Subarachnoid Haemorrhage

Question 1

Where does blood collect in a subarachnoid haemorrhage?

Answer 1

Between the arachnoid mater and pia mater

Question 2

In what age group do SAHs usually occur?

Answer 2

Middle aged < 60

Question 3

What is the cause of most SAHs?

Answer 3

Berry aneurysm rupture 70%

15% multiple

Question 4

How do patients usually present?

Answer 4

Sudden onset thunderclap headache
Meningism - stiff neck, photophobia, headache
Nausea and vomiting
Focal neurological deficits (CN lesions)
Seizure
Reduced consciousness - drowsiness, confusion, coma

Question 5

What signs are associated with SAH?

Answer 5

Neck stiffness
Kernig’s sign - thigh flexed at hip and knee at 90 degree angle and subsequent knee extension causes pain
Terson’s syndrome - intraocular haemorrhage
Focal neurology at presentation may suggest site of aneurysm e.g pupil changes may indicate CN III palsy with a posterior communicating artery aneurysm

Question 6

What are the common sites for berry aneurysms?

Answer 6

Artery junctions e.g between anterior communicating and anterior cerebral artery or posterior communicating and ICA

Question 7

Other than berry aneurysms, what else can cause a SAH?

Answer 7

Arterio-venous malformations 10%
Hypertension 10% 
Traumatic 
Vasculitis 
Tumour invading blood vessels 
Encephalitis

Question 8

Around what percentage of the population may have a berry aneurysm?

Answer 8

3%

Question 9

What are some risk factors?

Answer 9

FH
HTN
Heavy alcohol consumption
Smoking
Abnormal connective tissue disease, Ehlers-Danlos, Marfans, neurofibromatosis
Polycystic kidney disease (autosomal dominant)
Aortic coarctation
Bleeding disorders
Cocaine - raises BP and inflammation inside vessel walls

Question 10

What are some differentials for SAH?

Answer 10

Meningitis
Migraine
Intracerebral bleed

Question 11

What tests should be done?

Answer 11

CT scan urgent - detects 90% in first 24 hours
Fresh blood will show up bright on plain CT (don’t use contrast)
The sensitivity is 50% by 72 hours

Consider LP if CT negative but history suggestive of SAH

Question 12

Why does LP need to be done more than 12 hours after headache onset?

Answer 12

To allow breakdown of RBCs
Positive sample is xanthrochromic - yellow due to released bilirubin from RBC breakdown

Differentiates between a “bloody tap” and old blood from SAH

Question 13

How should SAH be managed?

Answer 13

Stabilise patient, re examine CNS often, chart BP, pupils and GCS
Treat cerebral vasospasm -nimodipine
Maintain hydration and avoid extremes of BP - control systolic below 150
Neurosurgical intervention if large bleed

Question 14

What are some potential complications?

Answer 14

Rebleeding = commonest cause of death - first few days 
Cerebral ischaemia due to vasospasms 
Hydrocephalus 
Focal neurological deficits
Coma 
Seizures 
Cognitive decline 
Frequent headaches

Question 15

What should be done before surgery?

Answer 15

Cerebral angiogram

Question 16

What 2 surgical techniques can be employed?

Answer 16

Coiling or clipping - depends on access and size of aneurysm
Coiling is preferred where possible

Question 17

How is the CSF analysed after LP?

Answer 17

A spectrometer used to look for bilirubin peak

Question 18

Rebleeding occurs in what percentage of patients at 24 hours, 14 days, 6 months?

Answer 18

4% at 24 hours
25% at 14 days
60% at 6 months

Question 19

Blood outside the arteries can cause?

Answer 19

Vasospasm - severe infarction can occur (nimodipine must be given early to prevent cerebral vasospasm)

Question 20

Due to vasospasm, 25% of patients will have signs of…after SAH

Answer 20

TIA/stroke

Question 21

When is LP contraindicated?

Answer 21

Raised ICP

Question 22

If a berry aneurysm is found incidentally, above what size should be treated?

Answer 22

Over 7mm should be treated with surgical clipping or coiling

Question 23

Describe coiling

Answer 23

Catheter inserted into artery in leg/groin - tube guided into aneurysm where tiny platinum coils passed through tube and into the aneurysm. Once aneurysm full of coils, blood cannot enter it - sealed off from main artery.