In Berry aneurysm, defect lies in:
Ans. b. Degeneration of media in muscle layer Berry' aneurysms (Saccular aneurysms) are believed to arise from a defect in the tunica media of the involved vessel."Saccular aneurysms (Berry aneurysms) develop over time because of an underlying defect in the media of vessel. Robbins 8/e p1297"Berry aneurysms are saccular in appearance (saccular aneurysms) presenting as out pouching of the vessel wall involving only a portion of the circumference tresembles a 'berry'' attached to a twig of the arterial tree). Berry aneurysms are rare in childhood but increase in frequency in young adults and middle life. They ate therefore not congenital anomalies but develop over the years from developmental defects of the "media' of the arterial wall at the bifurcation of arteries. These may however be predisposed by a congenital defect in the media of the involved vessel.""In the past, most berry aneurysm were thought to be congenital in origin arising from focal defects in the 'media 'and gradually developing over the years as arterial pressure, first weakens and subsequently balloons out the vessel wall. Recent studies however suggest that these intracranial aneurysms probably result from hemodynamically induced degenerative vascular injury to the tunica media."Berry Aneurysm (Saccular or Congenital Aneurysm)* MC type of Intra-crania I aneurysm^; Multipie in 20-30% cases* Predisposing factors: Smoking and hypertension^Increased Risk of Berry Aneurysm in* ADPKD* Ehlers-Danlos syndrome* NF-1* Marfan's syndrome* Fibromuscular dysplasia* Coarctation of aortaPathology:Wall of Berry aneurysm is made up of thickened hyalinized inrimaQ. The adventitia covering the sac is continuous with that of parent artery.* Saccular aneurysms (Berry aneurysms> 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%)
Degeneration of internal elastic lamina
Degeneration of media in muscle layer
Defect in muscular layer
Disturbance in vessel wail
C.N.S.