伴消化系统症状的成年型线粒体脑肌病伴乳酸血症和卒中样发作一例

线粒体脑肌病伴乳酸血症和卒中样发作(MELAS)是线粒体脑肌病中最为常见的临床类型,是以乳酸血症和卒中样发作为特征的脑和肌肉能量代谢障碍综合征.患者临床表现复杂多样,易被误诊为脑炎、脑梗死、癫痢、多发性肌炎、重症肌无力等疾病.笔者报告l例首诊被误诊为"脑梗死",后经肌肉组织活检和基因检测等证实为MELAS型线粒体脑肌病的病例,并结合文献对该病进行分析及讨论.     

线粒体DNA的变异及生物合成的异常与卒中发生的角色

1 线粒体与卒中的渊源 1984年Pavlakis等将线粒体异常所引起的疾病,依其临床表现分成3型,而命名其中第2型为线粒体脑肌病伴高乳酸血症和卒中样发作综合征（mitochondrial encephalomyopathy with lacticacidosis and strokelike episodes,MELAS）症候群,以综述患者出现的线粒体肌、脑病变并乳酸血及类卒中等症状。因使用“类卒中”的描述,     

乳酸血症和脑卒中样发作为主要临床表现的线粒体脑肌病(附1例报道)

目的报道线粒体脑肌病伴高乳酸血症和脑卒中样发作(MELAS)病1例,进行相关文献复习,探讨其临床表现、生化、影像学和组织病理学检查在该疾病诊断中作用。方法对线粒体脑肌病伴高乳酸血症和脑卒中样发作(MELAS)患者的临床表现、辅助检查、影像学、组织病理学、免疫组化等情况进行分析。结果 MELAS患者的主要临床表现为发作性头痛、脑卒中样发作、高乳酸血症;脑MRI示病灶位于顶叶、枕叶、颞叶脑回处;肌肉活检见肌纤维变性、破碎样改变以及异常线粒体。结论血乳酸、影像学及肌肉活检在诊断MELAS时有重要的诊断价值,但都缺乏特异表现,需要结合临床和各种检查结果而确诊。     

以乳酸血症和脑卒中样发作为主要临床表现的线粒体脑肌病

目的：报告线粒体脑肌病伴高乳酸血症和腩卒中样发作（MELAS）病1例,进行相关文献复习并探讨其临床表现、影像学和组织病理学特征。方法：对线粒体脑肌病MELAS患者的临床表现、影像学、组织病理学、免疫组化结果、辅助检查等情况进行分析,同时参考国内外文献对该病的报道。结果：MELAS的主要临床表现为发作性头痛和呕吐、全身性癫痫、精神障碍、脑卒中样发作、血乳酸增高;肌电图示神经源性改变;脑MRI示病灶多位于顶、枕、颞脑回处;肌肉活检见破碎样红纤维和异常线粒体,符合线粒体脑肌病MELAS的特征。结论：线粒体脑肌病MELAS的诊断主要根据临床表现和影像学特点,肌肉活检可确诊。     

MELAS型线粒体脑肌病3例误诊分析

线粒体脑肌病（mitochondrial encephalopathy,ME）是一组少见的遗传性疾病,由于线粒体结构和（或）功能异常导致的以脑和肌肉受累为主.线粒体脑肌病伴高乳酸血症和卒中样发作综合征是线粒体脑肌病中最具独立特点的疾病,临床表现多样,更易误诊,现报道3例如下：     

线粒体脑肌病

患者男性,31岁。间断性抽搐10余年,因头部外伤入院治疗,经脑组织、肌肉活检以及基因检测明确诊断为线粒体脑肌病伴高乳酸血症和卒中样发作(mitochondrial en-cephalomyopathy with lactic acidosis and stroke-like episodes,MELAS)。     

误诊为病毒性脑炎的MELAS型线粒体脑肌病1例报道

线粒体脑肌病伴高乳酸血症和卒中样发作（ mitochon-drial enceph-alomyopathy with lactic acidosis and stroke-like episodes, MELAS） 是线粒体脑肌病的一种临床类型,临床比较少见,症状复杂多样,极易误诊为其他神经系统疾病。     

线粒体脑肌病伴乳酸血症和卒中样发作

线粒体脑肌病伴乳酸血症和卒中样发作(mito-chondrial encephalomyopathies with lactic acidosis andstroke-like episodes,MELAS)是一种以线粒体脑肌病、酸中毒、卒中样发作为主要表现的进展性神经系统遗传病,部分病人还可伴有糖尿病、听力损害等多系统病变.     

