The bihemispheric posterior interior cerebellar artery: anatomic variations and clinical relevance in 11 cases

Andrew P Carlson,Ali Alaraj,Reza Dashti,Victor A Aletich

doi:10.1136/neurintsurg-2012-010527

Abstract

PurposeAlthough the anatomic course of the posterior interior cerebellar artery (PICA) is variable, it is thought to be very rare for the artery to cross midline, with an estimated incidence...

Highlights

Numerous variations of PICA have been described(1), but only a few cases of a single PICA serving bilateral cerebellar hemispheres have been reported(2-4)
Cullen et al have estimated the incidence at less than 0.1%.(2) When one PICA is hypoplastic or aplastic, the PICA territory is typically supplied by an enlarged anterior inferior cerebellar artery (AICA) or superior cerebellar artery (SCA)(1, 2)
It has been hypothesized that the true incidence of the finding may be higher than reported(2, 5), but the distal location of the crossing may make it easy to confuse a bihemispheric PICA with normal distal filling in the cerebellum from contralateral AICA, SCA, or PICA

Summary

Background

Numerous variations of PICA have been described(1), but only a few cases of a single PICA serving bilateral cerebellar hemispheres have been reported(2-4). The so-called bihemispheric PICA supplies both cerebellar hemispheres, and has clinical relevance especially in cases of PICA aneurysm, cerebellar AVM, and bilateral cerebellar infarction(4, 5) This variant is further subcategorized into the true bihemispheric PICA, serving the contralateral PICA territory, and the vermian variant, serving only the midline(2). There was aplasia of the contralateral PICA with no capillary filling of the cerebellar hemisphere visualized from the vertebral artery contralateral to the bihemispheric PICA. In case 8, the bihemispheric PICA arose from a hypoplastic vertebral artery This again made the relatively small crossing vessel of the distal PICA well visualized (Figure 2c). It is not clear whether this would have represented a bihemispheric or vermian variant, though since the AVM was in the cerebellar hemisphere in PICA territory, the vessel likely embryologically would have been the true bihemispheric type. The contralateral PICA aplasia is consistent with our remaining series of bihemispheric types

Findings

Discussion

Conclusion