The patient presented with fever, encephalopathy, and generalized tonic–clonic seizures requiring intubation. Initial CSF studies revealed pleocytosis with lymphocytic predominance; infectious and autoimmune evaluations were unrevealing. Despite broad antimicrobial therapy and multiple anti-seizure medications, including Perampanel and pentobarbital, the patient progressed to NORSE. Adjunctive immunotherapies included IVIG, high-dose steroids, and plasma exchange, with only transient electrographic improvement.

Imaging demonstrated bilateral thalamic and basal ganglia signal abnormalities. Infectious studies, including metagenomic sequencing and CDC reference testing, eventually confirmed Powassan disease. EEG monitoring revealed generalized periodic discharges (1–3 Hz) where painful stimuli and repositioning inducing heightened suppression, resulting in concomitant reduction in discharge frequency, consistent with paradoxical burst suppression. The patient was transferred to a quaternary epilepsy centre post Tracheostomy and PEG tube placement.