Ruptured temporal horn aneurysm associated with Moyamoya collateral vessel coexisting with contralateral arteriovenous malformation - technical note with clinical vignette.

The co-occurrence of a brain arteriovenous malformation, Moyamoya Disease, and intracranial aneurysm is exceedingly rare. We report the third case of this disease constellation, and the first where the aneurysm arises from the Moyamoya collateral vessel. We review the relevant literature and discuss proposed pathophysiological mechanisms and clinical implications.