Coil embolization for post-bypass aneurysm of middle meningeal artery for moyamoya disease - preservation of transdural anastomosis.

Middle meningeal artery (MMA) pseudoaneurysm following revascularization surgery for moyamoya disease (MMD) is rare. Here, a 29-year-old man presented with an MMA pseudoaneurysm after he underwent revascularization surgery (superficial temporal artery-to-middle cerebral artery bypass and encephalo-duro-myoarterio-pericranial synangiosis) for hemorrhagic MMD. At 3 months post-surgery, digital subtraction angiography showed a pseudoaneurysm in the right MMA. Transdural anastomosis to the parietal and occipital lobes was opacified at the distal MMA of the pseudoaneurysm. Intra-aneurysmal coil embolization was performed for preservation of transdural anastomosis. The postoperative course was uneventful. At 1 month post-embolization, angiography revealed an entirely occluded pseudoaneurysm. An increase in blood flow in the MMA due to bypass surgery may accelerate aneurysm development by increasing the hemodynamic stress. This case suggested that intra-aneurysmal embolization may be a potential treatment.