Hashimoto's encephalopathy: an unusual cause of seizures in the intensive care unit.

OBJECTIVE To present a case study of Hashimoto's encephalopathy. DESIGN Case report. SETTING Paediatric Intensive Care Unit, Nottingham University Hospital, UK. PATIENTS Two adolescent females presented with encephalopathy and raised venous lactate. Both had subtle signs of neurocognitive deterioration before initial presentation. Extensive investigation revealed elevated antithyroid antibody titer, suggesting Hashimoto's encephalopathy. INTERVENTIONS Steroid administration. MEASUREMENTS AND MAIN RESULTS Symptoms rapidly resolved in both cases after steroid treatment. CONCLUSION Hashimoto's encephalopathy should be considered in cases of unexplained encephalopathy presenting to the intensive care unit. Teenage girls with an antecedent history suggestive of thyroid disease or progressive cognitive decline warrant special attention. Antithyroid antibody titers should be measured even if standard thyroid function tests are normal. Although the etiology is unknown, prompt steroid responsiveness suggests an inflammatory or autoimmune disorder, and patients should be treated accordingly.