A case of leucine-rich glioma-inactivated 1 antibody encephalitis with schizophrenia-like symptoms as an initial clinical manifestation

Leucine-rich glioma-inactivated 1 (LGI-1) antibody encephalitis is a type of limbic encephalitis characterized by faciobrachial dystonic seizure and short-term memory loss as initial clinical symptoms. We present a case initially misdiagnosed as schizophrenia and finally diagnosed as LGI-1 antibody encephalitis. A 41-year-old female presented to the neurology clinic with a 4-month history of anxiety and disoriented speech and a new onset headache. Her explanation of symptoms was unclear, and she was unable to answer questions properly. Her brain magnetic resonance imaging (MRI) showed no specific lesions. After 6 months, depersonalization, place disorientation and memory impairment were noted. Her symptoms continue to progress, experiencing visual/auditory hallucinations. She was diagnosed with schizophrenia and admitted to a closed psychiatric ward. In the hospital, she showed mild fever, and her memory loss worsened faster than her psychiatric symptoms, unlike in schizophrenia. Follow-up MRI scans showed a diffusely enlarged right hippocampus with a 2.5 × 1.3-cm mass lesion. Electroencephalogram showed rhythmic theta activities/interictal spikes in the right frontal lobe, for which she was treated with an antiepileptic drug. Cerebrospinal fluid analysis results showed pleocytosis. Based on this, autoimmune encephalitis was diagnosed, and steroid pulse treatment and immunoglobulin treatment were performed. Positivity for LGI-1 antibody was reported and finally led to diagnosis of LGI-1 antibody encephalitis. Clinical symptoms gradually improved, and the lesion had shrunk considerably on MRI performed 6 months after immunoglobulin treatment. She reports persistent amnesia for 6 months but has returned to her daily life under follow-up observation.