Immune-mediated encephalitis for the infectious disease specialist

PURPOSE OF REVIEW: Autoimmune encephalitis is increasingly recognized and must be distinguished from infectious forms of encephalitis. Moreover, physicians should be aware of infectious triggers of autoimmune encephalitis and of infectious complications associated with treatment. RECENT FINDINGS: Recent epidemiological studies suggest that the incidence of autoimmune encephalitis may rival that of infectious encephalitis. Although distinguishing autoimmune from infectious forms of encephalitis on clinical grounds can be challenging, recently proposed diagnostic criteria can provide some assistance. There has been an explosion in our knowledge of autoimmune encephalitis associated with antibodies to neuronal cell surface antigens, and two of the most common forms, anti-NMDA receptor encephalitis and anti-LGI1 encephalitis, are typically associated with distinctive clinical features. Although tumors have long been known to trigger autoimmune encephalitis, it has been recently recognized that herpes simplex encephalitis may trigger the generation of antineuronal autoantibodies resulting in an autoimmune neurologic relapse. Both first and second-line therapies for autoimmune encephalitis are associated with infectious complications, whereas emerging treatments, including anakinra and tocilizumab, may also result in increased susceptibility to certain infections. SUMMARY: The diagnosis and management of autoimmune encephalitis is complex, and awareness of diagnostic criteria and modalities, typical clinical syndromes, infectious triggers of disease, and infectious complications of therapies is critical in optimizing care for affected patients.