Autoimmune Encephalopathy Associated With Anti-thyroid Antibodies: A Case Report.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), also known as Hashimoto encephalopathy (HE), is a rare condition. HE is characterized by abnormal brain function associated with elevated titers of anti-thyroid peroxidase (anti-TPO) and/or anti-thyroglobulin (anti-Tg) antibodies. We present a case of a 19-year-old female with rapidly progressing psychosis with mutism, catalepsy, echopraxia, and catatonia that developed over the course of three months. She was found to have high-level anti-thyroid antibodies raising suspicion of subclinical autoimmune thyroiditis and positive antinuclear antibodies. Imaging of the brain revealed generalized cerebral atrophy abnormal for her age. The patient was aggressively treated with corticosteroids and immunomodulators and her symptoms were greatly improved. This case emphasizes the significance of thyroid antibody measurement in patients presenting with psychiatric symptoms to evaluate patients for autoimmune encephalitis, since treatment with steroids and other immunosuppressive agents may be warranted.