Seizures in autoimmune encephalitis: Findings from an EEG pooled analysis

• Published in: Seizure (London, England) Vol. 83; pp. 160 - 168
• Main Authors: Morano, Alessandra, Fanella, Martina, Cerulli Irelli, Emanuele, Barone, Francesca A., Fisco, Giacomo, Orlando, Biagio, Albini, Mariarita, Fattouch, Jinane, Manfredi, Mario, Casciato, Sara, Di Gennaro, Giancarlo, Giallonardo, Anna Teresa, Di Bonaventura, Carlo
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2020
• Subjects: 24-h ambulatory EEG; Adolescent; Adult; Aged; Amygdala; Autoimmune Diseases - physiopathology; Autoimmune encephalitis; Brain - immunology; Brain - physiopathology; Electroencephalography - adverse effects; Encephalitis - diagnosis; Encephalitis - immunology; Encephalitis - physiopathology; Epilepsies, Partial - complications; Epilepsies, Partial - immunology; Epilepsies, Partial - physiopathology; Female; Hashimoto Disease - diagnosis; Hashimoto Disease - immunology; Hashimoto Disease - physiopathology; Humans; Late-onset epilepsy; Magnetic Resonance Imaging - methods; Male; Middle Aged; Retrospective Studies; Seizures - diagnosis; Seizures - immunology; Seizures - physiopathology; Subclinical seizures; Transient epileptic amnesia; CSs; MTLE; Amygdala; Late-onset epilepsy; EDE; NREM; CNS; TLE; HV; SOX1; Transient epileptic amnesia; CASPR2; CSF; AEEG; GABAR; Autoimmune encephalitis; AED; LGI1; NCSE; AE; mTL; IEDs; FBDS; AMPAR; GAD65; 24-h ambulatory EEG; Subclinical seizures; DRE; SCSs; SSW; GPDs; NMDAR; VEEG
• ISSN: 1059-1311; 1532-2688; 1532-2688
• DOI: 10.1016/j.seizure.2020.10.019

•Specific features suggesting the immune etiology of new-onset seizures are poor.•Most clinical (CSs) and subclinical seizures (SCSs) were recorded in AE acute stage.•Ictal autonomic and negative affective manifestations were prominent.•Multiple ictal EEG patterns were identified in 9 cases, 6/9 had both CSs and SCSs.•Multiple ictal EEG patterns suggest a widespread, multifocal hyperexcitability. Seizures are common in autoimmune encephalitis (AE), and an extensive work-up is required to exclude alternative etiologies. The aim of our study was to identify possible clinical/EEG peculiarities suggesting the immune-mediated origin of late-onset seizures. Thirty patients diagnosed with AE (19 men, median age 68 years, 18 seronegative) were included. Overall 212 video-electroencephalographic (EEG) and 31 24-h ambulatory EEG (AEEG) recordings were retrospectively reviewed. Posterior dominant rhythm, interictal epileptiform discharges (IEDs), clinical (CSs) and subclinical seizures (SCSs) were analyzed. Six-hundred-nineteen ictal events were recorded in 19/30 subjects, mostly (568/619) during AE acute stage. Among ten patients with CSs other than faciobrachial dystonic seizures, 7 showed prominent autonomic and emotional manifestations. SCSs were detected in 11 subjects, mainly via AEEG (260/287 SCSs vs 150/332 CSs, p < 0.001). Eight patients presented seizures during hyperventilation. IEDs, documented in 21 cases, were bilateral in 14 and focal temporal in 13. Multiple ictal EEG patterns were detected in 9/19 patients, 6 of whom had both CSs and SCSs, bilateral asynchronous seizures and ictal activities arising from temporal and extra-temporal regions. No correlation was found between the lateralization of MRI alterations and that of EEG findings. Our study confirms that adult-onset, high frequency focal seizures with prominent autonomic and emotional manifestations should be investigated for AE. Multiple ictal EEG patterns could represent a ‘red flag’, reflecting a widespread neuronal excitability related to the underlying immune-mediated process. Finally, our work enhances the crucial role of long-lasting EEG monitoring in revealing subclinical and relapsing seizures.