title: Epilepsy and respiratory chain defects in children with mitochondrial encephalopathies.
abstract: OBJECTIVE
  The purpose of this study was to determine the relationship between epilepsy and respiratory chain defects in children with mitochondrial encephalopathies (ME).
  
  
  METHODS
  We conducted a retrospective review of the medical records of children referred for evaluation of an ME. Only patients assigned a definite diagnosis of ME using modified Walker criteria and with a respiratory chain defect were included. Clinical data pertaining to the ME and epilepsy type were collected. Mitochondria were isolated by subcellular fractionation from a vastus lateralis muscle biopsy and studies were performed using polarographic and spectroscopic techniques for the quantitative determination of NADH and cytochrome components of the respiratory chain.
  
  
  RESULTS
  A total of 38 children with ME were identified. Seizures were present in 61%. Sixteen of 23 children with epilepsy (70%) had refractory epilepsy associated with a progressive encephalopathy. Children with epilepsy had a significantly higher incidence of complex I defects than children without epilepsy (p<0.01). Complex III and IV defects were significantly higher in patients without epilepsy (p<0.01 and p<0.05, respectively) than in those with epilepsy.
  
  
  CONCLUSIONS
  Epilepsy is an important component of ME. The higher incidence of complex I defects in patients with epilepsy suggests a possible relationship between mitochondrial oxidative stress dysfunction and epileptogenic process.
authors.affiliation: 1Section of Neurology, St Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia 19134, USA. dkhurana@drexelmed.edu
authors.forename: D S
authors.initials: DS
authors.lastname: Khurana
authors.forename: L
authors.initials: L
authors.lastname: Salganicoff
authors.forename: J J
authors.initials: JJ
authors.lastname: Melvin
authors.forename: E F
authors.initials: EF
authors.lastname: Hobdell
authors.forename: I
authors.initials: I
authors.lastname: Valencia
authors.forename: H H
authors.initials: HH
authors.lastname: Hardison
authors.forename: H G
authors.initials: HG
authors.lastname: Marks
authors.forename: W D
authors.initials: WD
authors.lastname: Grover
authors.forename: A
authors.initials: A
authors.lastname: Legido
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003580:Cytochromes / Q000378:metabolism; D004569:Electroencephalography / Q000379:methods; D004579:Electron Transport; D042967:Electron Transport Complex I / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004827:Epilepsy / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D017237:Mitochondrial Encephalomyopathies / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D009243:NAD / Q000378:metabolism; D018384:Oxidative Stress; D012189:Retrospective Studies
chemical_list: D003580:Cytochromes; D009243:NAD; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III