Despite adequacies in AED treatments and adherence, and the emergence of newer AEDs, over 30% of patients with epilepsy remain refractory to treatment and are said to have drug-resistant epilepsy (DRE). DRE is a serious problem that can be associated with developmental delay in infants & young children, and severe disability and morbidity in older children & adults, as well as a mortality rate 5-10 times higher than the general population, due primarily to sudden unexpected death in epilepsy, accidents, suicide.