Typical absence seizures ('petit mal' seizures) occur only in the syndrome of idiopathic generalized epilepsy. The traditional first-line treatment is with either ethosux-imide or valproate. For many years ethosuximide has been standard drug therapy and it is highly effective and in general well tolerated. However, it is relatively ineffective in controlling generalized tonic-clonic seizures, which often co-exist with absence seizures, and has a number of troublesome adverse effects (p. 131). It has therefore been largely superseded by valproate as first-line therapy in drug-naive patients. However, it still has a role, particularly in children where there is anxiety about the idiosyncratic effects of valproate. Valproate or ethosuximide can be expected to fully control absence seizures in over 90% of patients on initial therapy. Dosage should be titrated against response.
In patients in whom valproate is inappropriate, alternatives include phenobarbital and the benzodiazepine drugs. The newer drugs lamotrigine and topiramate have both shown clear evidence of effectiveness in absence epilepsy, and lamotrigine is occasionally used as first-line monother-apy. There is growing anecdotal evidence that levetiracetam is also effective in absence epilepsy. Currently this is an off-label indication, but if its promise is confirmed, leve-tiracetam may become a drug of first choice.
About 10 -20% of absence seizures will be resistant to monotherapy with either valproate or ethosuximide, and the combination of both drugs may be helpful.
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