Incomplete Susac syndrome exacerbated after natalizumab

A 66-year-old man with hypertension presented with right-sided numbness and slurred speech. MRI revealed a large left frontoparietal area of T2-weighted hyperintensity with focus of central enhancement (figure, A and B). The patient's symptoms self-resolved within weeks. Over the next 2 years, he experienced multiple relapses including encephalopathy characterized by headache with motor aphasia and sudden incomplete hearing loss. All symptoms except hearing loss were transient, improved with IV methylprednisolone, and were accompanied by new T2 lesions involving the periventricular white matter, corpus callosum, and subcortical white matter, with some demonstrating partial enhancement (figure, C and D).