|Fig 6: Basilar tip aneurysm on CTA (click to enlarge) |
|Fig 7: Internal carotid aneurysm seen on conventional catheter angiography (click to enlarge) |
Once the diagnosis of SAH is confirmed, patients should be transferred to a neurosciences unit that performs a high volume of SAH related surgical and endovascular procedures as outcomes in such centres are better [80,81].
In many centres CTA is used as a first line investigation in aneurismal SAH to define the relevant anatomy and plan intervention because it is quick and convenient (Fig 6).
Catheter angiography is then reserved for selective cases after a risk assessment . Catheter angiography remains the gold standard investigation in the detection of aneurismal SAH (Fig 7). It may be normal in cases of perimesencephalic haemorrhage, thrombosed aneurysm or severe vasospasm. It has a neurological complication rate of 1.3% though only 0.5% have permanent neurological dysfunction .