Ved tonisk- kloniske anfald var den gennemsnitlige reduktion i anfaldshyppigheden 28, 2% hos patienterne, der fik placebo, sammenholdt med 56, 5% hos patienterne, der fik Keppra.
For tonic-clonic seizures, there was an average reduction in seizure rate of 28.2% in the patients taking placebo, compared with 56.5% in those taking Keppra.