Two adolescent patients with coexistent Graves' disease and Moyamoya disease in Korea

Moyamoya disease is a cerebrovascular condition that results in the narrowing of the vessels of the circle of Willis and collateral vessel formation at the base of the brain. Although relationships between Graves' disease and cerebrovascular accidents in Moyamoya disease are obscure, the coexistence of the two diseases is noteworthy. Moyamoya disease has been rarely reported in adolescent patients with thyrotoxicosis. Recently, we encountered two adolescent Korean patients with Moyamoya disease associated with Graves' disease who presented with episodic right-sided hemiparesis and syncope. These two girls who had Graves' disease had no history of other diseases or head trauma. A thyroid function test revealed a euthyroid state and a high thyroid-stimulating hormone (TSH) receptor antibody titer at that time. The patients were diagnosed with Moyamoya disease based on brain magnetic resonance angiography and cerebral four-vessel angiography. The patients underwent cranial revascularization by encephalo-duroarterio-synangiosis as soon as a diagnosis was made, which resulted in successful symptom resolution. They fared well and had no additional neurological symptoms as of their last follow-up visits. Here, we report these two cases of confirmed Moyamoya disease complicated by Graves' disease with a review of the literature, and discuss the possible association between the two diseases. To our knowledge, this is the first report in South Korea on Moyamoya disease associated with Graves' disease in adolescents with a euthyroid.