Which feature best characterizes Moyamoya arteriopathy?

• A. Progressive intracranial internal carotid artery stenosis with collateral vessels
• B. Calcifications in basal ganglia
• C. Brainstem glioma
• D. Subarachnoid hemorrhage

Answer: (B)

Moyamoya arteriopathy is defined by progressive narrowing of the intracranial internal carotid arteries with the development of a dense network of fragile collateral vessels at the base of the brain. This combination—arterial stenosis in the brain’s main feeding arteries plus the formation of compensatory collateral vessels—produces the characteristic “puff of smoke” seen on angiography and explains why children may have ischemic events or, later, hemorrhages from these delicate vessels. Calcifications in the basal ganglia are not a hallmark of moyamoya and point to other conditions; brainstem glioma is a tumor of a different location, and though subarachnoid hemorrhage can occur from ruptured moyamoya collaterals, it is not the defining feature. The best single characterization is the progressive intracranial internal carotid artery stenosis with collateral vessel formation.