Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD), an X-linked disorder, is the most common muscular dystrophy in children, presenting in early childhood and characterized by proximal muscle weakness and calf hypertrophy in affected boys. Patients usually become wheelchair-bound by the age of 12 years, and die of cardiorespiratory complications in their late teens to early twenties. Advances in the management of DMD, including treatment with corticosteroids and the use of intermittent positive pressure ventilation have provided improvements in function, ambulation, quality of life and life expectancy, although novel therapies still aim to provide a cure for this devastating disorder. The clinical features, investigations, and management of DMD are reviewed, as well as the latest in some of the novel therapies.     

Duchenne muscular dystrophy manifesting carriers

Seven unrelated women were manifesting carriers of Duchenne muscular dystrophy. A manifesting carrier of Duchenne muscular dystrophy is defined as a female with a history of Duchenne muscular dystrophy in her pedigree who has symptomatic weakness. All were characterized by slowly progressive weakness that began in the second or third decade of life. Asymmetric weakness was present in only three of the seven patients. Serum creatine kinase values were elevated in all patients and none had an electrocardiogram indicating ventricular hypertrophy. The electromyogram and muscle biopsy specimens were reported as myopathic in all patients studied. In the absence of a male relative with Duchenne muscular dystrophy, clinical distinction from cases of autosomal recessive limb girdle muscular dystrophy may not be possible. The development of new techniques in molecular genetics should allow precise identification of manifesting carriers of Duchenne muscular dystrophy in the near future.     

Duchenne muscular dystrophy and epilepsy

Cognitive and behavioral difficulties occur in approximately a third of patients with Duchenne muscular dystrophy. The aim of our study was to assess the prevalence of epilepsy in a cohort of 222 DMD patients. Epileptic seizures were found in 14 of the 222 DMD patients (6.3%). The age of onset ranged from 3 months to 16 years (mean 7.8). Seizures were more often focal epilepsy (n = 6), generalized tonic–clonic seizures (n = 4) or absences (n = 4). They were present in 12 of the 149 boys with normal IQ (8.1%) and in two of the 73 with mental retardation (2.7%). In two cases the parents did not report any past or present history of seizures but only ‘staring episodes’ interpreted as a sign of ‘poor attention’. In both patients EEG showed the typical pattern observed in childhood absence epilepsy. Our results suggest that the prevalence of epilepsy in our study (6.3%) is higher than in the general pediatric population (0.5–1%). The risk of epilepsy does not appear to increase in patients with mental retardation.     

Therapeutics in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a fatal disorder affecting approximately 1 in 3500 live born males, characterized by progressive muscle weakness. Several different strategies are being investigated in developing a cure for this disorder. Until a cure is found, therapeutic and supportive care is essential in preventing complications and improving the afflicted child’s quality of life. Currently, corticosteroids are the only class of drug that has been extensively studied in this condition, with controversy existing over the use of these drugs, especially in light of the multiple side effects that may occur. The use of nutritional supplements has expanded in recent years as researchers improve our abilities to use gene and stem cell therapies, which will hopefully lead to a cure soon. This article discusses the importance of therapeutic interventions in children with DMD, the current debate over the use of corticosteroids to treat this disease, the growing use of natural supplements as a new means of treating these boys and provides an update on the current state of gene and stem cell therapies.     

Duchenne muscular dystrophy and poliomyelitis

Summary A systematic study of dystrophy-denervation in human muscle showed minimal morphometabolic differences between dystrophic and dystrophic-denervated muscle. The only certain conclusion is that denervation influences the rhythm of evolution of the dystrophy without impressing any of the few characteristics considered at present as peculiar to denervation.This work was supported by a grant-in-aid of the Muscular Dystrophy Associations of America, Inc.     

