Abstract: Objective：To summarize the clinical features of Hashimoto's encephalopathy (HE) in children. Methods：Children diagnosed with HE hospitalized in the Department of Neurology at Hebei Children's Hospital from January 2017 to December 2020 were selected. The clinical characteristics, laboratory examination results, imaging results, treatment and prognosis of the disease were retrospectively analyzed. Results：Among the 7 HE patients, there were 5 males with onset age of 5 to 12 years. Three cases had fever at the onset of the disease. Before the onset of the disease, infection, viral encephalitis, hyperappetite and increased defecation, and epilepsy were found in 1 case, respectively. Three cases had depileptic seizure and 2 of them were epileptic status. Three cases had abnormal mental behavior and 3 had consciousness change. One patient had cranial nerve injury. One case had increased WBC and CRP. CSF cells increased in 3 cases, and CSF protein increased in one case. The oligoclonal bands were positive in 2 of 5 cases receiving the examination. Thyroid peroxidase (TPO) antibodies were normal in 4 patients at the onset of the disease, but increased when the disease was aggravated within two weeks. Three cases had increased TPO antibodies at the onset of the disease. There were 2 cases of hyperthyroidism, 2 cases of central hypothyroidism, 1 case of low T3 syndrome, and 1 case of reduced free T3 and T4. One patient had normal thyroid function at the time of admission and central hypothyroidism occurred later. Thyroid ultrasound showed polycystic nodules in two cases. Three cases had cranial MR abnormality. Seven cases were abnormal in video electroencephalogram, showing different degrees of slow wave release, and 1 case was epileptic. All 7 cases were treated with immunoglobulin shock combined with high-dose methylprednisolone sodium succinate. The symptoms of 6 cases were relieved after 3 to 8 days of treatment and 1 case remained unchanged after 1 month of shock treatment, whose symptoms were relieved after 7 days of the second round of hormone shock treatment. Seven cases had been followed up for 1 to 4 years. One case recurred twice, and the symptoms were relieved after hormone or immunoglobulin shock treatment. Three patients with abnormal cranial MR were followed up within 2 months, and the imaging returned to normal. TPO antibodies were reexamined in 4 cases, thyroid function was followed up in 3 cases, and the relevant indexes returned to normal within 1 year. Conclusion：The clinical manifestations, laboratory indicators and imaging characteristics of HE are not specific, so it is necessary to distinguish it from various diseases. For pediatric patients with unknown encephalopathy, the possibility of HE should be considered after excluding autoimmune encephalitis, inflammation and demyelination diseases , and TPO antibodies should be detected for many times to assist in the diagnosis.

Key words: Hashimoto encephalopathy, Children, Thyroid peroxidase antibody