Subarachnoid Haemmorhage

Question 1

What is a subarachnoid haemorrhage?

Answer 1

Arterial haemorrhage into the subarachnoid space

Question 2

What is the aetiology of subarachnoid haemorrhage?

Answer 2

• Rupture of a saccular aneurysm at the base of brain (usually Circle of Willis): 85% - Perimesencephalic haemorrhage (e.g. parenchymal haemorrhages tracking onto surface of brain): 10% - Arteriovenous malformations, bleeding diatheses, vertebral or carotid artery dissection with intracranial extension, myotic aneurysms, drug abuse (e.g. cocaine, amphetamines): 5% - Associated with hypertension, smoking, excess alcohol intake, saccular aneurysms are associated with polycystic kidney disease, Marfan’s syndrome, pseudoaxanthoma elasticum and Ehler’s Danlos syndrome

Question 3

What is the epidemiology of Subarachnoid haemorrhage?

Answer 3

• Annual incidence is 10/100000 - Peak age of incidence in the fifth decade

Question 4

What are the presenting symptoms of a subarachnoid haemorrhage?

Answer 4

• Sudden onset severe headache (classically described ‘as if hit at back of the head) - Nausea, vomiting, neck stiffness, photophobia - Decreased level of consciousness

Question 5

What are the signs of a subarachnoid haemorrhage on examination?

Answer 5

• Meningism: Neck stiffness, Kernig’s sign (resistance or pain on knee extension when hip is flexed) because of irritation of the meninges by blood. Pyrexia may also occur - GCS: Assess and regularly monitor for deterioration. - Signs of increased intracranial pressure: Papilloedema, IV or III cranial nerve palsy. Hypertension and bradycardia - Fundoscopy: Rarely subhyaloid haemorrhage (between retina and virtreous membrane) - Focal neurological signs: Usually develop on second day and are caused by ischaemic from vasospasm and reduced brain perfusion. Aneurysms may cause pressure on cranial nerves causing ophthalmoplegia (classically III nerve or VI nerve palsy)

Question 6

What are the investigations for subarachnoid haemorrhage?

Answer 6

• Blood: FBC, U&E, ESR/CRP, clotting - CT scan: Hyperdense areas in the basal regions of the skull (caused by blood in the subarachnoid space). Identifies any intraparenchymal or intraventricular haemorrhages as well - Angiography (CT or intra-arterial): TO detect the source of bleeding if the patient is a candidate for surgery or endovascular treatment - Lumbar puncture: Raised opening pressure, increased red cells, few white cells xanthochromia (strawberry coloured CSF) because of breakdown of Hb, confirmed by spectrophometry of CSF supernatant after centrifugation