BACKGROUND A vertebral artery–anterior spinal artery (VA-ASA) aneurysm is very rare. The authors report a case of successful coil embolization of a ruptured aneurysm of the VA-ASA. OBSERVATIONS A 54-year-old man with World Federation of Neurosurgical Societies grade II subarachnoid hemorrhage presented with an aneurysm located at the region involving the origin of ASA on the VA. Endovascular treatment was chosen to prevent rerupture and preserve the perforating branches. The catheter shape was modified with steam forming to allow access to the aneurysm. Partial embolization was performed to preserve the ASA. The authors also prevented further rupture. On day 16, angiography showed thrombosis within the aneurysm and preserved blood flow in the ASA despite a neck remnant. The patient was discharged home with a modified Rankin Scale score of 0. Careful follow-up has been continued. LESSONS Endovascular coiling in the acute phase of rupture of a VA-ASA aneurysm achieved favorable results. The aneurysm could be safely treated by selecting the appropriate device and catheter geometry.

A case of ruptured anterior cerebral artery (ACA) dissection was treated with multiple neck-bridge stents, with modification of antiplatelet administration according to changes in the shape of the aneurysm in the acute phase. A 67-year-old woman presented with severe subarachnoid hemorrhage and fusiform dilatation was observed in the left ACA between the A1 and A2 segments. The use of stents in the acute phase is associated with high risk of ischemic complications. Prasugrel administration, which is considered to have low drug resistance, may have allowed safe stent use in the acute phase.