Central nervous system changes in mitochondrial encephalomyopathy: light and electron microscopic study

Summary An autopsy case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is reported. It presented with generalized muscle atrophy, stroke-like episodes, schizophrenia-like mental disorder and progressive dementia. Serum lactate and pyruvate levels were high. In the biopsied muscles, ragged-red fibers were observed by light microscopy and aggregation of abnormal mitochondria with paracrystaline formation by electron microscopy. The most characteristic neuropathological findings were infarct-like lesions widespread in the cerebral cortex. In addition, this case showed some unusual pathological features: (1) diffuse moderate fibrillary gliosis in the whole cerebral and cerebellar white matter, which might have been due to metabolic disturbances; (2) several focal lesions with demyelination and numerous spheroids in the pontocerebellar fibers; and (3) marked degeneration of the posterior columns and spinocerebellar tracts. Electron microscopic examination revealed that abnormal mitochondria were markedly aggregated in smooth muscle cells and endothelium of the cerebral and cerebellar blood vessels. These fine structural findings suggest a mitochondrial angiopathy.     

MELAS: clinical phenotype and morphological brain abnormalities

We describe the clinical and neuropathological findings of three unrelated autopsy cases of MELAS harboring the A3243G transition in the mitochondrial DNA (mtDNA). Using immunohistochemical techniques, we studied the expression of several subunits of the respiratory chain in various brain regions from the same cases. In all three cases there was a reduced immunocytochemical staining for mtDNA-encoded subunits of the respiratory chain, confirming the presence of a defective mitochondrial protein synthesis in this disease. Mitochondrial abnormalities were mostly confined to multiple areas of different size and shape, in agreement with the focal character of the brain pathology in MELAS, and were most prominent in the cerebral cortex, providing a morphological contribution to the explanation of the cognitive regression of the patients. Immunoreactivity for mtDNA-encoded subunits was reduced in the walls of many pial and intracerebral arterioles of different brain regions but there was no clear correlation between territories of affected vessels and distribution of the histological and immunohistochemical lesions. Cerebral focal lesions in MELAS might have a metabolic nature and several pathogenetic mechanisms might be involved in the genesis of stroke-like episodes when there is a local increased ATP demand.     

Muscle coenzyme Q10 in mitochondrial encephalomyopathies.

Coenzyme Q₁₀ (CoQ) content was measured in isolated muscle mitochondria from 25 patients with mitochondrial encephalomyopathies (MEM), most of whom had mitochondrial DNA mutations. The CoQ level was significantly lower in MEM patients than in controls. CoQ levels varied widely from patient to patient, especially in those with chronic progressive external ophthalmoplegia including Kearns-Sayre syndrome, which may explain, at least in part, the variable response of patients to CoQ administration.     

三例线粒体脑肌病伴高乳酸血症和卒中样发作患者的治疗和随访

目的初步探讨辅酶Q10和维生素B1、B2、C、E对于线粒体脑肌病伴高乳酸血症和卒中样发作的疗效。方法随访3例早期诊断的线粒体脑肌病伴高乳酸血症和卒中样发作的患者,观察治疗后其临床表现和影像学改变。结果本组3例患者用药后患者的卒中样发作和/或癫疒间发作的频率明显减少,头颅MRI出现新发病灶的次数明显减少,患者无明显残障。结论线粒体脑肌病伴高乳酸血症和卒中样发作的患者早期口服维生素B1、B2、C、E和辅酶Q10可能会改善预后,但有待于大宗病例进一步验证。     

Mitochondrial encephalomyopathy,lactic acidosis and stroke in adults: two cases

Two previously healthy women are described who in their late thirties suffered transient strokelike episodes, consisting of initial headache and vomiting, with various subsequent neurological signs that were only partially reversible. Investigations revealed elevated serum creatine kinase, lactic acidosis, hypertriglyceridaemia, and ragged red fibres in the muscle biopsy specimens. In both patients in vitro studies were performed on intact muscle mitochondria and muscle homogenate. Only in one was a mitochondrial defect found, located at the level of coenzyme Q. We conclude that these patients suffered from adult-onset mitochondrial encephalopathy, lactic acidosis and strokelike episodes (MELAS syndrome). Although the syndrome is often associated with long-standing neurological multisystem disease from childhood onwards, it should also be suspected in adults with strokelike signs of otherwise unexplained origin.     

