Moyamoya phenomenon

What it means

A noninflammatory, progressive occlusion of the intracranial carotid arteries owing to the formation of netlike collateral arteries arising from the circle of Willis.

Cerebral angiography shows puff-of-smoke (moyamoya) collaterals at the base of the brain.

Rare diseases that can present with this4

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category