understanding speech; visual disturbance; and impaired balance or coordination. A sudden severe headache can also occur. Less common presentations include double vision, vomiting, drowsiness, or disorientation. Not every stroke produces the same combination of symptoms. (ninds.nih.gov)
The effects depend on the location and extent of injury. Damage to motor pathways can cause weakness or paralysis. Aphasia affects the production or comprehension of language, sometimes including reading and writing. Dysarthria, by contrast, concerns the muscular control of speech rather than language itself. Other consequences include altered sensation, swallowing difficulty, emotional changes, and problems with memory or attention. These impairments may affect basic activities such as dressing, eating, and walking. (ninds.nih.gov)
Diagnosis
Diagnosis combines symptom history, neurological examination, and imaging. Assessment establishes when symptoms began, identifies affected functions, and distinguishes ischemic injury from hemorrhage. Clinicians also investigate other conditions that can produce similar symptoms. (nhlbi.nih.gov)
Computed tomography (CT) is commonly performed early because it can identify intracranial bleeding. Magnetic resonance imaging (MRI) provides detailed information about brain tissue and may reveal ischemic injury before it becomes apparent on a routine CT scan. Vascular imaging can identify blocked arteries, aneurysms, or other abnormalities. (nhlbi.nih.gov)
Blood tests examine glucose levels, blood-cell counts, and clotting function. An electrocardiogram can identify cardiac abnormalities, including atrial fibrillation, that may explain an embolic stroke. The diagnostic investigation therefore addresses both the immediate brain injury and its underlying cause. (nhlbi.nih.gov)
Acute treatment
Treatment differs fundamentally between ischemic and hemorrhagic stroke. In eligible patients with ischemic stroke, thrombolytic therapy dissolves the obstructing clot. Intravenous treatment is commonly considered within the first four and a half hours, although eligibility depends on clinical circumstances and imaging. Mechanical thrombectomy uses catheter-based devices to remove a clot from a blocked brain artery. Imaging can identify selected patients who may benefit from clot removal up to 24 hours after symptom onset. These intervals are treatment-selection criteria, not evidence that delaying care is harmless. (ninds.nih.gov)
Hemorrhagic stroke management focuses on controlling bleeding, managing blood pressure, and limiting complications from swelling or fluid accumulation. Selected cases require surgery or endovascular procedures. A ruptured aneurysm may be treated by surgical clipping or by inserting coils through a catheter. Drugs used to dissolve clots can worsen hemorrhage, making identification of stroke type essential before treatment. (ninds.nih.gov)
Risk factors and recurrence
Hypertension is a leading modifiable risk factor. Other established factors include tobacco use, diabetes mellitus, elevated blood cholesterol, physical inactivity, excess body weight, harmful alcohol use, and air pollution. Risk also increases with age and a history of stroke. Cardiac disorders, especially atrial fibrillation, can contribute by allowing clots to form and travel to the brain. (who.int)
Measures used to reduce recurrence depend on the original mechanism. They may include treatment of blood pressure and cholesterol, medicines that reduce clot formation, or procedures addressing significant carotid-artery disease. Anticoagulant therapy can reduce embolic stroke risk associated with atrial fibrillation; carotid endarterectomy removes plaque from a selected diseased artery. (nhlbi.nih.gov)
Recovery and rehabilitation
Recovery varies from complete restoration of function to lasting disability, and may continue over months or years. Rehabilitation involves repeated practice of affected skills and strategies that compensate for persistent impairments. Multidisciplinary care may include physical therapists, occupational therapists, speech-language pathologists, nurses, physicians, and psychologists. Neuroplasticity—the brain’s capacity to reorganize its circuits—contributes to recovery, but does not guarantee that all lost abilities return. Rehabilitation can take place in hospitals, outpatient facilities, skilled nursing settings, or the home. (ninds.nih.gov)
Population burden
Stroke is a major public health problem. The World Health Organization reports an estimated 11.9 million new strokes worldwide in 2021. Its burden includes premature death, long-term functional impairment, and substantial demand for acute care and rehabilitation services. Differences in access to these services affect the organization of stroke care across health systems. (who.int)