Hashimoto encephalopathy (HE) is a steroid-responsive, acute or subacute encephalopathy, characterised by autoimmune thyroiditis associated with elevated antithyroid antibody titres. An 11-year-old girl was admitted to the Department of Paediatrics with generalised tonic-clonic seizures, left facial paralysis and right hemiparesis. Ceftriaxone and acyclovir were applied, and methyl prednisolone 2 mg kg−1 day−1 was administered orally. The hemiparesis improved on the 3rd day of treatment, but the facial paralysis persisted into the 15th day. When she developed somnolence, she was transferred to the paediatric intensive care unit and provided with respiratory support after intubation. Antithyroid peroxidase (Anti-TPO) and Antithyroglobulin antibody (Anti-Tg) levels were measured at 112.3 IU mL−1 and 74.6 IU mL−1, respectively. HE was considered as the provisional diagnosis, for which intravenous methyl prednisolone 30 mg kg−1 for 5 days followed by prednisolone 1.5 mg kg−1 day−1 were administered. The patient’s clinical status did not improve; therefore, she underwent therapeutic plasma exchange (1/1 ratio) for 8 days, followed by intravenous immunoglobulin 1 gr kg−1 for 2 days. As her clinical condition did not improve, rituximab and endoxane treatments were planned. Unfortunately, these treatments were postponed as she developed ventilator-associated pneumonia at the follow-up. She developed septic shock on the 14th day of follow-up, and noradrenaline and dopamine infusions were commenced. Despite all the efforts, she remained unresponsive and died from cardiac arrest. By reporting this case, we aimed to stress that HE should be considered as an aetiology of encephalopathy when infectious, neoplastic, autoimmune, toxic and metabolic causes are excluded.

Keywords: Hashimoto encephalopathy, thyroid autoantibodies, children