Post-Encephalitic Parkinsonism

Synonyms:

Encephalitis lethargica a.k.a. postencephalitic parkinsonism a.k.a. Von Economo encephalitis:

Diagnosis:

Clinical:

  • Prodrome: pharyngitis
  • Subacute sleep disturbance (hypersomnolence, reversal of diurnal sleep pattern or insomnia), ophthalmoparesis, lethargy
  • Followed by: Parkinsonism, dyskinesia, oculogyric crisis, neuropsychiatric symptoms and central respiratory abnormalities

Pathology:

  • Midbrain and basal ganglia: lymphocyte (predominantly plasma cell) infiltration

Investigations to consider:

CSF:

  • Oligoclonal bands
  • Protein: Elevated

MRI:

  • FLAIR hyperintensity: Midbrain & periaqueductal grey. Also in Thalamus & putamen

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