1/4. Unmasking of carnitine palmitoyltransferase deficiency during an acute exacerbation of asthma complicated by rhabdomyolysis in a soldier.rhabdomyolysis is a life-threatening condition that may result from various etiologies. We report a rare case of severe rhabdomyosis in a soldier after a mild acute asthma exacerbation. Further work-up revealed an underlying deficiency of type II carnitine palmitoyltransferase. The case is discussed along with a review of the literature. It is concluded that acute asthma exacerbations may be a unique precipitating factor of rhabdomyolysis and may therefore unmask underlying metabolic myopathies. asthma may cause rhabdomyolysis through several different mechanisms, and thus the occurrence of rhabdomyolysis in the context of asthma exacerbations should warrant a work-up for metabolic diseases, especially in the presence of high creatine kinase levels. Given the high incidence of asthma, especially among young adults, a high index of suspicion is needed in order that rhabdomyolysis be promptly diagnosed and treated.- - - - - - - - - - ranking = 1keywords = myopathies (Clic here for more details about this article) |
2/4. Lipid storage myopathy due to glutaric aciduria type II: treatment of a potentially fatal myopathy.Several patients with lipid storage myopathies have been described, although in most cases the biochemical defect is unclear. A child is reported who presented with severe muscle weakness at age six months. She had lipid storage myopathy due to glutaric aciduria type II. It is probable that her brother died from the same disorder at the age of three months. She has responded well to treatment with a low-fat diet, riboflavin, carnitine and glycine.- - - - - - - - - - ranking = 1keywords = myopathies (Clic here for more details about this article) |
3/4. Metabolic myopathies.The most frequent metabolic myopathies of children and adults (glycogenoses; neutral fat myopathies; "mitochondrial" myopathies) are reviewed. In glycogenoses and neutral fat myopathies the most prominent histological feature is represented by a vacuolation of muscle fibres, vacuoles being filled with glycogen or neutral fat. Enzyme defects of glycogenoses are known. In some neutral fat myopathies, an involvement of carnitine metabolism can be found; in many other cases, biochemical investigations have failed to identify the enzyme defect(s), or have demonstrated the contemporaneous involvement of mitochondria ("mitochondrial" myopathy). The large group of "mitochondrial" myopathies is built up of many heterogeneous polygenetic syndromes, the appearance of which signalises only an impaired mitochondrial function due to underlying biochemical defect(s). In these cases, accumulations of mitochondria in muscle fibres, easily recognisable with trichrome stain ("ragged-red fibres") may be found. These mitochondria usually present very peculiar ultrastructural changes ("paracrystalline inclusions"). One of the leading clinical symptoms of metabolic myopathies is represented by myoglobinuria. In every case of "idiopathic" rhabdomyolysis, a metabolic myopathy should hence be suspected. The negative result of histological and enzymehistochemical investigations, does not exclude the presence of a metabolic disorder, however. research in this field requires a very strong cooperation between morphologists and biochemists. Future therapeutical approaches can in fact only come from and through biochemistry.- - - - - - - - - - ranking = 11keywords = myopathies (Clic here for more details about this article) |
4/4. An oxidative defect in metabolic myopathies: diagnosis by noninvasive tissue oximetry.Metabolic myopathies due to a variety of enzymatic deficiencies are well recognized. The dynamics of oxygen delivery and utilization during exercise have not been observed previously in these disorders. We used a noninvasive optical technique to measure oxygen consumption in the exercising limb in normal subjects and patients with metabolic myopathies. We measured near-infrared spectra of hemoglobin in the gastrocnemius muscle during treadmill exercise in 10 normal subjects, 1 patient with cytochrome c oxidase deficiency, 2 patients with myophosphorylase deficiency, 3 patients with phosphofructokinase deficiency, and 2 patients with carnitine palmityl transferase deficiency. All normal subjects demonstrated a sustained deoxygenation during exercise, indicating an efficient utilization of delivered oxygen. The patient with cytochrome c oxidase deficiency demonstrated consistent oxygenation during exercise, indicating an underutilization of delivered oxygen. In the patients with myophosphorylase or phosphofructokinase deficiency, abnormal oxygenation during exercise indicated an oxidative defect due to a lack of pyruvate production. In the patients with myophosphorylase deficiency, changes in oxidation coincident with glucose utilization and "the second wind phenomenon" were observed. patients with carnitine palmityl transferase deficiency demonstrated a normal deoxygenation during exercise. Noninvasive tissue oximetry during exercise demonstrates specific abnormalities in a variety of metabolic myopathies, indicating abnormal oxygen utilization, and will be a useful addition to the clinical investigation of exercise intolerance.- - - - - - - - - - ranking = 7keywords = myopathies (Clic here for more details about this article) |