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Objectives Vagus nerve stimulation (VNS) is reemerging as an exciting form of brain stimulation, due in part to the development of its noninvasive counterpart transcutaneous auricular VNS. As the field grows, it is important to understand where VNS emerged from, including its history and the studies that were conducted over the past four decades. Here, we offer a comprehensive review of the history of VNS in the treatment of major depression. Materials and methods Using PubMed, we reviewed the history of VNS and aggregated the literature into a narrative review of four key VNS epochs: 1) early invention and development of VNS, 2) path to Food and Drug Administration (FDA) approval for depression, 3) refinement of VNS treatment parameters, and 4) neuroimaging of VNS. Results VNS was described in the literature in the early 1900s; however, gained traction in the 1980s as Zabara and colleagues developed an implantable neurocybernetic prosthesis to treat epilepsy. As epilepsy trials proceed in the 1990s, promising mood effects emerged and were studied, ultimately leading to the approval of VNS for depression in 2005. Since then, there have been advances in understanding the mechanism of action. Imaging techniques like functional magnetic resonance imaging and positron emission tomography further aid in understanding direct brain effects of VNS. Conclusions The mood effects of VNS were discovered from clinical trials investigating the use of VNS for reducing seizures in epileptic patients. Since then, VNS has gone on to be FDA approved for depression. The field of VNS is growing, and as noninvasive VNS quickly advances, it is important to consider a historical perspective to develop future brain stimulation therapies.

Background Preliminary data suggest that focal electrically administered seizure therapy (FEAST) has antidepressant effects and less adverse cognitive effects than traditional forms of electroconvulsive therapy (ECT). This study compared the impact of FEAST and ultrabrief pulse, right unilateral (UB-RUL) ECT on suicidal ideation. Methods At 2 sites, patients in a major depressive episode were treated openly with FEAST or UB-RUL ECT, depending on their preference. The primary outcome measure was scores on the Beck Scale for Suicide Ideation (SSI). Scores on the suicide item of the Hamilton Rating Scale for Depression (HRSD-SI) provided a secondary outcome measure. Results Thirty-nine patients were included in the intent-to-treat sample (FEAST, n = 20; UB-RUL ECT, n = 19). Scores on both the SSI and HRSD-SI were equivalently reduced with both interventions. Both responders and nonresponders to the interventions showed substantial reductions in SSI and HRSD-SI scores, although the magnitude of improvement was greater among treatment responders. Conclusions Although limited by the open-label, nonrandomized design, FEAST showed comparable effects on suicidal ideation when compared with routine use of UB-RUL ECT. These results are encouraging and support the need for further research and a noninferiority trial.

Vagus nerve stimulation (VNS) is an established form of neuromodulation with a long history of promising applications. Earliest reports of VNS in the literature date to the late 1800’s in experiments conducted by Dr. James Corning. Over the past century, both invasive and non-invasive VNS have demonstrated promise in treating a variety of disorders, including epilepsy, depression, and post-stroke motor rehabilitation. As VNS continues to rapidly grow in popularity and application, the field generally lacks a consensus on optimum stimulation parameters. Stimulation parameters have a significant impact on the efficacy of neuromodulation, and here we will describe the longitudinal evolution of VNS parameters in the following categorical progression: (1) animal models, (2) epilepsy, (3) treatment resistant depression, (4) neuroplasticity and rehabilitation, and (5) transcutaneous auricular VNS (taVNS). We additionally offer a historical perspective of the various applications and summarize the range and most commonly used parameters in over 130 implanted and non-invasive VNS studies over five applications.