Abstracts

Rationale: While certain presenting clinical features may suggest autoimmune epilepsy, disease behavior over time, a relevant aspect given the potential chronicity of some patients, remains incompletely understood.  We sought to characterize the evolution of electroclinical characteristics of an autoimmune epilepsy cohort.  Methods: From a database of 104 patients (2008-2017) with autoimmune neurological disorders, 19 with seizures as exclusive or predominant presentation were included in this study. Neural autoantibody (VGKC-LGI1, NMDAR, GABA-B, GAD65) was present in 13 and tumor (teratoma, lung) was present in 2 patients. Four antibody-negative tumor-negative patients met diagnostic criteria for autoimmune encephalitis. Mean follow up period was 2.1 years (range 0.2-6 years). Electroclinical features were determined through chart review and review of video-EEG monitoring.  Results: Explosive onset of seizures (>5 seizures within 1 month of onset) was noted in 14 patients; 11 had status epilepticus. Seizure burden remained high with only brief (2-4 month) seizure freedom in 3 patients, until seizure remission occurred in 14 patients. Epileptic auras were frequently multimodal (7) and autonomic (5), and changed over time. Faciobrachial dystonic seizures (4) frequently coexisted with other seizure types. Focal myoclonic or clonic seizures occurred at various points in the disease course (4). Seizures associated with automatisms (2), awareness (5) and language (1) impairment were also noted. Number of seizure types in each patient decreased over time and 2 had multiple seizure types at last follow-up. Subclinical seizures were recorded initially in 5 patients (without concurrent clinical seizures in 3 patients), and persisted over time in 2 patients. Comorbid cognitive impairment was noted in 18 patients and psychiatric complaints in 11 patients.EEG at disease onset was available for 14 patients. Slow posterior background or generalized slow was present in all and 3 had periodic discharges. Extreme delta brush was noted in 2 patients with NMDA-R antibodies.  Despite frequent seizures, interictal epileptiform discharges- sharp waves and focal rhythmic slow, frequently temporal, were seen in in only 7 patients. Ictal EEG showed variable patterns: temporal (6), vertex (4), non-localized or diffuse (6).At last follow up, 14 patients had experienced seizure remission and 5 patients had persistent seizures. EEG seizures at last video-EEG evaluation were seen over bitemporal (2), unilateral temporal (2), or vertex (1) regions.Patients were treated with an average of 3.4 antiepileptic drugs. 16 received first line (steroids +/-  intravenous immunoglobulin +/- plasmapheresis) and 4 received additional rituximab, with time-correlated improvement of seizure frequency in 12/16 patients. Conclusions: Explosive onset of seizures and fluctuating seizure frequency is common in autoimmune epilepsy.  Autoimmune electroclinical syndromes evolve over time and are characterized by multimodal auras, autonomic involvement, and EEG seizures extending beyond temporal regions, likely representing involvement of limbic cortex and its connected regions.  Funding: None