背景：“粒線體腦肌肉病變合併乳酸血症及類中風症候群”的特徵為抽搐和反覆頭痛，成因來自小型腦血管的粒線體失去功能，導致類中風的症狀，為瞭解小兒科病人罹患MELAS症的臨床表現及診斷方法，我們完成本研究。方法：將六位罹患MELAS症的兒童被納入本研究，針對其臨床表徵、實驗室檢查結果作回顧分析。結果：本研究發現，病人全都出現乳酸過高，腦部MRI 影像都呈現腦皮質或基底核缺血和萎縮的異常變化，粒線體基因檢驗的結果，發現六位病患中有四人為3243A>G突變，一人為3291T>C 突變。臨床表徵上的分析如下，發生癲癇性抽搐的有四人佔66%，腦波檢查均呈現局部癲癇波活動及區域性腦皮質功能不良，另外，表現反覆頭痛嘔吐的有四人佔66%，肌肉無力感有兩人佔33%，身高矮小有四人佔66%，認知力障礙有四人佔66%，視野缺陷有三人佔50%，心臟疾病有一人佔16%。結論：MELAS 症常發生抽搐和頭痛，但不一定是最初發的症狀，身高矮小的病患也須考慮粒線體病變的可能性，腦部MRI 影像的異常變化可作為MELAS 症診斷的主要依據，在治療上MELAS 症病
患的癲癇性抽搐常不易控制而反覆發作，甚至造成死亡。

Background and purpose: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a disease characterized by recurrent headaches and epilepsy. The onset of symptoms is referred to as stroke-like episodes that are caused by mitochondrial dysfunction in small cerebral blood vessels. This study was performed to define the clinical features and diagnostic strategies in pediatric patients withMELAS in a medical center in Taiwan. Methods: A retrospective review of 6 patients with a diagnosis of MELAS was conducted with clinical, neuroradiologic, biochemical, and electrophysiologic analyses. Results: According to the biochemical studies, all of the patients had elevated lactic acid during the glucose-loading test. MELAS was initially suspected when magnetic resonance imaging (MRI) reported abnormal signal intensity in the cortex or basal ganglia that revealed cerebral atrophy and an infarction. Genetic testing of peripheral blood confirmed an A3243G transition within mitochondrial (mt) DNA in 4 patients and a T3291C transition in 1 patient. Seizures occurred in 4 cases (66%), and the mean age of onset was 7 years. We also evaluated electroencephalograms (EEGs) of 5 patients including 4 seizure cases and 1 case without seizures. Their EEGs showed focal or multifocal epileptiform activities and regional cortical dysfunction including the patient without seizures. In addition to seizures, there were recurrent headaches and vomiting in 4 cases (66%) and muscle weakness in 2 cases (33%) as early manifestations. Other features revealed a short stature and failure to thrive (66%), visual field defects (50%), cognitive impairment (66%), and cardiac involvement (16%). Conclusions: This study emphasizes that headaches and epileptic seizures are common in MELAS but are not the earliest presenting signs. Children with a short stature should be considered to possibly have a mitochondrial disease. A brain MRI evaluation is very useful in diagnosing suspected mitochondrial diseases. Epileptic seizures inMELAS seem difficult to control leading to frequent attacks in some patients.