A mitochondrial encephalomyopathy with a partial cytochrome c oxidase deficiency of muscle.

A 16 year old girl showed delayed psychomotor development. In infancy, exercise intolerance, cerebellar signs, deteriorated with increasing intercurrent infections, and disturbances of breathing and cardiac rhythm became manifest. From the age of 7 years there was chronic progressive psychomotor deterioration, with hypotonia, a bilateral pyramidal and cerebellar syndrome, and mild epilepsy. CSF pyruvate and lactate levels were elevated, and lactate content was elevated in the urine. There was an abnormally high rise of lactate levels on moderate exercise and an abnormal response to pyruvate loading. Quadriceps muscle biopsies obtained at age 10 and 16 years showed ragged-red fibres, and a decreased cytochrome c oxidase activity and cytochrome aa3 content. Cytochrome c oxidase activity in fibroblasts was normal. Clinical signs and symptoms in association with a disturbance of mitochondrial energy metabolism led us to diagnosis of probable Leigh syndrome.     

Ophthalmoplegia-plus, a real nosological entity

Four patients with chronic progressive external ophthalmoplegia (c.p.e.o.), retinal, neurological, endocrine and auditory anomalies, three of whom showed signs of cardio-myopathy, are described. On biochemical examination signs of disturbed pyruvate and lactate metabolism were found and there were indications of loss of respiratory control with loosely coupling of phosphorylation (from oxidation). In the muscle biopsy specimens from all four patients aggregates of abnormal mitochondria were seen, compatible with the diagnosis of a mitochondrial myopathy.
A cardiac biopsy was performed once also showing abnormalities.
The great similarity in the clinical, biochemical and morphological findings justifies one comprehensive diagnosis. The term "ophthalmoplegia-plus", although it has recently fallen into some discredit as a nosological entity, is the most obvious choice.
The pathogenesis of ophthalmoplegia-plus is a widespread general disturbance of mitochondrial function, affecting various organs and systems. This distinguishes it only gradually from true ocular myopathy, and descending ocular myopathy, where only the ocular muscles and skeletal muscles, are affected by the mitochondrial anomaly (at least there is no obvious clinical involvement of other organs). Within the nosological entity of ophthalmoplegia-plus a subdivision can be made for the Kearns-Sayre syndrome, in which the clinical picture suggests that the most severe and widespread mitochondrial lesions are to be found.     

Mitochondrial disorders: a potentially under-recognized etiology of infantile spasms

Infantile spasms represent an age-dependent response of the immature brain to a wide variety of insults. An unselected group of children with infantile spasms were reviewed to determine etiology; a metabolic work-up was undertaken if the etiology was unclear from history and examination (cryptogenic). Of the 56 infants, 34 had a recognizable etiology (symptomatic), 1 had normal development (idiopathic), and 21 had cryptogenic infantile spasms. Among the latter, results of plasma lactate and pyruvate or urine organic acids were available in 17. In 2 infants (monozygotic twins), mitochondrial DNA testing revealed the relatively common A3243G mitochondrial mutation. In these twins and 11 of the remaining 15, body fluid metabolite testing suggested possible defective energy metabolism. Our twins and previous reports suggest that mitochondrial disorders should be considered in the differential diagnosis of infantile spasms. Among our cases remaining cryptogenic, signs of abnormal energy metabolism were prevalent, suggesting that metabolic derangements may be common causes or secondary consequences of infantile spasms.     

Chronic relapsing course of encephalomyeloradiculopathy in a 6-year-old boy

We present a young child with an illness characterized by remissions and exacerbations and signs of disseminated lesions in the central nervous system. Visual evoked response and brainstem auditory evoked potential gave abnormal findings showing lesions also of the optic nerves and brainstem. The CSF IgG index was slightly elevated and myelin basic protein was high. There was also intrathecal antibody production against different viruses, the highest against measles. The HLA type was A3, B7, Dr2. The T4/T8 ratio reflected an immunological active disease. All these signs could have been diagnosed as multiple sclerosis. However, there were also lower motoneuron lesions and metabolic studies showed disturbances in pyruvate metabolism as in Leigh's disease. Cerebral tomography and magnetic resonance imaging showed scattered lesions in the nuclei lentiformis and capsula interna. We would like to stress the importance of careful etiological studies in cases of MS in childhood.     

