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.

Atypical presentation of an elderly male with autoimmune encephalitis: anti-LG1 limbic encephalitis

“…Most cases of autoimmune encephalitis have been reported as a paraneoplastic syndrome as a result of anti-neural autoantibodies directed against intracellular antigens produced by the tumors. Voltage-gated potassium channel complex (VGKC) is one of the common ion channels involved and consists of three different proteins, out of which antibodies against leucine-rich glioma inactivated 1 protein (LGI1) is commonly associated with NPLE [3,4].…”

“…Autoimmune encephalitis can have subacute presentation with limbic dysfunction, seizures, and occasional hyponatremia [3,5,6]. Involvement of the hypothalamus can also lead to hyperthermia, somnolence, and endocrine abnormalities.…”

Rare Case of Anti-LGI1 Limbic Encephalitis with New Onset Epilepsy: A Case Report

“…It is well tolerated in the older adult population and should be heavily considered as a therapeutic option, especially with complications that may arise with the use of IVIG, steroids, and plasma exchange. Additionally, one study also showed favorable outcome with the use of mycophenolate mofetil in decreasing seizure frequency and improving behavioral memory testing [20].…”

Immunotherapy in Autoimmune and Neuroinflammation-Related Epilepsies

“…Memory disturbances also improved. 45 Rituximab has been used in refractory cases. 41 Evidence has suggested relapse and long-term cognitive deficits, and hippocampal sclerosis can occur without treatment.…”