Powassan virus is a rare tick-born illness that may cause meningitis and encephalitis. There are several areas of the country where Powassan virus has been identified including the Northeast and Great Lakes Region. We present a case of Powassan encephalitis in a 74-year-old female employed as a dog-walker with rapid neurological decline secondary to NORSE.

Patient first presented with headaches, fatigue, unsteady gait, and clumsiness. Preliminary CT was unrevealing, and she was placed on the stroke pathway. On day 2, she developed acute fevers, hypersomnolence, and confusion. Was then witnessed to have generalized seizure activity. She required multiple rounds of benzodiazepines, intubation, and sedation to stop seizures. On video EEG monitoring, she was noted to be in non-convulsive status epilepticus. Her seizures remained difficult to control despite 4 anti-epileptic agents and sedation. MRI identified bilateral T2/FLAIR hyperintensities without diffusion restriction in the bilateral basal ganglia, thalami, and midbrain. Follow up MRI on day 8 revealed more extensive T2/FLAIR changes as well as new diffusion restriction of unclear etiology but suspected to be either infectious or inflammatory.  CSF studies were notable for elevated protein and HHV-6 IgM antibodies and was empirically treated with Ganciclovir. Further CSF studies resulted positive for Powassan virus which was also confirmed on serum studies. She was empirically treated with pulse-dose steroids and plasmapheresis but unfortunately had no significant improvement. At that point, her family chose to proceed with comfort-directed care until she passed.