Importance of the variations in the origin of the PICA: anatomical study

Abstract

Aim: Because the posterior inferior cerebellar artery (PICA) origin shows a very frequent anatomic variation, it is one of the vessels that has higher iatrogenic trauma exposure potential during surgical exposure. in this study, the aim is to investigate the variations in the origin of the PICA and stress the importance of these in terms of microsurgery. Method: This study was carried on 26 (52 hemispheres) adult cerebellum cadavers that were fixed with formalin. Red coloured latex was injected to the vertebral artery (VA) and the PICA. the diameters of each the PICA at the origin point, the origin surface from the VA, relationship to the lower cranial nerves and other anatomic variations were investigated. Findings: PICA originated from the VA in the 46 of 47 hemispheres, in one of them it originated from BA. in five hemispheres, the PICA was absent (10.6%). in two hemispheres, the PICA (4.25%) originated from the VA's extradural segment. We found that the PICAs were wider on the left side (mean: 1.50 +/- 0.42 mm on the right side, and mean: 1.63 +/- 0.34 mm on the left). in eight samples (30.7%) the right PICA, in twelve samples (46.3%) the left PICA was dominant. in alti samples (23%) both the PICAs were in equal diameter. the origin surface of the PICA from the VA was mostly posterior (36.1 %) and then lateral (31.9%) medial (23.4%) and anterior (8.4 %). the PICA left the brain stem by passing between the rootlets of the vagus nerve in the 34% of hemispheres, in the 29.8% between the rootlets of the accessory nerve, in the 25.5 % between the vagus and accessory nerves, in the 4.25% coursed rostral to the glossopharyngeal nerve, in the 2.2% between glossofaringeal and vagus nerves. Conclusions: We believe that this study is a significant research in its own field and it gives important messages in terms of knowing the anatomic variations of the PICA at origin in order to minimize surgical morbidity and mortality in the approach to the brain stem and cerebellum pathologies.