Hashimoto encephalopathy with pegylated interferon alfa-2b and ribavirin.

Objective: To report an instance of Hashimoto encephalopathy probably resulting from pegylated interferon alfa-2b and ribavirin.

Case Summary: A 36-year-old woman with a 10-year history of autoimmune thyroiditis presented with symptoms and signs consistent with Hashimoto encephalopathy during therapy with pegylated interferon alfa-2b and ribavirin for chronic hepatitis C.

Discussion: Hashimoto encephalopathy is a rare autoimmune condition that occurs in patients with Hashimoto thyroiditis and high titers of antithyroid antibodies.