A Case of Limbic Encephalitis: Antibody LGI1 Associated Encephalitis

Abstract

Limbic encephalitis (LE) is a rarely encountered disease in modern clinical practice. It is basically autoimmune in nature, with its pathophysiology determined by a number of antibodies to neural surface proteins. However, 20% of cases are paraneoplastic and have a tumour source in the body which leads to limbic encephalitis secondarily. Studies have shown that VGKC complex (Voltage Gated Potassium Channels) is one of the common antibodies found in this disease and is represented by three such proteins out of which LGI1 is most prevalent in limbic encephalitis. This entity is characterized by monophasic presentation with acute or subacute onset memory loss, confusion, seizures and psychiatric symptoms. The presence of anti LGI1 antibodies in serum or CSF confirms the diagnosis. We hereby report a case of a 65 year old woman with 8 months history of peripheral neuropathy followed by memory impairment, focal seizures with behavioural and psychiatric changes. No tumour was found on imaging and the classic paraneoplastic panel was negative. However, she was found to be positive for Antibody LGI1 proving autoimmune basis of her illness which responded majorly to immuno-modulatory therapy in the form of high dose steroids.