Correlation 10: Berry Aneurysm

The white arrow on the black card marks the site of a ruptured berry aneurysm in the circle of Willis.

About 1 person in 100 is born with a defect in one or more areas of a cerebral arterial wall. Such defects create a weak area in the wall of the artery that balloons out over time to form what is called an aneurysm. Such aneurysms are "congenital" in the sense that the defect in the arterial wall is present from birth, but the actual aneurysm takes years to develop. Aneurysms are prone to rupture. Rupture is most likely to occur in young to middle age adults. Rupture of the aneurysm leads to bleeding into the subarachnid space at the base of the brain. Patients with a ruptured berry aneurysm have the sudden onset of a severe headache and can quickly lose consciousness. The mortality rate is significant. A neurosurgeon can put a clip around the base of a berry aneurysm to prevent rupture or repair a ruptured aneurysm.