Proximal Hunterian ligation remains a treatment option for select complex brain aneurysms. Progressive occlusion over time (as accomplished with Selverstone clamping) can enable collateral flow to develop while the aneurysm regresses or occludes. A 50-year-old woman presented with an unruptured 16-mm posterior inferior cerebellar artery (PICA) aneurysm. The aneurysm was located 4 mm distal to the PICA origin. It was bilobed, incorporating the PICA. The PICA inflow and outflow zone orientation prevented direct stent reconstruction. Surgical clipping with bypass was considered. Alternatively, an attempt at proximal ligation of the PICA via flow-diverting stents was offered. After extensive counseling, the patient decided to proceed with endovascular treatment. Two overlapping pipeline embolization devices (PED) were placed into the vertebral artery, covering the PICA origin. The one-year follow-up angiography demonstrated flow reduction within the aneurysm and the distal PICA. A de novo (previously not opacified) accessory PICA collateral had developed, partially taking over the arterial supply of the PICA territory. The newly established accessory PICA originated from the vertebral artery 8 mm distal to the PICA origin. After two years, the aneurysm was fully obliterated, and the true PICA was occluded and functionally replaced by the accessory PICA. The current case suggests that progressive Hunterian ligation via endovascular flow diversion can be an effective treatment strategy for true PICA aneurysms. However, this strategy should only be considered if no immediate aneurysm occlusion is required or if all alternative methods are associated with substantial risk.