Stroke and Transient Ischaemic Attack: When Brain Blood Flow Is Disrupted

A stroke happens when part of the brain is injured because an artery becomes blocked or a blood vessel bleeds. A transient ischaemic attack causes sudden stroke like symptoms that resolve, but it remains an urgent warning. Rapid recognition, a 999 call and brain imaging determine which emergency treatment is safe.

What a stroke is A stroke is sudden brain injury caused by disrupted blood flow. The disruption can result from an arterial blockage or bleeding within or around the brain. Brain cells depend on continuous oxygen and glucose delivery. When circulation fails, neurological function can change within seconds or minutes. Stroke is therefore a medical emergency. The two main stroke families Most strokes are ischaemic strokes caused by an arterial blockage. Haemorrhagic strokes occur when a blood vessel ruptures and blood escapes into or around the brain. The symptoms can look identical at first. Urgent brain imaging is needed because treatments that help a blocked artery can worsen active bleeding. Ischaemic stroke An ischaemic stroke occurs when an artery supplying the brain becomes blocked. Blood can no longer deliver enough oxygen to the affected tissue. A central area may become irreversibly injured quickly. Surrounding tissue can remain threatened but potentially recoverable for a limited time. Emergency treatment aims to restore circulation before more tissue is lost. Thrombotic stroke A thrombotic stroke develops when a clot forms within an artery supplying the brain. Atherosclerotic plaque in a large neck or brain artery can rupture or become unstable. Platelets and clotting proteins then build a thrombus at that site. Small penetrating arteries can also become blocked through disease linked to hypertension and diabetes. Embolic stroke An embolic stroke occurs when material travels through the circulation and blocks a brain artery. The embolus is usually a blood clot. It can arise from the heart, the aorta or a more proximal artery. The blockage often occurs suddenly in an artery that was previously open. Atrial fibrillation and cardioembolic stroke Atrial fibrillation allows blood to become relatively static within the left atrium. A clot can form, commonly within the left atrial appendage. Part of the clot may travel through the aorta and into a brain artery. AF can be silent, so stroke may be the first recognised sign of the rhythm. Appropriate anticoagulation substantially reduces this risk. Carotid artery disease The carotid arteries carry blood through the neck towards the brain. Atherosclerotic plaque can narrow an internal carotid artery. Clot or plaque material can then travel into smaller brain arteries. Selected people with recent symptoms and substantial carotid narrowing benefit from urgent surgery. Small vessel or lacunar stroke Small vessel disease affects tiny arteries penetrating deep brain structures. A blockage can cause a small infarct called a lacunar infarct. The physical area may be small but can interrupt an important motor or sensory pathway. Hypertension, diabetes, smoking and age increase small vessel disease risk. Haemorrhagic stroke A haemorrhagic stroke results from bleeding caused by a ruptured blood vessel. Blood directly injures tissue and can increase pressure within the skull. It can also compress surrounding brain and disrupt normal circulation. The main categories are intracerebral haemorrhage and subarachnoid haemorrhage. Intracerebral haemorrhage Intracerebral haemorrhage means bleeding directly into brain tissue. Longstanding high blood pressure is an important cause. Other causes include cerebral amyloid angiopathy, vascular malformations, tumours and anticoagulant related bleeding. Symptoms depend on the location and size of the haematoma. Rapid neurological deterioration, headache, vomiting or reduced consciousness can occur. Subarachnoid haemorrhage Subarachnoid haemorrhage means bleeding into the space around the brain where cerebrospinal fluid circulates. A ruptured intracranial aneurysm is an important cause. The classic presentation is a sudden severe thunderclap headache reaching maximum intensity quickly. Neck stiffness, vomiting, collapse, seizure or reduced consciousness can accompany it. Not every subarachnoid haemorrhage produces focal FAST symptoms. Why stroke type changes treatment An arterial blockage may be treated with thrombolysis or mechanical thrombectomy in selected people. These treatments aim to dissolve or remove a clot. They can worsen bleeding when the stroke is haemorrhagic. Haemorrhage can instead require blood pressure management, reversal of anticoagulation, neurosurgical care or aneurysm treatment. Imaging