strokes. Moyamoya disease tends to affect adults in the third to fourth decade of life. In children it tends to cause strokes or seizures. In adults it tends to cause strokes or bleeding. The clinical features are strokes, recurrent transient ischemic attacks (TIAs), sensorimotor paralysis (numbness and paralysis of the extremities), convulsions and/or migraine-like headaches. Moreover, following a stroke, secondary bleeding may occur. Such bleeding, called hemorrhagic strokes, may also stem from rupture of the weak neovascular vessel walls. Diagnosis Cerebral angiography is the gold standard of diagnosing moyamoya disease and its progression. According to Suzuki's system, it can be classified into six stages: Stage 1 Narrowing of carotid fork Stage 2 Initiation of the moyamoya and dilatation of intracranial main arteries Stage 3 Intensification of the moyamoya and defects of the anterior cerebral artery and middle cerebral artery Stage 4 Minimization of the moyamoya and defects of the posterior cerebral artery Stage 5 Reduction of the moyamoya and development of external carotid artery collaterals Stage 6 Disappearance of the moyamoya and circulation only via external carotid artery and vertebral artery Magnetic resonance angiography (MRA) is also useful in diagnosing the disease with good correlation with Suzuki's grading system. Proliferation of smooth muscle cells in the walls of the moyamoya-affected arteries has been found to be representative of the disease. A study of six autopsies of six patients who died from moyamoya disease lead to the finding that there is evidence that supports the theory that there is a thickening, or proliferation, of the innermost layer of the vessels affected by moyamoya. These vessels are the ACA (anterior cerebral artery), MCA (middle cerebral artery), and ICA (internal carotid artery). The occlusion of the ICA results in concomitant diminution of the "puff-of-smoke" collaterals, as they are supplied by the ICA. Often nuclear medicine studies such as SPECT (single photon emission computerized tomography) are used to demonstrate the decreased blood and oxygen supply to areas of the brain involved with moyamoya disease. Conventional angiography provides the conclusive diagnosis of moyamoya disease in most cases and should be performed before any surgical considerations. Darren B. Orbach explains how the disease progresses as well as the role angiography plays in detecting the progression of moyamoya in a short video. In 2019, author and artist Sarah Lippett published a graphic novel about her decade-long struggle to get a diagnosis and treatment for moyamoya disease, called