Abstract
OBJECTIVE: Diagnosing autoimmune encephalitis (AIE) is difficult in patients with less fulminant diseases, like epilepsy. However, recognition is important, as patients require immunotherapy.
This study aims to identify antibodies in patients with focal epilepsy of unknown etiology, and to create a score to preselect patient requiring testing. METHODS: In this prospective, multicenter, cohort study, adults with focal epilepsy of unknown etiology, without recognized AIE, were included, between December 2014-2017, and followed for one year.
Serum, and if available CSF, were analyzed using different laboratory techniques. The ACES score was created using factors favoring an autoimmune etiology of seizures (AES), as determined by multivariable logistic regression.
The model was externally validated and evaluated using Concordance (C) statistic. RESULTS: We included 582 patients, with median epilepsy duration of 8 years (IQR 2-18).
Twenty patients (3.4%) had AES, of whom 3 anti-Leucine-rich-Glioma-Inactivated 1, 3 anti-Contactin-Associated Protein-like2, 1 anti-N-methyl-D-Aspartate Receptor, and 13 anti-Glutamic Acid Decarboxylase-65 (ELISA-concentrations>10,000 IU/ml). Risk factors for AES were: temporal MRI-hyperintensities (OR 255.3,95%-CI 19.6-3332.2;p = 2 had a sensitivity of 100% to detect AES, and a specificity of 84.9%.
INTERPRETATION: Specific signs point towards AES in focal epilepsy of unknown etiology. The ACES score (cut-off >=2) is useful to select patients requiring antibody testing.