Résumé :
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Background: Muscle histopathology, in myopathies does not give any information about the biochemical changes in the muscles in disease. MR spectroscopy can throw some light on the biochemical aspect of muscle pathology, and may be of incremental value in diagnosing various muscle diseases. Objective: To evaluate the role of in Vitro proton NMR spectroscopy in evaluating adult myopathies and to establish a clinicopathological and NMR spectroscopic correlation between various adult myopathies. Design/Methods: Adult patients with myopathy were subjected to a detailed clinical, electrophysiological, and histopathological evaluation and were then classified as having muscular dystrophy, inflammatory myopathies, mitochondrial myopathies, and indeterminate group. In vitro proton MR spectroscopy was performed in a subgroup of patients from each of the above groups and there NMR spectra analysed. A correlation was then attempted with the clinical picture of the patients, there histopathological group and the NMR spectra of the muscle biopsy specimens. Results: 77 adult patients were recruited in the study (58% muscular dystrophies, 18 % inflamatory myopathies, 12 % each mitochondrial and indeterminate group).Concentration of lactate was significantly increased in biopsies of patients with mitochondrial myopathies as compared to inflammatory myopathies and muscular dystrophies. Concentrations of alanine, glutamine, glucose and creatine were found to be significantly lowered in inflammatory myopathies and muscular dystrophies as compared to mitochondrial myopathies. Inflammatory myopathies showed significantly higher concentrations of glucose and creatine than patients with muscular dystrophies. MRS data also provided important diagnostic clues in six out of nine patients in whom no diagnosis could be established by traditional methods. Conclusions/Relevance: In vitro proton MR spectroscopy can be used as an adjunctive tool for evaluation of adult myopathies as it can indicate the spectroscopic differences between various subtypes of myopathies. In vivo studies can further establish its role in evaluation of myopathies.
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