title: Are There Any Specific EEG Findings in Autoimmune Epilepsies?
abstract: This study evaluated the EEG findings of patients whose seizures were associated with a possible autoimmune etiology. Our aim was to find clues to distinguish patients with antineuronal antibodies (Ab) through EEG studies. We reviewed our database and identified antineuronal Ab positive epilepsy patients with or without autoimmune encephalitis. These patients had Abs to N-methyl-d-aspartate receptor (NMDAR) (n = 5), glycine receptor (GLY-R) (n = 5), contactin-associated protein-like 2 (CASPR-2) (n = 4), uncharacterized voltage-gated potassium channel complex (VGKC) antigens (n = 2), glutamic acid decarboxylase (GAD) (n = 2), Hu (n = 1), and amphiphysin (n = 1). The control group consisted of 21 seronegative epilepsy or encephalopathy patients with similar clinical features. EEG findings were compared between the groups in a blindfolded design. We did not find any significant difference in EEG findings between antineuronal Ab positive epilepsy patients and seronegative control group. It was remarkable that four seropositive but none of the seronegative patients presented with nonconvulsive status epilepticus (NCSE) or focal motor status epilepticus. Continuous theta and delta rhythms were observed in 5 (71%) seropositive patients with autoimmune encephalitis and 2 (25%) seronegative patients. Eight (40 %) seropositive patients showed a frontal intermittent rhythmic delta activity (FIRDA) pattern as opposed to 5 (24%) seronegative patients. Two patients with NMDAR Ab positivity showed rhythmic delta waves superimposed with beta frequency activity resembling "delta brush" pattern. EEG seems as a limited diagnostic tool in differentiating epilepsy and/or encephalopathy patients with a possible autoimmune etiology from those without. However, antineuronal Abs associated with encephalitis should be considered in the etiology of status epilepticus forms. A possible autoimmune etiology for seizures may be considered in the presence of continuous slow waves, FIRDA, and delta brush pattern in the EEG.
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey baysalleyla@gmail.com.
authors.forename: Leyla
authors.initials: L
authors.lastname: Baysal-Kirac
authors.affiliation: Department of Neuroscience, Research Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Erdem
authors.initials: E
authors.lastname: Tuzun
authors.affiliation: Department of Neurology, Florence Nightingale Hospital, Istanbul, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Altindag
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Esme
authors.initials: E
authors.lastname: Ekizoglu
authors.affiliation: Department of Neurology, Okmeydanı Research and Training Hospital, Istanbul, Turkey.
authors.forename: Demet
authors.initials: D
authors.lastname: Kinay
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Basar
authors.initials: B
authors.lastname: Bilgic
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Pinar
authors.initials: P
authors.lastname: Tekturk
authors.affiliation: Department of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Betul
authors.initials: B
authors.lastname: Baykan
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000276:immunology*; D001921:Brain / Q000276:immunology; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000379:methods*; D004660:Encephalitis / Q000175:diagnosis* / Q000276:immunology*; D004827:Epilepsy / Q000000981:diagnostic imaging* / Q000276:immunology*; D005260:Female; D050031:Hashimoto Disease / Q000175:diagnosis* / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D001323:Autoantibodies
keywords: EEG; autoimmune epilepsy; limbic encephalitis; nonconvulsive status epilepticus