Psychosis and EEG abnormalities as manifestations of Hashimoto encephalopathy

Hashimoto encephalopathy (HE) is a distinct form of encephalopathy, which can manifest itself with purely psychiatric symptoms. A 38-year-old female with history of rheumatoid arthritis was treated with psychotropic drugs for a couple of years in psychiatric structures because of the onset of depressive symptoms, psychoticlike manifestations, and impairment of cognitive functions. The electroencephalography (EEG) was characterized by general slowing with high voltage (2 to 3 Hz) delta biphasic and triphasic waves. Once a firm diagnosis of HE was made, corticosteroid treatment resulted in resolution of her psychiatric symptoms, marked EEG improvement, and partial improvement in her cognitive functions. HE should be suspected in young females with history of autoimmune disorders and EEG abnormalities.