UMEM Educational Pearls

Category: Critical Care

Title: 2020 Hindsight - looking back at autoimmune encephalitis we may have misdiagnosed for decades

Keywords: Encephalitis, autoimmune, psychosis, movement disorders (PubMed Search)

Posted: 1/24/2020 by Robert Brown, MD (Emailed: 1/28/2020) (Updated: 2/27/2020)
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Takeaways

Dr. Bryan Hayes wrote a Pearl 10/4/2013 to remind us autoimmune encephalitis can present like neuroleptic malignant syndrome.

Dr. Danya Khouja wrote a Pearl 6/28/2017 to inform us autoimmune encephalitis is associated with tumors and can be investigated with serum and CSF antibody panels.

Since those publications, the number of validated autoimmune biomarkers in these panels has increased dramatically. In 2020 we now know, autoimmune encephalitis is at least as common as infectious encephalitis.

Here is how to diagnose it

1. Suspect the diagnosis in patients with subacute/rapidly progressive altered mental status, memory loss, or psychiatric symptoms. It can be mistaken for a new diagnosis of schizophrenia or bipolar disorder. 

2. Look for one or more additional findings: new seizures, focal CNS findings, CSF pleocytosis, MRI findings

3. Exclude other likely etiologies (but try not to get hung up on a positive drug test, especially if drug use was not recent).

Why is this important?

Early treatment with steroids and plasmapheresis can prevent progression of disease (prevent seizures, prevent months-long hospitalizations).

Young girls are especially likely to have teratomas as a cause for the disease. Finding and resecting those tumors is life-saving.

In-Depth

References

Titulaer M, McCracken L, Gabilondo I, et al. Treatment and prognostic factors for long-term outcome in patients with anti-NMDA receptor encephalitis: An observational cohort study. The Lancet Neurology 2013; 12(2):157-165.

Dubey D, Pittock S, Kelly C, et al. Autoimmune Encephalitis Epidemiology and a Comparison to Infectious Encephalitis. Annals of Neurology 2018;83:166-177

Guasp M, Modena Y, Armangue T, et al. Clinical features of seronegative, but CSF antibody-positive, anti-NMDA receptor encephalitis. Neurology: Neuroimmunology and Neuroinflammation 2020; 7(2):e659-664.