Down syndrome and Moyamoya disease: unusual cause of stroke.

Down syndrome is a frequent clinical entity, being considered one of the most frequent chromosomal aberrations. It is characterised by a typical clinical phenotype and is associated with a heterogeneous group of organ and system-specific abnormalities. The cardiovascular system is commonly affected and if so, it may be associated with an increased morbidity and mortality. Cerebrovascular events in patients with Down syndrome are multifactorial, being possibly related to congenital heart disease, vascular malformations and traditional cardiovascular risk factors. Moyamoya disease is a rare chronic occlusive vascular disease causing stenosis of the distal portion of the internal carotid artery, which has been associated with Down syndrome. The authors report the case of a 26-year-old woman with Down syndrome who presented with an acute stroke secondary to Moyamoya disease. The case is noteworthy for the rarity of this clinicopathological entity, and serves as a reminder for the possible association between these two conditions.