Subarachnoid Haemorrhage Flashcards
Where does blood collect in a subarachnoid haemorrhage?
Between the arachnoid mater and pia mater
In what age group do SAHs usually occur?
Middle aged < 60
What is the cause of most SAHs?
Berry aneurysm rupture 70%
15% multiple
How do patients usually present?
Sudden onset thunderclap headache
Meningism - stiff neck, photophobia, headache
Nausea and vomiting
Focal neurological deficits (CN lesions)
Seizure
Reduced consciousness - drowsiness, confusion, coma
What signs are associated with SAH?
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
What are the common sites for berry aneurysms?
Artery junctions e.g between anterior communicating and anterior cerebral artery or posterior communicating and ICA
Other than berry aneurysms, what else can cause a SAH?
Arterio-venous malformations 10% Hypertension 10% Traumatic Vasculitis Tumour invading blood vessels Encephalitis
Around what percentage of the population may have a berry aneurysm?
3%
What are some risk factors?
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
What are some differentials for SAH?
Meningitis
Migraine
Intracerebral bleed
What tests should be done?
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
Why does LP need to be done more than 12 hours after headache onset?
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
How should SAH be managed?
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
What are some potential complications?
Rebleeding = commonest cause of death - first few days Cerebral ischaemia due to vasospasms Hydrocephalus Focal neurological deficits Coma Seizures Cognitive decline Frequent headaches
What should be done before surgery?
Cerebral angiogram
What 2 surgical techniques can be employed?
Coiling or clipping - depends on access and size of aneurysm
Coiling is preferred where possible
How is the CSF analysed after LP?
A spectrometer used to look for bilirubin peak
Rebleeding occurs in what percentage of patients at 24 hours, 14 days, 6 months?
4% at 24 hours
25% at 14 days
60% at 6 months
Blood outside the arteries can cause?
Vasospasm - severe infarction can occur (nimodipine must be given early to prevent cerebral vasospasm)
Due to vasospasm, 25% of patients will have signs of…after SAH
TIA/stroke
When is LP contraindicated?
Raised ICP
If a berry aneurysm is found incidentally, above what size should be treated?
Over 7mm should be treated with surgical clipping or coiling
Describe coiling
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.
