Posterior inferior cerebellar artery (PICA)

The posterior inferior cerebellar artery (PICA), the largest branch of the vertebral artery, is one of the three main arterial blood supplies for the cerebellum.

Fm: Foramen of Magendie; imv: inferior medullary velum; icp: inferior cerebellar peduncle; pica: posterior inferior cerebellar artery (third and forth segments) tc: tela chorioidea; tvj: telovelar junction ( yellow discontinous line).

Occlusion of the posterior inferior cerebellar artery or one of its branches, or of the vertebral artery leads to Wallenberg syndrome, also called lateral medullary syndrome.

It winds backward around the upper part of the medulla oblongata, passing between the origins of the vagus and accessory nerves, over the inferior cerebellar peduncle to the undersurface of the cerebellum, where it divides into two branches.

The medial branch continues backward to the notch between the two hemispheres of the cerebellum; while the lateral supplies the under surface of the cerebellum, as far as its lateral border, where it anastomoses with the anterior inferior cerebellar and the superior cerebellar branches of the basilar artery.

Branches from this artery supply the choroid plexus of the fourth ventricle.

The ascending pharyngeal artery (APA) may, in very rare cases, supply the posterior inferior cerebellar artery (PICA). In reported cases, when such is the case, the ipsilateral vertebral artery (VA) does not supply the PICA, and most of the time it is hypoplastic.

Awareness of the existence of an extradural origin of the PICA and a direct connection of this vessel with the occipital artery (OA) is of great relevance to the muscular stage of surgical approaches to the posterior craniovertebral junction ¹⁾.

The posterior inferior cerebellar artery (PICA) is often involved in pathologies of the posterior cranial fossa. Therefore, understanding the vessel's normal and variant courses is important to the neurosurgeon or neuro-interventionalist.

see Posterior inferior cerebellar artery aneurysm.

Double origin of the posterior inferior cerebellar artery.

During the routine microdissection of the craniocervical junction, an unusual arrangement between the highest denticulate ligament and PICA was observed. On the right side, the PICA was given rise to by the Vertebral artery segment V4 9 mm after the artery entered the dura mater of the posterior cranial fossa. The artery made an acute turn around the lateral edge of the highest denticulate ligament to then recur 180 degrees and travel medially toward the brainstem. Invasive procedures that target the PICA should be aware of the variant as described herein ²⁾.