An individual recently diagnosed with endocarditis develops an intracranial aneurysm. What is the most likely diagnosis?

• A. Mycotic Aneurysm
• B. Atherosclerotic Aneurysm
• C. Berry Aneurysm
• D. Fusiform Aneurysm

Answer: (A)

When infective endocarditis seeds the brain with septic emboli, those microbes lodge in cerebral arteries and inflame the vessel wall. That infection weakens the artery and can form an infectious aneurysm, traditionally called a mycotic aneurysm. The term reflects infection rather than a fungal cause. This linkage between endocarditis and intracranial aneurysm is classic: septic emboli from the heart travel to the brain and create a fragile, infectious outpouching that may rupture.

Berry aneurysms are congenital saccular aneurysms in the circle of Willis and are not driven by infection. Atherosclerotic or fusiform aneurysms arise from degenerative vessel changes or generalized vessel-wall weakness due to long-standing atherosclerosis, not the acute infectious process seen with endocarditis. So the most likely diagnosis in this setting is a mycotic aneurysm.