Salvage medullary perforating artery revascularization using the muscular branch of the occipital artery following occipital artery-posterior inferior cerebellar artery bypass for trapping a ruptured vertebral artery dissecting aneurysm.

Vertebral artery dissecting aneurysms (VADAs) presenting with subarachnoid hemorrhage (SAH) are relatively rare. The re-rupture and mortality rates during the acute phase of SAH remain significantly high. Endovascular coil trapping is one of the definitive treatments to prevent re-rupture; however, it carries a potential risk of medullary infarction derived from occlusion of the medullary perforating arteries (Mperf). Here we present a case with poor-grade SAH resulting from a ruptured left VADA affecting the posterior inferior cerebellar artery (PICA). After obtaining informed consent, open surgery was selected. The OA and its muscular branches were preventively harvested in case an additional bypass was required. Following the occipital artery (OA)-PICA bypass, the aneurysm was then trapped using the transcondylar fossa corridor. The lateral Mperf, supplying the lateral medullary surface, arising directly from the VADA and having to be included in the trapped segment, was occluded shortly after the complete trapping. This necessitates additional Mperf revascularization. Consequently, a salvage end-to-side bypass was performed using the muscular branch of the OA to reestablish the flow to the Mperf and prevent medullary infarction. The patient tolerated the procedure well and was discharged without neurological deficits. Postoperative imaging demonstrated complete aneurysm obliteration and bypass patency without ischemic complications.