Question 12

In a suspected case of autoimmune encephalitis:

a)    List the investigations needed, and explain why they are required.    (50% marks)

b)    Outline a specific management plan for proven autoimmune encephalitis and its common complications. Do not include resuscitation in your answer.    (50% marks)

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College answer

Not available.


a) Investigations listed here are partly to to confirm the diagnosis of autoimmune encephalitis, and partly to exclude other competing differentials. 

CT brain 

  • To exclude structural brain lesions (stroke, haemorrhage, abscess)
  • To exclude the possibility of raised intracranial pressure for the LP that follows

LP and CSF analysis

  • Opening pressure, cell count with differential, protein, glucose (this helps exclude infections causes, and can reveal characteristic patterns)
  • Gram stain and bacterial culture (to exclude meningitis)
  • Specific infectious PCR on CSF
    • HSV-1/2 PCR (if test available, consider HSV CSF IgG and IgM in addition)
    • VZV PCR 
    • Enterovirus PCR
    • Cryptococcal antigen or India ink staining
    • VDRL for syphilis
    • Mycobacteria PCR
  • Specific autoimmune biomarkers in the CSF
    • Oligoclonal bands and IgG index
    • Numerous antibodies (see above) which are diagnostic for autoimmune encephalitis

Peripheral blood tests

  • Blood cultures (to exclude systemic sepsis and septic encephalopathy)
  • HIV serology (consider RNA)
  • Treponemal testing (rapid plasma reagin, specific treponemal test)
  • Autoimmune vasculitis screen (to exclude cerebral vasculitis)


  • MRI - because autoimmune encephalitis may have a characteristic pattern
  • CT imaging of the whole body, looking for:
    • Occult malignancy (associated with many types of autoimmune encephalitis)
    • Lymphadenopathy, granulomatous disease, etc (suspicion of TB) 


  • EEG

Other tissues/fluids

  • When clinical features of extra-CNS involvement are present, this may be appropriate (e.g., biopsy of skin lesions; bronchoalveolar lavage or endobronchial biopsy)


Management options for autoimmune encephalitis, and their complications:

  • High dose ("pulse") methylprednisolone or dexamethasone
    • Hyperglycaemia
    • Insomina, agitation, psychosis
    • Fluid retention
    • Muscle wasting, delayed weaning from ventilation
    • Impaired wound healing
    • Increased propensity to infection (eg. PJP)
  • Rituximab
    • Long term loss of humoral immunity
    • Infusion reaction
    • Lymphopenia
  • Cyclophosphamide
    • Bone marrow suppression
    • Renal tubular necrosis
    • Pulmonary fibrosis
    • Haemorrhagic cystitis
  • IV immunoglobulin
    • Risk of anaphylaxis
    • Large hyperoncotic fluid load (circulatory overload)
  • Plasmapheresis
    • Bleeding complications of anticoagulation and vascular access
    • Haemolysis and thrombocytopenia
    • Hypothermia and complement activation
    • Febrile reaction to replaced blood products
    • Unavoidable removal of useful blood components (eg. useful drugs)
    • Hypotension due to volume loss


Dalmau, Josep, and Myrna R. Rosenfeld. "Autoimmune encephalitis update." Neuro-oncology 16.6 (2014): 771-778.

Venkatesan, Arun, and Romergryko G. Geocadin. "Diagnosis and management of acute encephalitis: A practical approach." Neurology: Clinical Practice 4.3 (2014): 206-215.

Granerod, J., et al. "Causality in acute encephalitis: defining aetiologies." Epidemiology & Infection 138.6 (2010): 783-800.


Singh, Tarun D., Jennifer E. Fugate, and Alejandro A. Rabinstein. "The spectrum of acute encephalitis: causes, management, and predictors of outcome." Neurology 84.4 (2015): 359-366.