The use of plasma exchange in Hashimoto's encephalopathy: A case report and review of the literature.

Hashimoto's Encephalopathy (HE) is a very rare condition characterized by psychosis, seizures, cognitive fluctuations, and myoclonus. In a few published cases, plasma exchange has been used due to the theoretical removal of antithyroid peroxidase antibodies (anti-TPO), one of the postulated causes of the condition. We report a case of HE treated by plasma exchange where no clinical or neurophysiologic improvement was observed despite documented reduction of the anti-TPO antibody to levels below the limits of laboratory detection. We discuss these findings in the context of the known literature for this disease process.