EEG Contribution to the Diagnosis of Antibody-Negative Autoimmune Encephalitis: A Case Report

Abstract

Autoimmune encephalitis (AE) is a group of inflammatory brain diseases that are characterized by prominent neuropsychiatric symptoms. Early therapeutic intervention is important for AE. Therefore, without waiting for autoantibody test results, clinicians must consider the possibility of AE based solely on clinical symptoms and conventional test results. The case described herein is of antibody-negative encephalitis with abnormalities shown only by EEG, which contributed to the diagnosis and treatment. The patient, a 20-year-old woman, showed autonomic seizures in addition to movement disorders, psychiatric symptoms, and cognitive dysfunction, which worsened subacutely. Her seizures and movement disorders were not responsive to antiepileptic medications. Results obtained from MRI and cerebrospinal fluid (CSF) were normal; EEG findings showed repeated spikes in the right temporal area, with changes over time. Based on the clinical course and EEG, along with administered immunotherapy, which resolved seizures, movement disorders, and psychiatric symptoms, we suspected AE. For diagnosis of AE and for evaluating treatment responsiveness, EEG was useful. Results indicate that EEG can assist clinicians even with AE cases for which MRI and CSF findings are normal.

Study on clinical features and factors related to long‐term outcomes of antibody‐negative autoimmune encephalitis

“…5,6 The diagnostic criteria by Graus et al 4 showed that the absence of antibodies did not exclude AE, but the inclusion criteria for antibody-negative AE varied widely among available studies. [7][8][9] Recognition of antibody-negative AE patients is crucial as with prompt diagnosis and early administration of immunotherapy the majority have favorable outcomes. 4,10 According to data from Olmstead County published in 2015, the estimated prevalence was 6.5 per 100,000 persons ª 2024 The Authors.…”

“… 4 showed that the absence of antibodies did not exclude AE, but the inclusion criteria for antibody‐negative AE varied widely among available studies. 7 , 8 , 9 Recognition of antibody‐negative AE patients is crucial as with prompt diagnosis and early administration of immunotherapy the majority have favorable outcomes. 4 , 10…”