6548 A Young Female with Stroke

Abstract Disclosure: A. Bulut: None. E.N. Pearce: None. Introduction: Moyamoya disease (MMD), known as spontaneous occlusion of the circle of Willis, is a rare cause of stroke. MMD can be associated with hyperthyroidism. Case: A 22 year-old female presented to the emergency department with intermittent right-sided weakness and numbness for three weeks. Vitals were notable for sinus tachycardia with heart rates in the 140s. Due to abnormal neurologic evaluation a head/neck CT was obtained, which showed a large left middle cerebral artery ischemic stroke. Brain CTA demonstrated a beaded appearance of the anterior and posterior intracranial arterial vasculature, raising the possibility of vasculitis. TFTS were checked due to ongoing tachycardia and showed suppressed TSH (<0.01 mIU/L, reference range (RR): 0.35 - 4.9), high fT4 (>5.00 ng/dl, RR: 0.6 - 1.8), high total T3 (427 ng/dl, RR: 83 - 160) and high total T4 (23.7 ug/ml, RR: 5.1 - 11.4). Bedside thyroid ultrasound showed normal vascularity without nodules. She was started on methimazole and propranolol. Her thyroid stimulating immunoglobulin was subsequently found to be elevated (328%, RR: <140%), confirming Graves’ disease. Secondary workup for vasculitis detected no other disease pathology. Cerebral angiogram showed findings consistent with “Moyamoya disease” (bilateral hypoplastic internal carotid arteries (ICAs) along with bilateral occlusion of the ophthalmic arteries with collateral vessels reconstituting the left and right anterior cerebral arteries). Thyrotoxic symptoms were well controlled during hospitalization. The patient was discharged with a plan to perform an Encephaloduroarteriosynangiosis (EDAS) procedure in three months. Discussion: MMD was first described by Takeuchi and Shimizu in 1957. It is characterized by progressive stenosis and occlusion of the terminal portion of the ICAs and their branches, accompanied by the formation of net-like collateral vessels known as “puff of smoke” (moyamoya in Japanese). The most common presentation is ischemic stroke, however hemorrhagic stroke can also be seen due to of rupture of moyamoya vessels. In most cases the etiology is unknown. However, Moyamoya syndrome (MMS) refers to MMD that occurs in the setting of a known associated disease such as sickle cell disease, neurofibromatosis type 1, cranial irradiation, Trisomy 21 or hyperthyroidism. Fewer than 100 cases of MMS have been reported in association with hyperthyroidism, with most cases due to Graves’ disease. Although the exact pathophysiology is unknown, thyrotoxicosis is believed to increase cerebral metabolism and oxygen consumption, resulting in impairment of cerebral perfusion. In most cases, thyrotoxicosis is present on initial presentation with ischemic stroke, as seen in our patient. It is believed that controlling symptoms of hyperthyroidism may prevent progression of MMS. Presentation: 6/1/2024