Brain biochemistry in Duchenne muscular dystrophy: A H magnetic resonance and neuropsychological study

Duchenne muscular dystrophy (DMD) is a progressive muscle disorder associated with an intellectual deficit which is non-progressive. We obtained localised ¹H magnetic resonance spectra from the left frontal lobe and left cerebellum of 15 boys with DMD (mean age 106 months±32) and 15 similarly aged control boys (mean age 115 months±31); all boys underwent a battery of neuropsychological tests. We found a significant (P<0.01) increase in the ratio of choline-containing compounds to N-acetylaspartate (Cho/NA) in the left cerebellum in boys with DMD compared with control boys. There was no change in the creatine/NA ratio and a significant increase (P=0.03) in the Cho/creatine ratio, suggesting that the change in Cho/NA ratio was due to an increase in choline-containing compounds; this increase has been previously observed in the brain of the murine model of DMD, the mdx mouse. No significant changes were observed in spectra obtained from left frontal lobe in DMD compared to controls. We also observed a significant association between Cho/NA in the left cerebellum, and the performance of DMD boys on the Matrix Analogies Test (MAT). The MAT is a test of visuo-spatial ability and non-verbal reasoning which requires neither manual dexterity nor a verbal response for an adequate performance. A comparison of DMD boys whose cerebellar Cho/NA fell within 2 standard deviations of the control norm (0.56±0.24) with DMD boys whose cerebellar Cho/NA was outside this range (i.e. >0.80) revealed a significant difference in ability on the MAT (P<0.05). DMD boys whose Cho/NA ratio is more than two standard deviations higher than controls perform significantly better on the MAT than DMD boys whose Cho/NA ratio is within the normal range. This finding suggests that the observed elevation in Cho/NA and Cho/creatine is not associated with intellectual deficit (as sampled by the MAT), and may represent a compensatory mechanism. The possible interpretations of these metabolic changes are discussed.     

重视Duchenne型肌营养不良症的康复治疗

康复治疗对改善Duchenne型肌营养不良症患者生活质量、延缓病情进展至关重要,一些国家业已制定了康复治疗指南,我国尚缺乏这方面的指导性研究和意见。为了提高临床医师对该病症康复治疗的认识,现对其病情分期、临床特征,以及康复治疗的一般原则、常用方法和注意事项进行概述,为临床康复治疗提供一些参考。     

Cortical excitability in Duchenne muscular dystrophy

ObjectiveTo investigate the probable cortical excitability changes in DMD by electrophysiological means.MethodsSixteen cases with DMD, 10 age-matched control children (CC) and 10 healthy adult volunteers (AC) were studied with a transcranial magnetic stimulation (TMS) test battery composed of central conduction time, cortical silent period and paired TMS paradigm.ResultsThere were no significant differences between DMD and CC groups except for lower amplitude motor responses in DMD cases. These two groups showed a similar pattern of excitability with less short interval intracortical inhibitions and shorter silent period durations as compared to the AC subjects.ConclusionsThe electrophysiological tests performed in our DMD patients did not reveal abnormalities caused particularly by the disorder.SignificanceTMS excitability studies performed in DMD boys may not provide findings other than those related to the developmental age.     

Infantile autism and Duchenne muscular dystrophy

We report a boy with autism and Duchenne muscular dystrophy. Myopathy was noted after 2 years of age and has since progressed slowly. At present this autistic child, 11 years 4 months old, has shown no signs of deterioration. The first author wishes to express her sincere appreciation to Dr. Lauretta Bender, who directed her during the term of child psychiatric training at the children's unit of Creedmoor State Hospital, New York.     

Lipid changes in Duchenne muscular dystrophy

Thin layer chromatographic analysis of lipid extracts of rectus abdominis and gastrocnemius muscles from controls and patients with severe sex-linked Duchenne muscular dystrophy shows the dystrophic tissue to contain more sphingomyelin, less lecithin plus choline plasmalogen, and more total cholesterol than normal. Comparison of normal, dystrophic, and immature muscle suggests that these observations can be interpreted as showing a similarity between dystrophic and immature muscle and in this respect human Duchenne dystrophy resembles hereditary muscular dystrophy in the mouse. Although sphingomyelin was present in apparently normal amount in muscle biopsies from patients with various other neuromuscular disorders, it was raised in two cases showing evidence of peripheral neuropathy.