Metabolic changes in patients with mitochondrial myopathies and effects of coenzyme Q10 therapy

We used a standardized bicycle ergometry protocol with a stepwise increasing workload (30–100 W) to evaluate various metabolic factors for the diagnosis and metabolic monitoring of mitochondrial encephalomyopathies. All patients (n = 9) showed pathological venous lactate/pyruvate (L/P) ratios, which normalized in three patients after 6 months of coenzyme Q₁₀ (CoQ) therapy. Thus, the L/P ratio proved to be the clinically most useful parameter in the evaluation and monitoring of mitochondrial diseases, showing higher sensitivity than lactate measurements only. CoQ may exert a favourable effect in some patients with mitochondrial diseases. Received: 15 October 1997 Received in revised form: 6 February 1998 Accepted: 20 March 1998     

Mitochondrial encephalomyopathy with lactic acidosis and stroke like episodes (MELAS) with prominent degeneration of the intestinal wall and cactus-like cerebellar pathology

A 67-year-old woman had frequent subacute ileus, hearing difficulty, muscle atrophy and stroke-like episodes. Computed tomography revealed multiple low-density areas, which did not correlate with the vascular supply, in the cerebral cortex. She had metabolic disturbance comprising lactic acidosis and elevated pyruvate level. Her skeletal muscle biopsy specimen showed ragged-red fibers, and mitochondrial DNA analysis revealed a point mutation at position 3243, findings consistent with MELAS. Examination of her small intestine revealed a necrotic zone and numerous abnormal large mitochondria in the smooth muscle cells, vascular media and endothelium, and intestinal ganglion cells. The cerebral cortex showed multiple microcystic necrotic foci in cerebral cortex. Cactus-like pathology resembling the changes associated with Menkes’ kinky hair disease and torpedoes were observed in the cerebellar Purkinje cells. The intestinal dysmotility due to MELAS and cerebellar changes were presumed to be associated with a disturbance of copper metabolism. Received: 8 October 1999 / Revised, accepted: 18 January 2000     

Mitochondrial encephalomyopathy showing prominent microvacuolation and necrosis of intestinal smooth muscle cells: a case diagnosed by rectal biopsy

A 40-year-old woman who developed intestinal dysmobility was found, at rectal biopsy, to have marked microvacuolation of mucosal muscle layer cells, which corresponded to increased accumulation of abnormal mitochondria. Skeletal muscle biopsy specimens showed ragged-red fibers, vessels strongly reactive for succinic dehydrogenase, and focal deficiency of cytochrome c oxidase. Autopsy performed at the age of 50 revealed prominent accumulation of abnormal mitochondria in the intestinal smooth muscle cells with a mottled distribution of focal necrosis, multiple small cerebral infarcts with diffuse neuronal loss, and rarefaction of the perivascular white matter. Mitochondrial DNA analysis showed a point mutation at position 3243. This case, showing features of both mitochondrial neurogastrointestinal encephalomyopathy and mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), indicates that routine intestinal biopsy can detect mitochondrial encephalomyopathy with gastrointestinal involvement. The main intestinal changes were extensive accumulation of abnormal mitochondria in the leiomyocytes and scattered focal necrosis. Received: 13 July 1997 / Revised, accepted: 1 December 1997     

Mitochondrial myopathy,encephalopathy, lactic acidosis,and stroke-like episodes with acanthocytosis: a clinicopathological study of a unique case

Summary A case of a unique combination of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like syndrome (MELAS) with acanthocytosis is reported. Neuropathological examination revealed pellagra-like change in Betz cells, brain-stem neurons and anterior horn cells as well as findings compatible with mitochondrial encephalomyopathies. Abnormal function of nicotinic acid-related enzymes could be the cause of the complicated clinicopathologic findings in this case. This is the first report of MELAS with acanthocytosis.     

