<prompt> Berry aneurysm most commonly occurs due to?Endothelial injury of vessel due to HTNMuscle intimal elastic lamina layer defectMuscle and adventitial layer defectAdventitia defect  <response>: Berry aneurysm is due to defect in tunica media and intimal elastic lamina layer leading to weakening of vessel wall and outpouching in anterior poion of circle of willis. Saccular Aneurysms: is a 2nd most common cause of clinically significant subarachnoid hemorrhage is rupture of a saccular berry aneurysm in a cerebral aery following trauma. Patient will describe the pain as worst headache of his life. Bloody tap on lumbar puncture is seen. Nimodipine is a cerebro-selective vasodilatory drug helpful for treatment of symptoms associated with subarachnoid hemorrhage. Berry aneurysm is associated with adult polycystic kidney disease ADPKD. 