Microvascular anatomy of the lateral spinal artery: Origins, collateral channels, and other anatomical variations.

Background: The lateral spinal artery (LSA) corresponds to the posterolateral arterial axis of the craniocervical junction. Although implicated in various pathologies and injury risks during treatments, the existence and anatomical characteristics of the LSA are debated. We aim to demonstrate the characteristics of the LSA, including its origins, collateral channels, and anatomical variations.

Methods: Neurosurgeons performed far-lateral craniotomies and cervical laminectomies on 18 cadaver heads (36 sides). Neurovascular structures associated with the LSA were examined in epidural, subdural, and subarachnoid spaces.

Results: The main origins of the LSA were the V3 segment of the vertebral artery (VA) (n = 18), the V4 segment of the VA (n = 12), and the posterior inferior cerebellar artery (PICA) (n = 6). The PICA originated from V3 in 6 cases; in 5, the main LSA origin was the intradural PICA. In the 30 cases where the PICA originated from V4, only one main LSA originated from the PICA. In addition to the main origin, we identified supplementary origins, averaging 1.7 per case. In 4 cases, the LSA and posterior meningeal artery (PMA) shared an origin at V3. Twenty-seven cases had anastomosis between the LSA and PICA on the pial surface. Collateral channels at the C2 level through posterior radicular arteries were observed in 13 cases.

Conclusion: The main origins of the LSA are around the dural ring of the VA and are associated with the PICA's origin. Other potential channels supplying the LSA were also identified. The LSA and PMA may share an origin from the VA.