原发性辅酶Q_(10)缺乏症临床、病理和基因分析(附1例报告)

目的探讨原发性辅酶Q_(10)缺乏症的临床病理和基因突变特征。方法回顾性分析1例原发性辅酶Q_(10)缺乏症的临床资料。结果患者25岁男性,出现反复肌阵挛性癫痫发作、共济失调、轻度认知能力下降。头颅MRI显示桥脑和小脑萎缩;EEG显示全导棘波和棘慢波;肌肉病理学表现为少许肌肉变性坏死、脂质沉积,肌肉组织辅酶Q_(10)浓度降低;辅酶Q_(10)基因检查发现COQ2基因存在2个杂合突变:c.1178TC,p.Val393Ala;c.973AG,p.Thr325 Ala。按照体质量30 mg/千克给予补充辅酶Q_(10),定期随访2年,认知和运动能力改善,癫痫基本控制。结论 COQ2基因突变所致的原发性辅酶Q_(10)缺乏症以癫痫、共济失调为主要特征,通过分子病理学和酶学检测可确定诊断,充分补充辅酶Q_(10)可使临床症状显著改善。     

MELAS: a neuropsychological and radiological follow-up study. Mitochondrial encephalomyopathy,lactic acidosis and stroke

We report on a patient with long standing, full-blown mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). In contrast to earlier publications, detailed neuropsychological assessment revealed no dementia but a pattern of distinct cognitive deficits with marked impairment of visuo-constructive and executive functions. Focal lesions and progressing atrophy mainly of the basal ganglia and the temporo-parieto-occipital area with preservation of hippocampal and entorhinal structures were present. Furthermore, a 4-year follow-up assessment revealed an increasing deterioration of distinct cognitive functions, including phasic alertness, tactile functions and the discrimination of tone pitch and rhythm. This may be because of chronic regional metabolic disturbances, as there was no further stroke-like episode in that period of time.     

MELAS with prominent white matter gliosis and atrophy of the cerebellar granular layer: a clinical, genetic, and pathological study

This report concerns an autopsy case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with unusual neuropathological findings. The patient was a Japanese woman who was 21 years old at the time of death. Her mother is a patient with genetically confirmed MELAS. Her clinical manifestations included convulsions and lactic acidosis in the latter half of the first decade of life, followed by deafness, dementia, muscle weakness in the lower extremities, slight ataxia in the upper and lower extremities, and diabetes mellitus. Muscle biopsy revealed ragged-red fibers, and genetic study showed a point mutation at nucleotide pair 3243 in mitochondrial DNA. She died of lactic acidosis. In the clinical course, she did not develop stroke-like episodes. The neuropathological examination revealed not only minute to small necrotic foci in the cerebral cortex, amygdala, hippocampus, and cerebellum, but also prominent white matter gliosis in the central nervous system and cerebellar cortical degeneration of granular cell type. Our neuropathological findings, including prominent white matter gliosis of the central nervous system and cerebellar cortical degeneration of granular cell type, may indicate morphologically widespread cellular dysfunction, not restricted to either neuronal or vascular derangement, in the brain pathology of MELAS. Received: 28 July 1998 / Revised, accepted: 27 October 1998     

Early-onset encephalomyopathy associated with tissue-specific mitochondrial DNA depletion: A morphological,biochemical and molecular-genetic study

