Retrospective analysis of NMDA receptor antibodies in encephalitis of unknown origin

Authors:
  • JDJ. Dalmau
    J. Dalmau
  • LHL. Harms
    L. Harms
  • MHM. Höltje
    M. Höltje
  • GAG. Ahnert-Hilger
    G. Ahnert-Hilger
  • KBK. Borowski
    K. Borowski
  • WSW. Stoecker
    W. Stoecker
  • KWK.P. Wandinger
    K.P. Wandinger

Abstract
Background: Anti-NMDA-receptor (NMDAR) encephalitis is a severe disorder that occurs in association with antibodies to the NR1 subunit of the NMDAR and results in a characteristic syndrome. Objective: To determine in a single institution setting whether patients previously diagnosed with encephalitis of unknown origin had anti-NMDAR encephalitis. Methods: Charts of 505 patients aged 18 to 35 years admitted to the intensive care unit (ICU) during a 5-year period were retrospectively reviewed for criteria of encephalitis of unknown etiology. These included encephalitic signs with psychiatric symptoms (agitation, paranoid thoughts, irritability, or hallucinations); seizures; CSF inflammation; and exclusion of viral or bacterial infection. Archived serum and CSF samples of patients fulfilling these criteria were examined for NMDAR antibodies. Follow-up visits allowed the analysis of the natural disease course and estimation of prognosis. Results: Seven patients (all women) fulfilled the indicated criteria; 6 of them had NMDAR antibodies. Ovarian teratomas were detected in 2 patients, in one 3 years after the onset of encephalitis. Outcome was favorable in all patients. One patient without teratoma improved spontaneously along with disappearance of NMDAR antibodies. Conclusions: Anti-NMDAR encephalitis represented 1% of all young patients9 admissions to the ICU. Six of 7 cases with the indicated clinical criteria had anti-NMDAR encephalitis. NMDAR antibodies should be tested in all patients with encephalitis who fulfill these criteria.

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