The defect in berry aneurysm is: (A) Degeneration of internal elastic lamina, (B) Degeneration of media, (C) Deposition of mucoid material in media, (D) Low grade inflammation of vessel wall
Answer is B. Multiple aneurysms are observed in about 20-30% of cases of berry aneurysm. Such aneurysms are congenital in that defect in aerial wall may be present from bih, but actual aneurysm develops over years; thus, rupture is most likely to occur in middle-aged adults. Refer Robbins page no 1270