A male infant, born from consanguineous parents, suffered from birth with a progressive neuromuscular disorder characterized by psychomotor delay, hypotonia, muscle weakness and wasting, deep-tendon areflexia and spastic posture. High levels of lactic acid in blood and cerebrospinal fluid suggested a mitochondrial respiratory chain defect. Muscle biopsy revealed raggedred and cytochromec oxidase-negative fibres, lipid accumulation and dystrophic changes. Multiple defects of respiratory complexes were detected in muscle homogenate, but cultured fibroblasts, myoblasts and myotubes were normal. Southern blot analysis showed markedly reduced levels of mitochondrial DNA (mtDNA) in muscle, while lymphocytes, fibroblasts and muscle precursor cells were normal. Neither depletion of mtDNA nor abnormalities of the respiratory complexes were observed in innervated muscle fibres cultured for as long as 4 months. No mutations were observed in two candidate nuclear genes,mtTFA andmtSSB, retro-transcribed, amplified and sequenced from the proband's mRNA. Sequence analysis of the mtDNA D-loop and of the origin of replication of the mtDNA light strand failed to identify potentially pathogenic mutations of these replicative elements in the proband's muscle mtDNA. Our findings indicate that mtDNA depletion is due to a nuclear encoded gene and suggest that the abnormality underlying defective mtDNA propagation must occur after muscle differentiation in vivo.     

Epilepsy Characteristics and Clinical Outcome in Patients With Mitochondrial Encephalomyopathy,Lactic Acidosis,and Stroke-Like Episodes (MELAS)

BackgroundEpileptic seizures in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) are heterogeneous with no pathognomonic features. We reviewed epilepsy characteristics and clinical outcome exclusively in a pediatric population.MethodsTwenty-two children and adolescents (13 males) with confirmed mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes due to mitochondrial DNA A3243G mutation and epilepsy were recruited. Clinical data including seizure semiology, treatment response, neuroimaging findings, and electroencephalography were analyzed. We also examined the effect of the age at seizure onset and initial symptoms on the clinical variables.ResultsSeizure semiology and electroencephalography abnormalities showed no syndrome-specific findings. Focal seizures occurred in 21 of 22 subjects (95.5%), whereas generalized seizures developed in seven of 22 subjects (31.8%). Twenty of 22 subjects (90.9%) achieved partial to complete reduction of clinical seizures for more than one year with a combination of more than two antiepileptic drugs. The subgroup with earlier seizure onset presented significantly earlier and showed significantly higher rates of drug-resistant epilepsy compared with the late onset group, although there were no significant differences in the initial symptoms. The subjects with severe epileptic conditions tended to have more severe clinical dysfunction and more severe organ involvement.ConclusionsBoth focal and generalized seizures occurred in patients with MELAS. Epilepsy in this population is drug resistant, but a certain degree of clinical seizure reduction was achievable with antiepileptic drugs, with more favorable outcomes than historically expected. Close observation and active epilepsy treatment of individuals with MELAS episodes and earlier seizure onset might improve the prognosis.     

Coenzyme Q10 and vitamin E deficiency in Friedreich’s ataxia: predictor of efficacy of vitamin E and coenzyme Q10 therapy

Background and purpose: A pilot study of high dose coenzyme Q₁₀ (CoQ₁₀)/vitamin E therapy in Friedreich’s ataxia (FRDA) patients resulted in significant clinical improvements in most patients. This study investigated the potential for this treatment to modify clinical progression in FRDA in a randomized double blind trial. Methods: Fifty FRDA patients were randomly divided into high or low dose CoQ₁₀/ vitamin E groups. The change in International Co‐operative Ataxia Ratings Scale (ICARS) was assessed over 2 years as the primary end‐point. A post hoc analysis was made using cross‐sectional data. Results: At baseline serum CoQ₁₀ and vitamin E levels were significantly decreased in the FRDA patients (P < 0.001). During the trial CoQ₁₀ and vitamin E levels significantly increased in both groups (P < 0.01). The primary and secondary end‐points were not significantly different between the therapy groups. When compared to cross‐sectional data 49% of all patients demonstrated improved ICARS scores. This responder group had significantly lower baseline serum CoQ₁₀ levels. Conclusions: A high proportion of FRDA patients have a decreased serum CoQ₁₀ level which was the best predictor of a positive clinical response to CoQ₁₀/vitamin E therapy. Low and high dose CoQ₁₀/vitamin E therapies were equally effective in improving ICARS scores.     

