RESUMEN
BACKGROUND: The question of whether to treat a patient after a first unprovoked seizure is controversial. This prospective study assessed the time to recurrence and risk factors for seizure recurrence after a first unprovoked seizure in children. METHODS: Participants were recruited between 1 July 1997, and 30 June 2009. Eligible candidates were children between 1 month and 15 years old who presented with their first unprovoked afebrile seizure. After enrollment, recurrence of seizures was investigated. All participants were followed for at least 2 years. Log-rank test was used for bivariate analysis to check associations, and hazard ratios were used to analyze variables and clinical outcome (recurrence) during follow-up. RESULTS: Of 73 subjects, 42 (57.5%) experienced recurrence. The overall product-limit estimate of recurrence was 61.9% at 6 months, 85.7% at 1 year, and 95.2% at 2 years after seizure onset, respectively. Incidence of recurrence with partial and generalized seizures was 69.0% and 31.0%, respectively. Children with partial seizures had recurrence significantly more often than those with generalized seizures (P < 0.001). Recurrent seizures occurred after normal findings on electroencephalogram (EEG) in 21.4%, after generalized spike-and-wave complexes in 16.7%, and after focal epileptic discharge in 61.9%. Children with focal epileptic discharge had recurrence significantly more often than children with normal EEG findings (P < 0.001). CONCLUSION: The time to seizure recurrence after first unprovoked seizure may be within 1 year, and particularly within 6 months; and partial seizure and abnormal EEG with focal epileptic discharge may be risk factors for seizure recurrence.
Asunto(s)
Electroencefalografía , Medición de Riesgo , Convulsiones/epidemiología , Adolescente , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Lactante , Japón/epidemiología , Masculino , Estudios Prospectivos , Recurrencia , Factores de Riesgo , Convulsiones/diagnóstico , Tasa de Supervivencia/tendenciasRESUMEN
The EEG in childhood absence epilepsy (CAE) may contain focal and generalised spike-wave discharges (SWDs) with focal, mainly frontal, "lead-in". The term "frontal absence" has been used to imply fast, secondary, 3-Hz generalisation from occult frontal foci with potential impact on clinical EEG interpretation and syndrome classification. The aim of this study was to investigate the relationship between focal and generalised SWDs. We studied five children with CAE and examined a sufficient number of focal ("interictal") and generalised SWDs in order to obtain reliable analysis. All generalised SWDs with focal lead-in were "decomposed" into their "pre-generalisation" focal and "generalised" constituents, which were studied separately. Two types of focal SWD ("interictal" and "pre-generalisation") and generalised SWD were visually clustered into groups, waveform-averaged, and plotted in the 2D-electrode space. Spatiotemporal analysis demonstrated a variety (mean: 4.2 per child; SD: 2.12) of mainly frontal and occipital locations for pre-generalisation focal SWDs with propagation along the longitudinal axis in either direction and across homologous sites. Interictal focal SWDs demonstrated similar spatiotemporal characteristics. In contrast, the topography and propagation patterns of the first generalised spike of the SWD showed less variability (mean: 2.5 per child; SD: 2.07), mainly involved the fronto-temporal/temporal areas, and correlated poorly (<10%) with that of the pre-generalisation focal SWD. Our findings suggest that the process of generalised epileptogenesis in genetic epilepsies with electrographic "frontal absences" is far more complex than that proposed by the model for occult frontal focus with fast secondary generalisation. (Published with Supplemental data).