Brain hypoperfusion on Tc-99m-ethylene dicysteine diethyl ester single-photon emission computed tomography in Hashimoto's encephalopathy
We present a 17-year-old female who had an acute episode of left-sided weakness and hypoesthesia and dysphasia for around 15 min. It was associated with progressive right frontal headache and vomiting. As past medical history, she had recently been diagnosed of autoimmune hyperthyroidism, but she had undergone no treatment. Laboratory evaluation showed high free T4 (FT4) (26 pg/ml, normal 8-18) and remarkably elevated serum levels of antithyroperoxidase (3,228 Ul/ml, normal < 60) and antithyroglobuline antibodies (>22,200 UI/ml, normal < 280). Since clinical features were unspecific, it was necessary to exclude causes of encephalopathy (infectious, metabolic, toxic, vascular, neoplastic, paraneoplastic, etc.). Both brain computed tomography (CT) scan and magnetic resonance imaging (MRI) showed normal findings. Patient was noted to have elevated cerebral spinal fluid (CSF) protein as well as diffuse slowing on electroencephalogram (EEG). A brain SPECT 45 min after injection of 68.8 MBq (18.6 mCi) of Tc-99m ECD was performed. Projection data were obtained on a gamma camera millennium VG (GE, Medical Systems, USA) in a 128 × 128 matrix using zoom of 1.5, 64 views, 20 s/view. SPECT images showed diffuse and patchy defects of the cortical uptake [].\nWith all these findings, HE was diagnosed and steroid therapy was initiated. Clinical symptoms disappeared and there was a decrease in antithyroid antibody levels. Treatment for hyperthyroidism was started with antithyroid drug and titers of FT4 normalized. A repeat brain SPECT was performed 3 months later with the injection of 66.6 MBq (18.0 mCi) of Tc-99m ECD using a dual-head gamma camera (Elscint Helix, GE Medical Systems, USA). The data acquisition parameters were 64 × 64 matrix using ×2 zoom, 64 views, 20 s/view. SPECT images showed small uptake defects, but demonstrating significant improvement of perfusion respect from the previous study [].\nAfter 3 years of follow-up, patient remains free from relapse or recurrence of the neurological symptoms.