Box 1.

Diagnostic criteria for possible autoimmune encephalitis6

Diagnosis can be made when all three of the following criteria have been met.

  • Subacute onset (rapid progression of less than 3 months) of working memory deficits (short-term memory loss), altered mental status or psychiatric symptoms.

  • At least one of the following:

  • new focal CNS findings

  • seizures not explained by a previously known seizure disorder

  • CSF pleocytosis

  • MRI features suggestive of encephalitis.

  • Reasonable exclusion of alternative causes (eg HSV encephalitis).

  • CNS = central nervous symptoms; CSF = cerebrospinal fluid; MRI = magnetic resonance imaging.