Ruptured vertebral artery dissecting aneurysm with a presumed anterior spinal artery arising proximal to the posterior inferior cerebellar artery: A case report

Background: The anterior spinal artery (ASA) usually arises from the vertebral artery (VA) distal to the posterior inferior cerebellar artery (PICA) origin. Preserving the ASA is essential when treating VA dissecting aneurysms (VADAs), as its occlusion can cause brainstem or spinal cord ischemia. An ASA arising proximal to the PICA may alter the treatment strategy. Case Description: A 44-year-old man presented with subarachnoid hemorrhage from a ruptured left VADA proximal to the PICA origin. Angiography and three-dimensional (3D) rotational angiography showed a straight descending branch arising from the dissected segment and coursing along the ventral medulla, consistent with a presumed ASA. The presumed ASA arose from the VA within the dissected segment, proximal to the PICA origin. A separate proximal vessel was also observed near the PICA, although its precise anatomy remained uncertain. To avoid compromising the presumed ASA, stent-assisted coiling (SAC) was selected over parent artery occlusion to preserve VA and presumed ASA flow. Transient parent artery thrombosis occurred during the initial procedure. Because follow-up angiography 1 week later showed that the dissection had enlarged, additional embolization was performed. Complete aneurysm exclusion was achieved, and the patient recovered without brainstem or spinal cord infarction. Conclusion: Our case demonstrates a ruptured VADA with a presumed ASA arising from the VA within the dissected segment, proximal to the PICA origin. Evaluating these origins carefully with 3D angiography is essential. In such cases, SAC can exclude the dissecting lumen while preserving presumed ASA flow.