Risk factors for subarachnoid haemorrhage
Polycytic kidney disease (PKD)
10% of them have aneurysms
PKD makes up 1% of SAH
Connective tissue disease
Pseudoxanthoma elasticum, Marfan’s disease, Ehlers-Danlos type 4, HHT
Hypertension, smoking and excessive alcohol all roughly double risk of SAH, and are modifiable.
Larger berry aneurysms are more likely to rupture.
As the vast majority are small, the average size is under 1cm diameter