<prompt> A patient with suspected subarachnoid haemorrhage presents with blood isolated in the fouh ventricle on a CT scan. Aneurysmal rupture is likely to have resulted fromPosterior Inferior Cerebellar Aery AneurysmAnterior Communicating Aery AneurysmPosterior Communicating Aery AneurysmBasilar Aery Tip Aneurysm  <response>: Saccular aneurysm at size of 7mm and at top of basilar aery and at origin of posterior communicating aery are at greater risk of rupture . Ref Harrison20th edition pg 2445 