Overview
Acute Ischaemic Stroke
Topic Overview
Summary
Acute ischaemic stroke is sudden neurological deficit caused by cerebral artery occlusion. It is a time-critical emergency — "Time is Brain." Treatment within 4.5 hours with IV thrombolysis (alteplase/tenecteplase) and within 6-24 hours with mechanical thrombectomy (for large vessel occlusion) significantly reduces disability. Use FAST (Face-Arm-Speech-Time) for public recognition and immediate hyperacute stroke pathway activation.
Key Facts
- Pathology: Vessel occlusion → ischaemic core + penumbra (salvageable if reperfused)
- Time window: IV thrombolysis within 4.5 hours; thrombectomy up to 24 hours (selected)
- FAST: Face drooping, Arm weakness, Speech difficulty, Time to call 999
- Imaging: Non-contrast CT head (exclude haemorrhage) ± CTA (detect LVO)
- Treatment: IV alteplase 0.9mg/kg (max 90mg) OR tenecteplase + mechanical thrombectomy if LVO
- Stroke unit care: Proven to reduce death and disability
Clinical Pearls
Every 15 minutes of delay to treatment = 1 month of disability-free life lost
Door-to-needle target for thrombolysis: Under 60 minutes
Thrombectomy is the single most effective treatment in medicine for large vessel occlusion stroke (NNT 2.6 to reduce disability by 1 mRS grade)
Why This Matters Clinically
Stroke is the fourth leading cause of death in the UK and the leading cause of adult disability. Hyperacute treatment (thrombolysis and thrombectomy) has transformed outcomes, but only if delivered rapidly. Every clinician must recognise stroke and activate the stroke pathway immediately.
Visual Summary
Visual assets to be added:
- FAST campaign poster
- CT head: ischaemic stroke vs haemorrhagic
- CTA showing large vessel occlusion
- NIHSS scoring infographic
- Acute stroke pathway algorithm
Epidemiology
Incidence
- UK: ~100,000 strokes/year; 1 every 5 minutes
- Type: 85% ischaemic, 15% haemorrhagic
- Mortality: ~26,000 deaths/year in UK
- Disability: Leading cause of adult disability
Demographics
- Age: Risk doubles each decade after 55
- Sex: Slightly higher in men; women have worse outcomes
- Ethnicity: Higher in Black and South Asian populations
Risk Factors
| Modifiable | Non-Modifiable |
|---|---|
| Hypertension | Age |
| Atrial fibrillation | Family history |
| Diabetes | Prior stroke/TIA |
| Smoking | Ethnicity |
| Hyperlipidaemia | |
| Obesity | |
| Alcohol excess | |
| Physical inactivity |
Causes of Ischaemic Stroke
| Mechanism | Percentage |
|---|---|
| Large artery atherosclerosis | 30-40% |
| Cardioembolic (AF, valve, LV thrombus) | 25-30% |
| Small vessel disease (lacunar) | 20-25% |
| Other determined (dissection, vasculitis) | 5% |
| Cryptogenic | 10-20% |
Pathophysiology
Ischaemic Cascade
1. Arterial Occlusion
- Thrombus or embolus blocks cerebral artery
- Immediate cessation of blood flow
2. Ischaemic Core
- Tissue receiving under 10ml/100g/min blood flow
- Cell death within minutes (irreversible)
3. Ischaemic Penumbra
- Surrounding tissue with reduced but not absent blood flow
- Functionally impaired but viable (salvageable)
- Target of reperfusion therapy
4. Collateral Circulation
- Determines penumbra size and duration
- Better collaterals = larger penumbra = longer treatment window
Time is Brain
- 1.9 million neurons die per minute of untreated stroke
- Every 15—minute delay = 1 month of healthy life lost
- "Drip and ship" vs "mothership" models of care
Reperfusion Injury
- Restored blood flow can cause:
- Haemorrhagic transformation
- Cerebral oedema
- Free radical damage
Clinical Presentation
FAST (Public Awareness)
Common Stroke Syndromes
| Territory | Features |
|---|---|
| MCA (most common) | Contralateral hemiparesis (face/arm more than leg), hemisensory loss, aphasia (dominant), neglect (non-dominant) |
| ACA | Contralateral leg weakness more than arm, personality change |
| PCA | Visual field defect (homonymous hemianopia), memory impairment |
| Posterior circulation (basilar, vertebral) | Vertigo, diplopia, ataxia, dysphagia, crossed signs, coma |
| Lacunar | Pure motor, pure sensory, ataxic hemiparesis, dysarthria-clumsy hand |
Red Flags
| Feature | Significance |
|---|---|
| Sudden onset | Cardinal feature — vascular cause |
| Within thrombolysis window | Hyperacute treatment possible |
| Large vessel occlusion symptoms | Consider thrombectomy |
| Posterior circulation signs | Can be subtle; high mortality |
| Young patient | Consider dissection, PFO, thrombophilia |
Face drooping (asymmetry, inability to smile)
Common presentation.