A case of NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) with a T-to-C point mutation at nt 8993 of mitochondrial DNA]

We report a case of NARP with a T-to-C point mutation at nt 8993 of mitochondrial DNA. A 37-year old man with mild mental retardation, retinitis pigmentosa, and clonic-tonic seizure was admitted to our hospital. The neurological examination revealed scanning speech, dystonic neck turning to the left side, and pyramidal tract signs. Serum-, CSF-lactate and pyruvate level were slightly elevated. Brain MRI findings showed cerebral atrophy, cerebellar cortical atrophy accompanied with dilation of forth ventricle, and high intensity lesions in the bilateral lenticular nuclei on T2 weighted images. Nucleotide sequence analysis of the mitochondrial DNA in the leukocytes demonstrated a T-to-C point mutation at nt 8993. To our knowledge, this is the first report of a Japanese patient with NARP associated with the T-to-C mutation at nt 8993 of mt DNA. Mitochondrial DNA analysis should be considered in the differential diagnosis of patients with retinitis pigmentosa and various neurological signs.     

Treatment of Kearns-Sayre syndrome with coenzyme Q10

We studied the metabolism of coenzyme Q10 (CoQ) and the effects of CoQ therapy in five patients with Kearns-Sayre syndrome (KSS). Although the mitochondrial fraction was increased in muscles from KSS patients, CoQ content was slightly low. CoQ synthesis was normal in fibroblasts from KSS patients. Administration of 120 to 150 mg/d of CoQ improved abnormal metabolism of pyruvate and NADH oxidation in skeletal muscle. CoQ therapy decreased CSF protein concentration and CSF lactate/pyruvate ratio. ECG abnormalities and neurologic symptoms also improved.     

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.     

ND3基因突变导致的线粒体脑肌病重叠综合征二例

目的孤立的线粒体电子传递链复合物Ⅰ缺陷是线粒体病常见的原因之一,可导致几种独特的临床综合征。方法本文报道2例NADH脱氢酶(ND)基因突变导致的线粒体脑肌病的临床资料,分析该2例线粒体脑肌病患者的临床表现,头颅影像学,血乳酸,血生化,血氨基酸,尿有机酸等,脑电图(EEG),肌电图(EMG)和神经传导速度,以及线粒体全基因二代测序和线粒体相关核基因的检查。结果例1患者部分症状符合线粒体脑肌病伴乳酸血症和卒中样发作(MELAS),部分症状符合伴破碎红纤维肌阵挛癫痫(MERRF)。该患者头颅MRI除MELAS常见的皮质病变外,还可见中脑和四叠体对称性异常信号,符合Leigh综合征(LS)影像学表现。线粒体基因二代测序发现MT ND3,10158TC突变。例2患者临床表现完全符合MELAS的临床特征,但头颅MRI可见中脑红核双侧对称性病变,又符合LS的影像学特征。线粒体全基因二代测序发现ND3,10191TC突变。结论对于难以解释的神经系统症状和体征,尤其有多系统受累表现,即使临床表现不符合某种独特的线粒体病综合征,也要提高警惕,避免漏诊。     

Screening for mitochondrial cytopathies: the sub-anaerobic threshold exercise test (SATET).

A simple test is described for identifying patients with abnormalities of muscle energy metabolism secondary to mitochondrial dysfunction, based on the venous lactate response to exercise at 90% of predicted work rate at the anaerobic threshold. The test was standardised for age, weight and sex of subjects, and was abnormal in all cases of mitochondrial cytopathy tested, with a false positive rate of 7% in a control population. The test was abnormal in two cases of mitochondrial disease in which muscle biopsy was normal or showed only non-specific changes.     

Positron emission tomography using pyruvate-1-11C on mitochondrial encephalomyopathy

In order to investigate in vivo metabolism of pyruvate in the brain, positron emission tomography (PET) using pyruvate-1-11C were performed on two patients with mitochondrial encephalomyopathy, one patient with Leigh disease and one patient with epilepsy. PET images of epilepsy showed less RI uptakes in brain tissues than in skull muscles. And RI was cleared rapidly from the brain tissues. But PET images of mitochondrial encephalomyopathies showed increased RI uptakes and slow RI clearance in cerebral cortices, basal ganglia and thalamus. Also RI was cleared slowly or accumulated in ventricles. This suggested that pyruvate metabolism may be impaired with metabolical trapping of 11C by lactic acids, since it is said that 11C of pyruvate-1-11C is cleared rapidly from the normal brain tissues by decarboxylation of pyruvate. The usefulness of PET studies with pyruvate-1-11C are suggested for investigating pyruvate metabolism in brain tissues, and for diagnosing mitochondrial encephalomyopathy.     

