Epilepsy and respiratory chain defects in children with mitochondrial encephalopathies.
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.
Khurana
D S
DS
1Section of Neurology, St Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia 19134, USA. dkhurana@drexelmed.edu
Salganicoff
L
L
Melvin
J J
JJ
Hobdell
E F
EF
Valencia
I
I
Hardison
H H
HH
Marks
H G
HG
Grover
W D
WD
Legido
A
A
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
D003580:Cytochromes; D009243:NAD; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III