Stroke – medical revision notes

Stroke – medical revision notes

In this article we will 10 describe medical revision notes about stroke.

Key Points

• Stroke is a medical emergency caused by an interruption of blood supply to the brain, leading to brain tissue damage
• Strokes can be classified as ischaemic (85%) or haemorrhagic (15%)
• Rapid recognition and treatment are crucial to minimise neurological damage and improve outcomes.
• Risk factors include hypertension, smoking, diabetes, and atrial fibrillation
• Management of acute ischaemic stroke includes thrombolysis or thrombectomy, while hemorrhagic stroke requires management of bleeding and intracranial pressure
• Long-term management involves secondary prevention, rehabilitation, and managing complications.

1. Definition

A stroke occurs when blood supply to part of the brain is either interrupted or reduced, depriving brain tissue of oxygen and nutrients. Brain cells begin to die within minutes, making early intervention critical.

A stroke is not a single disease. It is a group of diseases, with two main types:

1. Ischaemic stroke: Caused by a blockage in a blood vessel supplying the brain, typically due to a thrombus or embolus.
2. Haemorrhagic stroke: Occurs when a blood vessel in the brain ruptures, leading to bleeding into or around the brain.

A transient ischaemic attack (TIA) is a temporary disruption of blood flow to the brain, with symptoms resolving within 24 hours.

Note. Doctors also call stroke a cerebrovascular accident (CVA). This a strange phrase as its not really an accident.

2. Epidemiology

• Prevalence: In the UK, approximately 100,000 strokes occur annually. Stroke is the fourth leading cause of death and a major cause of disability
• Age: Stroke risk increases with age, but up to 25% of strokes occur in people under 65
• Gender: Men are more likely to suffer a stroke at a younger age, but women, particularly older women, have a higher lifetime risk
• Ethnicity: South Asian, African, and Afro-Caribbean populations in the UK have a higher risk of stroke, partly due to higher rates of hypertension and diabetes.

3. Risk factors

Modifiable 

• Hypertension: The most significant modifiable risk factor
• Atrial fibrillation (AF): Increases the risk of ischaemic stroke from emboli
• Diabetes mellitus: Contributes to atherosclerosis
• Dyslipidaemia: Elevated LDL cholesterol increases the risk of atherosclerosis
• Smoking: Damages blood vessels and promotes clot formation
• Obesity and physical inactivity
• Excessive alcohol consumption.

Non-modifiable 

• Age: Risk increases significantly after age 55
• Gender: Men have a higher risk of stroke earlier in life, but women’s risk increases with age, especially after menopause
• Family history of stroke or cardiovascular disease
• Ethnicity: People of African, Caribbean, and South Asian descent have higher stroke risk due to higher rates of hypertension and diabetes.

4. Causes

• Ischaemic stroke:
  • Large vessel atherosclerosis: common site is the internal carotid artery
  • Small vessel occlusion: lacunar strokes due to lipohyalinosis or atheroma
  • Cardioembolic: atrial fibrillation, endocarditis, PFO, or ventricular thrombus
  • Other causes: arterial dissection, vasculitis, vasoconstriction, genetic conditions, haematological disorders.
• Haemorrhagic stroke:
  • Hypertension: most common cause, typically basal ganglia or thalamic haemorrhages
  • Cerebral amyloid angiopathy: causes lobar haemorrhages
  • Other causes: bleeding disorders, anticoagulants, vascular malformations, sympathomimetic drugs.

5. Symptoms

Stroke symptoms can vary depending on the affected part of the brain but typically include sudden onset of:

• Hemiparesis or hemiplegia: Weakness or paralysis on one side of the body.
• Facial droop: Often affecting one side.
• Aphasia: Difficulty speaking or understanding speech.
• Dysarthria: Slurred speech.
• Visual disturbances: Sudden loss of vision in one or both eyes, or visual field defects.
• Ataxia: Loss of coordination or balance.
• Severe headache: More common in hemorrhagic stroke.
• Loss of consciousness or confusion in severe cases.

The ‘FAST’ (Face, Arms, Speech, Time) mnemonic is useful for recognising common stroke symptoms:

• Face drooping
• Arm weakness
• Speech difficulty
• Time to call emergency services.

6. Diagnosis

Diagnosis is primarily clinical, but imaging is essential to distinguish between ischaemic and haemorrhagic stroke.

Key diagnostic criteria include:

1. Rapid onset of focal neurological deficits.]
2. Confirmation of stroke subtype using imaging.

Investigation

1. Non-contrast CT scan: The first-line imaging to differentiate between ischaemic and hemorrhagic stroke
   • Ischaemic stroke: May not show immediate changes but rules out haemorrhage
   • Haemorrhagic stroke: Shows evidence of bleeding
2. MRI brain: More sensitive for detecting early ischaemic changes, especially in the posterior circulation
3. Blood tests:
   • Full blood count (FBC) to check for anaemia or infection
   • Blood glucose to rule out hypoglycemia as a mimic
   • Coagulation profile to assess for bleeding risks
   • Lipid profile to assess cardiovascular risk factors.
4. ECG: To identify atrial fibrillation or other arrhythmias that may have led to an embolic stroke
5. Carotid doppler ultrasound: Assesses for carotid artery stenosis, a common cause of ischaemic stroke
6. Echocardiogram: May be indicated to look for cardiac sources of emboli in patients with suspected cardioembolic stroke (e.g. from infective endocarditis).

