What is smoldering disease? Smoky disease, also known as Moyamoya disease or spontaneous basilar artery ring occlusion, is a disease characterized by slow intimal thickening of the arteries at the ends of the internal carotid arteries and the beginning of the anterior and middle cerebral arteries bilaterally, gradual narrowing and even occlusion of the arterial lumen, and compensatory dilation of the penetrating arteries at the base of the brain. Smoke and fog disease. What are the symptoms of smog? The symptoms of smoky disease are cerebral ischemia caused by occlusion of the internal carotid artery and cerebral hemorrhage induced by rupture of the dilated smoke-like vessels. According to the rate of reduction of cerebral blood flow due to intracranial blood supply artery intima thickening and luminal narrowing and the rate of compensatory vasodilatation formation to increase cerebral blood flow are classified into 6 types from mild to severe. The mild cases are manifested as transient transient cerebral ischemia, headache, epilepsy, limb weakness, sensory abnormalities and visual field changes, while the severe cases start with cerebral infarction or cerebral hemorrhage and become life-threatening.