[Anti-leucine-rich glioma-inactivated 1 antibody-positive encephalitis with a poor response to corticosteroids 2 months after onset of impaired memory: a case report].

The patient was a 30-year-old man who was admitted to our department 2 months after the onset of anterograde amnesia. Cognitive function tests indicated memory impairment only. MRI FLAIR images of the head showed a high signal in the bilateral medial temporal lobes. Corticosteroid therapy did not improve his symptoms, and he subsequently developed status epilepticus. Concurrently, his cerebrospinal fluid was positive for anti-leucine-rich glioma-inactivated 1 (LGI1) antibody. He was diagnosed with anti-LGI1 antibody-positive encephalitis. Plasma exchange therapy and intravenous immunoglobulin therapy improved the status epilepticus, but memory impairment and bilateral medial temporal lobe atrophy remained. This case was characterized by memory impairment that only lasted for 2 months after onset and a poor response to corticosteroid therapy.