• E B Posner, K Mohamed, and A G Marson.
• Department of Child Health, The Royal Victoria Infirmary, Queen Victoria Road, Newcastle-upon-Tyne, UK, NE1 4LP.
• Cochrane Db Syst Rev. 2003 Jan 1 (3): CD003032.

BackgroundAbsence seizures are brief epileptic seizures which present in childhood and adolescence. They are characterised by sudden loss of awareness and an electroencephalogram (EEG) typically shows generalised spike wave discharges at three cycles per second. Ethosuximide, valproate and lamotrigine are currently used to treat absence seizures. This review aims to determine the best choice of anticonvulsant for a child with typical absence seizures.ObjectivesTo review the evidence for the effects of ethosuximide, valproate and lamotrigine as treatments for children and adolescents with absence seizures, when compared with placebo or each other.Search StrategyWe searched the Cochrane Epilepsy Group trials register, the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (January 1966 to March 2003) and EMBASE (1988 to March 2003). We also contacted Sanofi Winthrop, Glaxo Wellcome (now GlaxoSmithKline) and Parke Davis (now Pfizer), manufacturers of sodium valproate, lamotrigine and ethosuximide respectively.Selection CriteriaRandomised parallel group monotherapy or add-on trials which include a comparison of any of the following in children or adolescents with absence seizures: ethosuximide; sodium valproate; lamotrigine or placebo.Data Collection And AnalysisOutcome measures were: (i) proportion of individuals seizure free at 1, 6 and 18 months post randomisation; (ii) people with a 50% or greater reduction in seizure frequency; (iii) normalisation of EEG and/or negative hyperventilation test and (iv) adverse effects. Data were independently extracted by two reviewers. Results are presented as relative risks (RR) with 95% confidence intervals (95% CI).Main ResultsFour small trials were found, which were of poor methodological quality. One trial (29 participants) compared lamotrigine with placebo using a response conditional design. Individuals taking lamotrigine were significantly more likely to be seizure free than participants taking placebo during this short trial. Three studies compared ethosuximide, but because of diverse study designs and populations studied, we decided not to pool results in a meta-analysis. None of these studies found a difference between valproate and ethosuximide with respect to seizure control, but confidence intervals were wide and the existence of important differences could not be excluded.Reviewer's ConclusionsAlthough ethosuximide, lamotrigine and valproate are commonly used to treat people with absence seizures we have insufficient evidence to inform clinical practice, and the few trials included in this review were of poor methodological quality. More trials of better quality are needed.

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