Powassan virus (POWV) encephalitis is a rare tickborne illness. We describe the clinical course, laboratory findings, and imaging for a patient with POWV in Massachusetts, USA. Clinical presentation and laboratory findings were nonspecific. Improvement on brain magnetic resonance imaging after 2 weeks preceded clinical improvement by months, suggesting possible prognostic value.
Keywords: MRI; Powassan virus; United States; deer tick encephalitis; flavivirus; magnetic resonance imaging; meningitis/encephalitis; serial brain MRI; viruses.