A Case of Anti-Leucine-Rich Glioma-Inactivated Protein 1 (Anti-LGI1) Limbic Encephalitis With New-Onset Panic Attacks

Anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) limbic encephalitis is a rare autoimmune neurologic disorder with antibodies against LGI1. It was first recognized as a disease in 2010 and represents the second most common cause of autoimmune encephalitis. Clinically, it is characterized by subacute changes in cognition, memory, and behavior, associated with hyponatremia and faciobrachial dystonic seizures (FBDS). This report discusses a unique onset of anti-LGI1 limbic encephalitis where an elderly female presented with symptoms of new-onset panic attacks and rhythmic facial movements for one week. She was then admitted to neurology for further serum, cerebrospinal fluid(CSF), and lab testing. She was eventually found to be positive for antibodies against LGI1 voltage-gated potassium channels, which confirmed the diagnosis of limbic encephalitis. The quick recognition of symptoms and escalation of management allowed the patient to experience drastic improvements after the initiation of steroids, immunotherapy, and lacosamide. Since anti-LGI1 limbic encephalitis is underdiagnosed, it can lead to irreversible long-term cognitive sequelae (i.e., memory deficits). Thus, awareness of the typically associated findings of FBDS, cognitive disturbances, psychiatric changes, and hyponatremia can aid in early diagnosis and prompt treatment with immunotherapy, allowing for more favorable outcomes.