title: [Metabolic myopathies].
abstract: OBJECTIVE
  To review the metabolic myopathies manifested only by crisis of myalgias, cramps and rigidity of the muscles with decreased voluntary contractions and normal inter crisis neurologic examination in children and adolescents.
  
  
  METHODS
  These metabolic myopathies are autosomic recessive inherited enzymatic deficiencies of the carbohydrates and lipids metabolisms. The end result is a reduction of intra muscle adenosine triphosphate, mainly through mitochondrial oxidative phosphorylation, with decrease of available energy for muscle contraction. The one secondary to carbohydrates intra muscle metabolism disorders are triggered by high intensity brief (< 10 min) exercises. Those secondary to fatty acids metabolism disorders are triggered by low intensity prolonged (> 10 min) exercises. The conditions in the first group in order of decreasing frequency are the deficiencies of myophosforilase (GSD V), muscle phosphofructokinase (GSD VII), phosphoglycerate mutase 1 (GSD X) and beta enolase (GSD XIII). The conditions in the second group in order of decreasing frequency are the deficiencies of carnitine palmitoyl transferase II and very long chain acyl CoA dehydrogenase.
  
  
  CONCLUSIONS
  The differential characteristics of patients in each group and within each group will allow to make the initial presumptive clinical diagnosis in the majority and then to order only the necessary tests to achieve the final diagnosis. Treatment during the crisis includes hydration, glucose and alkalinization of urine if myoglobin in blood and urine are elevated. Prevention includes avoiding exercise which may induce the crisis and fasting. The prognosis is good with the exception of rare cases of acute renal failure due to hipermyoglobinemia because of severe rabdomyolisis.
authors.affiliation: Miami Children's Hospital, Miami, EE.UU.
authors.forename: Óscar
authors.initials: Ó
authors.lastname: Papazian
authors.forename: Rafael
authors.initials: R
authors.lastname: Rivas-Chacón
mesh_terms: D000293:Adolescent; D002239:Carbohydrate Metabolism, Inborn Errors / Q000235:genetics* / Q000378:metabolism; D002334:Carnitine O-Palmitoyltransferase / Q000172:deficiency / Q000235:genetics; D017079:Exercise Tolerance; D005808:Genes, Recessive; D024982:Glycogen Phosphorylase, Muscle Form / Q000172:deficiency / Q000235:genetics; D006012:Glycogen Storage Disease Type V / Q000235:genetics; D006014:Glycogen Storage Disease Type VII / Q000201:enzymology / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D008052:Lipid Metabolism, Inborn Errors / Q000235:genetics* / Q000378:metabolism; D008661:Metabolism, Inborn Errors / Q000235:genetics; D009119:Muscle Contraction; D009135:Muscular Diseases / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D025203:Phosphofructokinase-1, Muscle Type / Q000235:genetics
chemical_list: D002334:Carnitine O-Palmitoyltransferase; D024982:Glycogen Phosphorylase, Muscle Form; D025203:Phosphofructokinase-1, Muscle Type