Steroid-responsive encephalopathy in autoimmune thyroiditis (SREAT) as a differential diagnosis of Creutzfeldt-Jakob disease.

Steroid-responsive encephalopathy in autoimmune thyroiditis (SREAT) is characterised by a wide range of neuropsychiatric symptoms and elevated thyroid antibodies. SREAT can mimic sporadic Creutzfeldt-Jakob disease (sCJD) and distinguishing between both entities is important because SREAT responds to corticosteroids. Data of patients reported to the National Reference Centre for the Surveillance of CJD in Göttingen, Germany between August 1994 and October 2008 was retrospectively reviewed. In the case and control groups, 49 patients had SREAT and 48 had sCJD with elevated thyroid antibodies. Antibodies against thyroid peroxidase were the most common antibodies in both SREAT (86%) and sCJD (88%), followed by antibodies against thyroglobulin (SREAT, 63.3%; sCJD, 39.6%; p = 0.020) and TSH-receptor-antibodies (SREAT, 14.3%; sCJD, 2.1%; p = 0.059). Epileptic seizures were observed more frequently in the SREAT group (SREAT, 44.9%; sCJD, 12.5%; p < 0.001). Dementia (SREAT, 61.2%; sCJD, 100%; p < 0.001), ataxia (SREAT, 44.9%; sCJD, 89.6%; p < 0.001), visual impairment (SREAT, 22.4%; sCJD, 50%; p = 0.005), extrapyramidal disorder (SREAT, 32.7%; sCJD, 60.4%; p = 0.006), myoclonus (SREAT, 38.8%; sCJD, 81.3%; p < 0.001) and akinetic mutism (SREAT, 6.1%; sCJD, 37.5%; p < 0.001) were observed more frequently in sCJD. Cerebrospinal fluid (CSF) pleocytosis was observed more frequently in SREAT patients (SREAT, 33.3%; sCJD, 6.4%; p = 0.001), as was a pathological increase in protein concentration (SREAT, 68.8%; sCJD, 36.2%; p = 0.001). In a case of encephalopathy, the diagnosis of SREAT should also be considered in suspected cases of CJD so as to be able to start corticosteroid treatment quickly.