MMS is a chronic
occlusive cerebrovascular disease characterized by steno-occlusive changes around the terminal portions of bilateral or unilateral internal carotid artery and proximal arteries accompanied by the development of fragile collateral network usually with various underlying diseases (hematopathy, Down's syndrome, and autoimmune disorder).[6] However, to the best of our knowledge, PNH-MMS was rare, with only four published cases reported in the literature to date.[2],[3],[4],[5]