Hashimoto's encephalopathy masquerading as acute psychosis.

Hashimoto's encephalopathy (HE) is a relapsing, but exquisitely corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis. Although a rare disease, with just over 100 cases reported, it may be under-recognised. Its presentation can be protean with prominent neuropsychiatric features, stroke-like episodes, seizures and myoclonic jerks. Prompt corticosteroid treatment usually leads to rapid recovery. Here we report a patient with HE, initially presenting with florid neuropsychiatric symptoms. Recent developments in the understanding of this condition are discussed.