must therefore precede clot directed treatment. What a transient ischaemic attack is A transient ischaemic attack is usually shortened to TIA. It causes sudden focal neurological symptoms from temporary brain or retinal ischaemia. The symptoms resolve completely, often within minutes or hours. A specialist assessment determines whether the event was a TIA, minor stroke or another condition. TIA is not safely defined by a stopwatch Older descriptions defined TIA as symptoms lasting less than 24 hours. Modern assessment also considers whether brain tissue has been injured. Brief symptoms can accompany an infarct visible on MRI. A completed stroke can also improve rapidly. Duration alone cannot safely distinguish TIA from stroke at home. Why mini stroke can mislead TIA is sometimes called a mini stroke. The phrase can sound minor or reassuring. In reality, a TIA indicates an increased risk of a completed stroke, particularly soon afterwards. The same 999 response is required when symptoms begin, even if they resolve. FAST recognition FAST is a public emergency recognition prompt. F means facial weakness, such as one side of the face drooping. A means arm weakness, such as one arm drifting or being difficult to lift. S means speech difficulty, including slurring, incorrect words or inability to speak. T means time to call 999 immediately. One FAST sign is enough A person does not need all three main signs. Any sudden facial weakness, arm weakness or speech change justifies a 999 call. The person should not wait to see whether another feature appears. They should not drive themselves to hospital. FAST is not a diagnostic test FAST identifies common stroke presentations but does not confirm the diagnosis. Low blood glucose, seizure, migraine and other conditions can mimic stroke. Stroke can also occur without any FAST sign. Emergency professionals assess the complete neurological pattern and arrange imaging. Sudden leg weakness or numbness Stroke can cause weakness or numbness affecting one side of the body. The leg may buckle, drag or feel unusually heavy. Some people lose sensation without obvious weakness. Sudden one sided symptoms require emergency assessment even when the face and speech appear normal. Visual symptoms Stroke or TIA can cause sudden loss of vision in one eye. It can remove one side of the visual field in both eyes. Double vision can occur with posterior circulation stroke. Brief painless visual loss can be a retinal TIA and needs the same urgent pathway. Balance and coordination Posterior circulation stroke can cause sudden severe imbalance, unsteadiness or inability to walk. Vertigo, nausea, double vision, slurred speech or limb incoordination may accompany it. Dizziness alone is commonly caused by non stroke conditions. A sudden new combination of neurological symptoms requires emergency assessment. Language and speech are different Dysarthria means that speech sounds slurred because the muscles are not controlled normally. Aphasia means difficulty producing or understanding language. A person may speak clearly but use the wrong words or fail to understand a simple request. Both can result from stroke. Neglect and spatial problems Some strokes reduce awareness of one side of the body or surrounding space. The person may ignore food on one half of a plate or collide with objects on one side. They may not recognise their own weakness. This lack of awareness does not mean the deficit is voluntary. Cognitive and behavioural changes Stroke can cause sudden confusion, impaired attention, memory difficulty or altered behaviour. These symptoms are common in several medical emergencies. When they begin abruptly with another neurological change, stroke becomes an important possibility. Headache Most ischaemic strokes do not present mainly through headache. A sudden severe headache raises concern for subarachnoid haemorrhage or another vascular emergency. Headache with weakness, speech change, seizure, vomiting or reduced consciousness requires a 999 call. A milder headache does not exclude stroke. Seizure at stroke onset A seizure can occur at the onset of stroke, particularly with cortical injury or haemorrhage. Weakness can also follow a seizure without stroke, called Todd's paresis. The two situations cannot be separated safely without urgent assessment and imaging. Stroke in older adults Older adults can present with classic FAST signs. They may also show sudden confusion, falls, reduced alertness or loss of function. Frailty, dementia and communication difficulties can obscure the change. A sudden departure from the person's usual state should not be attributed automatically to ageing. Stroke in younger adults Stroke can occur at any adult age. Causes in