Figure 1.

Brain magnetic resonance imaging findings. T2-fluid-attenuated inversion recovery sequences show hyperintensity in the cerebellum (top row) and brainstem (bottom row), consistent with rhombencephalitis, in Subject A after 4 days of symptoms, Subject B after 5 days of symptoms, and Subject C after 7 days of symptoms. While highly suspicious for POWV infection, other infectious etiologies as well as autoimmune diseases and paraneoplastic syndromes remain in the differential diagnosis, and confirmation by serology or viral RNA detection is required. Abbreviation: POWV, Powassan virus.