Vagus nerve stimulation (VNS) has an established role in the management of medically refractory partial‑onset (focal) seizures. Randomized controlled trials and multiple observational studies have reported significant reductions in seizure frequency and clinically meaningful improvements in some patients with partial‑onset seizures, supporting VNS as a treatment option when seizures persist despite medication or when therapeutic drug levels cannot be used because of intolerable adverse effects (i.e., medically refractory seizures).
Mechanistically, VNS delivers electrical stimulation to axons of the vagus nerve with afferent projections from the nodose and jugular ganglia to the nucleus of the solitary tract; from there vagal afferent pathways project diffusely throughout the central nervous system. VNS may also activate vagal efferent fibers that influence cardiac, laryngeal, pharyngeal, and gastrointestinal parasympathetic function. These diffuse CNS and autonomic effects are the putative basis for therapeutic benefit across neurologic and other indications.
Peripheral nerve stimulation (PNS) refers to implanted lead(s) and a pulse transmitter that deliver electrical pulses directly to peripheral nerves for relief of chronic, focal or neuropathic pain. Several PNS systems have FDA clearance and randomized trials have reported short‑term responder differences versus control; however, the evidence base is limited by small, heterogeneous trials, variable follow‑up, and concerns about long‑term durability and generalizability. For chronic pain indications, current evidence is judged insufficient to conclude a net health benefit.
Restorative neurostimulation (ReActiv8) targets lumbar multifidus dysfunction by delivering stimulation intended to elicit repetitive multifidus contractions and restore neuromuscular control as a treatment for intractable chronic low back pain. Although there are randomized and long‑term follow‑up studies, key pivotal sham‑controlled data did not meet the primary endpoint at 120 days and longer‑term uncontrolled results are at risk of bias; therefore the evidence is considered insufficient to determine a net health benefit for ReActiv8 at this time.