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目的:总结线粒体脑肌病伴高乳酸血症和卒中样发作（MELAS）患者的临床影像病理特征，旨在提高该罕见病的诊疗水平。方法:病例系列研究。收集2012年至2021年在南京大学医学院附属鼓楼manbet官网登录 确诊的35例MELAS病例，总结其临床表现、影像学、肌肉活检、基因检测以及治疗转归结果。数据采用平均值、标准差、频率百分比的形式进行描述性统计分析。结果:35例MELAS患者发病年龄为（30.2±2.3）岁，20%有家族史。首发症状以肢体无力、肢体抽搐常见；神经肌肉系统症状以近端肌无力和运动不耐受为主；神经肌肉系统之外的其他系统症状以内分泌系统（糖尿病）受累最多。5例患者行头颅CT检查，示低密度灶4例、钙化灶2例。26例患者行头颅MRI示病灶区累及顶叶、基底节区、颞叶、枕叶、额叶等部位；较少累及幕下；其中12例出现不同程度的脑萎缩。10例患者行头颅 1H-MRS，9例出现NAA峰减低，8例出现异常乳酸峰，6例同时出现NAA减低合并乳酸峰。31例患者行基因检测，25例检测到mt.3243A>G突变，其余6例为其他罕见突变。21例患者行肌肉活检，15例病理肌活检观察到代表线粒体异常增殖的破碎红纤维和代表氧化磷酸化障碍的COX酶缺陷型肌纤维。 结论:MELAS综合征患者的临床表现具有多样性及复杂性，早期症状容易误诊和漏诊。详细的临床病史、影像波谱和肌活检、基因检测是MELAS确诊的必要条件。

Objective:To summarize the clinical, imaging, and pathological characteristics of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS) to improve the diagnosis of this rare disease.Methods:A retrospective case series was conducted to collect the clinical data and results of genetic testing, muscle biopsy, and imaging studies including computed tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRS) of 35 patients with MELAS admitted to the Nanjing Drum Tower Hospital from 2012 to 2021. Descriptive statistical analysis including mean, standard deviation, and frequency percentage were carried out.Results:The average age of onset of the patients was 30.2±2.3 years; the prevalence of family history was 20%. The two main initial symptoms were limb weakness and convulsions. The clinical manifestations of the neuromuscular system were proximal muscle weakness and exercise intolerance. The endocrine system is the most affected outside the neuromuscular system, with diabetes being the most common condition. Among the five patients who underwent brain CT, four showed hypodense lesions and two had calcified lesions. Brain MRI in 26 patients showed that the lesions more often affected the parietal lobe, basal ganglia, temporal lobe, occipital lobe, and frontal lobe than the infratentorial areas. Twelve of these individuals exhibited different levels of brain atrophy. Among the 10 patients who underwent 1H-MRS, nine showed a decrease in N-acetylaspartate (NAA) levels, eight exhibited abnormal lactate elevation (Lac peaks), whereas six had both reduced NAA levels and the presence of Lac peaks. Thirty-one patients underwent genetic testing; among them, 25 were found to have the mt.3243A>G mutation, while the remaining six exhibited rare gene alterations. Muscle biopsies were performed in 21 patients, and 15 showed abnormal mitochondrial proliferation manifested by ragged red fibers and defective oxidative phosphorylation manifested by cytochrome C oxidase (COX) enzyme-deficient muscle fibers. Conclusion:The clinical manifestations of MELAS syndrome are variable and complex, and early atypical symptoms could be missed or misdiagnosed. A detailed clinical history, imaging MRS analysis, muscle biopsy, and genetic testing are necessary to confirm the accurate diagnosis of MELAS.