Early pattern of epilepsy in the ring chromosome 20 syndrome.
OBJECTIVE
The characteristics of epilepsy in ring chromosome 20 have been reported in adolescents and adults. The mode of onset most often remains imprecise. To clarify this onset period, we studied the early-onset features in our personal series and in the reported pediatric cases.


METHODS
Our series comprises one child with an onset of epilepsy in the neonatal period and five others with an onset before age 8 years. The cases in the literature with an epilepsy onset before 8 years also were reviewed.


RESULTS
Seizures in the neonatal period were described as motor seizures. Our personal patient with a neonatal onset had severe psychomotor delay. In both infancy and early childhood, the EEG showed no interictal frontal localization of the anomalies, and no long-lasting seizure was recorded. Seizures with terror and hallucinations usually appeared from about age 4 years. It is not before the age of 8 years that the usual interictal EEG pattern appeared of rhythmic theta slow-waves activity with spikes predominating in frontal areas described in adolescence and adulthood. The interictal EEG showed 1- to 2-Hz delta slow waves and spike-and-waves predominating in frontal areas, but no physiologic activity.


CONCLUSIONS
In ring 20 chromosome, specific epilepsy features are lacking in the neonate, but the whole phenotype shows a more severe expression in terms of mental delay. The characteristic frontal EEG pattern and ictal terror do not appear before age 4 to 5 years.
Ville
Dorothée
D
Department of Clinical Neurophysiology, Hôpital Necker Enfants Malades, Paris, France.
Kaminska
Anna
A
Bahi-Buisson
Nadia
N
Biraben
Arnaud
A
Plouin
Perrine
P
Telvi
Louise
L
Dulac
Olivier
O
Chiron
Catherine
C
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D002648:Child; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics*; D015897:Comorbidity; D018450:Disease Progression; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D020936:Epilepsy, Benign Neonatal / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D005260:Female; D006212:Hallucinations / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D008297:Male; D009030:Mosaicism; D010641:Phenotype; D011596:Psychomotor Disorders / Q000453:epidemiology / Q000235:genetics; D012303:Ring Chromosomes; D013577:Syndrome