At the end of the baseline period, subjects who continued to be eligible were stratified based on previous therapy history (Early: previously treated with 2 to 5 AEDs versus Non-early: previously treated with >5 AEDs). Within each stratification, the investigator randomized each subject to receive one of the 2 treatments (VNS Therapy treatment or AED treatment) at the end of visit 2 using a randomization schedule provided by an independent third party (Synergos).