An investigation of pyruvate metabolism in patients with cerebellar and spinocerebellar degeneration

This study extends previous observations of pyruvate metabolism in the spino-cerebellar degenerations by screening for abnormalities of pyruvate oxidation using the rise in blood pyruvate after an oral glucose load and examining the activity of the lipoamide dehydrogenase (LAD) moeity of the pyruvate dehydrogenase complex in the serum of 31 patients with Friedreich's ataxia, hereditary spastic ataxia and primary cerebellar degeneration. Serum LAD activity was significantly reduced in 10 Friedreich's ataxia patients when compared to controls and to 10 patients with spastic ataxia, thus confirming previous studies. Two patients with Friedreich's ataxia and 2 with primary cerebellar degeneration had abnormal blood pyruvate curves after oral glucose loading. The findings suggest that abnormal pyruvate oxidation occurs in some cases of Friedreich's ataxia and primary cerebellar degeneration and that the abnormality of pyruvate metabolism is not necessarily reflected in the serum LAD activity of these patients. The relevance of these findings to the heterogeneity of the hereditary ataxias is discussed.     

Clinical and radiologic improvements in mitochondrial encephalomyelopathy following sodium dichloroacetate therapy

We administered sodium dichloroacetate (DCA), which reduces the circulating lactate and pyruvate concentrations by stimulating the activity of the pyruvate dehydrogenase complex (PDHC), to three children with mitochondrial encephalomyelopathy. Significant clinical, biochemical and radiologic improvements were obtained following DCA therapy (approximately 30 mg/kg per day, divided into three doses). All three patients had non-pyruvate dehydrogenase complex (PDHC) deficiencies: two exhibited Leigh syndrome (complex I deficiency and unknown etiology), and one abnormal myelination (multienzyme deficiency), demonstrated on magnetic resonance imaging (MRI). The lactic and pyruvic acid concentrations in serum and cerebrospinal fluid (CSF) were decreased significantly by the oral DCA treatment. The lactic acid peak on MR spectroscopy also markedly decreased in parallel with the CSF level. In addition, the brain lesions observed on MRI were improved in all patients. No exacerbation was observed in any of the patients, who have been followed-up more than 21 months following the DCA therapy. These results suggest that DCA therapy should be considered in all patients with a mitochondria-related enzyme deficiency.     

Absence attacks with secondary bilateral synchrony]

Three cases with petit mal absence attacks with secondary bilateral synchrony were presented. The interictal EEG showed unilateral focal epileptic discharges in the frontal area with normal background activity. The ictal EEG disclosed 3-Hz generalized symmetrical spike-wave patterns preceded by unilateral focal discharges, which were elicited by hyperventilation. None of the three cases had abnormal neurological findings or abnormal CT findings. All three cases had normal psychomotor development. One case had a history of febrile convulsions. The ictal manifestations were as follows; impairement of consciousness without any other signs in one case, with decreased posture tone in the second, and automatism in the third. The authors suggest that there can be petit mal absence with 3-Hz generalized spike-wave discharges induced by secondary bilateral synchrony.     

Cerebral white matter involvement in children with mitochondrial encephalopathies

In childhood mitochondrial encephalopathies the common MRI features are bilateral symmetric abnormalities in basal nuclei and brainstem. The presence of diffuse white matter abnormality has been described only in a few cases. Among a series of 110 children with mitochondrial encephalopathies, 8 patients with MR imaging consistent with a leukoencephalopathy were retrospectively evaluated. Diagnosis was based on the recognition of the biochemical defect in muscle homogenate. H-MR spectroscopic imaging was performed in six of them. Biochemical analysis demonstrated a defect of respiratory chain complexes in six patients: complex I in two cases, complex II in two, complex IV in one, multiple complexes defect in one. Pyruvate dehydrogenase deficiency was demonstrated in two patients. MRI showed severe involvement of the brain white matter without significant basal nuclei or brainstem abnormalities. Two patients developed large cystic areas since onset; in two others progressive vacuolisation of affected white matter was seen later in the course of the disease. One patient with pyruvate dehydrogenase deficiency also presented with a diffuse cortical polymicrogyria. H-MR spectroscopic imaging showed a decrease of N-acetylaspartate, choline and creatine with lactate accumulation in five patients, and was normal in one. These findings suggest that mitochondrial disorders should be included in the differential diagnosis of white matter disorders.     

