Anatomical Study on the “Perforator-free Zone”: Reconsidering the Proximal Superior Cerebellar Artery and Basilar Artery Perforators

Abstract

Abstract Background: The proximal superior cerebellar artery (pSCA) is often considered a perforator-free area. Precise anatomical knowledge of this region clarifies the pathophysiology underlying posterior fossa ischemic syndromes and helps avoid treatment-related complications. Objective: To anatomically evaluate perforating branches arising from the pSCA and the upper basilar artery (BA). Methods: Forty-four SCAs from 20 cadaveric heads were examined to determine patterns of the pSCA; its morphometry for medial and lateral branches; and frequency, number, diameter, distribution, and vascular territory of perforators arising from the pSCA and rostral BA. Results: SCA arose as a single trunk in 36 sides (90%): mean diameter at origin was 1.38 mm; mean length was 14.± 6 7.9 mm. Ninety-nine pSCA perforator branches were present in 82% of specimens (mean, 2.3 ± 1.6; range, 0-7 perforators/side). Of these, 59% were direct, belonging to the interpeduncular group in 85% of cases; 28% were short circumflex, belonging to lateral and medial pontine group; and 13% were long circumflex, reaching the medullary perforation zone (basal cerebellar group). Median distance to the first perforator was 2.0 mm (range, 0.1–15 mm). There were 132 perforator branches in the last centimeter of the BA. Conclusion: The pSCA should not be regarded as a perforator-free area. Although the pSCA territories likely overlap with the posterior cerebral artery, BA, and anterior inferior cerebellar artery, the pSCA segment cannot be surgically manipulated with impunity.