Anti-NMDA receptor encephalitis
- generally, affects younger individuals (95% younger than 45, 37% younger than 18)
- Typically, presentation begins with abnormal behavior (psychosis, delusions, hallucinations, agitation, aggression, or catatonia) with irritability and insomnia
- Over weeks followed by speech dysfunction, dyskinesias, memory deficits, autonomic stability, and decreased level of consciousness.
Patients with relapsing symptoms s/p herpes simplex encephalitis should also be tested for NMDA receptor antibodies, which is an autoimmune reaction affecting 20% of patients with HSE, manifesting as either new onset choreoathetosis or psychiatric symptoms a few weeks after viral infection.
Diagnosis
Diagnostic criteria for probable anti-NMDA receptor encephalitis
1) Rapid onset (<3 months) of at least 4 of the 6 following major groups of symptoms:
- a. Abnormal (psychiatric) behavior or cognitive dysfunction
- b. Speech dysfunction (pressured, verbal reduction, mutism)
- c. Seizures
- d. Movement disorder, dyskinesias, or rigidity/abnormal postures
- e. Decreased level of consciousness
- f. Autonomic dysfunction or central hypoventilation
2) At least one of the following laboratory study results:
- a. Abnormal EEG (focal or diffuse slow or disorganized activity, epileptic activity, or extreme delta brush)
- b. CSF with pleocytosis or oligoclonal bands
3) Reasonable exclusion of other disorders
Diagnosis can also be made in the presence of three of the above groups of symptoms accompanied by a systemic teratoma.
Diagnostic criteria for definite anti-NMDA receptor encephalitis
1) Diagnosis can be made in the presence of one or more of the six major groups of symptoms and IgG anti-GluN1 antibodies (CSF), after reasonable exclusion of other disorders
References
Graus, F. et al. A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol. 15, 391–404 (2016). https://pubmed.ncbi.nlm.nih.gov/26906964/
