Subarachnoid haemorrhage

Question 1

Define a subarachnoid haemorrhage

Answer 1

Spontaneous bleeding between arachnoid and pia mater
usually due to rupture of a cerebral aneurysm. Mainly communicating
branches of the circle of Willis

Question 2

What is the epidemiology of subarachnoid haemorrhage?

Answer 2

• Age 35-65
• Incidence is 8 per 100000
• High mortality (50% die straight away), 10-20% more from rebleeding, 50% left with significant disability

Question 3

What are risk factors of subarachnoid haemorrhage (SAH)?

Answer 3

• PKD*
• Coarctation of aorta*
• Connective tissue*
  disorders - ED, Marfans
• Hypertension
• Known aneurysm
• Previous SAH
• Smoking
• Alcohol
• Family history
• Bleeding disorders
• Associated with berry
  aneurysms

Question 4

What are the causes of subarachnoid haemorrhage?

Answer 4

• Traumatic injury
• Aneurysmal rupture - berry (70-80%) at communicating branches
• AV malformations - abnormal artery and venous connections (15% of cases)
• Idiopathic

Question 5

Describe the pathophysiology of subarachnoid haemorrhage

Answer 5

• Tissue ischaemia - due to bleeding loss, causing cell death
• Raised ICP - Blood into cranial space, space occupying lesion
• Blood causing meningism - could obstruct CSF outflow (hydrocephalus)
• Vasospasm - bleeding irritates other vessels causing ischaemic injury

Question 6

What are the symptoms of subarachnoid haemorrhage?

Answer 6

• Thunderclap headache - typically occipital, excruciating, sudden onset
• Sentinel headache - Before main rupture, early sign - 6%
  cases
• Nausea, vomiting, seizures, visual disturbance, loss of consciousness,
  photophobia

Question 7

What are signs of subarachnoid haemorrhage?

Answer 7

• Meningeal irritation - Neck stiffness, Kernig’s (leg raise - pain), Brudzinski (neck raise - hip\knee flexion)
• Retinal, vitreous and subhyaloid bleeds w/ or without papilloedema
• Focal neurological signs - e.g. 3rd nerve palsy
• Increased BP

Question 8

What are investigations for subarachnoid haemorrhage?

Answer 8

• Immediate CT head - detects >95%, star shaped sign
• Lumbar puncture - if normal ICP, after 12 hours (xanthochromia -
  confirms SAH, raised red cells)
• MR/CT angiography - establish source, in all patients fit for surgery

Question 9

What is the treatment for subarachnoid haemorrhage?

Answer 9

• IV fluids - maintain cerebral perfusion
• Nimodipine - Ca2+ antagonist, reduce risk of vasospasm
• Neurosurgery (first line)- Endovascular coiling or surgical clipping, ventricular drainage (hydrocephalus)

Question 10

What is the differential diagnosis for subarachnoid haemorrhage?

Answer 10

• Meningitis (this has no thunderclap headache, will present with signs of infection)
• Migraine (no meningism or thunderclap)