Device will be set to use stimulation parameters from set A first (e.g. 145 Hz) and then from set B (e.g. low frequency stimulation).

Device will be set to use stimulation parameters from set B first (e.g. low frequency stimulation) and then from set A (e.g. 145 Hz).

Subjects will receive one stimulation parameter set first for 3 months and then the other for three months. Sets will include Set A (145 Hz high frequency stimulation) and Set B (Low frequency stimulation less than 40 Hz, which is similar to stimulation frequencies used during cortical stimulation). The 145 Hz stimulation will be set to cycling (1 min on, 5 min off) while the low frequency setting will be continuous. Both sets include stimulation parameter sets that have been used in clinical practice as a part of standard of care. However, it is unclear which set is better or whether they are similarly effective.

Using the Mayo Epilepsy Short Assessment as well as patient diaries, seizure frequency is determined.

The Mayo Post-Stimulation Activation questionnaire is a 9-item survey measuring post-stimulation symptoms such as speech problems, numbness, muscle tightness, balance, lightheadedness, vision, mood changes, and memory. The questionnaire is ranked on a Likert scale of 1 - Mild; 2 - Moderate; 3 - Severe; 4 - N/A. The minimum value is 1 and the maximum value is 4, where 1 represents less severe.