Spontaneous arterial bleeding into the subarachnoid space; accounts for 5% of strokes (1/4 of ischaemic strokes)

Aetiology

• Saccular (Berry) aneurysms
• Arteriovenous malformation
• Rare assocations include bleeding disorders, tumours, Marfans or Ehlers-Danlos syndromes

Clinical features

Symptoms

• Sudden, very severe headache, often occipital - ‘thunderclap headache’ often described as like being hit on the back of the head
• Headache is usually followed by vomiting and often by coma and death
• Survivors of SAH may remain comatose or drowsy for hours, days or longer

Signs

• Following major SAH, there is neck stiffness and a positive Kernig’s sign (like in meningitis)
• Papilloedema is sometimes present

Investigations

• CT brain: irregular shaped bleed, hyperattenuation in the subarachnoid space that expands bilaterally

• Lumbar puncture: performed 12-hours post symptom onset if there is high clinical suspicion of SAH and a negative or inconclusive CT head
  • If patient presents after 8 hours, a negative CT scan does not rule out a subarachnoid haemorrhage
  • Blood may be present → pink CSF
  • Xanthochromia in older bleeds - yellowing of the CSF due to haemolysis
  • Increase in CSF bilirubin

Management

• Bed rest and supportive measures
• Control hypertension