线粒体脑肌病伴高乳酸血症和卒中样发作的临床研究进展

线粒体病是一组与线粒体氧化磷酸化功能异常相关的遗传代谢性疾病。其中线粒体脑肌病伴高乳酸血症和卒中样发作（MELAS）是最常见的类型。其标志性的临床表现为卒中样发作，多同时伴随其他系统损害。辅助检查可以发现血乳酸酸中毒，MRI检查多显示大脑后部皮质和皮质下白质的灶性损害。肌肉病理检查发现不整红边纤维（RRF）、琥珀酸脱氢酶深染的肌纤维（RBF）和微血管。     

MELAS综合征

MELAS综合征是一组以卒中样发作为丰要特征的线粒体疾病,全称为线粒体脑肌病伴高乳酸血症卒中样样发作。任何年龄均可发病．大多数患者为母系遗传,少数呈散发。     

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.     

Beneficial effects of creatine, CoQ10, and lipoic acid in mitochondrial disorders

Mitochondrial disorders share common cellular consequences: (1) decreased ATP production; (2) increased reliance on alternative anaerobic energy sources; and (3) increased production of reactive oxygen species. The purpose of the present study was to determine the effect of a combination therapy (creatine monohydrate, coenzyme Q(10), and lipoic acid to target the above-mentioned cellular consequences) on several outcome variables using a randomized, double-blind, placebo-controlled, crossover study design in patients with mitochondrial cytopathies. Three patients had mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), four had mitochondrial DNA deletions (three patients with chronic progressive external ophthalmoplegia and one with Kearns-Sayre syndrome), and nine had a variety of other mitochondrial diseases not falling into the two former groups. The combination therapy resulted in lower resting plasma lactate and urinary 8-isoprostanes, as well as attenuation of the decline in peak ankle dorsiflexion strength in all patient groups, whereas higher fat-free mass was observed only in the MELAS group. Together, these results suggest that combination therapies targeting multiple final common pathways of mitochondrial dysfunction favorably influence surrogate markers of cellular energy dysfunction. Future studies with larger sample sizes in relatively homogeneous groups will be required to determine whether such combination therapies influence function and quality of life.     

Vitamin A potently destabilizes preformed alpha-synuclein fibrils in vitro: implications for Lewy body diseases

Alpha-synuclein (alphaS) is the major component of the filamentous inclusions that constitute defining characteristics of Lewy body diseases (LBD) and multiple system atrophy (MSA). Clinically, antioxidant vitamins, such as vitamin E and the vitamin-like substance coenzyme Q10, have been used in the treatment of LBD with some efficacy. Using fluorescence spectroscopy with thioflavin S, electron microscopy and atomic force microscopy, here we examined the effects of ten antioxidant vitamins and vitamin-like substances, vitamin A (retinol, retinal and retinoic acid), beta-carotene, vitamins B2, B6, C, E, coenzyme Q10 and alpha-lipoic acid, on the formation of alphaS fibrils (falphaS) and on preformed falphaS. Among them, vitamin A, beta-carotene and coenzyme Q10 dose-dependently inhibited the formation of falphaS. Moreover, they also dose-dependently destabilized preformed falphaS. With such potent anti-fibrillogenic as well as fibril-destabilizing activities, these compounds could be useful in the treatment and prevention of LBD and MSA.     

Complex-1 activity and 18F-DOPA uptake in genetically engineered mouse model of Parkinson's disease and the neuroprotective role of coenzyme Q10

Regional distribution of coenzyme Q10 and mitochondrial complex-1 activity were estimated in the brains of control-(C57BL/6), metallothionein knock out-, metallothionein transgenic-, and homozygous weaver mutant mice; and human dopaminergic (SK-N-SH) cells with a primary objective to determine the neuroprotective potential of coenzyme Q10 in Parkinson's disease. Complex-1 activity as well as coenzyme Q10 were significantly higher in the cerebral cortex as compared to the striatum in all the genotypes examined. Complex-1 activity and coenzyme Q10 were significantly reduced in weaver mutant mice and metallothionein knock out mice, but were significantly increased in metallothionein transgenic mice. The reduced complex-1 activity and 18F-DOPA uptake occurred concomitantly with negligible differences in the coenzyme Q10 between in the cerebral cortex and striatum of weaver mutant mice. Administration of coenzyme Q10 increased complex-1 activity and partially improved motoric performance in weaver mutant mice. Direct exposure of rotenone also reduced coenzyme Q10, complex-1 activity, and mitochondrial membrane potential in SK-N-SH cells. Rotenone-induced down-regulation of complex-1 activity was attenuated by coenzyme Q10 treatment, suggesting that complex-1 may be down regulated due to depletion of coenzyme Q10 in the brain. Therefore, metallothionein-induced coenzyme Q10 synthesis may provide neuroprotection by augmenting mitochondrial complex-1 activity in Parkinson's disease.     

