A 45-year-old woman with no medical history presented with intermittent episodes of right hand and leg discoordination and paresthesia of increasing frequency 2 weeks prior to presentation. She denied any antecedent trauma or neck manipulation. She had no known history of renal dysfunction or poorly controlled hypertension and was a lifelong nonsmoker. She was seen in the emergency department and underwent brain magnetic resonance imaging, which demonstrated patchy enhancement in the left basal ganglia and corona radiata concerning for demyelinating lesions. She was admitted and underwent further workup. Pertinent laboratory results included C-reactive protein level of 0.01 mg/L (to convert to nanomoles per liter, multiply by 9.524), erythrocyte sedimentation rate of 6 mm/h (to convert to millimeters per hour, multiply by 1), and normal cholesterol panel. She underwent an extensive imaging workup consisting of bilateral carotid duplex, computed tomographic neck angiography (Figure 1A) and cerebral arteriogram (Figure 1B).