|

Ischaemic Stroke

Last updated:

Overview

“A stroke is a clinical syndrome characterised by clinical signs of focal or global neurological deficits due to an interruption in the blood supply to the brain. Strokes can be ischaemic or haemorrhagic:

  • Ischaemic strokes: blockages stopping blood flow
  • Haemorrhagic strokes: blood vessels “rupturing” leading to reduced blood flow.

Time is brain. Identifying and managing strokes as soon as possible is essential to reduce the risk of permanent neurological damage.”

Epidemiology

  • Ischaemic strokes make up around 80% of strokes 
  • Haemorrhagic strokes make up around 20% of strokes 
  • Stroke is the 4th most common cause of death in the UK 
  • Strokes most commonly affect people >65 years but can happen at any age.

Causes

Risk Factors

  • Older age
  • Family or personal history of stroke/TIA
  • Hypertension
  • Smoking
  • Dyslipidaemia
  • Diabetes mellitus
  • Atrial fibrillation
  • Ischaemic heart disease
  • Carotid artery stenosis
  • Intracardiac defects (patent foramen ovale or atrial/ventricular septal defects)
  • Clotting disorders and hypercoagulable states
  • Vasculitis
  • Sickle cell disease

Classification

Oxford (Bamford) Classification System

The Oxford (Bamford) Classification System is used to classify ischaemic strokes based on presenting signs and symptoms. It assesses 3 criteria:

  • Unilateral hemiparesis and/or hemisensory loss of the face, arm, and leg
  • Visual changes – homonymous hemianopia
  • Problems with higher function e.g. dysphasia

Total anterior circulation stroke (TACS)

  • All 3 of the above features are present
  • The middle and anterior cerebral arteries are affected

Partial anterior circulation stroke (PACS)

  • 2 of the above features are present
  • Part of the anterior cerebral arteries are affected

Posterior circulation syndrome (POCS)

  • Posterior circulation is affected i.e. the vertebrobasilar arteries
  • 1 of the following must be present:
  • Cerebellar or brainstem symptoms
  • Loss of consciousness
  • Isolated homonymous hemianopia

Lacunar infarcts

  • Perforating arteries around the internal capsule, basal ganglia, and thalamus are affected
  • There is no loss of higher cerebral function e.g. dysphasia
  • 1 of the following must be present:
    • Pure sensory stroke
    • Pure motor stroke
    • Ataxic hemiparesis

Presentation

A stroke should be suspected in any patient with new-onset focal neurological symptoms. Some features may be:

  • Unilateral weakness or paralysis in the face, arm, or leg
  • Unilateral sensory loss
  • Problems with speech or comprehending speech
  • Visual changes
  • Headaches – sudden-onset and severe
  • Difficulties with coordination
  • Difficulties with gait
  • Vertigo or loss of balance
  • Features of a Stroke Syndrome

Assessment

FAST

In the community, the FAST screening tool can be used:

  • Face – has their face fallen on one side? Can they smile?
  • Arm – can they raise both arms and keep them there?
  • Speech – is their speech slurred?
  • Time – time to call 999

ROSIER Score

After ruling out hypoglycaemia, the Recognition of Stroke in the Emergency Room (ROSIER) score can be used to assess patients in the emergency department. A score greater than 0 suggests a stroke:

  • Loss of consciousness/syncope: -1 point
  • Seizures: -1 point
  • New asymmetrical facial weakness: +1 point
  • New asymmetrical arm weakness: +1 point
  • New asymmetrical leg weakness: +1 point
  • Speech problems e.g. slurring: +1 point
  • Visual field defects: +1 point

Investigations

Initial investigations

  • Capillary blood glucose:
    • Must be done to rule out hypoglycaemia which can mimic a stroke
  • Immediate non-contrast CT head – the first investigation:
    • Used to rule out haemorrhagic strokes as their management is different
    • May show hypoattenuation (darkness) of the brain tissue
    • May show hyperattenuation (brightness) in an artery indicating a clot
    • May show a loss of differentiation between grey and white matter
  • U&Es:
    • To rule out electrolyte disturbances which may cause neurological signs
    • To assess kidney function to guide treatment
  • ECG and troponins:
    • To rule out cardiac ischaemia or arrhythmia
  • FBC:
  • Coagulation testing – prothrombin time, APTT, and INR:
    • To exclude coagulation problems
  • Do not delay treatment by waiting for results

Other investigations

  • Diffusion-weighted MRI head:
    • If the patient is outside the thrombolysis and thrombectomy window and there is diagnostic doubt
  • CT angiography (CTA) or MR angiography (MRA) – CTA is faster:
    • If the patients are eligible for thrombectomy after the initial CT
    • Do not delay treatment waiting for results
  • CT or MRI perfusion-weighted imaging:
    • If patients are outside the thrombolysis and thrombectomy window, this may show salvageable tissue and allows patients to undergo thrombectomy provided they were well between 6-24 hours previously
  • Carotid artery ultrasound:
    • If carotid artery stenosis is suspected to have caused the stroke
  • Echocardiography:
    • If structural cardiac pathology is suspected to have caused the stroke e.g. paradoxical strokes following a deep vein thrombosis

