MELAS (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes): report of a case

The case of 12 years-old boy with seizures, headache, severe vomit and focal neurological signs is reported. These episodes had several recurrences and regression with little neurologic deficits. In the investigation it was found: lactic acidosis; stroke like episodes and calcification in the basal ganglia on computerized axial tomography; ragged red fibers on muscle biopsy and decreased of cytochrome C oxidase in the muscle tissue. A revision about mitochondrial disorders with involvement of the central nervous system and muscle is made, with emphasis on diagnosis and recognition of MELAS.     

Alzheimer-type pathology in a patient with mitochondrial myopathy,encephalopathy, lactic acidosis and stroke-like episodes (MELAS)

A 53-year-old Japanese woman with a point mutation in mitochondrial DNA (tRNA^Leu(UUR), nt3243) consistent with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and Alzheimer-type brain pathology is reported. This woman had suffered myopathy and psychosis without any clinical evidence of, stroke-like episodes during the last 10 years of her life, and had died after an accident. At autopsy 30 h post mortem, a part of the brain was snap frozen for biochemical and histochemical studies, and the remaining part was processed for a routine examination and electron microscopy. In the brain there were no ischemic lesions. Instead, primitive/diffuse senile plaques were found throughout the brain, predominantly in the frontal and temporal lobes, while Alzheimer neurofibrillary tangles were found only in the parahippocampal gyrus. These plaques were positive for β-protein and mostly negative for tau protein, ubiquitin, neurofilaments, α-choline acetyltransferase, and acetylcholinesterase. Mutations in codon 331 of the ND2 gene as well as codons 693, 713 and 717 of the β-amyloid precursor protein gene, known to be responsible for some cases of familial Alzheimer disease, were not found. Furthermore, coincidental Down syndrome was ruled out by chromosome analysis. The results suggest a possible correlation between this mitochondrial DNA abnormality and Alzheimer-type pathology. Received: 30 January 1996 / Revised, accepted: 26 March 1996     

Acute hearing loss in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS)

The mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a rare congenital disorder of mitochondrial DNA. Patients with this syndrome may present acute onset of sensorineural hearing loss, which is genetic in origin. An impression of the MELAS syndrome is favored because hearing loss is part of the syndrome for some patients with epilepsy. We report a 20-year-old man who suffered from acute onset of bilateral hearing loss with epilepsy and two stroke-like events which recovered without any sequela. Epilepsy with complex partial seizures was controlled by antiepileptic drugs. Brain magnetic resonance images showed high signal lesions in bilateral temporal lobes. Serum levels of pyruvate and lactate were elevated. Muscle biopsy showed ragged-red fibers and molecular genetic study showed a point mutation of the mitochondrial A3243G gene. Mitochondrial disease with the MELAS syndrome was diagnosed and then he was treated with Co-enzyme Q10 and carnitine. The symptoms recovered gradually.     

Intestinal pseudo-obstruction in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) associated with phenytoin therapy

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is most commonly associated with a mitochondrial DNA A to G point mutation at nucleotide 3243 (A3243G) and individuals with the disorder present a wide range of multisystemic symptoms. Seizures in MELAS patients are often intractable and require multiple antiepileptic drugs. Here we report a MELAS patient who presented with acute intestinal pseudo-obstruction following the administration of phenytoin (PHT) as an antiepileptic treatment. She presented with the first stroke-like episode at the age of 6 years and mitochondrial DNA analysis revealed A3243G with 94% mutation load in skeletal muscle. Despite treatment with phenobarbital and clobazam at the age of 16 years, she developed status epilepticus which ceased following PHT infusion. Thereafter, she was started on PHT treatment. One month later, however, she was readmitted because of remarkable abdominal distention. Although abdominal CT showed acute ileus with hepatic portal venous gas mimicking surgical emergency, the abdominal distention gradually recovered over several days following the discontinuation of PHT. Our clinical observations suggest the possibility that intestinal pseudo-obstruction in this patient related to PHT therapy. Careful clinical observation including gastrointestinal symptoms is required in the management of epilepsy in MELAS patients.     

A case of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) with progressive cytochrome c oxidase deficiency

