Paired Vagus Nerve Stimulation Mechanisms

In this mechanistic study, 40 individuals with chronic stroke will be implanted with a small vagus nerve stimulation (VNS) device. The study will use a randomized, blinded, crossover design to deliver two conditions in six-week blocks: active VNS or sham VNS, each paired with upper extremity (UE) motor rehabilitation. Assessment visits will occur before and after each block, and will examine neural pathway strength, functional connectivity, and motor and non-motor behaviors. Investigators will test for VNS-induced changes in motor, cognitive, and affective systems, and will identify biomarkers predictive of clinical response.


Eligibility Criteria:
Inclusion Criteria:

* Ability to provide signed and dated informed consent form
* Stated willingness to comply with all study procedures and availability for the duration of the study
* 22-79 years of age
* Unilateral supratentorial ischemic stroke that occurred ≥ 12 months prior to enrollment
* Upper extremity Fugl-Meyer Assessment score of 20 to 50
* Modified Rankin Score of 2, 3, or 4
* Appropriate surgical candidate for VNS electrode implantation

Exclusion Criteria:

* Subarachnoid or intraventricular hemorrhage or traumatic brain injury
* Deficits in language or attention that interfere with study participation
* Severe spasticity (Modified Ashworth ≥ 3)
* Psychiatric disorders and/or cognitive impairments that would interfere with study participation, as assessed by medical evaluation
* Receiving any therapy (medication or otherwise) that would interfere with VNS, such as drugs that perturb neurotransmitter action (anticholinergics, adrenergic blockers, etc.)
* Presence of any other implanted electrical stimulation device
* Prior injury to vagus nerve
* Females of childbearing potential who are either pregnant, lactating, heterosexually active, or planning to become pregnant or heterosexually active during study participation; and who are not using, or will not agree to use, the following medically acceptable birth control methods:\* (1) sterilization surgery for women, (2) Surgical Sterilization Implant for Women, (3) sterilization surgery for men, (4) long-acting reversible contraceptives (LARC) - implantable rod and IUD; (5) contraceptive shot/injection every 3 months; (6) oral contraceptives ("The Pill"); (7) contraceptive patch; and (8) vaginal contraceptive ring.
* Concurrent participation in another interventional clinical trial
* Ferromagnetic metal in head (except dental work) or torso
* Persons with a current or past: (a) medical (psychiatric, non-psychiatric) condition, disease, disorder, injury, or disability\*; or (b) non-medical situation or circumstance that, in the opinion of the principal investigator, study participation: may pose a significant or undue risk to the person; make it unlikely the person will complete all the study requirements per protocol; or may adversely impact the integrity of the data or the validity of the study results. \[\*Examples include, but are not limited to, the following types of conditions, diseases or disorders: renal, peripheral vascular, cardiac, endocrinologic (e.g., diabetes), immunologic, psychiatric (e.g., substance use), neurologic (e.g., cognitive), or dysphagia\]
* Non-English speaking
* As determined by the principal investigator, is under current incarceration or legal detention