Note. CT head can be normal initially in stroke.

Differential diagnosis

Several conditions can mimic the symptoms of a stroke, including:

• Seizures: Can cause postictal paralysis (Todd’s paresis)
• Migraine with aura: Can present with transient neurological symptoms
• Hypoglycaemia: Can cause confusion, hemiparesis, or focal deficits
• Brain tumours: Can present with focal neurological deficits
• Multiple sclerosis (MS): Acute demyelination episodes can mimic stroke
• Subdural hematoma: Can cause focal neurological deficits, often with a history of trauma.

7. Treatment

The treatment approach depends on the type of stroke: ischaemic or haemorrhagic.

Ischaemic 

• Thrombolysis
  • Intravenous alteplase (tPA) can be administered if the patient presents within 4.5 hours of symptom onset and meets eligibility criteria (e.g. no major bleeding risk)
• Thrombectomy
  • Endovascular thrombectomy may be performed within 6-24 hours for large-vessel occlusions
• Antiplatelet therapy
  • Aspirin 300 mg is started after ischaemic stroke unless thrombolysis is planned
• Anticoagulation
  • In patients with atrial fibrillation, anticoagulation (e.g. warfarin or DOACs) is initiated after haemorrhage is excluded and typically delayed for several days to reduce bleeding risk.

Haemorrhagic 

• Blood pressure management
  • Aggressive lowering of blood pressure, often with IV antihypertensives, to prevent further bleeding.
• Surgical intervention
  • Considered in cases of large hematomas, aneurysm repair, or hydrocephalus due to intraventricular haemorrhage. Craniectomy (decompressive) may also be required
• Management of raised intracranial pressure (ICP)
• Osmotic agents (e.g. mannitol) or hypertonic saline may be used in severe cases.

Ward management

• Initial ward care: admit to ASU or HASU, manage aspiration risk, blood sugar, VTE risk, fever, seizures, BP control, cardiac rhythm monitoring
• Long-term care: multidisciplinary rehabilitation, risk factor modification (BP, lipids, antiplatelets, anticoagulation, lifestyle).

8. Complications

Stroke can lead to several acute and chronic complications:

• Cerebral oedema: Swelling that can lead to increased intracranial pressure and herniation
• Haemorrhagic transformation: In ischaemic stroke, the infarcted area can bleed
• Seizures: Can occur due to cortical damage
• Deep vein thrombosis (DVT) and pulmonary embolism (PE): Due to immobility after stroke
• Aspiration pneumonia: Resulting from swallowing difficulties
• Pressure ulcers: Due to immobility
• Depression and anxiety: Common psychological sequelae of stroke.

9. Prognosis

The prognosis following stroke varies widely depending on:

• Stroke severity: Assessed using tools like the NIH Stroke Scale (NIHSS)
• Time to treatment: Early thrombolysis or thrombectomy significantly improves outcomes in ischaemic stroke
• Comorbidities: Pre-existing conditions like hypertension and diabetes worsen the prognosis
• Age: Older patients generally have worse outcomes.

Despite advances in treatment, stroke is a major cause of disability, with many survivors requiring long-term rehabilitation and support.

10. Prevention

Prevention of stroke focuses on managing modifiable risk factors through primary prevention (before stroke occurs) and secondary prevention (after a TIA or stroke to prevent recurrence).

Primary 

• Hypertension control: Regular blood pressure checks and treatment with antihypertensive medications
• Anticoagulation for atrial fibrillation: Use of warfarin or direct oral anticoagulants (DOACs) for patients with AF
• Lipid-lowering therapy: Statins reduce stroke risk in patients with hyperlipidaemia
• Smoking cessation: Reduces the risk of atherosclerosis and stroke
• Healthy diet and regular physical activity
• Diabetes management: Good glycaemic control reduces vascular complications.

Secondary 

• Antiplatelet therapy: Long-term low-dose aspirin or clopidogrel after an ischaemic stroke
• Anticoagulation: For patients with atrial fibrillation or cardioembolic strokes
• Blood pressure management: A target BP of <130/80 mmHg is often recommended post-stroke
• Carotid endarterectomy: In patients with significant carotid artery stenosis
• Statins: Continued use in all patients to reduce cholesterol and stabilise atherosclerotic plaques
• Lifestyle modifications: Including smoking cessation, weight loss, and exercise.

Other information

Where should I go if I think I’m having a stroke?
If you are having a stroke (or think you are), the ambulance will take you to the nearest ‘Stroke Unit’. This will usually be in a regional teaching hospital, i.e. they may drive past your local hospital. Or it may be better if you get someone to drive you to such a hospital, i.e. quicker than an ambulance.

There are more treatment options there, including thrombolysis (see treatment below) – and you can have a CT of your brain 24 hours a day.

Note. If you do not absolutely need an ambulance, please do not call one. Ask your family to take you to A&E, having checked its in a hospital with a Stroke Unit.

Summary

We have described 10 medical revision notes about stroke. Stroke is a medical emergency. Prompt treatment is crucial – especially thrombolysis for ischaemic stroke.

Other resource

The Stroke Association website is very good.