Epileptic phenotypes in children with respiratory chain disorders.
OBJECTIVE
Epilepsy is a commonly reported but rarely described clinical hallmark of mitochondrial respiratory chain defects (RCDs) with encephalopathy.


METHODS
From 1990-2006 we collected data about 56 children with RCD (single, n = 24 or multiple, n = 20 mitochondrial complex deficiencies; mtDNA mutation, n = 11; mtDNA depletion n = 10 of 21; and nuclear gene mutation n = 11). Epileptic features were reviewed retrospectively.


RESULTS
First seizures were frequently (47 patients, 82.5%) preceded by failure to thrive, psychomotor delay, ataxia, or multisystemic dysfunction. Sixty percent of the patients had several seizure types. Six age-related epilepsy phenotypes could be identified: status epilepticus complicating neonatal multivisceral deficiency (2 patients), neonatal myoclonic encephalopathy (3 patients), infantile spasms (8 patients), refractory or recurrent status epilepticus (21 patients), epilepsia partialis continua (4 patients), and myoclonic epilepsy (18 patients). Except for infantile spasms, epilepsy was difficult to control in most patients (95%). Valproate was administered to 25 patients, one of whom developed acute liver failure 6 days later. Twenty-two patients (45%) died, half of them within 9 months from the onset of epilepsy.


CONCLUSIONS
In RCD, epilepsy is not only difficult to control but its occurrence often indicates a severe turn in the course of the disease. For one-third of the patients, classical biochemical measures failed to reveal any abnormality and RCD could be detected in the liver only.
El Sabbagh
Sandra
S
Pediatric Neurology, Hôpital Necker, APHP, Paris, France. isabelle.desguerre@nck.aphp.fr
Lebre
Anne-Sophie
AS
Bahi-Buisson
Nadia
N
Delonlay
Pascale
P
Soufflet
Christine
C
Boddaert
Nathalie
N
Rio
Marlène
M
Rötig
Agnès
A
Dulac
Olivier
O
Munnich
Arnold
A
Desguerre
Isabelle
I
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004579:Electron Transport / Q000235:genetics; D004827:Epilepsy / Q000150:complications / Q000235:genetics* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D028361:Mitochondrial Diseases / Q000150:complications / Q000235:genetics* / Q000503:physiopathology*; D010641:Phenotype; D012189:Retrospective Studies