33 Autoimmune encephalitis

Patients with autoimmune encephalitis can present with a variety of neurological symptoms such as short-term memory loss, behavioral changes, abnormal movements, seizures or focal deficits.^{1 2} These complex and severe disorders have become increasingly recognized in the past 15 years, thanks to the discovery and characterization of neural autoantibodies that cause autoimmune encephalitis.³ They can affect people of all ages and the clinical progression is acute or subacute, from days to weeks, in contrast to neurodegenerative disorders. Evaluation for infectious or other alternative conditions is of high clinical relevance as a first approach. Cerebrospinal fluid studies, magnetic resonance imaging and appropriate detection of neural antibodies have a key role in the diagnosis and management of patients with autoimmune encephalitis.^{4 5} A rapid identification is crucial, as these diseases are treatable. Neural antibodies associate with specific clinical syndromes, different comorbidities (such as tumours), and show different responses to immunotherapy and prognosis. These novel antibody-mediated syndromes have changed dramatically the field of neurology, with impact in other disciplines such as pediatrics, psychiatry, or infectious diseases.

References

1. Graus F, et al. A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol. 2016 Apr;15(4):391–404. doi: 10.1016/S1474-4422(15)00401-9. Epub 2016 Feb 20.

2. Armangue T, et al. Frequency, symptoms, risk factors, and outcomes of autoimmune encephalitis after herpes simplex encephalitis: a prospective observational study and retrospective analysis. Lancet Neurol. 2018 Sep;17(9):760–772. doi: 10.1016/S1474-4422(18)30244-8. Epub 2018 Jul 23.

3. Dalmau J, Graus F. Antibody-mediated encephalitis. N Engl J Med. 2018 Mar 1;378(9):840–851. doi: 10.1056/NEJMra1708712.

4. Venkatesan A, et al. Acute encephalitis in immunocompetent adults. Lancet. 2019 Feb 16;393(10172):702–716. doi: 10.1016/S0140-6736(18)32526-1. Epub 2019 Feb 14.

5. Armangue T, et al. Associations of paediatric demyelinating and encephalitic syndromes with myelin oligodendrocyte glycoprotein antibodies: a multicentre observational study. Lancet Neurol. 2020 Mar;19(3):234–246. doi: 10.1016/S1474-4422(19)30488-0. Epub 2020 Feb 10. Erratum in: Lancet Neurol. 2020 Apr;19(4):e4.

Learning Objectives

• Describe the general clinical features of autoimmune encephalitis and the diagnostic and therapeutic approach

• Explain the difference between cell-surface and intracellular neural antibodies and their implications

• Discuss the role of potential triggers of paraneoplastic and post-infectious syndromes