TABLE 5.
Key clinical features for the differential diagnosis between FSE, FIRES, and NORSE without fever
| Clinical features | FSE | NORSE of unknown etiology | |
|---|---|---|---|
| FIRES | NORSE without fever | ||
| Time from fever onset to SE onset | <24 h | >24 h | No fever |
| Age | 1 month–6 years | School‐aged | Variable |
| <2 years in 79% | >2 years in 81% | >2 years in 80% | |
| SE duration | Most <48 h (90%) | Most >48 h (86%) | All <48 h |
| Abnormal findings on MRI, CSF, or EEG | None in CSF and MRI | At least one abnormal finding: 90% | Variable |
| EEG: focal/diffuse slowing in 47% | CSF 63% | ||
| MRI 69% | |||
| EEG 80% | |||
| Outcome | Generally good | Generally poor | Variable |
Abbreviations: CSF, cerebrospinal fluid; EEG, electroencephalogram; FIRES, febrile infection‐related epilepsy syndrome; FSE, febrile SE; MRI, magnetic resonance imaging; NORSE, new onset refractory SE; SE, status epilepticus.