Hashimoto's Encephalopathy Presenting with Smoldering Limbic Encephalitis

Intern Med. 2019;58(8):1167-1172. doi: 10.2169/internalmedicine.1289-18. Epub 2019 Apr 15.

Abstract

Hashimoto's encephalopathy (HE) is a steroid-responsive autoimmune encephalopathy associated with Hashimoto thyroiditis. We herein report a case of HE manifesting "smoldering" limbic encephalitis with persisting symptoms and abnormalities on examinations. Although our patient experienced partial clinical remission after treatment, hippocampal hypermetabolism on [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) and subclinical seizures on video electroencephalography persisted. Hypermetabolism on FDG-PET was improved by additional prednisolone therapy. Thus, as with other autoimmune limbic encephalitis cases, HE can take a course of "smoldering" encephalitis. FDG-PET and electroencephalogram findings can reflect the disease activity degree in such patients, although with certain neurophysiological and biochemical distinctions.

Keywords: FDG-PET; Hashimoto's encephalopathy; anti-NAE antibody; autoimmune limbic encephalitis; video EEG.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Autoimmune Diseases / diagnosis
  • Autoimmune Diseases / physiopathology*
  • Biomarkers / analysis
  • Electroencephalography / methods
  • Encephalitis / diagnosis
  • Encephalitis / physiopathology*
  • Female
  • Hashimoto Disease / diagnosis
  • Hashimoto Disease / physiopathology*
  • Humans
  • Limbic Encephalitis / complications
  • Limbic Encephalitis / diagnosis
  • Limbic Encephalitis / physiopathology*
  • Positron-Emission Tomography / methods

Substances

  • Biomarkers

Supplementary concepts

  • Autoimmune limbic encephalitis
  • Hashimoto's encephalitis