Antibody-mediated encephalitis is an immune-mediated inflammatory condition of the brain. Both paraneoplastic syndromes and autoimmune syndromes can be associated with antibodies against neural cell proteins. Paraneoplastic encephalitis syndromes occur in association with cancer and may precede the diagnosis of a malignancy. Autoimmune encephalitis syndrome may occur in the absence of cancer. These syndromes preferentially affect the limbic system, brain stem, or cerebellum but may also have widespread involvement of the neuraxis.

This condition has many known antibodies and can present differently based on the antibody involved. Common presentations include mental status changes, headaches, psychiatric symptoms (anxiety, mood dysregulation, psychosis), memory disturbance, movement disorders, seizures, brain stem symptoms (dysphagia, nystagmus, opsoclonus, vertigo), and autonomic dysregulation. These conditions can occur in children and adults. Prognosis is variable based on the antibody involved, underlying malignancy, and severity of the neurologic syndrome.

LGI1 (leucine-rich, glioma-inactivated 1) antibody limbic encephalitis is a common type of limbic encephalitis associated with fatigue, hyponatremia, and faciobrachial dystonic seizures.