Management

Acute management in all patients

Overall, in all patients:

  • 1st-line: aspirin 300mg orally/rectally once haemorrhagic strokes are ruled out
  • Maintain blood glucose, O2 saturations, temperature, and hydration within normal limits
  • Do not lower blood pressure unless there is a hypertensive emergency e.g. hypertensive encephalopathy/hypertensive nephropathy/aortic dissection/cardiac failure/pre-eclampsia
  • If cholesterol is >3.5mmol/L initiate statin after stroke treatment

Proximal anterior circulation occlusion

Proximal anterior circulation describes the branches that emerge from the internal carotid arteries. Management varies depending on the time of presentation and results of CTA/MRA:

  • Thrombectomy (if within 6 hours) + IV thrombolysis (if within 4.5 hours) if:
    • Haemorrhage has been ruled out and
    • CTA/MRA shows proximal anterior circulation occlusion
  • Thrombectomy if patients were well in the previous 6-24 hours (including wake-up strokes) if:
    • Haemorrhage has been ruled out and
    • CTA/MRA shows proximal anterior circulation occlusion and
    • CT/MRI perfusion-weighted imaging shows salvageable tissue i.e. limited infarct core volume

Proximal posterior circulation

Proximal posterior circulation describes the branches that emerge from the vertebral arteries i.e. the basilar or posterior cerebral artery. Management varies depending on the time of presentation and results of CTA/MRA:

  • Consider thrombectomy (if within 6 hours) + IV thrombolysis (if within 4.5 hours) if:
    • Haemorrhage has been ruled out and
    • CTA/MRA shows proximal posterior circulation occlusion
  • Consider thrombectomy if patients were well in the previous 6-24 hours (including wake-up strokes) if:
    • Haemorrhage has been ruled out and
    • CTA/MRA shows proximal posterior circulation occlusion and
    • CT/MRI perfusion-weighted imaging shows salvageable tissue i.e. limited infarct core volume

Patients with atrial fibrillation

  • Patients are treated with 300 mg aspirin for the first 2 weeks before anticoagulation is considered (provided a haemorrhagic stroke has been ruled out).

After acute treatment

Secondary stroke prevention should be initiated:

  • 1st-line: continue aspirin 300mg daily for 2 weeks then start lifelong clopidogrel
  • 2nd-line: if clopidogrel not tolerated/contraindicated, continue aspirin 300mg daily for 2 weeks then start lifelong aspirin + modified-release (MR) dipyridamole
  • 3rd-line: if clopidogrel and aspirin are not tolerated/contraindicated, start lifelong MR dipyridamole
  • Carotid endarterectomy should be considered if there is >50% stenosis

Monitoring

  • After treatment, all patients should have their swallowing function assessed ideally within 24-72 hours after admission and consider involving speech and language therapists (SALT).
  • The Barthel index is often used to measure how dependent a patient is after a stroke and can be used to score disability. It starts at 0 (completely dependent) to 100 (completely independent) and can be used to guide rehabilitation
  • Patients should be monitored for complications such as raised intracranial pressure (ICP) and seizures.
  • Patients should regularly have their level of consciousness measured using the Glasgow Coma Scale (GCS):
  • Any patient with a decreased GCS must have haemorrhages and stroke mimics ruled out e.g. hypoglycaemia, seizures etc.
  • Blood glucose should be maintained between 4-11mmol/L
  • Antihypertensives should only be given if there are hypertensive emergencies due to the risk of hypoperfusion to the brain and worsening of symptoms.
  • Oxygen should only be given if saturations are below 93%

Patient Advice

  • Patients should make lifestyle measures such as regular exercise, a healthy diet, weight loss if appropriate, reducing alcohol intake, and stopping smoking
  • Patients and their family/carers should be offered advice on stroke and when to seek help and the principles of rehabilitation

Complications

  • Neurological complications e.g. balance/movement/sensation/tone
  • Cognitive impairment: aphasia/apraxia/visual agnosia/disinhibition
  • Haemorrhagic transformation in an acute ischaemic stroke
  • Dysphagia and aspiration pneumonia
  • Visual impairments
  • Bowel and bladder incontinence/retention
  • Sexual dysfunction 
  • Pain: may be neuropathic and/or musculoskeletal
  • Psychiatric: depression/anxiety/changes in personality
  • Stress in carers

Prognosis

  • Almost 2/3 of patients have a permanent disability after treatment
  • Around 1/4 of patients have a stroke again within 5 years
  • Around 1/2 of patients have residual neurological deficits

Author