Arm weakness (drift, cannot raise)
Common presentation.
Speech difficulty (slurred, absent, nonsensical)
Common presentation.
Time to call 999
Common presentation.
Clinical Examination
NIHSS (National Institutes of Health Stroke Scale)
- Standardised assessment of stroke severity
- Score 0-42 (higher = more severe)
- Components: LOC, gaze, visual fields, facial palsy, motor, ataxia, sensory, language, dysarthria, neglect
Key Clinical Components
| Category | Assessment |
|---|---|
| Level of consciousness | Alert, drowsy, obtunded, coma |
| Gaze | Conjugate deviation, gaze palsy |
| Visual fields | Hemianopia |
| Facial movement | Upper and lower face |
| Motor | Arm and leg strength, pronator drift |
| Ataxia | Finger-nose, heel-shin |
| Sensory | Light touch, pinprick |
| Language | Aphasia (expressive, receptive, global) |
| Dysarthria | Slurred speech |
| Neglect | Inattention to one side |
Cardiovascular Examination
- Pulse (AF)
- BP (usually elevated acutely)
- Heart murmurs (embolic source)
- Carotid bruits (stenosis)
Investigations
Hyperacute (Before Treatment Decision)
| Investigation | Purpose |
|---|---|
| Non-contrast CT head | Exclude haemorrhage — must be done ASAP |
| CT angiography (CTA) | Detect large vessel occlusion (LVO) for thrombectomy |
| Blood glucose | Hypoglycaemia mimics stroke; hyperglycaemia worsens outcome |
| ECG | AF, acute MI |
| FBC, U&E, coagulation | Coagulopathy (contraindication to thrombolysis) |
CT Interpretation
| Finding | Significance |
|---|---|
| Normal | Does not exclude acute ischaemic stroke (early infarct often invisible) |
| Hyperdense artery sign | Thrombus in vessel |
| Loss of grey-white differentiation | Early ischaemic change |
| ASPECTS score | Quantifies early ischaemic change (lower = worse) |
| Haemorrhage | Contraindicates thrombolysis |
After Acute Phase
- MRI brain (DWI sequence most sensitive for infarct)
- Carotid Doppler or CTA/MRA (carotid stenosis)
- Echocardiography (embolic source)
- 24h ECG/telemetry (paroxysmal AF)
- Lipids, HbA1c (risk factor modification)
Classification & Staging
TOAST Classification (Aetiology)
- Large artery atherosclerosis
- Cardioembolism
- Small vessel occlusion (lacunar)
- Stroke of other determined aetiology
- Stroke of undetermined aetiology (cryptogenic)
Bamford (Oxfordshire Community Stroke Project) Classification
| Type | Features |
|---|---|
| TACI (Total Anterior Circulation Infarct) | All of: motor/sensory deficit, hemianopia, higher cortical dysfunction |
| PACI (Partial ACI) | 2 of 3 above |
| LACI (Lacunar) | Pure motor/sensory, ataxic hemiparesis, dysarthria-clumsy hand |
| POCI (Posterior Circulation) | Brainstem/cerebellar signs, isolated hemianopia |
Modified Rankin Scale (mRS) — Outcome
- 0: No symptoms
- 1: No significant disability
- 2: Slight disability
- 3: Moderate disability (requires some help)
- 4: Moderately severe (requires assistance for all ADLs)
- 5: Severe disability (bedridden)
- 6: Death
Management
Pre-Hospital
- Recognise FAST symptoms
- Call 999 — pre-alert receiving hospital
- Record time of onset (or last known well)
- Transfer to stroke centre
Hyperacute Management (Door to Treatment)
CT Brain Within 20 Minutes of Arrival
- If no haemorrhage → consider thrombolysis
IV Thrombolysis (Within 4.5 Hours of Onset)
| Drug | Dose |
|---|---|
| Alteplase | 0.9 mg/kg (max 90mg); 10% bolus, 90% infusion over 1 hour |
| Tenecteplase | 0.25 mg/kg (max 25mg) IV bolus — increasingly preferred |
Thrombectomy (Within 6-24 Hours for LVO)
- CTA confirms large vessel occlusion (ICA, M1, basilar)
- Selection based on imaging: salvageable tissue (mismatch on CT perfusion/MRI)
- Mechanical clot retrieval in interventional suite
