Smoky disease? The name seems odd! What is Moyamoya disease? Moyamoya disease is a special cerebrovascular disease in which the main blood supplying artery in the skull, the internal carotid artery, is occluded and many compensatory blood vessels grow in the blood supply area. The disease was first named by the Japanese, and the word “moyamoya” means “smoke curling around” in Japanese. Moyamoya is common in East Asian countries, including Japan, Korea and China, and is much less prevalent in Western countries. Smog is a common cerebrovascular disease in children, but it can also occur in adults. In children, the main manifestation of smog is cerebral ischemia, while in adults smog can manifest as both cerebral hemorrhage and cerebral ischemia. Other symptoms include epilepsy, involuntary movements, and headache, among other manifestations. The diagnosis of smog disease requires cerebral angiography (DSA) with femoral artery cannulation, but there is some cannulation trauma. With the popularity of MRI machines, the diagnosis of smoker’s disease can be confirmed noninvasively by magnetic resonance imaging (MRI) and magnetic resonance arteriography (MRA). In children with unexplained headache and weakness of the limbs, the possibility of smog disease should be considered, and the diagnosis can often be confirmed if MRI of the head is performed together with MR arteriography (MRA); otherwise, the diagnosis is easily missed by MRI alone.