Atonic seizures in children with surgically remediable epilepsy: a motor system seizure phenotype?

Aim. Atonic seizures are common in some epileptic syndromes beginning in infancy or early childhood but they are rarely described in epilepsy with focal seizures of structural aetiology. We aimed to characterize the electroclinical features of atonic seizures in surgically remediable paediatric pati...

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Bibliographic Details
Published in:Epileptic disorders 2017-09, Vol.19 (3), p.315-326
Main Authors: Scholly, Julia, Bartolomei, Fabrice, Valenti‐Hirsch, Maria Paola, Boulay, Clotilde, De Saint Martin, Anne, Timofeev, Alexander, Kehrli, Pierre, Hirsch, Edouard
Format: Article
Language:English
Subjects:
atonic seizure
Bioengineering
Child, Preschool
Children
EEG
Electroencephalography
Epilepsy
epileptogenicity index
Genotype & phenotype
Human health and pathology
Humans
Imaging
Infant
intracerebral EEG
Life Sciences
Male
Motor Cortex - physiopathology
negative motor area
Phenotype
premotor cortex
Retrospective Studies
Seizures
Seizures - diagnosis
Seizures - physiopathology
Spatial distribution
Surgery
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Summary:Aim. Atonic seizures are common in some epileptic syndromes beginning in infancy or early childhood but they are rarely described in epilepsy with focal seizures of structural aetiology. We aimed to characterize the electroclinical features of atonic seizures in surgically remediable paediatric patients and to study the spatiotemporal organization of the underlying epileptogenic networks. Methods. We retrospectively analysed two consecutive, longitudinally evaluated and surgically treated paediatric patients presenting with atonic seizures as a manifestation of pharmacoresistant epilepsy of structural aetiology, evidenced by scalp‐ and stereotactic intracerebral video‐EEG‐recordings. A quantitative analysis of the epileptogenic zone organization was performed using the “epileptogenicity index”. Results. Long‐lasting generalized ictal atonia, occurring in infancy, was a predominant clinical feature in both patients, with some hints of focal origin present in one case. The seizure phenotype evolved at later age into subtle segmental atonia, associated with prominent positive motor signs. The epileptogenic zone was localized within the dorsolateral or mesiolateral premotor region. Its spatial organization was focal, matching the lesional cortex in one and distributed involving several lesional and non‐lesional structures in the other case. The emergence of atonic semiology temporally correlated with involvement of both lateral and mesial premotor, as well as primary motor areas. Conclusion. We hypothesize that atonic seizures may be considered as a motor system seizure phenotype in the setting of structural epilepsy. Complete removal of the epileptogenic area provided excellent seizure control.
ISSN:1294-9361
1950-6945
DOI:10.1684/epd.2017.0930