Hashimoto's encephalopathy. Case report and literature review

We present a 43-year-old man with recurrent episodes of Hashimoto's encephalopathy who was diagnosed with autoimmune thyroiditis in childhood. Encephalopathy started with subacute dementia followed by extrapyramidal and psychiatric symptoms of insidious onset. He had also status epilepticus which occurred within the first year of the disease. The patient was in euthyreosis, but increased levels of antithyroid antibodies were found. MRI of the brain was normal. Electroencephalography was initially normal and later showed diffuse slowing with generalized theta/delta activity. The cerebrospinal fluid examination revealed a high level of protein which decreased when remission of the disease was achieved. After other etiology was excluded Hashimoto's encephalopathy was diagnosed. Almost complete clinical recovery after steroid administration was observed. Attempts of prednisone withdrawal led to recurrence of neurological and psychiatric symptoms. The diagnosis of Hashimoto's encephalopathy should be considered in each case with subacute encephalopathy associated with high levels of antithyroid antibodies (despite normal thyroid function) and in the absence of other brain diseases.