Anti-voltage-gated potassium channel complex antibody–mediated limbic encephalitis: a case report of a 53-year-old man admitted to intensive care psychiatric unit with psychotic mania

Limbic encephalitis represents a cluster of autoimmune disorders, with inflammation in the medial temporal lobe characterised by subacute onset of neuropsychiatric symptoms such as anxiety, affective symptoms, psychosis, short-term memory impairment as well as faciobrachial and grand mal seizures. We aim to present a case of a 53-year-old man with positive anti–voltage-gated potassium channel (VGKC) complex antibodies who initially presented with symptoms of psychotic mania. Six weeks post-psychiatric symptomatology, he presented with neurological symptoms such as faciobrachial jerking and tonic-clonic seizure. The patient had no previous psychiatric history and was initially treated with psychotropic medications. Our experience emphasises the fact that limbic encephalitis is not easy to identify as most patients initially present with psychiatric symptomatology than neurological symptoms. Furthermore, immunological and laboratory testing takes a rather long time to determine the diagnosis. What is more, few psychiatrists consider autoimmune nature of the neuropsychiatric presentation. Therefore, it is important to consider autoimmune encephalitis in patients with new-onset psychosis or mania who also present with neurological symptoms at some stage of their illness. Characteristic indicators of autoimmune encephalitis include neurological symptoms such as facial twitching, seizures, confusion and cognitive decline.