We report a 9 year-old boy with MELAS. High dosed oral thiamine administration and high fat diet induced remarkable neurological and biochemical improvement. His mother had episodic headaches and hemiplegia, probably MELAS. He complained muscle weakness and repeated episodes of vomiting started from 2 years of age. High levels of serum lactate and pyruvate were recognized, but with no metabolic acidosis. He developed generalized muscle weakness, growth retardation, generalized convulsions and stroke-like episodes at 5 years old. Optic nerve atrophy and mental retardation gradually appeared. A muscle biopsy at 5 years old revealed numerous ragged-red fibers with excess accumulation of lipid droplets and glycogen particles. Scattered fibers had no cytochrome c oxidase (CCO) activity representing focal CCO deficiency. An electron microscopy showed markedly increased number of giant mitochondria filled with markedly proliferated complicated cristae. Pyruvate dehydrogenase complex level in the fibroblasts was within normal ranges. Serum carnitine level was normal. With oral administration of thiamine hydrochloride (1000 mg) and high fat diet (60-70%), muscle weakness improved, and lactate and pyruvate levels in the serum reduced to normal ranges, whereas the mental deterioration, muscle atrophy, pes cavus progressed very slowly. He died from cardiac and renal failures at 9 years old. Autopsied muscles showed a marked decrease in cytochrome c oxidase activity (biochemically 12.8% of the normal level), and almost all muscle fibers had no cytochrome c oxidase activity histochemically. The progression of the MELAS was probably in parallel with the decrease in CCO activity.     

Single muscle fiber analysis of mitochondrial myopathy,encephalopathy, lactic acidosis,and stroke-like episodes (MELAS)

We examined muscle sections from 3 patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), using single-fiber polymerase chain reaction, histochemistry, and in situ hybridization. Most type 1 ragged-red fibers showed positive cytochrome c oxidase activity at the subsarcolemmal region, while type 2 ragged-red fibers had little cytochrome c oxidase activity. However, there was no difference in the amount of total (mutant and wild-type) mitochondrial DNAs (mtDNAs) and the proportion of mutant mtDNA between type 1 and type 2 ragged-red fibers. These observations suggest that mitochondrial proliferation and nuclear factors affect muscle pathology, including cytochrome c oxidase activity, in MELAS. Total mtDNAs were greatly increased in ragged-red fibers (about 5–17 times over those in non–ragged-red fibers). The proportion of mutant mtDNA was significantly higher in ragged-red fibers (88.1 ± 5.5%) than in non–ragged-red fibers (63.2 ± 21.6%). Thus, the amount of wild-type mtDNA as well as mutant mtDNA was increased in ragged-red fibers in MELAS, failing to support the contention of a replicative advantage of mutant mtDNA. The proportion of mutant mtDNA was significantly higher in the strongly succinate dehydrogenase–reactive blood vessels (83.2 + 4.2%) than in non–succinate dehydrogenase–reactive blood vessels (38.8 ± 16.2%). It seems likely that systemic vascular abnormalities involving cerebral vessels lead to the evolution of stroke-like episodes in MELAS.     

Thalamic aphasia associated with mitochondrial encephalopathy,lactic acidosis,and stroke-like episodes: A case report

BackgroundMitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with aphasia is a rare disorder, with the associated aphasia reported as either Wernicke’s or Broca’s. Herein, we report a patient with MELAS complicated by thalamic aphasia.CaseA 15-year-old right-handed girl presented with headache, nausea, right homonymous hemianopsia, and aphasia. She could repeat words said by others, but had word-finding difficulty, paraphasia, and dysgraphia. Brain MRI revealed abnormal signals from the left occipital lobe to the temporal lobe and left thalamus, but Wernicke’s area and Broca’s area were not involved. Additionally, she had short stature, lactic acidosis, bilateral sensorineural hearing loss, and a maternal family history of diabetes and mild deafness. Based on clinical findings and the presence of a mitochondrial A3243G mutation, she was diagnosed with MELAS. With treatment, the brain MRI lesions disappeared and her symptoms improved. Her aphasia was classified as amnesic aphasia because she could repeat words, despite having word-finding difficulty, paraphasia, and dysgraphia. Based on MRI findings of a left thalamic lesion, we diagnosed her with thalamic aphasia.ConclusionThalamic aphasia may be caused by MELAS. Assessment of whether repetition is preserved is important for classifying aphasia.     

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) associated with hypothalamo-pituitary hypofunction--a case report

A case of 25-year-old woman with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) was reported. She had short stature, episodic vomiting with headache, several episodes with homonymous hemianopsia, progressive intellectual decline, generalized convulsion, muscular atrophy, sensory disturbance on the left side of the body, and primary amenorrhea. Lactate, pyruvate and the lactate to pyruvate ratio were elevated in the serum and cerebrospinal fluid. Muscle biopsy revealed ragged-red fibers. On electron microscopy there were subsarcolemmal aggregations of abnormal mitochondria with proliferation of crista and inclusions. Activities of the respiratory chain enzymes of the muscle mitochondria were normal. She showed a failure of GH response to arginine and levodopa and delayed response of serum GH to growth hormone releasing factor (GRF). She also showed decreased gonadotropin levels and delayed response of the hormone to LH-RH. In this case, a dysfunction of the hypothalamo-pituitary axis may be related to the short stature and primary amenorrhea. It is suggested that the hypothalamo-pituitary hypofunction may be one of the characteristic features in MELAS.     

