An 85-year-old case with Hashimoto's encephalopathy, showing spontaneous complete remission.

We report an 85-year-old man with Hashimoto's encephalopathy (HE) who showed spontaneous complete remission. The autoantibody against the amino (NH2) terminal region of alpha-enolase was positive in our patient. Neuropsychological manifestations, such as personality change and progressive cognitive impairment, gradually improved over approximately 6 weeks after onset of disease without corticosteroid treatment in parallel with a decrease in the anti-thyroglobulin antibody in the cerebrospinal fluid. HE should be considered as a possible diagnosis even in elderly patients with neuropsychiatric symptoms, particularly when a previous history of thyroid disease is present.