Continuous EEG Findings in Autoimmune Encephalitis

• Authors: Suzette Laroche, Emory University; Anna-Marieta Moise, Emory University; Ioannis Karakis, Emory University; Aline Herlopian, Yale University; Monica Dhakar, Emory University; Lawrence J Hirsch, Yale University; George Cotsonis, Emory University; Suzette LaRoche, Mission Health, Asheville; Christian Cabrera M Kang, Laureate Medical Group; Brandon Westover, Massachusetts General Hospital; Andres Rodriguez, Emory University
• Journal Title: JOURNAL OF CLINICAL NEUROPHYSIOLOGY
• Volume: Volume 38, Number 2
• Publisher: LIPPINCOTT WILLIAMS & WILKINS | 2021-03-01, Pages 124-129
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1097/WNP.0000000000000654
• Subjects: Biology, Neuroscience
• Keywords: Science & Technology; Life Sciences & Biomedicine; Clinical Neurology; Neurosciences; Neurosciences & Neurology; Continuous EEG; Autoimmune encephalitis; Electrographic findings in autoimmune encephalitis; Encephalitis; Anti-NMDA-receptor encephalitis; Limbic encephalitis; Hashimoto encephalopathy; NORSE; EXTREME DELTA BRUSH; DIAGNOSIS; SEIZURES

Abstract

Purpose:Autoimmune encephalitis (AE) is a cause of new-onset seizures, including new-onset refractory status epilepticus, yet there have been few studies assessing the EEG signature of AE.Methods:Multicenter retrospective review of patients diagnosed with AE who underwent continuous EEG monitoring.Results:We identified 64 patients (male, 39%; white, 49%; median age, 44 years); of whom, 43 (67%) were antibody-proven AE patients. Of the patients with confirmed antibody AE, the following were identified: N-methyl-D-aspartate receptor (n = 17, 27%), voltage-gated potassium channel (n = 16, 25%), glutamic acid decarboxylase (n = 6, 9%), and other (n = 4, 6%). The remaining patients were classified as probable antibody-negative AE (n = 11, 17%), definite limbic encephalitis (antibody-negative) (n = 2, 3%), and Hashimoto encephalopathy (n = 8, 13%). Fifty-three percent exhibited electrographic seizures. New-onset refractory status epilepticus was identified in 19% of patients. Sixty-three percent had periodic or rhythmic patterns; of which, 38% had plus modifiers. Generalized rhythmic delta activity was identified in 33% of patients. Generalized rhythmic delta activity and generalized rhythmic delta activity plus fast activity were more common in anti-N-methyl-D-aspartate AE (P = 0.0001 and 0.0003, respectively). No other periodic or rhythmic patterns exhibited AE subtype association. Forty-two percent had good outcome on discharge. Periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome (OR, 6.4; P = 0.0012; OR, 3; P = 0.0372; OR, 12.3; P = 0.02, respectively).Conclusion:Our study confirms a signature EEG pattern in anti-N-methyl-D-aspartate AE, termed extreme delta brush, identified as generalized rhythmic delta activity plus fast activity in our study. We found no other pattern association with other AE subtypes. We also found a high incidence of seizures among patients with AE. Finally, periodic or rhythmic patterns, seizures, and new-onset refractory status epilepticus conferred an increased risk of poor outcome regardless of AE subtype.