Ischaemic Stroke
Summary
Ischaemic stroke is the sudden infarction of brain tissue due to arterial occlusion (thrombus or embolus). It accounts for 85% of all strokes (15% are Haemorrhagic). Time is Brain: 1.9 million neurons die every minute until flow is restored. Management relies on rapid differentiation from haemorrhage via CT, followed by reperfusion (Thrombolysis/Thrombectomy). [1,2]
Clinical Pearls
The Wake-Up Stroke: If a patient wakes up with a stroke, the "time of onset" is defined as the last time they were seen well (i.e., when they went to bed). This usually puts them outside the thrombolysis window (4.5 hours), but they may still be eligible for Thrombectomy (up to 24 hours).
Aspirin Danger: NEVER give Aspirin until the CT Head has ruled out a bleed. Giving Aspirin to a haemorrhagic stroke will kill the patient.
Reactive Hypertension: BP is often sky-high (200/110) acutely. This is a physiological response to maintain cerebral perfusion pressure (CPP). Do NOT lower it unless >220/120 or if thrombolysing (where target is less than 185/110). Dropping BP precipitates watershed infarction.
Demographics
- Prevalence: Third leading cause of death globally.
- Risk Factors: Hypertension (No. 1), Atrial Fibrillation (No. 2), Smoking, Diabetes, Cholesterol, Age.
Aetiology (TOAST Classification)
- Large Artery Atherosclerosis: Carotid stenosis.
- Cardioembolism: AF, Mural thrombus, Endocarditis.
- Small Vessel Disease: Lacunar (Lipohyalinosis).
- Cryptogenic: PFO (Patent Foramen Ovale) in young patients.
Mechanisms
- Core Infarct: Irreversibly damaged tissue (necrosis).
- Penumbra: Salveagable tissue surrounding the core. It is electrically silent but metabolically active. Reperfusion therapy aims to save this zone.
- Malignant MCA Syndrome: Massive oedema from a large infarct causes midline shift and coning (herniation). Decompressive Hemicraniectomy prevents death.
| Condition | Features |
|---|---|
| Hypoglycaemia | Sweating, low BM. ALWAYS CHECK GLUCOSE FIRST. |
| Todd's Paresis | Transient weakness after a seizure. |
| Migraine Aura | Spreading paresthesia, visual aura. Headache follows. |
| Bells Palsy | LMN facial nerve palsy (Forehead involved). Stroke spares forehead. |
| Functional (Conversion) | Inconsistent signs (Hoover's sign positive). |
Bamford Classification (Oxford)
Predicts prognosis and vascular territory.
1. TACS (Total Anterior Circulation Stroke) - Needs 3/3:
2. PACS (Partial) - Needs 2/3 of TACS.
3. LACS (Lacunar) - Needs 1/1:
4. POCS (Posterior) - Any 1:
Immediate (Code Stroke)
- Blood Glucose: Exclude hypo.
- CT Head (Non-contrast): Gold Standard.
- Purpose: Determines Ischaemic vs Haemorrhagic. (Ischaemia may be invisible for 6 hours; Bleed is white immediately).
- CT Angiogram (CTA): To identify Large Vessel Occlusion (LVO) for thrombectomy.
Secondary Screen
- Carotid Doppler: Stenosis >50-70% warrants Endarterectomy.
- ECG / Holter: Look for AF.
- Echocardiogram: PFO (Bubble study) or Thrombus.
Management Algorithm
"FAST POSITIVE"
↓
CT HEAD (Immediate)
┌───────────┴───────────┐
BLEED NO BLEED (Ischaemic)
(Neurosurgery) Check Onset Time
↓
┌───────────────────┐
< 4.5 HOURS 4.5 - 24 HOURS
↓ ↓
Thrombolysis? LVO present on CTA?
(Alteplase) (Large Vessel Occlusion)
(Verify NO NO YES
contraindications) ↓ ↓
↓ Aspirin Thrombectomy
└───────────┤ │
│ │
ASIPRIN │
(300mg immediately)** │
**Wait 24h if lysed │
↓ │
STROKE UNIT CARE │
(Swallow Screen) <────┘
1. Reperfusion (The "Drain Unblockers")
- Thrombolysis (IV Alteplase): Clot buster.
