[Clinical Features and Treatment of Hashimoto Encephalopathy]

Hashimoto encephalopathy (HE) is characterized by heterogeneous neurological symptoms. HE is diagnosed based on three criteria-the presence of antithyroid antibodies, neurological symptoms from the cerebrum and/or cerebellum, and a positive response to immunotherapy. We clinically analyzed 18 patients (3 men, 15 women; age range, 38-81years) diagnosed with HE in our hospital from May 2013 to January 2016. Eleven patients showed sensory abnormalities such as strong pain, deep muscle pain, dysesthesia, paresthesia, or neuralgia. Surprisingly, the majority of the pain was distributed in a manner that was not explainable anatomically. Seventeen patients showed motor disturbances, such as weakness, paresis of extremities, or dexterity movement disorder, and eight patients showed give-way weakness, which is disruption of continuous muscle contraction. Other symptoms indicative of brain-related anomalies such as tremor, dystonia, involuntary movements, cerebellar ataxia, parkinsonism, memory loss, and chronic fatigue were also seen. In most patients, such motor, sensory, or higher brain functions were markedly improved with immunosuppressive therapies such as prednisolone, azathioprine, or immunoadsorption therapy. Although give-way weakness and anatomically unexplainable pain are typically considered as being psychogenic in origin, the presence of these symptoms is indicative of HE. HE exhibits diffuse involvement of the entire brain and thus, these symptoms are explainable. We propose that physicians should not diagnose somatoform disorders without first excluding autoimmune encephalopathy.