Pilot trial of high dosages of coenzyme Q10 in patients with Parkinson's disease

The safety and tolerability of high dosages of coenzyme Q10 were studied in 17 patients with Parkinson's disease (PD) in an open label study. The subjects received an escalating dosage of coenzyme Q10--1200, 1800, 2400, and 3000 mg/day with a stable dosage of vitamin E (alpha-tocopherol) 1200 IU/day. The plasma level of coenzyme Q10 was measured at each dosage. Thirteen of the subjects achieved the maximal dosage, and adverse events were typically considered to be unrelated to coenzyme Q10. The plasma level reached a plateau at the 2400 mg/day dosage and did not increase further at the 3000 mg/day dosage. Our data suggest that in future studies of coenzyme Q10 in PD, a dosage of 2400 mg/day (with vitamin E/alpha-tocopherol 1200 IU/day) is an appropriate highest dosage to be studied.     

Serial electroencephalographic findings in patients with MELAS

To clarify the electroencephalographic characteristics of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), the medical records and electroencephalograms of six patients with MELAS and two of their relatives with MELA (mitochondrial myopathy, encephalopathy, and lactic acidosis, without strokelike episodes) were retrospectively reviewed. All have a point mutation in the mitochondrial DNA at nucleotide position 3243. The electroencephalograms (n = 79) were divided into four groups according to the time relation to the strokelike episode: (1) before the first strokelike episode, (2) within 5 days after the strokelike episode (acute stage), (3) between 6 days and 1 month after the strokelike episode (subacute stage), and (4) more than 1 month after the strokelike episode (chronic stage). In the acute stage, 10 of the 11 electroencephalograms (9 strokelike episodes in four patients) revealed focal high-voltage delta waves with polyspikes (FHDPS), which were recognized as ictal electroencephalogram. Ictal events during FHDPS included focal clonic or myoclonic seizure and migrainous headache. In the subacute and chronic stages, focal spikes or sharp waves and 14- and 6-Hz positive bursts were frequently recorded. The authors' results suggest that FHDPSs present a reliable and accurate indicator of a strokelike episode in patients with MELAS.     

MELAS--mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome--two cases confirmed by biochemical and molecular investigations. Differential diagnosis of stroke causes

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (MELAS) is a maternally inherited multisystem disease caused by mutations of the mitochondrial DNA. The characteristic clinical features are: encephalopathy manifesting as dementia and seizures, stroke-like episodes at young age (usually < 40), lactic acidosis and myopathy with ragged-red fibres. Other frequent manifestations include: sensorineural deafness, diabetes, hypoparathyroidism, peripheral neuropathy and cardiomyopathy. We present two patients with MELAS who were diagnosed 4 and 9 years respectively following the onset of the disease despite the characteristic clinical pictures. The differential diagnostics of inborn and acquired disorders causing stroke is included. We regard that mitochondrial diseases are still insufficiently known and are frequently misdiagnosed. The knowledge is indispensable for establishing diagnosis and accurate genetic counselling. Although there is no specific therapy for mitochondrial diseases to date, coenzyme Q and various vitamins as well as moderate degree exercise might be recommended.     

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.     

Hyperthyroidism associated with papilloedema and pyramidal tract involvement

Summary In a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes [MELAS] who had normal mitochondrial enzyme activity, high doses of coenzyme Q₁₀ (CoQ) were administered. Clinical improvement with decreased serum lactate and pyruvate levels was observed. Though the mechanism of action of CoQ is not known, a trial is worthwhile in patients with MELAS.     

Mitochondrial encephalomyopathy (MELAS): pathological study and successful therapy with coenzyme Q10 and idebenone

Two patients with mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes (MELAS) in one family are reported. Pathological examination of case 1 showed ragged-red fibers, with 7% of the fibers being unstained by cytochrome c oxidase stain, peripheral nerve damage, multiple areas of softening in the cerebrum and midbrain, and spongy changes in the cerebrum, optic nerve and pons. Electron microscopic examination revealed abnormal accumulations of mitochondria in the skeletal muscle, smooth muscle and cardiac muscle. The activity of cytochrome c oxidase in the brain and liver showed a tendency to decrease. In case 2 (maternal aunt of case 1), muscular weakness and peripheral nerve damage improved by treatment with coenzyme Q₁₀. By adding idebenone to the coenzyme Q₁₀ therapy, the EEG and Wechsler's Adult Intelligence Scale (WAIS) improved. Furthermore, in the cerebral spinal fluid (CSF), the protein, lactate, and pyruvate decreased, and the monoamines and monoamine metabolites increased.