Rapid Review: anti-NMDA receptor encephalitis

In the Rapid Review series I briefly review the key points of a clinical review paper.

The topic: anti-NMDA receptor encephalitis

The paper: Lasoff D, Vilke G, Nordstrom K, Wilson M. Psychiatric Emergencies for Clinicians: Detection and Management of Anti-N-Methyl-D-Asparate Receptor Encephalitis. The Journal of emergency medicine. 51(5):561-563. 2016. PMID: 27431869

What is it?

This is an autoimmune encephalitis caused by antibodies that are directed at the NMDA receptor.

How common is it?

Although rare, it is thought to be more common than herpes encephalitis, so it should definitely be on your radar.

What are the symptoms?

No finding on history or physical is specific for the disease. It seems follows a general pattern:

  1. Viral-like prodrome: fever, fatigue, headaches, nausea and vomiting
  2. Psychiatric symptoms: hallucinations, depression, and paranoia
  3. Neurologic symptoms: movement disorders, speech difficulties, seizures, and potentially coma
  4. Autonomic instability

That being said, the disease has only recently been described, and we could be missing patients with different presentations, so we shouldn’t be surprised if this symptom complex is adjusted with time.

How do I test for it?

Imaging is not helpful in making the diagnosis. The test of choice is a lumbar puncture, specifically looking for an elevated anti-NMDA antibody titer.

What is the treatment?

Emergency department management is supportive, focusing on control of psychosis, seizures, and autonomic instability. Empiric treatment for meningitis and herpes encephalitis should also be started, as the results of definitive testing will take a while. Ultimately, the patient will require IVIG, steroids, and plasma exchange.

What is the prognosis?

When diagnosed and treated, the majority of patients will improve, but up to 20% will be left with significant neurologic deficits, and mortality is still 4-5%.

Trivia

The syndrome was initially described in healthy young females with teratomas and was thought to be a paraneoplastic syndrome, but we now know that it can be present without a tumor.

Want to hear about this condition from the patient’s perspective? Check out the brilliant book, “Brain on Fire: My Month of Madness” by Susannah Cahalan.

Author: Justin Morgenstern

Community emerg doc, FOAM enthusiast, evidence junkie “One special advantage of the skeptical attitude of mind is that a man is never vexed to find that after all he has been in the wrong.” - William Osler

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