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autoimmune encephalomyelitis

Etiology: - NMDA receptor autoantibody - viruses can also induce an autoimmune response - Herpes simplex virus encephalitis can trigger subsequent anti-NMDA receptor encephalitis - LGI1 encephalitis Epidemiology: - women < 35 years Clinical manifestations: - subacute presentation (symptom duration > 5 days) - memory or psychiatric manifestations - behavioral changes, headaches, & fever followed by - altered mental status, seizures, abnormal movements, & autonomic instability [3] - no comorbidities Laboratory: - CSF leukocyte count < 50/uL or CSF protein < 50 mg/dL - NMDA receptor IgG in CSF - LGI1 Ab in CSF - see ARUP consult [1] Radiology: - brain MRI normal (case report) [3] Differential diagnosis: - West Nile virus encephalitis - normal MRI makes West Nile virus less likely - insidious onset, positive nonspecific serum antibodies suggest other diagnosis [2] Management: - intravenous glucocorticoids, intravenous immune globulin - in some cases, plasmapheresis & rituximab - removal of ovarian tumor (if present)

Specific

anti-NMDA receptor encephalitis; NMDAR Ab encephalitis experimental autoimmune encephalomyelitis paraneoplastic encephalomyelitis sensory neuropathy

General

encephalomyelitis

References

  1. ARUP Consult: N-methyl-D-Aspartate (NMDA) type Glutamate Receptor Autoantibody Disorders Anti-NMDA-Receptor Encephalitis The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/n-methyl-d-aspartate-nmda-type-glutamate-receptor-autoantibody-disorders - Anti-NMDA Receptor (NR1) IgG Antibodies https://arupconsult.com/ati/anti-nmda-receptor-nr1-igg-antibodies
  2. Flanagan EP et al. Autoimmune encephalitis misdiagnosis in adults. JAMA Neurol 2022 Nov 28; [e-pub]. PMID: 36441519 PMCID: PMC9706400 Free PMC article https://jamanetwork.com/journals/jamaneurology/fullarticle/2799083
  3. Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025
  4. Granillo A, Le Marechal M, Diaz-Arias L, et al. Development and validation of a risk score to differentiate viral and autoimmune encephalitis in adults. Clin Infect Dis. 2023;76:e1294-e1301. PMID: 36053949