Abstract
BACKGROUND: Normal posterior inferior cerebellar artery (PICA) anatomy is highly variable, but bihemispheric PICA crossing the midline to supply the vascular territory of bilateral cerebellar hemisphere is rare. Herein, the authors reported a rare case of ruptured aneurysm that was associated with bihemispheric PICA and successfully treated endovascularly. OBSERVATIONS: A 46-year-old woman presented with sudden headache and loss of consciousness because of an intraventricular hemorrhage due to a ruptured aneurysm that was associated with the bihemispheric PICA. Angiography revealed that the aneurysm was located at the bifurcation between the bihemispheric PICA and the bilateral distal PICA. The ruptured aneurysm was successfully occluded using coil embolization, which preserved the parent artery with no procedural-related complication. LESSONS: To the best of the authors' knowledge, this was the first report of a ruptured aneurysm associated with bihemispheric PICA being successfully treated endovascularly. Aneurysm formation may be accelerated by hemodynamic stress and vascular fragility. For neurosurgeons and neurointerventionalists, it is important to understand the anatomical variation of PICA, especially bihemispheric PICA, which is a potential risk factor for a fatal stroke.