younger people can include arterial dissection, inherited conditions, pregnancy related factors and heart abnormalities. Recreational drugs and inflammatory disease can contribute. Age should never be used to dismiss sudden focal neurological symptoms. Stroke mimics Low blood glucose can produce weakness, confusion or reduced consciousness. Migraine aura, seizure, functional neurological disorder and inner ear disease can resemble parts of a stroke presentation. Brain tumours and infection can also cause neurological symptoms. Emergency assessment is still required because treatment delay can cause permanent harm. Record when symptoms began The emergency team needs the exact time symptoms were first noticed. When onset was unwitnessed, they use the last time the person was known to be well. This information helps determine eligibility for thrombolysis and thrombectomy. Do not delay the 999 call while trying to reconstruct every detail. The 999 pathway Call 999 immediately for suspected stroke or TIA symptoms. This remains necessary when symptoms improve or disappear while waiting. Ambulance clinicians assess vital signs, blood glucose and neurological features. They alert an appropriate stroke service and transport the person without avoidable delay. Do not give food, drink or tablets Stroke can impair swallowing without the person realising it. Food, drink or tablets can enter the airway and cause choking or aspiration. Do not give aspirin during an active suspected stroke unless an emergency clinician specifically instructs this. Brain bleeding must be excluded before routine acute stroke aspirin is given. Specialist stroke unit care People with acute stroke should receive care within a specialist stroke service. Stroke units bring together medical, nursing, therapy and imaging expertise. Organised specialist care improves outcomes compared with general ward care. Initial hospital assessment The team rapidly assesses airway, breathing, circulation, blood glucose and neurological function. They record symptom onset or last known well time. They review anticoagulants, recent surgery, bleeding risk and previous function. A structured stroke scale can describe neurological severity. Brain CT A non contrast CT head scan can identify intracranial bleeding quickly. It can also show some established ischaemic changes and alternative diagnoses. Early ischaemic stroke can look normal on CT. A normal early scan therefore does not prove that no ischaemic stroke occurred. When CT is immediate NICE requires immediate non contrast CT when reperfusion treatment may be indicated. Immediate imaging is also required with anticoagulant use, reduced consciousness, progressive symptoms or severe headache at onset. Other suspected strokes should still be scanned as soon as possible and within 24 hours. Modern stroke pathways aim to image potential treatment candidates without delay. CT angiography CT angiography uses intravenous contrast to show arteries in the head and neck. It can identify a large vessel occlusion suitable for thrombectomy. It can also show carotid stenosis, arterial dissection or an aneurysm. When thrombectomy is possible, CT angiography follows the initial non contrast scan. Perfusion imaging CT perfusion or specialised MRI estimates established infarction and potentially salvageable brain tissue. It is particularly useful when thrombectomy is considered beyond six hours or after a wake up stroke. The scan supports specialist selection rather than predicting recovery with certainty. MRI MRI is more sensitive than CT for many small or early infarcts. Diffusion weighted imaging can identify acute ischaemic injury. MRI can also detect posterior circulation lesions and some alternative diagnoses. It is not always the fastest or most practical first emergency scan. Imaging after suspected TIA NICE does not recommend routine CT brain scanning for suspected TIA unless another diagnosis requiring CT is suspected. After specialist assessment, same day MRI can be considered to identify ischaemia, haemorrhage or an alternative cause. The urgent TIA pathway should not be delayed while waiting for routine imaging. Thrombolysis Intravenous thrombolysis uses a medicine that promotes clot breakdown. Current NICE options include alteplase and tenecteplase. Treatment is offered to eligible adults within 4.5 hours of symptom onset after intracranial haemorrhage is excluded. It is delivered only within an organised stroke service able to manage complications. Thrombolysis is not suitable for everyone The team assesses stroke severity, imaging, bleeding risk, blood pressure and recent medical events. Thrombolysis can cause serious bleeding, including intracranial haemorrhage. The