文獻有報告少數毛毛樣腦血管病變與葛瑞夫茲氏症有關聯之個案，但尚無與無痛性甲狀腺炎有關之報告。一位55 歲男性主訴頭痛及右邊視力缺損一個月。患者並沒有頸部疼痛之症狀。腦部磁振造影發現於左枕葉有急性腦血管栓塞。患者兩側的中大腦動脈並不存在，兩側有不少的側支血管。腦部血管攝影診斷為毛毛樣腦血管病變，患者的甲狀腺功能為原發性的甲狀腺亢進，但其甲狀腺抗體為陰性。為了避免患者在急性中風時併發甲狀腺風暴，我們先給予抗甲狀腺藥物治療。甲狀腺锝-99 的核子掃描呈現非常低的同位素吸收率，因此診斷為無痛性甲狀腺炎。抗甲狀腺藥物於使用兩週後停用。當時甲狀腺功能已恢復正常，抗甲狀腺過氧化脢抗體卻略為升高，但其甲狀腺激素受器抗體仍為陰性。甲狀腺功能亢進時，腦組織的代謝需求增加，導致其腦部側支血管無法負荷。文獻有報告無痛性甲狀腺炎後可續發葛瑞夫茲氏症，因此有必要定期追蹤患者的甲狀腺功能及抗體。

A few cases of the coexistence of Moyamoya disease and Graves’ disease have been reported. But there was no reported case of Moyamoya disease with thyrotoxic painless thyroiditis. A 55-year-old man experienced headache and loss of right temporal vision for one month. He did not have neck pain. Brain MRI showed acute infarct with cortical lamina necrosis at left occipital lobe. Invisible bilateral middle cerebral artery and adjacent collateral vessels were noted. Cerebral angiography was performed and the result was compatible with Moyamoya disease. Thyroid function test showed suppressed TSH and elevated free T4 level. Thyroid autoantibodies were initially negative. Anti-thyroid medication was started for concern of thyroid crisis during acute stroke. Thyroid scintigraphy with Technetium-99 was performed. Thyroid scan uptake was very low. A diagnosis of thyrotoxic painless thyroiditis was confirmed. Two weeks later, patient’s thyroid function returned to normal. His anti-thyroid peroxidase antibody became slightly elevated but TSH receptor antibody was still negative. Anti-thyroid treatment was discontinued. Hyperthyroid state was thought to increase cerebral metabolic demand, altered cerebral perfusion and may thus precipitate cerebral ischemia. Development of Graves’ disease after painless thyroiditis has been reported. Long term follow up of thyroid function and autoantibodies is necessary for this patient.