Funnel Shaped Anterior Communicating Artery Fenestration Mistaken for an Aneurysm: A Cautionary Tale.

This report portrays a case of a funnel shaped anterior communicating artery (ACoA) fenestration which was mistaken as a small A1 aneurysm in a subarachnoid hemorrhage case. Although tridimensional rotational digital subtraction angiography improves aneurysm diagnosis specially at the ACoA complex, current spatial resolution might leave behind a considerable percentage of ACoA fenestrations. This may lead to diagnostic errors and unnecessary treatments risking iatrogenic complications. Luckily for our patient, a concomitant aneurysm warranted clipping and subsequent surgical exploration of the ACoA complex revealed the pitfall, thus preventing further action. Interestingly, another group of authors who reported similar misdiagnosis with ACoA aneurysms were able to prevent a third error, thanks to the experience acquired with 2 prior cases. Therefore, this clinical image aims to raise wider awareness of the need for very cautious consideration of imaging depicting small and/or atypical aneurysms in the ACoA complex.