5. Location and pattern of the SAH must have the majority of the SAH in the supratentorial space caused by either an intradural anterior circulation aneurysm OR a basilar apex posterior circulation aneurysm with primarily supratentorial hemorrhage extension. Angiographic location of the aneurysm will be confirmed by catheter digital subtraction angiography (DSA) usually obtained during the coil embolization procedure. Patients with PICA or other posterior circulation aneurysms as the cause of the SAH will be excluded.