Biomarkers of new onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES).

New Onset Refractory Status Epilepticus (NORSE) and Febrile Infection-Related Epilepsy Syndrome (FIRES) present significant diagnostic challenges. To date, no single testing modality has emerged as the standard to confirm or exclude NORSE/FIRES. However, there has been increasing characterization of NORSE/FIRES by magnetic resonance imaging (MRI), electroencephalogram (EEG), and serum and cerebrospinal fluid (CSF) biomarkers. Here we briefly summarized the MRI abnormalities including "The claustrum sign". Dynamic contrast-enhanced MRI, a novel MRI sequence, highlighted increased blood-brain barrier permeability in individuals with NORSE. Several EEG features such as prolonged focal fast activity at seizure onset, shifting seizures, and extreme delta brush may be early findings in children with FIRES. Serum cytokine profiles demonstrated distinct immunophenotypes in adults with cryptogenic NORSE and were separate from the control subjects. Conventional genetic study is unlikely to identify a genetic etiology; however, it remains an important diagnostic tool. Novel genetic analysis such as polygenic risk score demonstrated cryptogenic NORSE sharing similar genetic landscape with other autoimmune/autoinflammatory diseases, further supporting aberrant inflammation as a main pathological mechanism. Collectively, these modalities may be complementary; therefore, a multimodal approach should be considered for the diagnosis of NORSE/FIRES.