A 24-year-old woman presented with sudden-onset slurred speech and right-side weakness. Ten months previously, she had had an episode of transient consciousness loss. The patient denied smoking, had no history of miscarriage, was not taking oral contraceptives, and had a body mass index (calculated as weight in kilograms divided by height in meters squared) of 21.2. She denied any family history of stroke. On admission, her blood pressure was 103/65 mm Hg in the right arm and 76/40 mm Hg in the left arm. Her body temperature, heartbeat, and respiration rate were within normal limits. Simultaneous palpation of pulses in the 2 arms revealed that the left radial pulse was weak. A neurological examination revealed clinically significant right-side hemiparesis and dysarthria. Other findings of general physical and neurological examinations were normal. The patient’s blood work results were unremarkable, aside from an elevated erythrocyte sedimentation rate (90.0 mm/h) and C-reactive protein level (4.06 mg/dL [to convert to milligrams per liter, multiply by 10.0]). Hypercoagulable laboratory studies, chest radiography, transthoracic echocardiography, electrocardiography, and 24-hour Holter monitoring yielded normal findings. Head computed tomography (CT) images showed an acute infarct in the left basal ganglia. Head-and-neck CT angiography with digital subtraction angiography revealed left carotid artery occlusion and subclavian artery stenosis (Figure 1). These findings were believed to be consistent with Takayasu arteritis. The patient was given prednisolone (initial dosage, 60 mg/d, tapered very slowly). Regular clinical follow-up, including physical examinations, radiographic evaluations, and other medical tests, was performed every 6 to 12 months.