Cytochromec oxidase and coenzyme Q in neuromuscular diseases: a histochemical study

Summary Cytochromec oxidase (CCO) has been histochemically studied in 250 muscle biopsies from patients with different neuromuscular diseases. The results were compared with those obtained on serial sections stained with Gomori's trichrome and with the methods for NADH tetrazolium reductase, succinate dehydrogenase and lactate dehydrogenase. In 58 selected cases serial sections were also stained with a method demonstrating coenzyme Q (CoQ) activity. Demonstration of structural alterations was as good with CCO as with the methods for other oxidative enzymes: particularly evident were alterations of the distribution of mitochondria, such as core areas in central core and multiminicore diseases. Unstained fibers were observed in mitochondrial myopathies, in Becker, Emery-Dreifuss, limb-girdle, facio-scapulo-humeral muscular dystrophies, muscle infarction, polymyositis, motor neuron diseases and neuropathies. The histochemical method for CoQ showed only low specificity, since partial staining was also present in areas devoid of mitochondria, such as cores. CoQ deficiency was not observed in any of the 19 mitochondrial myopathies examined.     

Long-term coenzyme Q10 therapy for a mitochondrial encephalomyopathy with cytochrome c oxidase deficiency: a 31P NMR study

For 2 years we administered high doses of coenzyme Q10 (CoQ) to a patient having mitochondrial encephalomyopathy with cytochrome c oxidase deficiency. Abnormal elevation of the serum lactate per pyruvate ratio and the increased concentration of serum lactate plus pyruvate induced by exercise decreased with CoQ treatment. This therapeutic effect continued for 2 years. 31P nuclear magnetic resonance spectroscopy showed acceleration of the postexercise recovery of the ratio of phosphocreatine to inorganic phosphate in muscle during CoQ treatment. These observations support the beneficial effect of CoQ on the impaired mitochondrial oxidative metabolism in muscle. Also, impaired central and peripheral nerve conductivities consistently improved during CoQ treatment. These results indicate that CoQ has clinical value in the long-term management of patients with mitochondrial encephalomyopathies, even though there are clinical limitations to the effects of this therapy.     

Mitochondrial encephalomyopathy,lactic acidosis,stroke-like episodes (MELAS): Clinical,radiological, pathological,and genetic observations

We reviewed 10 patients (5 males, 5 females) with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. The age of symptom onset ranged from 3 months to 12 years. All had lactic acidosis, multiple stroke-like events with secondary neurological deficits, radiological changes of progressive brain infarction, and muscle biopsy showing ragged-red fibers. In patients with earlier onset of symptoms (<2 yr), involvement tended to be more diffuse, with failure to thrive and early onset of delayed development. Patients whose symptoms appeared later tended to have focal neurological deficits with migraine-like headache, and a rate of cognitive regression reflecting the rapidity of disease progression. Radiological changes included multiple areas of infarction with initial predilection for parietal occipital areas, progressing to generalized atrophy. Pathological findings in muscle biopsies included type 1 fiber predominance, ragged-red fibers, increased intermyofibrillar lipid deposition, and abnormal mitochondria. Four patients showed mitochondrial DNA tRNA mutation at position 3,243. No difference was noted in clinical, radiological, or pathological findings in patients with and without this mutation, suggesting that multiple sites of point mutation may give rise to mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes.     

An experimental model of mitochondrial myopathy: Germanium-induced myopathy and coenzyme Q10 administration

In skeletal muscles from rats treated with germanium for 23 weeks, there were numerous ragged-red fibers and cytochrome-c oxidase (COX)-deficient fibers. Biochemically, germanium reduced the enzyme activities in the mitochondrial respiratory chain. Rotenone-sensitive NADH–cytochrome-c reductase as well as COX activities were markedly reduced, while succinate–cytochrome-c reductase was less severely, but significantly, affected. The histopathological findings in these muslces were similar to those seen in patients with mitochondrial encephalomyopathy, suggesting that germanium-induced myopathy may be a useful experimental model. Coenzyme Q₁₀ administration appeared to be ineffective in preventing this experimental myopathy. © 1992 John Wiley & Sons, Inc.