Subarachnoid haemorrhage

Question 1

What are the causes of a subarachnoid haemorrhage?

Answer 1

rupture of saccular aneurysm - 85%

ateriovenous malformation - 15%

Question 2

What are the risk factors for developing a SAH?

Answer 2

smoking
alcohol misuse
HTN
bleeding disorders
mycotic aneurysm - SBE
close relative with history of SAH - 3-5 fold increased risk

Question 3

What are the layers of the meninges?

Answer 3

Dura mater
Arachnoid mater
Pia mater

Question 4

Where are the common sites for berry aneurysms?

Answer 4

junction of posterior communicating artery with the internal carotid
junction of anterior communicating artery with the anterior cerebral artery

Question 5

What are the associations with berry aneurysms?

Answer 5

polycystic kidneys
coarctation of the aorta
Ehlers-Danlos syndrome (hypermobile joints with increased skin elasticity - connective tissue disease)

Question 6

What are the symptoms of SAH?

Answer 6

sudden, devastating (usually occipital, “thunderclap”) headache.
Nausea, Vomiting, collapse, seizures and coma can follow

Coma/drowsiness may last days

Question 7

What are the signs of SAH?

Answer 7

Neck stiffness, Kernig’s sign (takes 6h to develop), meningism, retinal, subhyaloid and vitreous bleeds

focal neurology at presentation may relate to site of haemorrhage

Question 8

What is the differential to SAH?

Answer 8

Meningitis
migraine
intracerebral bleeds
cortical vein thrombosis

Question 9

What tests should be ordered in suspected SAH?

Answer 9

CT - detects >90% SAH within 1st 48hr

LP if CT -ve and no CI >12h after headache onset

Question 10

What CSF result would suggest SAH?

Answer 10

xanthochromic (yellow) - initially bloody but Hb breaks down after several hours

Question 11

What is the management of SAH?

Answer 11

refer to neurosurgery immediately
re-examine CNS often - chart BP, pupils and GCS
maintain cerebral perfusion by good hydration, aim for <160mmHg
Nimodipine (1mg/h IVI) - Ca antagonist that reduces vasospasm and consequent morbidity from cerebral ischaemia
Endovascular coiling

Question 12

What are the complications of SAH?

Answer 12

rebleeding - commonest cause of death and occurs in 20% often in first few days
Cerebral ischaemia - due to vasospasm, may cause permanent CNS deficit, and is commonest cause of morbidity
Hydrocephalus - due to blockage of arachnoid granulations, requires a ventricular or lumbar drain
Hyponatraemia - common but should not be managed with fluid restriction, seek expert help. Often due to SIADH

Question 13

What is the CT appearance of an SAH?

Answer 13

Hyperdense/bright (acute blood) areas distributed in the basal cisterns, sucli and in severe cases the ventricular system.

Star sign/loss of sulci definition