Fenestration of posterior cerebral artery at the junction of P1 and P2 segments.

Purpose: Fenestrations of posterior cerebral artery are exceedingly rare and, therefore, deserve being reported.

Methods: During an educational dissection, a peculiar anatomical variant of the posterior cerebral artery (PCA) was found.

Results: During an educational dissection targeting the right cerebellopontine angle, a peculiar variant of the right PCA was found. The respective posterior communicating artery inserted posteriorly into the junction of the P1 and P2 segments of the PCA. The P1 segment was thinner than the P2 segment. That junction was superior to the oculomotor nerve and was fenestrated, with a thin postero-medial arm facing the cerebral peduncle, and a larger antero-lateral arm formed by the distal end of the P1 segment and the proximal end of the P2 segment.

Conclusions: To the authors' knowledge, fenestrated P1-P2 junctions of PCA were not found previously by dissection. The evidence presented here recommends such variations not to be ignored.