探讨酷似免疫性脑炎的线粒体脑肌病伴乳酸酸中毒及卒中样发作(MELAS)综合征的临床、神经电生理及影像学改变的诊断学特征，总结诊疗过程。

回顾性分析1例酷似免疫性脑炎的MELAS综合征的发病过程及临床资料，并复习相关文献。

患儿曾以发热、头痛、恶心、呕吐、视物模糊、眼球阵挛、步态不稳等相似症状分别于3，6个月前误诊为病毒性脑炎、免疫性脑炎两次住院，经治疗症状逐渐好转出院。现以相同症状加重并出现视物不清、行走困难再次入院。检查脑脊液常规及抗N-甲基-D-天冬氨酸受体(NMDA-R)抗体阴性，脑电图显示右侧枕部、后颞部大量散发－阵发性棘波/棘慢复合波、尖波/尖慢复合波，可波及右侧顶部；头颅磁共振(MRI)表现多样，可累及皮质和髓质，以灰质为主，表现为脑回明显肿胀，脑沟变窄、变浅，DWI呈弥散受限高信号，晚期脑组织可出现局部软化、脑萎缩改变，病灶可反复出现，基因检测A3243G位点突变，最终确诊为MELAS综合征。

临床症状酷似免疫性脑炎的患儿，遇有病情不稳、症状反复出现，应做进一步检查，排除或确诊是否为MELAS综合征。

To explore the clinical, electrophysiological and imaging characteristics of a case of mitochondrial encephalomyopathy with lactic academia and stroke-like episodes (MELAS) syndrome mimicking an autoimmune encephalitis and summarize the treatment process.

The pathogenesis and clinical data one case of MELAS syndrome mimicking an autoimmune encephalitis was analyzed retrospectively, and relevant literatures were reviewed.

The patient was admitted to hospital for fever, headache, nausea, vomiting, blurred vision, eye myoclonus, ataxia and other symptoms twice 3 and 6 months ago, and misdiagnosed as viral encephalitis and autoimmune encephalitis.The symptoms gradually improved after treatment and discharged.The patient was transferred to our hospital for the third time, because of blurred vision and difficult walking.Routine examination of cerebrospinal was performed and anti-N-methyl-D-aspartate receptor (NMDAR) antibody was negative.EEG showed the right side of the occipitalia, posterior temporal distributed a large number sporadic-paroxysmal spikes/spike slow wave complex, spike/sharp slow wave complex, which could be spread to the top of the right side.MRI showed temporal gyrus was markedly swollen, sulci was narrower and lighter.DWI showed high signal, local softening in the left temporal occipital cortex, genetic testing showing A3243G mutation, eventually diagnosed as MELAS syndrome.

Children whose clinical symptoms resemble autoimmune encephalitis, should be given further examination to rule out or confirm the diagnosis of MELAS syndrome in case of illness instability and recurrent symptoms.