Stroke is an acute neurological disorder caused by interruption of blood supply to part of the brain or by bleeding within or around brain tissue. Ischaemic stroke occurs when an artery supplying the brain becomes blocked, most commonly by a thrombus or embolus, whereas haemorrhagic stroke results from rupture of a blood vessel. Brain cells are highly dependent on continuous oxygen and glucose delivery, so prolonged interruption of circulation can cause irreversible injury. The consequences depend on the affected brain region and can include weakness, sensory loss, speech or language impairment, visual disturbance, coordination problems, cognitive impairment or altered consciousness. Stroke is a medical emergency because treatment effectiveness is strongly influenced by time.
Ischaemic Stroke accounts for the majority of strokes and can arise from several mechanisms. Large-artery atherosclerosis can produce local plaque and thrombosis, while emboli can travel from the heart or other arteries and obstruct cerebral vessels. Small-vessel disease can cause lacunar infarcts affecting deep brain structures. Cardioembolic stroke is particularly associated with conditions such as atrial fibrillation that permit thrombus formation in the heart. Haemorrhagic stroke can be divided broadly into intracerebral haemorrhage and subarachnoid haemorrhage, each involving different anatomical and pathological processes. Identifying the mechanism is important because secondary prevention and acute treatment differ according to stroke type.
The classic warning pattern includes sudden facial weakness, arm or leg weakness, speech disturbance or other sudden neurological dysfunction. However, Stroke can also present with sudden visual loss, severe imbalance, sensory abnormalities, confusion or other focal deficits depending on the affected circulation. The term "time is brain" reflects the fact that continued interruption of blood supply causes progressive neuronal injury, although the exact rate varies by collateral circulation and other factors. Emergency assessment commonly involves brain imaging to determine whether bleeding is present and to identify the nature and location of the lesion. A person should not wait for symptoms to improve before seeking urgent help.
Acute ischaemic Stroke treatment may include intravenous thrombolysis for eligible patients within appropriate time and clinical criteria and mechanical thrombectomy for selected patients with a large-vessel occlusion. Advanced imaging can sometimes identify people who remain eligible for treatment beyond conventional time windows. Thrombolysis aims to dissolve an obstructing clot, while thrombectomy physically removes clot from an accessible artery using an endovascular procedure. These treatments are not appropriate for every stroke because treatment decisions depend on timing, imaging, stroke severity, bleeding risk and other factors. Haemorrhagic Stroke requires different management, including control of blood pressure and reversal of relevant anticoagulation when appropriate, alongside neurosurgical or neurocritical care in selected cases.
Rehabilitation is a major component of Stroke recovery. Physiotherapy can address weakness, balance and mobility, while occupational therapy can support activities of daily living and adaptation to functional changes. Speech and language therapy can address communication disorders and swallowing difficulties. Cognitive and psychological consequences may require additional specialist support. Recovery is influenced by the location and size of the brain injury, initial severity, age, health status, rehabilitation intensity and neuroplastic adaptation. Improvement can continue for months or longer, but the trajectory differs substantially among individuals, and rehabilitation should not be understood as proof that the original brain injury has been reversed.
Secondary prevention depends on the cause of Stroke. Hypertension is one of the most important modifiable risk factors, while diabetes, smoking, abnormal LDL cholesterol and physical inactivity also contribute to vascular risk. Atrial fibrillation can cause cardioembolic stroke and may require anticoagulation according to individual risk. Carotid artery disease may require specific assessment, while antiplatelet treatment is commonly used for many non-cardioembolic ischaemic strokes. Lifestyle measures and appropriate treatment of vascular risk factors can substantially reduce recurrence risk. Prevention therefore requires identifying the stroke mechanism rather than applying the same treatment to every patient.
Stroke can affect more than movement and speech. Depending on the affected networks, people may experience neglect, impaired vision, swallowing problems, fatigue, changes in executive function, memory difficulties, emotional changes or problems controlling bladder and bowel function. Some deficits are subtle and may become apparent only when complex activities are resumed. Post-stroke seizures can occur in some circumstances, and immobility can increase risks such as venous thrombosis. Stroke can therefore become a long-term condition requiring coordinated medical, rehabilitative and social support even after the acute vascular event has stabilised.
A Transient Ischaemic Attack differs from Stroke because its neurological dysfunction is transient and does not produce the same established tissue infarction definition used for completed stroke, although the symptoms can be identical at onset. A common misconception is that a stroke always causes complete paralysis or loss of consciousness; many strokes produce relatively focal deficits. Another is that recovery means no further prevention is necessary, when in fact the period following a stroke or transient ischaemic event can carry substantial recurrent vascular risk. Sudden neurological symptoms require urgent assessment even if they disappear because early treatment and prevention can be critical.