Intravenous pyruvate loading test in Leigh syndrome

Diagnosis of defective pyruvate metabolism can present difficulties in clinical practice. In search of a diagnostic procedure that can give a clear indication of a disturbance of pyruvate metabolism, we have developed an intravenous pyruvate loading test. The loading test was applied to 9 patients with Leigh syndrome. Results and characteristics are described. The test proved to be a sensitive procedure to detect disturbances in pyruvate oxidation. The intravenous pyruvate loading test can be a useful tool in the diagnosis of mitochondrial (encephalo) myopathies.     

Antimitochondrial autoantibodies of primary biliary cirrhosis as a novel probe in the study of 2-oxo acid dehydrogenases in patients with mitochondrial myopathies

Autoantibodies present in the autoimmune disease primary biliary cirrhosis react by immunoblotting with four human skeletal muscle mitochondrial antigens of 70 kDa, 52 kDa, 50 kDa and 45 kDa, identified as the lipoate acetyl transferases (E2) of the pyruvate dehydrogenase, component X of E2 pyruvate dehydrogenase, E2 of 2-oxo glutarate dehydrogenase and E2 of branched-chain 2-oxo acid dehydrogenase complexes respectively. These autoantibodies have been employed as a novel probe to study whether there is a defect in the synthesis of the 2-oxo acid dehydrogenase complexes in patients with mitochondrial respiratory chain disorders. The reactive antigens are present normally in four patients with oculomyopathy in whom partial deletions of the mtDNA have been detected, and in two patients with MERRF and MELAS encephalomyopathy. Thus, unlike in the yeast Saccharomyces cerevisiae, there appear to be no regulatory interactions which coordinate the assembly of the mitochondrial respiratory chain with the development of the pyruvate dehydrogenase complex, which plays an important role in regulating the flow of metabolic intermediates to oxidative energy metabolism.     

100例癫痫患者脑电图与磁共振分析

目的:观察脑电图和头颅MRI在确诊癫痫及其病因诊治方面的应用,探讨痫性放电与结构异常之间的关系。方法:选100例癫痫患者,均作REEG、AEEG、头颅CT和MRI检查。比较四种检查方法的阳性率和异常病灶的分布。应用卡方检验,比较痫性放电与结构异常之间的关系。结果;REEG痫性放电35例(35%),AEEG76例(76%),比REEG多提供了41%的异常信息。CT发现颅内异常25例(25%),MRI发现异常58例(58%)。在EEG单侧局灶放电的53例中,MRI异常42例,18例双侧半球放电中,MRI异常5例,经x2检验,局灶痫性放电者MRI异常率显著高于双侧半球痫性放电者(P<0.01);MRI正常的42例患者中EEG痫性放电26例,异常率为61.9%,MRI发现结构异常的58例患者中,EEG异常放电50例,异常率为86.2%,经x2检验发现MRI结构异常患者,痫性放电出现率高(P<0.01)。结沦:AEEG是确诊癫痫、指导治疗的有利依据;MRI可作为癫痫患者病因诊断的首选影像检查。痫性放电与结构异常有一定关系。     

1-[11C]pyruvate turnover in brain and muscle of patients with mitochondrial encephalomyopathy. A study with positron emission tomography (PET)

We examined pyruvate turnover using 1-[11C]pyruvate in the brain and epicranial muscle of 6 patients with mitochondrial encephalomyopathy (MEM), diagnosed by muscle biopsy and mitochondrial enzyme assay. The radioactivity was measured by positron emission tomography (PET). The time-activity curve for 11C in both brain and muscle generated after i.v. injection of 1-[11C]pyruvate consisted of 2 components in normal subjects and patients, i.e. a fast and a slow component which were assumed to represent the aerobic (mitochondrial) and anaerobic (glycolytic) metabolism of pyruvate, respectively. In the brain and muscle of patients, the aerobic component was smaller and the anaerobic larger than in normals. The extent of this abnormality seemed to reflect the severity of the disease. The same slight abnormality for [11C]pyruvate turnover was also observed in the brain of MEM patients who were without cerebral symptoms. Cerebral blood flow (CBF) and cerebral oxygen consumption (CMRO2) of most patients were lower than those of normals, and the oxygen extraction fraction (OEF) was decreased in many patients.     

