VNS Prospective Neuromodulation of Immune and Gastrointestinal Systems

Inclusion criteria: 1. Undergoing VNS implantation for the first time as a treatment for epilepsy and 2. Documented follow up with a Louisville-based neurologist in the past 1 year. If at the University of Utah or Baylor University documented ability to travel to their corresponding neurologist. 3. Documented ability to travel to Louisville for outpatient medical care. If at the University of Utah or Baylor University documented ability to travel to their facilities. Exclusion criteria: 1. Previous treatment with VNS (other than the one implanted for this study) 2. Current pregnancy (contraindication to surgery) 3. Active infection 4. History of cancer or treatment with chemotherapy 5. History of autoimmune disease: Patients who received high effect anticholinergic medication within 30 days of enrollment will be excluded, whereas moderate to low effect anticholinergic medication will be discussed with and decided by the PI. 6. If any high effect anticholinergic medication is started after enrollment, it will be the PI's decision to drop or postpone the corresponding visit or exclude the patient entirely. 7. Patients who received high effect corticosteroids within 30 days of enrollment will be excluded, whereas moderate to low effect corticosteroids will be discussed with and decided by the PI. 8. If any high effect corticosteroid is started after enrollment, it will be the PI's decision to drop or postpone the corresponding visit or exclude the patient entirely. 9. Treatment with antiarrhythmic or (heart) rate controlling medication, 10. Pre-existing cardiac arrhythmia or presence of cardiac pacemaker / defibrillator