develop over time because ofan underlying defect in the media of vesselCharacteristic Features:Berry aneurysms: MC intracranial aneurysm^, saccular in appearance, arising at the bifurcation of intracranial arteries.* About 85% aneurysms occur in the anterior circulation, on the circle of willis.* Rupture of aneurysm usually occurs at the apex (dome) resulting in subarachnoid hemorrhage or intraparenehymal hemorrhage or both.* Unruptured aneurysms are usually completely asymptomatic.Occurrence of Berry aneurysm in order of frequency:1. Anterior communicating artery- Anterior Cerebral junction (29%)2. Posterior communicating artery-Internal carotid junction (28%)3. Middle cerebral bifurcation (18%)4. Intracranial carotid bifurcation (8%)5. Vertebrobasilar or basilar bifurcation (3%)">