A 14-year-old girl with a 5-year history of hallucinations and depression and a diuagnosis of Hashimoto’s thyroiditis is reported from the Mayo Clinic, Rochester, MN. Thyroid-stimulating hormone (TSH) and anti-thyroid antibody titers were significantly elevated. MRI of the brain showed small T2 weighted white matter changes in the frontal lobe, and SPECT scans showed cerebral hypoperfusion deficits. Corticosteroid therapy resulted in significant clinical improvement and resolution of the MRI and temporal lobe SPECT changes. A review of the literature found a total of 16 cases aged 9 to 17 years, all but 2 being female. Thirteen presented with seizures. Only 2 had primarily behavioral presentations, including the Mayo Clinic case. One child, aged 10 years, had longstanding attentional problems, which improved with steroid treatment. Unlike adult patients and the present case, MRI in pediatric cases is usually reported normal. Relapses and residual cognitive deficits may occur. [1]

COMMENT. Steroid-responsive encephalopathy with Hashimoto’s thyroiditis may present with seizures, myoclonus, focal neurologic deficits, and delusions or hallucinations. TSH and thyroid antibody titers are elevated. Patients are usually female and are euthyroid or hypothyroid. Two subtypes are described: 1) vasculitis type with acute stroke-like episodes and focal neurologic deficits and seizures; and 2) diffuse progressive type, with impairment of mental status, confusion, somnolence, and psychosis. Symptoms and MRI changes respond to steroid therapy. The condition was previously named “Hashimoto’s encephalopathy.”