Improvement of Cerebral Hypoperfusion with Levothyroxine Therapy in Hashimoto's Encephalopathy Demonstrated by (99m)Tc-HMPAO-SPECT.

BACKGROUND Hashimoto's encephalopathy (HE) is a rare immune-mediated encephalopathy associated with autoimmune Hashimoto's thyroiditis. OBJECTIVES AND METHODS We report on a patient with HE and significant clinical improvement correlating with an increase in cerebral blood flow demonstrated by hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT). HMPAO-SPECT was performed with 740 MBq of technetium-99m-HMPAO. To demonstrate the improvement in regional cerebral blood flow, individual regions of interest were drawn around visually diminished HMPAO uptake, the lesion to reference region ratio was calculated and transverse section images and semi-quantitative measurements were performed. RESULTS We show a 5-year follow-up with significant clinical improvement, a 10-fold reduction in autoantibodies to thyroid peroxidase and an approximately 20% improvement in cerebral blood flow with HMPAO-SPECT. CONCLUSION Adequate levothyroxine treatment achieving and maintaining euthyroidism should be considered as therapy to lower autoantibodies and improve clinical outcome in patients with Hashimoto's thyroiditis and encephalopathy.