8291 Graves’ Disease and Moyamoya Syndrome: A Complex Case of Thyroid Dysfunction and Neurovascular Abnormalities

Abstract Disclosure: A. Jamil: None. Q.V. Luong: None. A. Llorens Bonilla: None. A. Siddiqui: None. Background: Moyamoya disease is a cerebrovascular disease characterized by progressive stenosis and occlusion of cerebral arteries, particularly the internal carotid arteries, proximal anterior and middle cerebral arteries associated with a net-like collateral vessel formation. Moyamoya disease in association with certain systemic conditions (e.g. Graves’ disease, sickle cell anemia, neurofibromatosis type 1, and Down Syndrome) has been referred to as moyamoya syndrome. Graves’ disease is an autoimmune disease in which the development of thyroid-stimulating hormone (TSH) receptor autoantibodies leads to overproduction of thyroid hormones. Although the pathophysiology is unclear, Graves’ disease can adversely impact the clinical course of moyamoya syndrome.Clinical Case: A 26-year-old woman diagnosed with Graves’ disease at the age of 20 years who was in remission presented to the ED with right upper extremity weakness and headache. A stroke work-up was performed, and an initial CT head without contrast showed an acute infarct in the left temporal area. Extensive workup for hypercoagulability and cardiac causes were negative. MRI brain showed multiple infarcts of the left cerebral hemisphere with ivy sign, which are prominent linear or punctate high intensity areas in the subarachnoid space reflecting the development of collaterals that occurs in moyamoya disease. TSH at the time was noted to be <0.01 uIU/mL (range: 0.30-4.20 uIU/mL), indicating a thyrotoxic state. She was discharged on methimazole and antiplatelet therapies. However, the patient continued to have hypertension and headaches which did not resolve with the return to euthyroidism. At age 29, she again developed acute right upper and lower extremity weakness, and consequently presented to the ED. Imaging studies showed multiple punctate infarcts in her bilateral frontal lobes and bilateral ICA stenosis consistent with moyamoya disease. However, her biochemical studies showed euthyroidism. Ultimately, she underwent right frontotemporal craniotomy and direct parietal superficial temporal artery to middle cerebral artery bypass by neurosurgery to decrease her future stroke risk for her moyamoya syndrome, and her Graves’ disease remains in remission.Conclusions: The coexistence of Graves’ disease in moyamoya syndrome may suggest a pathophysiologic connection. It has been suggested that hemodynamic changes in cerebrovascular flow due to thyrotoxicosis might contribute to ischemic neurologic deficits. Surgical intervention for revascularization procedures should be attempted after optimal control of thyrotoxicosis, as this may help to prevent further ischemic events in the future and improve patient outcomes. Presentation: 6/1/2024