A 42-year-old white woman with a history of episodic migraine with visual aura presented for evaluation of transient right upper extremity weakness and word-finding difficulty associated with headache. She admitted to having developed new intermittent vertigo and more frequent and severe throbbing migraine with transient blurry vision and nonpulsatile tinnitus several months prior. She had recently developed hearing loss with a robotic quality of auditory perception. She denied mouth or genital ulcers. A neurologic examination revealed diminished hearing to a finger rub on the right side. Fundoscopy showed several segmental retinal arterial plaques, with the right side worse than the left. A brain magnetic resonance image (MRI) with gadolinium revealed multiple white-matter lesions that were hyperintense on diffusion-weighted imaging (DWI), including some with enhancement, as well as a small DWI-negative lesion in the left thalamus and corpus callosum that was hyperintense on T2/fluid-attenuated inversion recovery magnetic resonance imaging (FLAIR; Figure 1). An MRI of the spine with gadolinium did not reveal a signal abnormality in the spinal cord. Infectious, rheumatologic, and hypercoaguable test results were negative. A lumbar puncture revealed a white blood cell count of 8 cells/μL (normal range, 0-5 cells/μL; to convert to cells × 109/L, multiply by 0.001) with 78% lymphocytes and 22% monocytes (to calculate these as proportions of 1.0, multiply by 0.01), and a protein level of 0.067 g/dL (normal range, 0.015-0.045 g/dL; to convert to grams per liter, multiply by 10). Cerebrospinal fluid (CSF) glucose and IgG index test results were normal, with culture and oligoclonal bands negative. An audiogram revealed bilateral sensorineural hearing loss, with the right side worse than the left. Retinal fluorescein angiography was obtained.