Abstract
In order to determine the prevalence of neural autoantibodies in adult patients with drug-resistant temporal lobe epilepsy (DRTLE) of unknown etiology, we compared the characteristics of patients with and without autoantibodies and applied antibody predictive scores to the patients. Patients aged ≥18 years with DRTLE of unknown etiology and ≥12 months of evolution were prospectively recruited. Neural autoantibodies in serum and CSF were systematically determined in all patients. We created the ARTE (antibody in drug-resistant temporal lobe epilepsy) score based on the variables associated with the presence of neural autoantibodies. Twenty-seven patients were included. The mean (SD) age in years at the index date was 52 (±14.2) and at epilepsy onset was 32 (±17.1). The mean epilepsy duration was 19 (±12.5) years. Neural autoantibodies were detected in 51.85% (14/27) of patients. The presence of bitemporal, independent, interictal epileptiform discharges (BIIED) had a higher frequency in patients with neural autoantibodies (57.1% vs. 15.4%; p = 0.025) as well as those patients with a previous history of status epilepticus (49.2% vs. 0.0%; p = 0.007). The ARTE score showed an area under the curve (AUC) of 0.854. Using a cut-off point of ≥1, the sensitivity was 100% and the specificity was 46.1%, whereas when using a cut-off point of ≥3, the results were 35.7% and 100%, respectively. We found a high prevalence of neural autoantibodies in patients with DRTLE of unknown etiology, indicating an autoimmune mechanism. The presence of BIIED and a history of SE in DRTLE of unknown etiology are possible markers for autoimmune-associated epilepsy. The proposed ARTE score requires future validation in larger independent cohorts.
Highlights
The presence of neural autoantibodies is considered to be one of the hallmarks of autoimmune epilepsy
A systematic review and meta-analysis of the studies, with an a priori low suspicion of autoimmune encephalitis and prospective recruitment, estimated a pooled prevalence of neural autoantibodies in patients with epilepsy of unknown etiology of 7.6% (CI 95%, 4.6–11.2) [6], with a higher prevalence in studies focused on patients with drug-resistant epilepsy
This confirmed our initial hypothesis that patients with these characteristics are at risk of the presence of neural autoantibodies because drug resistance is a hallmark of autoimmune seizures [20] and there is a predilection of autoimmune encephalitis affecting the temporal lobe and limbic system structures [7,21]
Summary
The presence of neural autoantibodies is considered to be one of the hallmarks of autoimmune epilepsy. Several studies with remarkable differences in their methodology attempted to determine the possibility of an autoimmune mechanism in a heterogeneous group of patients with epilepsy of unknown etiology by determining the presence of neural autoantibodies. Many of these studies were performed only in patients with a high suspicion of autoimmune encephalitis [4]. A systematic review and meta-analysis of the studies, with an a priori low suspicion of autoimmune encephalitis and prospective recruitment, estimated a pooled prevalence of neural autoantibodies in patients with epilepsy of unknown etiology of 7.6% (CI 95%, 4.6–11.2) [6], with a higher prevalence in studies focused on patients with drug-resistant epilepsy. None of the included studies performed a systematic determination of the neural autoantibodies in CSF, leading to the possibility of false negative results [7], and a lower prevalence of neural autoantibodies
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