potential benefit depends strongly on how quickly treatment begins. The decision is made urgently with the available clinical information. Blood pressure before thrombolysis Very high blood pressure increases bleeding risk during thrombolysis. NICE advises considering reduction to 185 over 110 mmHg or lower in treatment candidates. Blood pressure management occurs in a monitored clinical setting. It is not a target for self treatment during suspected stroke. Mechanical thrombectomy Thrombectomy removes a clot from a large brain artery using an endovascular catheter. A specialist passes the catheter through an artery, usually from the groin or wrist. A stent retriever or suction device captures the clot. The procedure can restore flow when intravenous thrombolysis alone is unlikely to clear a large occlusion. The six hour thrombectomy pathway NICE offers thrombectomy as soon as possible and within six hours for eligible proximal anterior circulation occlusion. Intravenous thrombolysis is also given when the person remains eligible within its time window. The two treatments are complementary rather than automatic alternatives. Thrombectomy from six to twenty four hours Selected people can benefit when last known well was between six and twenty four hours earlier. This includes some wake up strokes. Imaging must show a treatable large vessel occlusion and brain tissue that may still be saved. Clinical status and the amount of established infarction also guide selection. Posterior circulation thrombectomy NICE advises considering thrombectomy up to twenty four hours for selected basilar or posterior cerebral artery occlusion. Advanced imaging and specialist assessment identify people likely to benefit. Posterior circulation symptoms can be missed by FAST, which reinforces the need to recognise sudden visual, balance and coordination problems. Thrombectomy is not minor surgery The procedure carries risks including vessel injury, bleeding, further embolism and contrast complications. Its potential benefit can be substantial when a major artery is blocked. Treatment should occur as soon as possible after selection. Aspirin after ischaemic stroke Once imaging has excluded intracerebral haemorrhage, NICE gives aspirin 300 mg as soon as possible and within 24 hours. A swallowing screen determines whether oral treatment is safe. Another antiplatelet is used when aspirin is genuinely unsuitable. Long term antithrombotic treatment is then selected according to the stroke cause. Anticoagulation is not routine acute stroke treatment Full anticoagulation does not dissolve an ordinary acute arterial stroke safely. It can increase intracranial bleeding and haemorrhagic transformation. NICE does not recommend routine anticoagulation for acute ischaemic stroke. Its later role depends on conditions such as atrial fibrillation, venous thrombosis or another specific indication. Blood pressure in acute ischaemic stroke Blood pressure often rises during acute ischaemic stroke. The threatened brain may depend on this pressure to maintain collateral blood flow. NICE avoids routine rapid lowering unless there is a hypertensive emergency or thrombolysis requires a lower pressure. Reducing it too aggressively can worsen cerebral perfusion. Blood pressure in intracerebral haemorrhage High blood pressure can contribute to continued bleeding and haematoma expansion. For selected people presenting within six hours with systolic pressure from 150 to 220 mmHg, NICE considers rapid reduction. The target is systolic pressure of 140 mmHg or lower without dropping more than 60 mmHg in the first hour. Important exclusions require specialist judgement. Blood pressure treatment is not one rule for all stroke The safe approach differs between blocked and bleeding strokes. It also differs according to thrombolysis, neurosurgery, organ emergencies and the person's usual pressure. This is another reason stroke type must be established quickly. Reversing anticoagulation in haemorrhage Anticoagulant associated intracerebral haemorrhage can expand rapidly. Warfarin effects are reversed urgently using prothrombin complex concentrate and intravenous vitamin K when the INR is elevated. Specific reversal strategies exist for some direct acting oral anticoagulants. Specialist protocols balance bleeding control against the reason anticoagulation was prescribed. Treating aneurysmal subarachnoid haemorrhage Urgent non contrast CT investigates suspected subarachnoid haemorrhage. Confirmed bleeding is followed by CT angiography to identify an aneurysm. Specialists secure a ruptured aneurysm using endovascular coiling or surgical clipping. Treatment aims to prevent rebleeding while complications such as hydrocephalus and delayed