To analyze the clinical features of the leucine-rich glioma-inactivated 1 protein (LGI1) antibody related encephalitis in children and review the literature.

From March to November 2016, in Department of Neurology of Children′s Hospital, Capital Institute of Pediatrics, and Beijing Tian Tan Hospital, two cases of LGI1 antibody related encephalitis children (patient 1 and patient 2) were chosen as research objects. Case data of 2 children were analyzed and clinical features of disease were summarized. With the following key words of ＂leucine rich glioma inactivation 1 protein＂ and ＂immunity encephalitis＂ in Chinese, ＂LGI1＂ ＂leucine-rich glioma-inactivated 1 protein＂ and ＂autoimmune diseases of the nervous system＂ in English, literature of anti-LGI1 antibody related encephalitis were searched from WanFang data knowledge service platform, the medical knowledge network, PubMed database, and National Center for Biotechnology Information, literature retrieval time start from the establishment of database to October 2017, and clinical features of searched literature were summarized. This study was consistent with the World Medical Association Declaration of Helsinki revised in 2013.

①Patient 1 was a 8 years old boy, who was the youngest child currently reported to have anti-LGI1 antibody related encephalitis. Chief complaint was ＂night sleep reduced for 50 days＂, the mainly clinical manifestations were night sleep reduced and accompanied by night excitement, no abnormal family history and growth history, no abnormal neurophysical examination. Head MRI showed left hippocampal lesions. Cerebrospinal fluid and serum anti-LGI1 antibody were positive. After treated by intravenous injection of human immunoglobulins (IVIG) and prednisone, the clinical manifestations and head MRI of the child were improved obviously. ②Patient 2 was a 15 years old boy and chief complaint was＂paroxysmal seizures for 7 days＂, the main clinical manifestation was tic, tic form were complex partial seizure and tonic-clonus secondary to partial seizures, not accompanied with memory decline, cognitive disorders, mental disorders, sleep disorders and movement disorders, and serum anti LGI1-IgG antibody positive (1: 100). This child was treated with IVIG and levetiracetam tablets, follow-up for more than 1 year without nerve system and mental symptoms, and with good academic performance. ③ With the retrieval strategy we setting up, literature retrieval results showed that only 3 foreign literature reported anti-LGI1 antibody related encephalitis involving 3 cases of patients of age under 18 years old as 14, 15, 17 years old, respectively. The clinical symptoms of 14 years old anti-LGI1 antibody related encephalitis child were recent memory disorder and mental behavior disorder, who was the youngest child with anti-LGI1 antibody related encephalitis currently reported in public.

The 8-year-old child in this study was the youngest child with anti-LGI1 antibody related encephalitis currently reported at home and abroad. The clinical manifestations of children with anti-LGI1 antibody related encephalitis can be simply onset with sleep disorder or seizure disorder, and head MRI performance has the typical characteristics, the effect of IVIG and glucocorticoid therapy is good.