The Broad Clinical Spectrum of Autoimmune Limbic Encephalitis: From Executive Dysfunction to Non-Convulsive Status Epilepticus -Two Case Reports

Abstract

Objective: This report aims to present two atypical cases of autoimmune limbic encephalitis with distinct clinical manifestations and to emphasize the diagnostic challenges when neuroimaging findings are normal or non-specific. Methods: Comprehensive clinical, neurological, and psychiatric evaluations were performed. Diagnostic work-up included brain magnetic resonance imaging (MRI), electroencephalography (EEG), cerebrospinal fluid (CSF) analysis, and autoimmune antibody testing. Results: The first case was a 34-year-old male presenting with isolated executive dysfunction without psychosis, seizures, or movement disorders. MRI showed minimal nonspecific hyperintensities and EEG was normal. CSF analysis revealed mildly elevated protein and strongly positive anti-NMDAR antibodies. Significant cognitive improvement was observed after intravenous methylprednisolone followed by azathioprine. The second case was a 69-year-old male presenting with acute consciousness impairment due to non-convulsive status epilepticus. EEG demonstrated continuous 2–3 Hz spike-wave activity predominantly in the left hemisphere. CSF protein levels were elevated and GAD65 antibodies were positive. Clinical improvement was achieved after treatment with high-dose corticosteroids and intravenous immunoglobulin. Conclusions: Autoimmune encephalitis may present with heterogeneous and atypical clinical features, including isolated cognitive dysfunction or non-convulsive status epilepticus. Normal or nonspecific MRI findings do not exclude the diagnosis. Early recognition and timely immunotherapy are crucial to prevent irreversible neurological damage.