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

Abstract

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. To anatomically evaluate perforating branches arising from the pSCA and the upper basilar artery (BA). 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. SCA arose as a single trunk in 36 sides (90%): mean diameter at origin was 1.38 mm; mean length was 14.4 ± 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. 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.