<prompt> A female presented with a severe headache of sudden onset. On CT scan a diagnosis of subarachnoid hemorrhage is made. The most common cause of subarachnoid hemorrhage is :Middle meningeal arteryBerry aneurysm ruptureBasilar arterySubdural venous sinuses  <response>: Ans. is b ie. Berry Aneurysm Ref. : Harrison, 17e pl726 16e, p 2387, 15e, p 238 Excluding head trauma the most common cause of SAH is rupture of a saccular aneurysma Berry aneurysm or congenital aneurysm. Berry aneurysms - also ka as congenital aneurysm although they are not present at birth. There is however a congenital defect of the media of the artery, which becomes the site of aneurysm in later life.Common sites :Junction of the anterior communicating artery with the anterior cerebral artery MC.Junction of the post communicating artery with the 1C A Internal carotid arteryThe bifurcation of MCA Middle carotid artery 