Moyamoya disease initially mimicking MELAS syndrome in a 14-month-old child.

Moyamoya disease is a neurological disease rarely seen in children outside Japan. It is difficult to differentiate moyamoya disease in its early stage from mitochondrial disorders in children when nontraumatic ischemic stroke is considered. We present a 14-month-old Taiwanese female child who had suffered from sudden onset of nontraumatic seizure attack, after which progressive left limb weakness was noted. Initial brain imaging and a series of laboratory studies were performed which suggested mitochondrial disorders, especially mitochondrial encephalopathy, lactic acidosis, and strokelike episodes (MELAS) syndrome. The patient underwent an oral glucose lactate stimulation test (OGLST), and mitochondrial disorders were not favored. MR angiography of the circle of Willis showed moyamoya disease. The patient then underwent an encephalo-duro-arterio-myo-synangiosis (EDAMS) operation. Evaluation of the neurodevelopmental and intelligence outcome required close long-term follow-up.