Fenestrations and Various Duplications of the Posterior Communicating Artery in the Prenatal and Postnatal Periods

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.

Fenestrated P1 segment of posterior cerebral artery, partly duplicated posterior communicating artery

PURPOSE

Anatomic variations at the junction of primitive internal carotid and basilar arteries are exceedingly rare. We aimed at reporting such rare variants involving the posterior communicating artery (PComA) and the P1 segment of posterior cerebral artery (PCA).

METHODS

The circle of Willis was dissected in an adult cadaver after removal of the cranial vault and cerebral hemispheres.

RESULTS

The basilar end was rotated axially to the right. The P1 segment of the right PCA was fenestrated and occupied the interpeduncular fossa. The right PComA passed over the oculomotor nerve to join the anterior arm of the P1 fenestration. On the opposite side, the PComA coursed supero-medially to the oculomotor nerve and it had a partly duplicated posterior end, with two arms, medial, larger, and lateral, thinner, inserting successively into the left PCA.

CONCLUSION

Extremely rare anatomic variations of the circle of Willis should not be ignored when endovascular or microneurosurgical specific approaches are intended.