cerebral ischaemia are managed. Swallowing assessment Stroke can weaken or uncoordinate swallowing muscles. The person may aspirate without coughing. NICE requires a trained swallowing screen before oral food, drink or medication. A specialist assessment follows when the screen identifies difficulty. Oxygen and glucose Routine oxygen is not recommended when saturation is adequate. NICE gives oxygen when saturation falls below 95%. Low blood glucose must be excluded because it can mimic stroke. Very high or low glucose can also worsen neurological injury and requires clinical management. Stroke complications Stroke can cause brain swelling, seizures, aspiration pneumonia and venous thrombosis. Immobility can lead to pressure injury and muscle loss. Urinary problems, constipation and infection can delay recovery. Specialist stroke unit care aims to prevent and treat these complications early. Secondary prevention begins quickly Secondary prevention aims to reduce another stroke, TIA, heart attack or vascular death. The correct plan depends on whether the event was non cardioembolic, cardioembolic, haemorrhagic or caused by another mechanism. The team investigates arteries, heart rhythm and cardiovascular risk factors. Antiplatelet treatment Long term antiplatelet treatment is used after many non cardioembolic ischaemic strokes and TIAs. Clopidogrel is a common NICE recommended option after ischaemic stroke. Alternative regimens are used when it is contraindicated or not tolerated. Antiplatelets are not a substitute for anticoagulation when AF is the embolic cause. Anticoagulation for atrial fibrillation AF related stroke prevention usually requires an oral anticoagulant rather than an antiplatelet. The start or restart timing after stroke depends on infarct size, bleeding risk and brain imaging. A disabling infarct may receive aspirin initially before anticoagulation is considered. The stroke and anticoagulation teams make the timing decision. Statins Lipid lowering treatment reduces future atherosclerotic cardiovascular events after ischaemic stroke or TIA. NICE usually offers atorvastatin 80 mg for secondary prevention when suitable. A lower dose or another treatment may be used because of interactions, intolerance or other clinical factors. Statins do not dissolve the clot that caused the acute stroke. Long term blood pressure control High blood pressure is a major preventable cause of both ischaemic and haemorrhagic stroke. Treatment usually resumes or begins after the acute phase when clinically safe. The target and medicine choice depend on age, kidney function, diabetes, frailty and stroke mechanism. Home readings can support treatment when measured correctly. Diabetes and vascular risk Diabetes increases atherosclerotic and small vessel disease risk. Management includes glucose care, blood pressure control, lipid treatment, smoking cessation and physical activity. One high glucose during acute illness does not by itself diagnose diabetes. Smoking and alcohol Smoking damages arteries and increases clotting and stroke risk. Stopping reduces future vascular events. Heavy alcohol use raises blood pressure and can increase haemorrhagic and AF related stroke risk. Support should be practical, non judgemental and tailored to dependence risk. Carotid imaging People with TIA or non disabling ischaemic stroke may need urgent carotid imaging. Ultrasound, CT angiography or MR angiography measures the narrowing. The report must use a recognised measurement method because treatment thresholds depend on it. Carotid endarterectomy Carotid endarterectomy removes atherosclerotic plaque from the internal carotid artery. NICE urgently assesses people with stable symptoms and substantial symptomatic carotid stenosis for surgery. This includes 50% to 99% narrowing using NASCET measurement criteria. Surgery is combined with antithrombotic, cholesterol, blood pressure and lifestyle treatment. Carotid surgery is selective The operation treats a specific recently symptomatic carotid artery. It is not used for every stroke or every minor plaque. NICE does not recommend surgery for symptomatic stenosis below 50% by NASCET criteria. The person's neurological stability, anatomy and operative risk also matter. Patent foramen ovale and other causes Some younger people have a patent foramen ovale that may allow a venous clot to enter arterial circulation. Closure is considered only after specialist investigation excludes more likely causes and confirms suitability. Arterial dissection, inflammatory disease and inherited conditions require mechanism specific care. Rehabilitation starts in the stroke service Rehabilitation begins with assessment as soon as the person is medically stable. It does