Neuromuscular disorders : NMD
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Neuromuscul. Disord. · Sep 2001
Case ReportsVecuronium-associated axonal motor neuropathy: a variant of critical illness polyneuropathy?
Neuromuscular blocking agents are routinely used as an adjunct therapy for critically ill patients. Unlike many neuromuscular blocking agents, vecuronium does not cause significant histamine release, which may lead to bronchoconstriction. ⋯ We report a case of an 8-year-old girl who had a primarily motor axonopathy presenting with weakness after extended vecuronium administration with prolonged course of recovery. This primarily motor neuropathy with axonal features may be a variant of critical illness polyneuropathy, a rarely reported condition in pediatric patients.
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Neuromuscul. Disord. · Feb 2000
Fibrillation potential amplitude to quantitatively assess denervation muscle atrophy.
Denervated muscle fibers exhibit spontaneous, repetitive single muscle fiber discharges and display fibrillation potentials detectable by electromyography. To explore the changing pattern of fibrillation potential amplitude after peripheral nerve injury and its relationship to the degree of muscle atrophy, fibrillation potential amplitudes were recorded on completely denervated biceps brachii of 173 patients with brachial plexus injury. Biceps brachii biopsies were taken at the same sites as the electromyogram recordings in 63 patients. ⋯ The fibrillation potential amplitude correlates positively with both type I and II fiber cross-sectional areas (P < 0.0005-0.01). Our results show that fibrillation potential amplitude is closely correlated with muscle fiber size during the first 15 months after nerve injury, and it may therefore serve as a convenient index to evaluate quantitatively the degree of atrophy of denervated muscles. Electromyographic studies thus may help in designing treatment strategies.
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A 14-year-old boy presented with a 3-year history of a skin rash typical of juvenile dermatomyositis, and a 2-month history of mild proximal weakness, myalgia, and weight loss. A quadriceps biopsy showed perifascicular fibre atrophy, focal necrosis and regeneration, immunohistochemical labelling for HLA-1 on the surface of the fibres, and focal C5-9 deposition in capillaries. Macrophages with diastase-resistant, PAS-positive cytoplasm were present. ⋯ The 16S ribosomal RNA specific for Tropheryma whippelii was identified by polymerase chain reaction (PCR) analysis in skeletal and cardiac muscle. The myalgia and skin rash responded to prednisolone and oral co-trimoxazole, and the tachycardia is controlled by oral verapamil. This patient appears to have a novel association of juvenile dermatomyositis and Whipple's disease.
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Neuromuscul. Disord. · Jul 1999
Specific removal of the nonsense mutation from the mdx dystrophin mRNA using antisense oligonucleotides.
The mdx mouse, which carries a nonsense mutation in exon 23 of the dystrophin gene, has been used as an animal model of Duchenne muscular dystrophy to evaluate cell or gene replacement therapies. Despite the mdx mutation, which should preclude the synthesis of a functional dystrophin protein, rare, naturally occurring dystrophin-positive fibres have been observed in mdx muscle tissue. These dystrophin-positive fibres are thought to have arisen from an exon-skipping mechanism, either somatic mutations or alternative splicing. ⋯ Approximately 50% of the dystrophin gene mRNAs were missing this exon 6 h after transfection of primary mdx myotubes, with all transcripts showing skipping of exon 23 after 24 h. Deletion of exon 23 does not disrupt the reading frame and should allow the synthesis of a shorter but presumably functional Becker-like dystrophin. Molecular intervention at dystrophin pre-mRNA splicing has the potential to reduce the severity of a Duchenne mutation to the milder Becker phenotype.
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Neuromuscul. Disord. · May 1998
Case ReportsCritical illness myopathy unrelated to corticosteroids or neuromuscular blocking agents.
Acute myopathy occurs in critically ill patients, receiving neuromuscular blocking agents or corticosteroids during intensive care hospitalisation. We report three patients with acute quadriplegic myopathy, two of whom were not exposed to corticosteroids or neuromuscular blocking agents. The first of these latter two patients had a history of generalised anoxia with coma related to surgery, complicated by multiple organ failure and sepsis. ⋯ Electrophysiological studies and muscle biopsy findings were consistent with the diagnosis of critical illness myopathy with loss of myosin filaments. Selective loss of myosin was confirmed by biochemical analysis of muscle. These findings demonstrate that acute myopathy with loss of myosin filaments may occur in patients with severe systemic illness without exposure to corticosteroids or neuromuscular blocking agents.