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

Background: Middle meningeal artery (MMA) pseudoaneurysm following revascularization surgery for moyamoya disease (MMD) is rare. Case Description: 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. Conclusion: 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.