Summary: Moyamoya syndrome (MMS) refers to a rare cerebrovascular disorder characterized by progressive stenosis of the intracranial internal carotid arteries and their proximal branches, leading to an increased risk of stroke. While prevalent in Asia, this condition is considerably less common in Western countries, including Europe. The association between MMS and Graves' disease (GD) has been well documented, primarily in Asian and American populations, notably Latin Americans. In this report, we report the first case of GD with MMS in a Caucasian woman from Western Europe. The precise mechanisms underpinning the correlation between these two conditions remain poorly elucidated but are hypothesized to involve hemodynamic alterations, the toxic effects of anti-thyroid-stimulating hormone receptor antibodies, or a shared genetic predisposition. Our clinical case underscores the significance of thyroid disease screening in suspected MMS cases, as the management of thyroid dysfunction may suffice to improve neurological symptoms.
Learning points: The association between Graves' disease (GD) and Moyamoya syndrome (MMS) can manifest in a Caucasian European patient. Screening for thyroid disease is essential when MMS is suspected, as treating GD might effectively alleviate neurological symptoms. The mechanisms linking GD and MMS remain incompletely understood but may involve hemodynamic shifts, the toxic effect of anti-TSH receptor antibodies, or shared genetic factors.