Double adjacent basilar artery fenestration with cerebellar infarct: Case report and new classification of double basilar fenestrations

Basilar artery (BA) fenestration is an uncommon congenital variant associated with aneurysms and posterior circulation infarcts. We present a 42-year-old male, smoker and hypertensive who came with acute onset vertigo and gait ataxia. Cerebellar signs were positive on the left side. Diffusion-weighted brain magnetic resonance imaging showed acute infarct in the left anterior inferior cerebellar artery (AICA) territory. Computed tomography angiography showed BA double adjacent fenestration of proximal segment of BA, without thrombus, dissection/aneurysm. To the best of our knowledge, only three cases of double adjacent BA fenestration have been described so far. The association between vertebro-BA fenestrations and posterior circulation stroke is controversial. It has been suggested that turbulent flow at the site of fenestration predisposes to thrombus formation, which may be cause of stroke. This rare anatomic variant of the posterior circulation is important to recognize and may have associated neurologic consequences (double BA fenestrations are rare yet known congenital variants associated with aneurysms and associated neurological implications) (double adjacent BA fenestration presenting with AICA infarct are still rarer with only three cases reported across the world).