not wait until every spontaneous recovery has occurred. The plan is based on the person's impairments, activities, goals and previous function. Family and carers are involved when appropriate. The multidisciplinary team Stroke rehabilitation can involve doctors, specialist nurses, physiotherapists and occupational therapists. Speech and language therapists assess communication and swallowing. Psychologists, dietitians, orthoptists, pharmacists and social care professionals contribute according to need. The person remains central to goal setting. Physiotherapy Physiotherapy addresses strength, balance, movement, posture and walking. Treatment uses repeated task practice and progressive activity. The aim is safe function and participation rather than normal looking movement at any cost. Occupational therapy Occupational therapists assess everyday activities such as washing, dressing, cooking and work. They practise tasks, recommend adaptations and assess equipment or environmental barriers. The goal is the greatest safe independence possible. Speech and language therapy Speech and language therapists assess aphasia, dysarthria and swallowing. They provide communication therapy and teach supportive strategies to families and staff. Communication aids can help a person participate in decisions and daily life. Cognitive and psychological rehabilitation Stroke can affect attention, memory, perception, mood and emotional control. Assessment should include depression, anxiety, adjustment and suicide risk where relevant. Psychological support is part of stroke care rather than an optional extra. Early mobilisation People should sit out, stand or walk as soon as their clinical condition permits. The timing and intensity depend on neurological stability, blood pressure and medical complications. NICE advises against high intensity mobilisation within the first 24 hours when the person needs help to mobilise. Early movement must be safe and individualised. Rehabilitation intensity NICE recommends needs based rehabilitation for up to at least three hours daily on at least five days each week when the person can participate. People unable to tolerate that intensity should still receive needed therapy on at least five days each week. Quality and relevance matter alongside the number of therapy minutes. Recovery is not linear The fastest change often occurs in the first weeks and months. Improvement can continue for years through practice, adaptation and treatment of complications. Fatigue or illness can temporarily reduce performance. A plateau does not mean that support and participation goals no longer matter. Fatigue after stroke Post stroke fatigue can be severe and disproportionate to activity. It can coexist with sleep problems, depression, pain or medicine effects. Energy planning and treatment of contributing conditions can help. Fatigue is not laziness or lack of motivation. Spasticity and pain Some muscles become stiff or overactive after stroke. This is called spasticity. It can interfere with movement, comfort, hygiene and positioning. Treatment can include therapy, splinting in selected cases, medicines or injections. Shoulder pain requires assessment because several mechanisms are possible. Returning home Early supported discharge allows selected medically stable people to continue specialist rehabilitation at home. The community team should provide rehabilitation of suitable intensity and expertise. Home discharge must account for transfers, medication, communication, swallowing and carer support. Long term review Needs can change after discharge. NICE recommends review of health and social care needs at six months and then annually. People can require renewed therapy, equipment, psychological care or vocational support. New stroke symptoms always require a fresh 999 response rather than waiting for follow up. What this lesson should not be used for This lesson cannot distinguish ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage or a mimic from symptoms alone. Do not use symptom duration to decide that an event was only a TIA. Do not give food, drink, aspirin or anticoagulants during an active suspected stroke unless emergency clinicians direct this. Do not delay a 999 call while checking blood pressure, researching symptoms or waiting for improvement. Every sudden focal neurological deficit requires emergency assessment.

Stroke is sudden brain injury caused either by arterial blockage or bleeding. The presentations overlap, so urgent imaging must determine the type before clot directed treatment. FAST supports rapid recognition, while resolved TIA symptoms still require emergency action and specialist assessment because early recurrent stroke risk is high.