2023 Volume 28 Issue 1 Pages 60-
A 56-year-old man, diagnosed with juvenile Alzheimer's disease by his primary care physician, presented with worsening symptoms after initiation of acetylcholinesterase inhibitor therapy. Head magnetic resonance imaging（MRI）revealed a unilateral limbic hyperintensity associated with a contrast effect. Cerebrospinal fluid analysis revealed no abnormality except for positive results for anti-leucine-rich glioma-inactivated 1 protein（LGI1）antibodies, which were also detected in the serum. Therefore, the patient was definitively diagnosed with anti-LGI1 antibody-positive limbic encephalitis. He responded to immunotherapy and successfully returned to social life. The patient did not show any faciobrachial dystonic seizure during the course of the disease and was conclusively diagnosed with this condition based on minor findings detected on head MRI. A high index of clinical suspicion is extremely important for accurate and early diagnosis of this disease based on imaging studies to avoid missed diagnosis of a treatable neurological condition.
