Acute cerebral infarction combined with a thyroid storm in a patient with both Moyamoya syndrome and Graves' disease

Moyamoya syndrome (MMS) associated with hyperthyroidism, such as Graves' disease, is a rare condition that causes ischemic stroke with thyrotoxicity. A 43-year-old woman with symptoms of right hemiparesis was admitted. Brain magnetic resonance imaging revealed a small cerebral infarction in the left frontal lobe. Cerebral angiography revealed multi-vessel intracranial occlusive disease. Several days later, neurologic deterioration and aggravation of cerebral infarction developed due to a thyroid storm. A thyroid function test revealed the following: thyroid-stimulating hormone (TSH) ＜0.01 μunits/mL (reference range, 0.55-4.78 μunits/mL); triiodo-thyronine ＞8.0 ng/mL (reference range, 0.77-1.81 ng/mL); free thyroxine (T4) of 9.47 pmol/L (reference range, 11.4-22.6 pmol/L); and TSH receptor antibody of 37.10 U/L (reference range, 0-10 U/L). For thyroid storm management, we initiated treatment with methimazole, Gemstein's solution, and hydrocortisone. Finally, the thyroid disease was controlled, and neurologic deficits improved. We describe a case of acute cerebral infarction combined with a thyroid storm in a patient with Moyamoya syndrome and Graves' disease. Hyperthyroidism such as Graves' disease should be considered in the differential diagnosis for patho-etiologic mechanisms associated with MMS. A cerebrovascular disease with a thyroid storm can lead to severe mortality and morbidity. Prompt diagnosis and strict treatment are important.