Epileptic seizures in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes (MELAS)

This study reports a case of MELAS with epileptic seizure, and reviews the characteristics of seizures in patients with this syndrome. They are characterized by: (1) generalized and/or partial seizures, (2) frequent association with visual symptoms and hemiparesis, and (3) posteriorly predominant EEG abnormalities.     

线粒体脑肌病伴高乳酸血症和卒中样发作综合征的临床特点分析

目的探讨线粒体脑肌病伴高乳酸血症和卒中样发作(MELAS)综合征的临床、影像学、肌肉病理及分子生物学特点。方法回顾性分析6例MELAS患者的临床资料。结果首发症状表现为肢体抽搐4例,轻偏瘫1例,失语1例;其他症状包括发作性头痛和视力障碍。合并心脏功能异常2例,ECG提示预激综合征。6例患者行血乳酸运动试验,均为阳性。6例患者MRI检查显示大脑皮质和皮质下与血管分布不一致的长T_1、长T_2病灶。3例伴有脑萎缩,其中2例为小脑萎缩,1例为全脑萎缩。1例患者4个月后复查头颅MRI提示病灶完全消失。磁共振波谱可见病灶内多个体素的乳酸峰值升高,N-乙酰天冬氨酸值降低,乳酸/胆碱比降低。2例患者肌肉组织活检的病理均见到不同程度的萎缩肌纤维,未见到破碎红纤维。5例患者基因检测发现线粒体DNA(mtDNA)A3243G点突变,1例患者发现mtDNA T3271C点突变。结论 MELAS综合征临床表现复杂多样,以头痛、肢体抽搐及反复卒中样发作为突出特点。卒中样发作期影像学主要表现为脑内与供血区分布不一致的病灶;血乳酸运动试验阳性;典型肌肉病理检查MGT染色可见破碎红纤维;分子遗传学检查可发现基因突变。最终确诊有赖于基因检测。     

An autopsy case of mitochondrial encephalomyopathy,lactic acidosis and stroke-like episodes (MELAS) with a point mutation of mitochondrial DNA

A 14-year-old boy with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is reported. He had suffered blepharoptosis and cataracts prior to the stroke-like episodes, and was thus reported in 1984 as having Kearns-Shy (Sayre) syndrome. After his death, an A-to-G mutation of the mitochondrial DNA (mtDNA) at bp 3243 was identified in cardiac muscle and the liver. Neuropathologically, multiple old and recent necrotic foci were observed in the gray and white matter of the cerebrum and cerebellum. These lesions were occasionally observed in areas outside of the distribution of major blood vessels of the brain. In the recent necrotic foci, neural loss and sponginess were observed while some neurons were preserved intact. The latter finding has not been described in MELAS and suggests that metabolic degeneration had occurred in the neurons of this patient. This is the first report of a confirmed 3243 mutation of the mtDNA in an autopsied MELAS case.     

Coenzyme Q 10 improves lactic acidosis, strokelike episodes, and epilepsy in a patient with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes)

Mitochondrial encephalomyopathies encompass a group of disorders that have impaired oxidative metabolism in skeletal muscles and central nervous system. Many compounds have been used in clinical trials on mitochondrial diseases, but the outcomes have been variable. It remains controversial whether treatment of mitochondrial diseases with coenzyme Q 10 is effective. This paper describes a case of mitochondrial myopathy, encephalopathy, lactic acidosis, strokelike episodes, and exercise intolerance successfully treated with coenzyme Q 10. Efficacy of this therapy in this patient is correlated to control of lactic acidosis and serum creatine kinase levels. Disappointingly, larger studies with coenzyme Q 10 failed to demonstrate a clear beneficial effect on the entire study population with regard to clinical improvement or several parameters of the oxidative metabolism. They suggest that the use of coenzyme Q in treatment of mitochondrial diseases should be confined to protocols. There is a confounding variation in phenotype and genotype, and the natural history of the disorders in individual patients is not accurately predictable. The unpredictable a priori efficacy of therapy suggests that a long-term trial of oral coenzyme Q may be warranted.     

Effect of coenzyme Q10 in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS): evaluation by noninvasive tissue oximetry

We evaluated the effect of coenzyme Q10 supplementation to two patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) by using noninvasive tissue oximetry with near-infrared spectra of hemoglobin from the quadriceps muscle during bicycle ergometer exercise. Patients showed distinct oxygen consumption patterns reflecting the defect in oxidative phosphorylation and the impairment in oxygen utilization during exercise. Based on the oxygen consumption pattern, we considered one patient as having severe mitochondrial disorder and another patient as having mild one. After coenzyme Q10 supplementation, the oxygen consumption pattern of the patient with the severe form shifted to the mild one, while that of the patient with mild form remained unchanged. The shift of the pattern to the mild form correlated well with reduction of the sum of the serum lactate and pyruvate content during exercise. Noninvasive tissue oximetry may be useful to evaluate the effect of coenzyme Q10 supplementation to patients with mitochondrial encephalomyopathy including MELAS.