31例延髓梗死患者的临床分析

目的:根据头颅MRI对延髓梗死病灶的定位并结合延髓的解剖学特点,探讨延髓梗死临床表现的特征.方法:31例急性延髓梗死患者均行头颅MRI检查,对其病灶位置分布、神经系统症状体征,出院当天改良Rankin量表(mRS)评分等指标进行分析.结果:31例急性延髓梗死病例中:外侧延髓梗死(LMI)16例;内侧延髓梗死(MMI)13例;双侧延髓梗死(BMI)2例.LMI组病灶位于延髓背外侧或外侧;MMI组病灶位于延髓腹内侧,且多位于延髓上段.LMI多表现为不典型或部分性的"Wallenberg综合征",最常见的症状或体征为眩晕,Homer征、构音障碍、吞咽障碍、软腭麻痹,肢体共济失调.MMI多表现为感觉运动性卒中(SMS)或纯运动性卒中(PMS),最常见的症状或体征为对侧肢体偏瘫、构音障碍、中枢性面舌瘫.31例延髓梗死患者中,BMI 2例均为双侧MMI,其中1例出现四肢瘫痪、双侧肢体深浅感觉障碍、核间性眼肌麻痹、构音以及吞咽障碍,另1例表现为左侧肢体偏瘫、构音障碍、强哭、强笑等症状体征.结论:典型的延髓梗死综合征在临床上少见,LMI多表现为不典型,部分性的"Wallenberg综合征".而MMI往往与桥脑、基底节区腔隙性梗死的临床表现相似.双侧MMI导致四肢瘫痪等双侧锥体束受损表现,预后较差.     

Clinical findings of intracranial vertebral artery disease using magnetic resonance angiography

The vertebral artery lesion has a variety of clinical characteristics. We sought to clarify the clinical patterns and the location of the intracranial vertebral artery (ICVA) diseases according to analyses of images obtained using magnetic resonance angiography (MRA). We studied vascular lesions, risk factors, symptoms, signs, and outcomes in 35 patients with ICVA disease (3 had bilateral occlusion; 9, unilateral occlusion; 6, bilateral stenosis; and 17, unilateral stenosis). The most common site of unilateral and bilateral lesions was the distal ICVA after the origin of posterior inferior cerebellar artery (PICA). We found accompanying basilar artery disease in 28.6% of patients with unilateral and bilateral ICVA disease. The majority of the ICVA lesions were associated with internal carotid arteries disease (48.8%). The common vascular risk factors were hypertension (71%), diabetes mellitus (34%), hyperlipidemia (31%), smoking (29%), and coronary artery disease (23%). Eighteen patients (51.4%) had transient ischemic attacks (TIAs) only, 10 patients (28.6%) had TIAs before stroke, and 5 patients (14.3%) had strokes without TIAs. Most patients (80%) with TIAs, with or without stroke, had multiple episodes. Vertigo or dizziness, ataxia, limbs weakness and abnormal gait were the common symptoms and signs. At 6 months follow-up, 66.7% patients had no symptoms or only slight symptoms that caused no disability. Our data showed (1) the usual location of ICVA disease (occlusion or severe stenosis) was distal to PICA, especially near the vertebrobasilar junction; (2) the risk factors were hypertension, diabetes mellitus, hyperlipidemia, smoking, and coronary artery disease; (3) patients with ICVA disease had a high frequency of accompanying internal carotid, middle cerebral, or basilar artery disease; (4) vertigo or dizziness, and ataxia were the common symptoms and signs; (5) TIA was the most common clinical pattern; (6) the outcome was favorable, except in cases with bilateral ICVA occlusion.