Early clinical features of new-onset refractory status epilepticus (NORSE) in adults

The aim of this study was to identify early clinical features of patients with new-onset refractory status epilepticus (NORSE) that could direct the treatment in the first days of hospitalisation.

A retrospective cohort study of adult NORSE patients treated in the intensive care units of Helsinki University Hospital 2007-2018.

We found 19 adult NORSE patients who divided into three subgroups on the basis of their clinical features: viral encephalitis (n = 5, 26%), febrile infection-related epilepsy syndrome (FIRES) (n = 6, 32%) and afebrile NORSE (n = 8, 42%). FIRES and afebrile NORSE patients remained without confirmed etiology, but retrospectively two paraneoplastic and two neurodegenerative causes were suspected in the afebrile NORSE group. Viral encephalitis patients were median 64 years old (IQR 55-64), and four (80%) had prodromal fever and abnormal findings in the first brain imaging. FIRES patients were median 21 years old (IQR 19-24), all febrile and had normal brain imaging at onset. In the afebrile NORSE group, median age was 67 (IQR 59-71) and 50% had prodromal cognitive or psychiatric symptoms. FIRES patients differed from other NORSE patients by younger age (p = 0.001), respiratory prodromal symptoms (p = 0.004), normal brain MRI (p = 0.044) and lack of comorbidities (p = 0.011). They needed more antiseizure medications (p = 0.001) and anesthetics (p = 0.002), had a longer hospital stay (p = 0.017) and more complications (p < 0.001).

Among febrile NORSE patients, FIRES group was distinctive due to patients' young age, prodromal respiratory symptoms and normal first brain imaging. These features should be confirmed by subsequent studies as basis for selecting patients for early intensive immunotherapy.