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Diagnosis of Exclusion


HE is a diagnosis of "exclusion."

Alternative diagnosis

must be ruled out (examples):

  • Toxic, infectious or metabolic causes.

  • Nutrient deficiencies (especially B vitamins- potentially masked by MTHFR gene variants)

  • Other autoimmune encephalitis with known antibodies (see here)

  • Traditional (non-autoimmune) epilepsy

  • Complications of thyroid disease

  • Migraine variants

  • Parathyroid tumors

  • Adrenal insufficiency



Testing blood and spinal fluid for:

  • Antithyroid autoantibodies including Thyroid Peroxidase Antibody (TPO) or Thyroglobulin Antibody (TgAb)


  • Thyroid and Stimulating Hormone Receptor Antibody (TRAb)


  • Check for the presence of other antibodies associated with cognitive or psychiatric symptoms such as Anti-NMDA Receptor (NMDAR) encephalitis or other AE's. (See here)


  • Vital lab tests to rule out life-threatening or debilitating conditions such as viral or bacterial encephalitis, meningitis or Creutzfedt-Jakov disease. 


  • Check for presence of inflammation markers such as C-reactive protein or erythrocyte sedimentation rate (ESR)


  • Protein levels


  • Glucose levels


  • Oligoclonal bands


  • Opening pressure in the CSF


  • Checked for significant vitamin deficiency


  • Presence of heavy metals

PET or SPECT scans to look for hypoperfusion or hypometabolism

MRI to check for evidence of physical damage to brain

EEG to look for evidence of seizure-activity or of noticeable slight slowing

Neuropsychological testing to objectively identify specific areas and degrees of impairment.

MAYO Clinic Lab Panel: Spinal Fluid

Encephalopathy, Autoimmune/Paraneoplastic Evaluation, Spinal Fluid

MAYO Clinic Lab Panel: Serum

Encephalopathy, Autoimmune/Paraneoplastic Evaluation, Serum

with US

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