Hashimoto's encephalopathy (HE) is rarely reported with only a few hundred cases published. Diagnosis is made in patients with an appropriate clinical picture and high antithyroperoxidase (anti-TPO) antibodies after infectious, toxic and metabolic causes of encephalopathy have been excluded. There is little objective data on the neurocognitive impairment in patients with HE and their improvement with treatment. We present the case of a 28-year-old woman with HE. Approach to management was novel as objective neuropsychological assessment was used to assess her clinical condition and response to treatment. Intravenous immunoglobulin (IVIg) as the first-line treatment instead of steroids. She responded well. The case illustrates that a different approach is required for the diagnosis and treatment of HE. A new diagnostic criteria is proposed that includes neurocognitive assessment, serum and CSF antibodies, an abnormal EEG and exclusion of other causes of encephalopathy. Furthermore, treatment should be tailored to the patient.

Clinical Haematology, Nottingham University Hospitals NHS Trust, Nottingham, Department of Haematology, University College Hospital, London, Department of Haematology, Division of Cancer Sciences, School of Medical Sciences, Aintree Hospital NHS Trust, Liverpool, University of Manchester, Manchester, Velindre Cancer Centre, Cardiff, Department of Haematology, Barking, Havering and Redbridge University Hospitals, Essex, Division of Clinical Neuroscience, Radiological Sciences, University of Nottingham, Nottingham, Department of Neuropsychology, Barking, Havering and Redbridge University Hospitals, Essex, Department of Medical Oncology, Southampton General Hospital, Southampton, and Department of Haematology, Beatson West of Scotland Cancer Centre, Glasgow, UK