- NNT = 2.6 (most effective treatment in medicine)
Blood Pressure Management
- Do NOT treat aggressively in acute phase unless over 220/120
- If thrombolysis: Keep under 185/110 pre-treatment, under 180/105 post-treatment
- Use IV labetalol or glyceryl trinitrate infusion
Acute Stroke Unit Care
- Multidisciplinary team (stroke physician, nurse, physio, OT, SALT, dietitian)
- Swallowing assessment before oral intake
- VTE prophylaxis (IPC initially; LMWH later if haemorrhage excluded)
- Glucose control (target 4-11 mmol/L)
- Temperature control (treat fever)
- Early mobilisation (after 24h if stable)
Secondary Prevention (Start Early)
| Intervention | Details |
|---|---|
| Antiplatelet | Aspirin 300mg OD for 2 weeks (or clopidogrel 300mg loading) → then clopidogrel 75mg long-term |
| Anticoagulation | For AF — start after haemorrhage excluded, usually 1-14 days depending on infarct size |
| Statin | High-intensity (atorvastatin 80mg) |
| BP control | Target under 130/80 (after acute phase) |
| Carotid intervention | Endarterectomy or stenting for symptomatic 50-99% stenosis (within 2 weeks) |
| Lifestyle | Smoking cessation, exercise, diet, weight |
Complications
Acute
- Haemorrhagic transformation (especially after thrombolysis)
- Cerebral oedema → herniation (malignant MCA syndrome)
- Aspiration pneumonia
- Seizures
- DVT/PE
- UTI
Long-Term
- Residual disability (motor, sensory, cognitive, language)
- Post-stroke depression (30%)
- Post-stroke epilepsy (3-5%)
- Vascular dementia
- Recurrent stroke
Prognosis & Outcomes
Mortality
- 30-day mortality: 10-15%
- 1-year mortality: 30%
- Higher in TACI, posterior circulation, older age
Functional Outcomes
- 30% recover fully or near-fully
- 40% have moderate-severe disability
- 30% die within 1 year
Impact of Treatment
| Treatment | Benefit |
|---|---|
| Stroke unit care | Reduces death and dependency (NNT ~20) |
| Thrombolysis under 4.5h | Reduces disability (NNT ~10) |
| Thrombectomy for LVO | Reduces disability dramatically (NNT ~2.6) |
Evidence & Guidelines
Key Guidelines
- NICE NG128: Stroke and TIA in Over 16s (2019)
- RCP National Clinical Guideline for Stroke (2023)
- ESO/ESC Guidelines for Stroke Management
Key Trials
- NINDS, ECASS, IST-3: Established IV thrombolysis benefit
- MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT: Thrombectomy for LVO
- DAWN, DEFUSE 3: Extended thrombectomy window to 24 hours
Patient & Family Information
What is a Stroke?
A stroke happens when blood supply to part of the brain is blocked. Brain cells start to die, causing sudden symptoms like weakness, speech problems, or vision loss. It is a medical emergency.
Act FAST
- Face: Is it drooping on one side?
- Arm: Can they raise both arms?
- Speech: Is it slurred or strange?
- Time: Call 999 immediately
Treatment
- Clot-dissolving medicine (thrombolysis) if given within 4.5 hours
- Clot removal procedure (thrombectomy) for large blockages
- Care on a specialist stroke unit
Recovery
- Rehabilitation (physiotherapy, speech therapy, occupational therapy)
- Medication to prevent another stroke
- Lifestyle changes (diet, exercise, stop smoking)
Resources
References
Primary Guidelines
- NICE. Stroke and Transient Ischaemic Attack in Over 16s: Diagnosis and Initial Management (NG128). 2019. nice.org.uk
- Intercollegiate Stroke Working Party. National Clinical Guideline for Stroke for the UK and Ireland. 2023. strokeguideline.org
Key Trials
- Berkhemer OA, et al. A randomized trial of intraarterial treatment for acute ischemic stroke (MR CLEAN). N Engl J Med. 2015;372(1):11-20. PMID: 25517348
- Nogueira RG, et al. Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct (DAWN). N Engl J Med. 2018;378(1):11-21. PMID: 29129157