Considerations on the morphological variability of the posterior inferior cerebellar artery origin

To investigate the morphological variability of the posterior inferior cerebellar artery (PICA) origin utilizing computed tomography angiography (CTA) within a substantial adult cohort, and to establish a refined, clinically pertinent classification system for neuroradiologists and neurosurgeons.

A retrospective review of 500 CTA brain scans, comprising 1,000 arteries, was undertaken. The origin, pathway, and morphological variants of the PICA were systematically documented and classified according to segmental origin and anatomical characteristics.

The PICA most commonly originates from the intradural (V4) segment of the vertebral artery (VA) (63.4%), followed by the extradural (V3) segment (16.4%) and the basilar artery (BA) (15.8%). Bilateral origins from the same segment were seen in 41.6% (V4), 4.4% (V3), and 3.2% (BA). The absence of PICA was found in 4.4% of cases. In these cases, the contralateral PICA was enlarged and compensated for the absent artery. Rare variants included duplicate origin (0.1%), duplication (0.3%), VA terminating in PICA (PICA-VA) (3.4%), and intradural origin with an abnormal course below the foramen magnum (1.2%).

This study provides a thorough radiological classification of the origin and morphology of the PICA, offering significant insights into preoperative planning, endovascular access planning, and neurovascular risk assessment. Recognizing these anatomical variations is crucial for enhancing diagnostic accuracy, surgical safety, and interventional strategies. Future multicenter investigations are recommended to validate and further develop this classification system.