What is autoimmune encephalitis?

Autoimmune encephalitis is the term used to describe a broadening group of autoimmune inflammatory diseases that primarily affect the grey matter of the central nervous system. This includes the limbic system, neocortex, basal ganglia, cerebellum and brain stem. The various autoimmune encephalitides can lead to epileptic seizures, movement disorders, coordination disturbances as well as neurocognitive and psychiatric disorders.

On magnetic resonance imaging (MRI) scans, the different autoimmune encephalitides are often characterized by temporary or persistent T2/FLAIR signal intensity and increased volume (swelling) of the predominantly affected structures, which subsequently can result in a volume reduction (atrophy). Frequently, however, no changes will show up on the MRI.

In a proportion of patients, the cerebrospinal fluid (CSF) displays low-grade inflammatory changes such as an increased number of inflammatory cells mainly consisting of B and T lymphocytes, monocytes and macrophages, indicative of lymphocytic and monocytic pleocytosis. A disturbance of the blood-CSF barrier may also be observed involving an increased concentration of protein in the CFS and antibody production triggered by B lymphocytes entering into the blood and CSF, with intrathecal immunoglobulin synthesis being one key feature. In other patients, such inflammatory changes are not detectable.