Objective:

To describe a case of new-onset refractory status epilepticus (NORSE) in a patient with a diagnosis of Powassan Encephalitis highlighting the presence of paradoxical burst suppression in the EEG, and implications in critically ill patients.

Background:

Burst suppression is an electroencephalographic marker of profound cortical suppression often targeted during treatment of refractory status epilepticus. On the other hand, paradoxical burst suppression is a phenomenon in which the pattern of stimulation leads to a paradoxical suppression on the EEG, hence complicating management and prognosis.

Design/Methods:

Case report of a previously healthy 21-year-old man with a diagnosis of Powassan encephalitis and new-onset refractory status epilepticus.

Results:

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.

Conclusions:

This case illustrates the diagnostic and therapeutic challenges of NORSE and highlights paradoxical burst suppression as a distinct EEG phenomenon that can complicate interpretation. Recognition of its stimulus-dependent nature is important, as it may mimic pharmacologic burst suppression yet does not reliably indicate stable cortical quiescence. Careful differentiation is essential to avoid overestimation of seizure control during the management of refractory status epilepticus.