Subarachnoid Haemorrhage

Question 1

What is the definition of a subarachnoid haemorrhage?

Answer 1

An arterial haemorrhage into the subarachnoid space

Question 2

Explain the aetiology involved with subarachnoid haemorrhages?

Answer 2

85% - rupture of a saccular aneurysm at the base of the brain (Berry aneurysms)

10% - perimesencephalic haemorrhage

5% - arteriovenous malformations, bleeding diathesis, vertebral artery dissection

Question 3

What risk factors are involved increase the risk of subarachnoid haemorrhages?

Answer 3

• Hypertension
• Smoking
• Excess alcohol intake
• Saccular/ Berry aneurysms are associated with:
  Polycystic kidney disease
  Marfan’s syndrome
  Ehlers-Danlos syndrome

Question 4

What is the epidemiology of subarachnoid haemorrhage?

Answer 4

• Incidence: 1/10,000

- Peak incidence is in the 40s

Question 5

What are the presenting symptoms of a subarachnoid haemorrhage?

Answer 5

Sudden-onset worst headache ever

Nausea/vomiting

Neck stiffness

Photophobia

Reduced level of consciousness

Question 6

What are the signs of subarachnoid haemorrhage on physical examination?

Answer 6

• Meningism (Neck stiggness, Pyrexia and Kernigs sign +ve)
• GCS - Check for deterioration
• Signs of raised ICP - papilloedema, IV or III nerve palsies, hypertension, bradycardia
• Focal neurologica signs (eg. cranial nerve palsies)

Question 7

What are the appropirate investigations when suspecting a subarachnoid haemorrhage?

Answer 7

• Bloods - FBC, U&Es, ESR/CRP and Clotting
• CT scan - Hyperdense areas in basal regions of skull due to blood
• Angiography to identify source of bleeding
• Lumbar puncture - Increased opening pressure, increased RBCs and Xanthochromia (straw coloured CSF due to breakdown of red cells)