Stroke

• Haemorrhagic strokes are the result of bleeding within the brain parenchyma, ventricular system or subarachnoid space. Haemorrhagic strokes account for approximately 15% of all strokes.

  They are further divided into an intracerebral haemorrhage (ICH) or subarachnoid haemorrhage (SAH)
• Haemorrhagic strokes are most commonly due to hypertension. Other causes of non-traumatic intracerebral haemorrhage include vascular malformations, brain tumours, vasculitis and bleeding disorders
• Patients with a haemorrhagic stroke are more likely to present with global features such as headache and altered mental status
• A CT head without contrast is very sensitive for detecting a cerebral haemorrhage
• Treatment of haemorrhagic stroke:

  • Aggressive treatment of hypertension
  • Anticoagulant reversal
  • Referral to neurosurgery for potential surgical intervention
• Ischaemic strokes account for 85% of all strokes:

  • Thrombosis - local blockage of a vessel due to atherosclerosis
  • Emboli - propagation of a blood clot - typically due to atrial fibrillation or carotid artery disease
  • Dissection - intramural haematoma that compromises cerebral blood flow
• Risk factors for ischaemic stroke:

  • Smoking
  • Diabetes
  • Hypertension
  • Atrial fibrillation
  • Hypercholesterolaemia
  • Carotid artery disease
  • Age over 65
  • Thrombophilic disorders
• The anterior circulation of the brain arises from the carotid arteries

  The posterior circulation of the brain arises from the vertebrobasilar arteries
• There are 3 major cerebral vessels which are connected by communicating arteries at the circle of willis

  • Anterior cerebral artery - supplies part of the frontal and parietal lobe - forms part of the anterior circulation
  • Middle cerebral artery - supplies large portion of lateral surface of each hemisphere - forms part of the anterior circulation
  • Posterior cerebral artery - supplies occipital lobe and inferior portion of the temporal lobe - supplies some deep structures such as the thalamus - forms part of the posterior circulation
• The middle cerebral artery is the most common site of infarction
• The posterior cerebral artery supplies the brain stem, cerebellum, occipital lobe, and temporal lobe
• Anterior ischaemic stroke:

  • Unilateral weakness and/or sensory deficit - contralateral
  • Homonymous hemianopia - visual field loss on same both of both eyes
  • Higher cerebral dysfunction - dysphasia and visuospatial dysfunction
  • TACS = all three of above
  • PACS = 2 of above
  • LACS = no loss of higher function, normally only motor/sensory
• A lacunar stroke (LACS) is a subcortical stroke that occurs secondary to small vessel disease. There is no loss of higher cerebral functions (e.g. dysphasia).

  One of the following needs to be present for a diagnosis of a LACS:

  • Pure sensory stroke
  • Pure motor stroke
  • Sensori-motor stroke
  • Ataxic hemiparesis
• Posterior ischaemic strokes can affect balance, vision and the cranial nerves:

  • Dizziness
  • Diplopia
  • Dysarthria
  • Dysphagia
  • Ataxia
  • Visual field defects
  • Brain stem syndromes - ipsilateral cranial nerve lesions with contralateral sensory and motor limb defects
• Diagnosis of ischaemic stroke:

  • History and neurological exam
  • CT without contrast - to rule of haemorrhage
  • Rule out hypoglycaemia
  • ECG - look for AF
• 1st line treatment for an ischaemic stroke is thrombolysis:

  • Ensure haemorrhage is ruled out on CT scan
  • Has to be within 4.5 hours
  • Alteplase - synthetic tissue plasminogen activator
  • NIH stroke score - ensure no contraindications
• A thrombectomy can be done for an ischaemic stroke:

  • If acute ischaemic stroke is due to large artery occlusion in anterior circulation
  • Within 24 hours of last time known to be well
  • Can be combined with thrombolysis
• All patients suffering with a stroke need admission to a specialist stroke centre

  They need to be immediately started on 300mg aspirin for 2 weeks

  Caution giving anti-hypertensive treatment in an ischaemic stroke as it can worsen the ischaemia

  Blood pressure is aggressively lowered in a haemorrhagic stroke
• Ongoing management of an ischaemic stroke:

  • Gradual reintroduction of anti-hypertensives
  • Blood glucose control between 4-11 mmol/L
  • Start atorvastatin 80mg 48 hours after stroke
  • 2 weeks of 300mg aspirin then 75mg clopidogrel
  • Only start anticoagulation for AF after completion of 2 weeks of aspirin
  • ECG/ambulatory ECG if AF suspected
  • Carotid dopplers or CT angiography to assess for stenosis
• Ischaemic strokes are classified by the bamford stroke classification
• In the event of a stroke of unknown cause, a bubble echo may be done. This can reveal a patent foramen ovale. These are responsible for rare strokes where a blood clot can travel between the right and left atrium
• Patient eligible for thrombectomy should have an immediate CT angiogram
• 300mg aspirin should not be started until 24 hours after thrombolysis
• Baseline CXR is needed for all patients as they are high risk for aspiration
• Aim systolic BP <130 for patients who have had a stroke or transient ischemic attack (long term, not immediately)
• Endarterectomy within a week if carotid vessel occluded >50% on the side the stroke occurred
• For patients who have had a haemorrhagic stroke, systolic blood pressure should be lowered to 130-140 for up to a week after the bleed to prevent haematoma expansion