Autoimmune Voltage-Gated Potassium Channel Limbic Encephalitis With Auditory and Visual Hallucinations

The limbic system (LS) coordinates an important role in memory generation, creating an emotional response to stress, and helping regulate autonomic and endocrine functions. Dysfunction of the limbic system can present secondary to many pathologies including autoimmune, infectious, paraneoplastic, etc. Lesions to the limbic system can also lead to varying symptoms which can be challenging for physicians to correctly identify and treat. Here we report a 59-year-old male with aggressive mood changes and acute onset of auditory and visual hallucinations. The cerebrospinal fluid (CSF) and serum immunological antibody panel confirmed the presence of voltage-gated potassium channel (VGKC) antibodies. Significant radiographic findings included an MRI revealing T2 hyperintensities in the bilateral hippocampus. Paraneoplastic screening with testicular ultrasound and chest CT was completed and was negative. A primary diagnosis of voltage-gated potassium channel limbic encephalitis (VGKC-LE) was made. Management included five days of intravenous immunoglobulin (IVIG) with subsequent resolution of symptoms. The limbic system is an intricate network of neurons that generates and relays key information to other parts of the brain. Its function and, in this case, its dysfunction remain an area of continued research. This case aimed to highlight the importance of recognizing the clinical presentation and objective findings of a rare type of autoimmune encephalitis and identifies the significance of paraneoplastic screening.