What is known about the cause of berry aneurysms?

• A. Hypertension-induced
• B. Unknown
• C. Trauma
• D. Genetic mutation in collagen

Answer: (B)

Berry aneurysms are thought to arise from a weakness in the arterial wall at branching points, especially in the circle of Willis, but the exact initiating cause is not definitively known. Hypertension and trauma are not the primary causes of their formation; hypertension mainly increases rupture risk, and trauma tends to produce different, pseudoaneurysms rather than true berry aneurysms. There can be associations with connective tissue disorders, and certain genetic factors may predispose, yet no single genetic mutation in collagen or other gene has been proven to cause berry aneurysms in the general population. This ambiguity is why the best answer is that the cause is unknown.