Acute symptomatic seizures in patients admitted with autoimmune encephalitis.

BACKGROUND: There is a paucity of information on factors that could identify patients hospitalized with autoimmune encephalitis at risk of developing acute symptomatic seizures.

METHODS: In this retrospective cohort study, patients hospitalized with probable or definite AE who underwent an electroencephalogram (EEG) were identified from two tertiary care centers located in New York (NY, USA) between 2010 and 2021. Electrographic, immunologic, and clinical features associated with the development of seizures were incorporated into a logistic regression model using a stepwise forward model.

RESULTS: One-hundred-and-five patients were included. Median age at symptomatic onset was 42 years and 57 patients (54 %) were female. The median time from symptom onset to admission, length of hospital stay, and duration of EEG recording were, respectively, 38, 23, and 5 days. Seventy-two patients hospitalized for autoimmune encephalitis (69 %) had acute symptomatic seizures. Interictal discharges on EEG (OR=3.91; p = 0.045)-especially when periodic (OR=12.63; p = 0.015)-and cell-surface autoantibodies (OR=6.77; p = 0.008) were associated with the development of acute seizures. While lower CSF protein concentration was associated with the development of seizures in univariate analysis, this was no longer statistically significant after adjusting for age and autoantibody status (OR=0.99; p = 0.052).

SIGNIFICANCE: Acute symptomatic seizures are common in patients hospitalized with AE, especially in those with interictal epileptiform or periodic discharges on EEG and cell-surface autoantibodies. The association between lower CSF protein concentration and acute symptomatic seizures is likely confounded by age and autoantibody status.