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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the cases of 2 siblings with progressive encephalopathy. The first symptoms were noted when they were 6 years old. The full clinical picture included myoclonus, seizures, cerebellar ataxia, blindness due to optic atrophy and retinal degeneration, deafness, swallowing difficulties with relatively spared intellectual functions. The course was progressive and led to death within 8 years. The pathological findings included bilateral and almost symmetrical lesions involving the thalami, the colliculi, and the pontine and medullar tegmentum, similar to the changes described in Leigh disease. Neuronal loss and gliosis were noted in the dentate nucleus and in the inferior olive, as in MERRF syndrome. Laminar necrosis of the cerebral cortex could have been due to episodes of severe hypotension before death. Cytochrome c oxidase deficiency was found in case 2. The enzyme deficiency was present in muscle and in fibroblasts in culture.
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PMID:[Familial mitochondrial encephalopathy. A clinicopathologic study]. 166 Jan 81

Leigh's disease is one of the mitochondrial encephalomyopathies. This article presents a 7-month-old baby boy who had been well-being since birth until 6 months of age when episodic downward gaze of both eyes with limitation of horizontal eye movement were noted. This episode of cranial nerve palsies lasted about 4-5 days and subsided spontaneously. The second attack was noted one month later, to be associated with hypotonia and truncal ataxia. Episodic hyperventilation with resultant gasping and myoclonus was noted at the third attack but spontaneous respiration resumed soon with persistent ophthalmoplegia and truncal ataxia. Lumbar puncture, brain MRI, amino acid assay and cardiac echo all showed negative finding. The oral glucose lactate stimulation test revealed an elevation of lactic acid, brain stem evoked potential indicated bilateral obscure 4th and 5th waves, and muscle biopsy showed ragged red fibres with aggregation of structurally abnormal mitochondria noted under electron microscope. Coenzyme Q, thiamine and carnitine had been given before biochemical study; however, the neurological symptoms did not show any improvement. Biochemical study finally revealed normal respiratory chain enzymes including NADH-coenzyme Q reductase, succinate coenzyme Q reductase and cytochrome c oxidase while other enzymes were technically unavailable for study. Unfortunately the patient died at 18-month-old due to respiratory failure.
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PMID:Mitochondrial encephalomyopathy presenting with clinical Leigh's disease: report of a case. 184 64

A 6-month-old female infant was diagnosed with Leigh syndrome after an abnormal muscle specimen was obtained and after magnetic resonance imaging demonstrated characteristic cranial lesions. She presented with episodic hyperventilation, myoclonus, ophthalmoplegia, hypotonia, and elevation of lactate in the cerebrospinal fluid and blood. A series of cranial ultrasounds revealed progressive ventricular enlargement before the typical lesions were detected by magnetic resonance imaging. Myelin destruction is believed to play an important role in the early stage of Leigh syndrome. Ultrasonography may provide a convenient way to document changes in brain that provide early suspicion of Leigh syndrome.
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PMID:Leigh syndrome with progressive ventriculomegaly. 806 Apr 29

We looked for the A-->G transition at position 8344 of mtDNA in 150 patients, most of them with diagnosed or suspected mitochondrial disease, to assess the specificity of this mutation for the MERRF phenotype, to define the clinical spectrum associated with the mutation, and to study the relationship between percentage of mutation in muscle and clinical severity. Our results confirm the high correlation between the A-->G transition at position 8344 and the MERRF syndrome, but they also show that this mutation can be associated with other phenotypes, including Leigh's syndrome, myoclonus or myopathy with truncal lipomas, and proximal myopathy. The absence of the mutation in four typical MERRF patients suggests that other mutations in the tRNA(Lys) gene, or elsewhere in the mitochondrial DNA, can produce the same phenotype.
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PMID:Clinical features associated with the A-->G transition at nucleotide 8344 of mtDNA ("MERRF mutation"). 817 May 67

Fourteen patients (10 boys, 4 girls) aged from 4 months to 14 years old were diagnosed with mitochondrial disease based on the clinical manifestations together with abnormal muscle mitochondrial morphologies. Their clinical diagnoses included Leigh syndrome, three; Menkes' syndrome, three; Kearns-Sayre syndrome, two; myoclonic epilepsy with ragged fibres, one; and infant-onset progressive myoclonic epilepsy, one; fatal infantile mitochondrial myopathy, one; fatty acid oxidation defect, two; and myopathy with cardiopathy, one. Organs involved other than muscles included central nervous system, ten; heart, six; eye, two; liver, two; and kidney, two. Clinical manifestations varied to include hypotonia, seizures, myoclonus, mental retardation, nystagmus, ataxia, ptosis, ophthalmoplegia, retinal degeneration, muscle atrophy, spasticity etc. Nine had an abnormal rise in lactate after glucose loading. Ragged-red fibres were found in four patients. Abnormal mitochondrial morphology included abnormal accumulation, abnormal cristae pattern of tubular, concentric, or parallel form, some contained osmiophilic inclusion bodies. One patient of Leigh syndrome had had brain necropsy which showed intramyelin splitting of myelinated axons.
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PMID:Clinical manifestation of mitochondrial diseases in children. 821 54

