NORSE Versus FIRES: What's in a Name?

New-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) of unknown aetiology: A comparison of the incomparable?

PURPOSE

The discussion is ongoing whether new-onset refractory status epilepticus (NORSE) in adults and febrile infection-related epilepsy syndrome (FIRES) in children are one syndrome if the aetiology is unknown. In this study we will compare an adult cohort with NORSE and a paediatric cohort with FIRES in order to determine if they are similar or different.

METHODS

We retrospectively compared 18 adults with NORSE versus 48 children with FIRES, both cohorts without identifiable cause despite extensive investigations. We analyzed demographic and clinical data using Mann-Whitney-U and χ²- tests.

RESULTS

NORSE affected more women (78% vs. 42%; P = 0.009) than in FIRES. Median acute hospital stay was longer in FIRES (35 days [interquartile range, IQR=36] vs. 20 days [IQR=19]; P<0.001). FIRES was treated more frequently with coma therapy (82% vs. 28%; P<0.001) and with a higher median number of antiseizure medicines (7 [IQR=5] vs. 4 [IQR=2]; P<0.001). Children with FIRES showed a higher cerebrospinal fluid (CSF) cell count (10 cells/μl; P = 0.002) but a lower CSF protein level than adults with NORSE (48 mg/dl; P = 0.028). Immunotherapy was administered more frequently in FIRES (73% vs. 22%; P<0.001) than in NORSE. Group differences in number of antiseizure medicines after hospital stay (P = 0.229) and in overall mortality (P = 0.327) were not significant.

CONCLUSION

In our explorative comparison, differences prevailed. NORSE and FIRES should be compared prospectively in age-matched cohorts.