- Window: 4.5 hours from onset.
- Contraindications: Recent surgery, previous bleed, BP >185/110, anticoagulated (INR>1.7).
- Thrombectomy: Mechanical retrieval of clot via groin puncture.
- Window: Up to 6 hours standard, extended to 24 hours with perfusion imaging (CT Perfusion). Standard of care for LVO (MCA/Basilar).
2. Acute Medical Care
- Aspirin: 300mg daily for 2 weeks. Start >24 hours after lysis (or immediately if no lysis).
- Statin: Atorvastatin 80mg (Pleiotropic plaque stabilising effect).
- BP: Permissive hypertension (allow up to 220/120).
- Swallow: Patient NBM until screen passed (Risk of aspiration pneumonia). NG Tube if failing.
3. Secondary Prevention
- Antiplatelet: Clopidogrel 75mg lifelong (First line).
- Anticoagulation: DOAC (Edoxaban/Apixaban) if AF present (Start usually after 2 weeks to avoid haemorrhagic transformation of the infarct).
- Surgery: Carotid Endarterectomy if symptomatic stenosis >50-70%.
- Hemorrhagic Transformation: Bleeding into the infarct.
- Malignant MCA Syndrome: Decompressive Craniectomy needed if less than 60yo.
- Aspiration Pneumonia: Leading cause of death.
- DVT/PE: Immobile.
- Stroke Units: Admission to a dedicated stroke unit significantly reduces mortality and dependency compared to general wards.
- Recurrence: High risk (10% at 1 week) without treatment. Prevention reduces risk by 80%.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Stroke | NICE NG128 (2019) | Thrombectomy for all eligible LVO. Aspirin 300mg. Stroke unit care. |
| Prevention | RCP Guidelines | Clopidogrel > Aspirin for long term. |
Landmark Evidence
1. MR CLEAN (2015)
- Demonstrated efficacy of Endovascular Thrombectomy for anterior circulation stroke. Changed practice globally.
2. IST-3 (2012)
- Confirmed benefit of Thrombolysis up to 4.5 hours and in patients >80 years old.
What is a stroke?
A stroke is like a heart attack, but in the brain. A blood clot blocks an artery, starving a part of the brain of oxygen.
How do I spot one? (FAST)
- Face: Drooping on one side.
- Arms: Weakness, can't lift one.
- Speech: Slurring or jumbled words.
- Time: Call 999 immediately.
What is the treatment?
If you get to hospital quickly, we can give a strong drug to dissolve the clot (thrombolysis) or physically pull the clot out (thrombectomy). Afterward, we give blood thinning tablets and statins to stop it happening again.
Will I recover?
The brain is amazing at rewiring itself (neuroplasticity). Recovery is fastest in the first few months but can continue for years. Rehabilitation (Physio, Speech therapy) is just as important as the drugs.
Primary Sources
- NICE. Stroke and transient ischaemic attack in over 16s: diagnosis and initial management (NG128). 2019.
- Intercollegiate Stroke Working Party. National Clinical Guideline for Stroke. 2016.
- Berkhemer OA, et al. A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke (MR CLEAN). N Engl J Med. 2015.
Common Exam Questions
- Imaging: "Blood on CT is what colour?"
- Answer: White (Hyperdense). Ischaemia is dark (Hypodense).
- Anatomy: "Leg weakness > Arm weakness?"
- Answer: Anterior Cerebral Artery (ACA) stroke.
- Anatomy: "Macular sparing hemianopia?"
- Answer: Posterior Cerebral Artery (PCA) stroke.
- Management: "BP 190/100 post stroke?"
- Answer: Leave it alone! (Unless thrombolysing).
Viva Points
- Rosier Score: Used in A&E to distinguish stroke from mimics.
- Hemicraniectomy: Criteria? Age less than 60, Large MCA infarct, GCS dropping. Ideally within 48 hours.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.