Pathogenesis → antibodies against NMDA receptor

Epidemiology → Early 20s or pediatrics; female predominance

Clinical → often present with bizarre behavior or AMS or “weird movements”

• About 60% have to have cancer → paraneoplastic → ovarian teratoma most common
• Initial flu like prodrome that progress overs 1-2 weeks to psychosis, AMS, dyskinesias/
  choreiform, seizures
• Increased muscle tone, memory problem
• New psych symptoms → hallucinations, paranoia, agitation
• Autonomic instability → tachycardia, hypertension, hypoventilation

Differential Diagnosis → When considering Meningitis/ Encephalitis v. Brain mass v. Endocrine emergency v.
Serotonin Syndrome/ Neuroleptic Malignant Syndrome v. Ketamine/ PCP intoxication - consider
NMDA receptor

Diagnosis → CSF (100% sensitive) and serum (85% sensitive); send for a NMDA-R antibody

• MRI abnormal in 40% of cases but very non-specific; EEG non-specific
  Management = supportive care + high dose steroids/ GC/ IVIG/ plasma exchange
• Pelvic US needed as inpatient, along with cancer work up
• Prognosis → 75% cured with zero to mild deficits; 7% mortality

References

• Lawrence JE, Fountain DM, Agius M. Anti-NMDA Encephalitis in the Acute Setting. Psychiatr Danub. 2014;26 Suppl 1:269-272