Overview

Vagal nerve stimulation is a neurosurgical procedure consisting of implantation of an impulse generator battery with leads placed into the vagus nerve in the neck. This procedure was FDA approved for epilepsy in the 1990s and is commonly performed as an outpatient surgery. The mechanism of action is not well understood; however it is increasingly recognized that electrical stimulation of the vagus nerve may impact other organ systems in the body including the immune and gastrointestinal systems. Concrete characterization of the peripheral effects of VNS in human gut microbiome and immune systems will: (1) elucidate peripheral mechanism of action of chronic VNS therapy, (2) identify peripheral preoperative biomarker of VNS efficacy, and (3) create a foundation for research investigating new GM and IM-related disease indications for VNS.

The primary objective of this study is to characterize the pre- and post-operative oral and gut microbiome of patients implanted with vagal nerve stimulator (VNS) for epilepsy. Secondary objectives of this study include: (1) to characterize the pre-operative and post-operative immune profile of patients undergoing VNS implantation for epilepsy, (2) to elucidate whether oral and/or gut microbiota changes are related to VNS efficacy for epilepsy and (3) identification of a biomarker predicting VNS efficacy.

Eligibility

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