A Grave Initial Presentation of Graves’ Disease in a Patient With Moyamoya

Background: Moyamoya syndrome is chronic stenoocclusive disease involving the intracranial internal carotid arteries and their proximal branches along with an associated condition, such as hyperthyroidism(1). The concurrence of moyamoya and Graves’ disease is rare. Ischemic stroke in moyamoya syndrome is postulated to be precipitated by thyrotoxicosis-induced hemodynamic instability. Clinical Case: A 63-year old Korean female with history of moyamoya disease with two prior ischemic strokes, hypertension and type 2 diabetes mellitus presented to the ER with 6 hours of left leg weakness and involuntary arm movements. A code stroke was activated and neurologic examination was notable for left leg paresis and left arm stereotypy. CT head showed loss of gray-white matter differentiation in the right frontal lobe concerning for acute ischemia. CT angiography of the head and neck noted diffuse stenosis of intracerebral vasculature and significant stenosis of the cavernous and supraclinoid portions of the internal carotid arteries. MRI brain later confirmed an acute infarct in the right ACA distribution. Neuroimaging incidentally showed a multinodular goiter with a 1.7 cm right thyroid nodule. Subsequently TSH was obtained and resulted as <0.030 mcIU/mL (0.27-5.00 mcIU/mL) with a reflex FT4 of >7.00 ng/dL (0.6-1.8 ng/dL). A review of her prior TFTs showed biochemical euthyroidism. Due to iodinated contrast administration on admission, RAIU scan was deferred. Thyroid ultrasound showed multinodular goiter with diffuse increased vascularity and multiple TI-RADS 4 and 5 nodules bilaterally. On further questioning, the patient reported tachycardia, diarrhea, weight loss and decreased appetite prior to hospitalization. A diagnosis of Graves’ disease was confirmed with TSI of 70.7 IU/L (0.00-0.55 IU/L). She was started on methimazole 20 mg twice daily and propranolol 20 mg q6h. FT4 downtrend from >7.00 to 3.3 ng/dL at time of discharge. Following four weeks of methimazole 20 mg daily, FT4 normalized to 1.70 ng/dL. The patient chose to continue antithyroidal drug therapy for treatment of Graves’ disease. Conclusion: Thyroid function assessment should be considered when evaluating a patient with moyamoya and acute ischemic stroke. If moyamoya syndrome associated with Graves’ disease is identified, treatment should be aimed at maintenance of euthyroidism. Reference: 1. Scott RM, Smith ER. Moyamoya disease and moyamoya syndrome. N Engl J Med. 2009 Mar 19;360(12):1226-37. Disclaimer: The views expressed herein are those of the authors and do not reflect the official policy or position of Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, the Department of the Air Force and Department of Defense or the U.S. Government.