We welcome the review of Hashimoto encephalopathy (HE) by Chong et al1 and share their concern regarding the indiscriminate use of this poorly defined term. There is sparse evidence for the pathogenicity of antithyroid antibodies in this condition: HE has been associated with variable titers of either thyroglobulin or microsomal antibodies, and these antibodies have different antigenic targets. We agree that HE is likely to represent a heterogeneous group of disorders, probably due to a variety of autoimmune causes, with thyroid antibody elevation being a bystander effect. It is interesting to speculate whether some of the patients might have had the recently described encephalopathy associated with voltage-gated potassium channel antibodies.2,3