Résumé
Background: Posterior Inferior cerebellar artery (PICA) is the largest and most distal branch of Vertebral artery(VA) arising near the lower end of olive. Variations of PICA are numerous but have been infrequently reported inthis region. Occlusion or blockage of PICA may cause an infarction of the medulla oblongata which plays animportant role in circulatory and respiratory functioning. This may lead to lateral medullary syndrome, alsocalled Wallenberg syndrome. The study focuses on normal and variant anatomy of PICA in Uttar Pradesh regionof North India.Materials and Methods: The study population included 100 subjects, of either sex, who underwent Head and NeckCT Angiography in the Department of Radiodiagnosis, King George’s Medical College, Lucknow, Uttar Pradesh. Thediameters of PICAs of both sides were measured and variations encountered were noted.Results: Mean diameter of PICA was 1.76±0.64 mm on right side and 1.73±0.60 mm on left side. Mean diameter inmales was 1.75±0.62 mm and in females was 1.73±0.62 mm. Variations observed included: Unilateral aplasia ofPICA in 16% with equal prevalence on both sides; bilateral aplasia in 3% cases; hypoplasia of RPICA in10% andhypoplasia of LPICA in 6%. VA-PICA variation where the VA continued as posterior inferior cerebellar artery wasobserved in 8 subjects (4 right, 4 left).Conclusion: The knowledge of normal diameters and variations in PICA supplying the brain can be a useful guideto the surgeons and interventional radiologists for careful pre-operative planning thus helping them in avoidingpotentially life threatening complications.