What is the time course of autoimmune encephalopathy?

From the Guidelines

Autoimmune encephalopathy typically follows a subacute course, with symptoms developing over days to weeks, and the time course of improvement can vary, but with high dose oral steroids, antibody levels will normalize within 3-6 months, and the dose can then be tapered over the next 12 months 1. The disease may fluctuate with periods of improvement and deterioration, and without treatment, symptoms typically worsen progressively, potentially leading to coma or death in severe cases.

• Key factors influencing the time course include:
  • The specific autoantibody involved
  • The severity of the initial presentation
  • The response to immunotherapy
• With appropriate immunotherapy, many patients show improvement within weeks, though complete recovery can take months, and the improvement in memory may take several months to years after the initial presentation 1.
• The mainstay of treatment is supportive care and corticosteroids, and for grade 2 or higher ICANS, corticosteroids are generally used, and patients who do not show improvement within 24 hours should have repeat neuroimaging followed by CSF evaluation including opening pressure measurement, if possible 1.
• First-line treatments include corticosteroids, intravenous immunoglobulin (IVIG), and plasma exchange, and some patients require second-line therapies like rituximab or cyclophosphamide, and approximately 70-80% of patients respond to immunotherapy, but relapses occur in 20-25% of cases, necessitating long-term immunosuppression 1.
• Early diagnosis and prompt immunotherapy initiation are crucial for improving outcomes and reducing the risk of permanent neurological damage, and the disease course varies based on the specific autoantibody involved, for example, anti-NMDAR encephalitis often has a more prolonged recovery period compared to LGI1 antibody-associated encephalitis 1.

From the Research

Time Course of Autoimmune Encephalopathy

The time course of autoimmune encephalopathy can vary depending on the specific type of encephalitis and the treatment approach.

• The study 2 discusses the management of autoimmune encephalitis, including the use of bridging therapy and maintenance immunosuppression, but does not provide specific information on the time course of the disease.
• Another study 3 found that patients with anti-N-methyl-D-aspartate receptor antibody encephalitis who received therapeutic plasma exchange (TPE) had improved modified Rankin scores compared to those who received steroids, with the largest sustained improvement occurring immediately following the third-fifth exchange.
• A study 4 on anti-glutamic acid decarboxylase 65 antibody autoimmune encephalitis found that patients who received intravenous methylprednisolone (IVMP) or immunoglobulin (IVIG) had clinical improvements in the short term, but there was no significant difference between the two treatments in terms of therapeutic response.
• The review 5 highlights the importance of early recognition and treatment of autoimmune encephalitis to improve outcomes and achieve complete recovery, but does not provide specific information on the time course of the disease.
• Another review 6 discusses the clinical spectrum and management of autoimmune encephalitis, including the identification of pathogenic autoantibodies and the importance of early treatment, but does not provide specific information on the time course of the disease.

Treatment Response

The treatment response of autoimmune encephalopathy can also vary depending on the specific type of encephalitis and the treatment approach.

• The study 4 found that the response rates of IVMP and IVIG were 45.56% and 36.71%, respectively, in patients with anti-GAD65 autoimmune encephalitis.
• The study 3 found that TPE was more effective than steroids in improving modified Rankin scores in patients with anti-N-methyl-D-aspartate receptor antibody encephalitis.
• The review 2 discusses the use of maintenance immunosuppression after a second relapse in patients with neuronal surface antibodies or seronegative autoimmune encephalitis, but does not provide specific information on the treatment response.

Clinical Spectrum

The clinical spectrum of autoimmune encephalopathy can be highly heterogeneous, with a wide range of cognitive, seizure, and movement disorder phenotypes.

• The review 6 discusses the clinical spectrum of autoimmune encephalitis, including the identification of pathogenic autoantibodies and the importance of early treatment.
• The review 5 highlights the importance of early recognition and treatment of autoimmune encephalitis to improve outcomes and achieve complete recovery, and discusses the challenges of diagnosing autoimmune encephalitis due to the wide spectrum of clinical presentations.