About Autoimmune Encephalitis

Autoimmune encephalitis (AIE) is an immune-mediated condition that induces brain inflammation and is one of the most common causes of non-infectious encephalitis. In the past decade, AIE has become an emerging addition to the differential diagnosis when a classical infection cannot explain focal neurological symptoms. While the exact mechanism of AIE is unknown, current literature suggests that autoimmune antibodies target synaptic proteins leading to widespread inflammation.[1]

AIE commonly presents as new onset of memory loss, psychosis, altered mental status, or seizures, with the presentation taking place over a few weeks to three months. AIE involves several parts of the nervous system, including the limbic system, the spinal cord, and/or the entire neuraxis. AIE can be confirmed by multiple modalities, including laboratory testing (antibody detection), neuroimaging, and electrophysiological studies (electroencephalogram).

Although the exact mechanism is currently under investigation, autoimmune encephalitis is thought to be an autoimmune process with an exaggerated response to a neuronal self-antigen. Unlike paraneoplastic encephalitis, which is a T-cell mediated response, antibodies in AIE are intrinsically pathogenic. They induce inflammation by targeting specific neuronal proteins. Synaptic proteins, ion channels, and intracellular receptors are the target proteins that have been established so far. When bound to target proteins, these antibodies induce conformational changes that lead to an inflammatory response. 

Approximately 70% of patients have prodromal manifestations of headache, fever, and other symptoms resembling viral etiology. Then, it progresses with acute to subacute onset of memory deficits, altered mental status, behavior changes, psychosis, orofacial dyskinesia, hallucinations, agitation, delusions, catatonia, seizures, or abnormal movements.

Source: https://www.ncbi.nlm.nih.gov/books/NBK578203/