THE MORE desperate the patient and the physician, the more likely patients are to respond to a new treatment. Seasoned epileptologists estimate that about 50% of patients with epilepsy obtain good control with monotherapy, a further 15% with the addition of a second drug, and an additional 5% with polytherapy. That leaves about 30% who need a new treatment. Although both Ben-Menachem and McLachlan assume the effectiveness of resective surgery, this procedure has yet to be proved effective in a rigorous, prospective randomized trial. This keeps the door open for new therapies, such as vagus nerve stimulation (VNS).