Progression of isolated middle cerebral artery stenosis into moyamoya disease

The etiology of isolated middle cerebral artery (MCA) stenosis in young patients and that of moyamoya disease remain unclear. 1 A 25-year-old woman with chronic headache underwent brain MRI and cerebral angiography, which showed isolated MCA stenosis (figure , A). Physical and neurologic examinations were normal.She had no risk factors for atherosclerosis or stroke.Findings of the follow-up angiography, which was taken due to transient left arm weakness, were consistent with those of moyamoya disease (figure, B). 2 Isolated MCA stenosis in a young patient with no other medical conditions may be an initial feature of moyamoya disease.