Moyamoya syndrome in a child with Noonan syndrome.

Previous studies have rarely described the association between Noonan syndrome and moyamoya syndrome. Although most affected children with moyamoya exhibit ischemic symptoms, headache is also a frequent symptom. We report the case of a 9-year-old girl with Noonan syndrome and moyamoya syndrome that manifested as recurrent headaches without history of transient ischemic attack. Brain magnetic resonance imaging and magnetic resonance angiography revealed bilateral moyamoya syndrome and mild ventriculomegaly with focal encephalomalacia at right peritrigonal region. Disruption of vascular development during the prenatal stage has been proposed as the cause of cerebrovascular disease in Noonan syndrome. However, genetic factors may also contribute.