Leigh syndrome (LS) is the clinical prototype of a genetically-determined mitochondrial encephalopathy. Twenty-two of 34 patients with LS had evidence of a movement disorder (MD). Dystonia, the most common MD, was present in 19 cases, rigidity in 4, tremor in 2, chorea in 2, hypokinesia in 2, myoclonus in 1, and tics in 1. Dystonia was most commonly multifocal at onset and showed progression in six patients. In half of the cases an enzymatic defect was detected, most commonly cytochrome C oxidase. The neuroradiologic findings showed prominent basal ganglia lesions in 20/21 patients. Putamen, caudate, substantia nigra and globus pallidus were involved in this order of frequency. This experience was reflected in a literature review encompassing 284 cases of LS. However, only 26.4% had MD. Eleven patients, including one of our cases, presented as the primary torsion dystonia phenotype. There are clinical and pathological similarities between LS and other metabolic diseases affecting the central nervous system. The enhanced vulnerability of the nervous system to metabolic stress and the resemblance in the distribution of the pathology of these diverse conditions suggests a common pathogenetic mechanism. An excitotoxin-mediated mechanism is favored, one which might account for the frequent involvement of the basal ganglia in LS.
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PMID:Disorders of movement in Leigh syndrome. 839 42

The mitochondrial DNA (mtDNA) transfer RNA (tRNA)Lys A-->G(8344) mutation was identified in seven patients. These patients and their relatives were assessed clinically; in one family the mutation was deduced to be present in four generations. The phenotype in index cases was consistent with the syndrome of myoclonic epilepsy with ragged red fibres, with the core clinical features of myoclonus, ataxia and seizures. Amongst other features, progressive external ophthalmoplegia, Leigh's syndrome and stroke-like episodes were observed, well recognized in mitochondrial myopathies but novel manifestations of this genotype. Samples of blood and muscle were analysed for the proportion of mutant mtDNA using an oligonucleotide hybridization technique. The proportion of mutant mtDNA in blood was significantly greater in symptomatic than asymptomatic cases. Furthermore, the proportion of mutant mtDNA in blood correlated with age of onset of disease and clinical severity assessed by a simple scale. Study of disease associated with the tRNA(Lys) A-->G(8344) mutation provides further insight into the pathogenesis and transmission of mitochondrial diseases. Quantification of the proportion of mtDNA in tissues demonstrates that this is a major factor determining the course of disease, but other, as yet unidentified factors are also likely to play a role.
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PMID:The mitochondrial DNA transfer RNA(Lys)A-->G(8344) mutation and the syndrome of myoclonic epilepsy with ragged red fibres (MERRF). Relationship of clinical phenotype to proportion of mutant mitochondrial DNA. 851 95

We report a 6-month-old girl with episodic hyperventilation, myoclonus, disturbed consciousness, and lactic acidosis. Brain sonogram revealed progressive ventriculomegaly, and MRI showed symmetric low densities over the putamen bilaterally with diffuse cortical cystic lesions. Ragged-red fibers were noted in the muscle biopsy. Molecular analysis revealed a heteroplasmic T-->G mutation at nucleotide position (np) 8993 of mitochondrial DNA (mtDNA). The proportion of the mutant mtDNA in the muscle of the proband was estimated to be 86%. Her mother and maternal uncle also harbored the same mutant mtDNA (54 and 48% in their leukocytes, respectively). One of her sisters carried 64% mutant mtDNA in her leukocytes, but another sister did not. These results suggest that this mutant mtDNA is transmitted through the maternal lineage in this family in a randomly segregated manner. To our knowledge, this is the first report of a Chinese patient with Leigh syndrome associated with the T-->G substitution at np 8993 of mtDNA.
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PMID:Leigh syndrome associated with mitochondrial DNA 8993 T-->G mutation and ragged-red fibers. 885 7

Four autopsied cases of myoclonus, ataxia, and epilepsy from 2 separate pedigrees are described. An identical pattern of focal brainstem lesions was found in all the cases with selective and symmetrical degeneration of the dentate and second order somatosensory nuclei. The combined clinical and pathological features did not appear to match any familial disorder previously described as causing progressive myoclonus epilepsy. Myoclonus epilepsy with ragged red fibres was excluded on the grounds of paternal inheritance and negative muscle biopsy findings, but the more acute lesions seen in 1 case are reminiscent of those found in Leigh's syndrome, and suggest that some other form of inherited defect of oxidative metabolism may be involved.
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PMID:Progressive myoclonus epilepsy with focal brainstem degeneration and paternal inheritance. An autopsy report of 4 cases from 2 pedigrees. 892 94

Neuroimage studies of thirty-eight infants and children with mitochondrial disorders were reviewed: 24 ultrasound (US), 21 computed tomography (CT), and 27 magnetic resonance image (MRI) examinations were analyzed. Patients included seventeen with Leigh syndrome, two with Kearns-Sayre syndrome (KSS), one with myoclonus, epilepsy, and ragged red fibers (MERRF), one with Alpers disease, five with Menkes disease, two with fatty acid metabolic defect, two with Rett syndrome, and eight with unspecified mitochondrial disorders. KSS and MERRF tended to occur in older children, whereas Leigh syndrome, Menkes disease, and Alpers disease occurred in infants and young children. The deep cerebral nuclei and the cerebral white matter were commonly involved in Leigh syndrome and KSS. Subdural hematomas or effusions with profound cerebral atrophy was found in Alpers disease and Menkes disease. Tortuosities of basilar, Willis circle, and cerebral vessels were also noted in Menkes disease. MRI and CT examinations of Rett syndrome, fatty acid metabolic defect, and most of the unspecified mitochondrial disorders were normal. Our results indicate that neuroimage studies have characteristic findings for specific mitochondrial syndromes.
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PMID:Neuroimage in infants and children with mitochondrial disorders. 893 6


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