Reversible cerebral hypoperfusion observed with Tc-99m HMPAO SPECT in reversible dementia caused by hypothyroidism

Clin Nucl Med. 1999 Sep;24(9):666-8. doi: 10.1097/00003072-199909000-00005.


A 69-year-old man had hypothyroid dementia as a result of I-131 therapy and an overdose of methimazole. Tc-99m HMPAO SPECT revealed diffuse cerebral hypoperfusion. The findings of brain SPECT normalized with the disappearance of symptoms and a return to the euthyroid state. There was a 25% or 26% reduction of the mean cerebral blood flow during dementia. This may be the first report in which SPECT brain imaging revealed reversible hypoperfusion associated with reversible hypothyroid dementia.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Antithyroid Agents / adverse effects*
  • Brain / diagnostic imaging
  • Cerebrovascular Circulation
  • Dementia / diagnostic imaging
  • Dementia / etiology*
  • Graves Disease / radiotherapy*
  • Humans
  • Hypothyroidism / complications*
  • Hypothyroidism / etiology
  • Iodine Radioisotopes / adverse effects*
  • Male
  • Methimazole / adverse effects*
  • Radiopharmaceuticals*
  • Technetium Tc 99m Exametazime*
  • Tomography, Emission-Computed, Single-Photon*


  • Antithyroid Agents
  • Iodine Radioisotopes
  • Radiopharmaceuticals
  • Technetium Tc 99m Exametazime
  • Methimazole