Electrical stimulation of the auricular vagus nerve (aVNS) is an emerging technology in the field of bioelectronic medicine with applications in therapy. Modulation of the afferent vagus nerve affects a large number of physiological processes and bodily states associated with information transfer between the brain and body. These include disease mitigating effects and sustainable therapeutic applications ranging from chronic pain diseases, neurodegenerative and metabolic ailments to inflammatory and cardiovascular diseases. Given the current evidence from experimental research in animal and clinical studies we discuss basic aVNS mechanisms and their potential clinical effects. Collectively, we provide a focused review on the physiological role of the vagus nerve and formulate a biology-driven rationale for aVNS. For the first time, two international workshops on aVNS have been held in Warsaw and Vienna in 2017 within the framework of EU COST Action “European network for innovative uses of EMFs in biomedical applications (BM1309).” Both workshops focused critically on the driving physiological mechanisms of aVNS, its experimental and clinical studies in animals and humans, in silico aVNS studies, technological advancements, and regulatory barriers. The results of the workshops are covered in two reviews, covering physiological and engineering aspects. The present review summarizes on physiological aspects – a discussion of engineering aspects is provided by our accompanying article ( Kaniusas et al., 2019 ). Both reviews build a reasonable bridge from the rationale of aVNS as a therapeutic tool to current research lines, all of them being highly relevant for the promising aVNS technology to reach the patient.

Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice.

Continuous electrical stimulation of auricular acupuncture points using the new point stimulation device P-stim significantly decreases pain intensity and improves psychological well-being, activity, and sleep in chronic low back pain patients.

Electrical stimulation of the auricular vagus nerve (aVNS) is an emerging electroceutical technology in the field of bioelectronic medicine with applications in therapy. Artificial modulation of the afferent vagus nerve – a powerful entrance to the brain – affects a large number of physiological processes implicating interactions between the brain and body. Engineering aspects of aVNS determine its efficiency in application. The relevant safety and regulatory issues need to be appropriately addressed. In particular, in silico modeling acts as a tool for aVNS optimization. The evolution of personalized electroceuticals using novel architectures of the closed-loop aVNS paradigms with biofeedback can be expected to optimally meet therapy needs. For the first time, two international workshops on aVNS have been held in Warsaw and Vienna in 2017 within the scope of EU COST Action “European network for innovative uses of EMFs in biomedical applications (BM1309).” Both workshops focused critically on the driving physiological mechanisms of aVNS, its experimental and clinical studies in animals and humans, in silico aVNS studies, technological advancements, and regulatory barriers. The results of the workshops are covered in two reviews, covering physiological and engineering aspects. The present review summarizes on engineering aspects – a discussion of physiological aspects is provided by our accompanying article ( Kaniusas et al., 2019 ). Both reviews build a reasonable bridge from the rationale of aVNS as a therapeutic tool to current research lines, all of them being highly relevant for the promising aVNS technology to reach the patient.

MR phase contrast blood flow velocity measurements in the human index finger were performed with triggered, nontriggered, and cine acquisition schemes. A strong (G max ‫؍‬ 200 mT/m), small bore (inner diameter 12 cm) gradient system inserted in a whole body 3 Tesla MR scanner allowed highresolution imaging at short echo times, which decreases partial volume effects and flow artifacts. Arterial blood flow velocities ranging from 4.9 -19 cm/sec were measured, while venous blood flow was significantly slower at 1.5-7.1 cm/sec. Taking into account the corresponding vessel diameters ranging from 800 m to 1.8 mm, blood flow rates of 3.0 -26 ml/min in arteries and 1. Phase contrast (PC) MRI to quantify blood flow velocities has been validated in several studies (1-3). Most human applications focus on large vessels such as the aorta, carotids, or femoral arteries. This is due to the fact that systematic errors strongly increase with decreasing number of image pixels that cover the vessel lumen under investigation (4,5). Models that correct for partial volume effects have been developed which allow the acquisition of flow velocity values from vessels covered by only a few pixels (6 -8). In this study, a different approach was performed to overcome problems associated with partial volume effects. We used a strong gradient system that allows high-resolution phase contrast MRI of the human finger. In our experiments, the main vessels of the human index finger were covered by at least 16 pixels, which is sufficient to keep systematic errors due to partial volume effects small (4). So far, in vivo MRI investigations of the human distal extremities have been limited to morphologic imaging of skin layers, joints, and vessel anatomy (9 -12), not including functional parameters. Commonly, blood flow velocities in the human distal extremities are obtained by ultrasound (US) investigations (13,14). US flow measurements have the advantage of being fast and flexible; on the other hand, they do not provide detailed anatomic information. The information about the patency of large vessels is a cardinal aspect in the assessment of general arteriosclerosis in tissues (15). However, little is known about the role of smaller arteries. Although their general functionality can be tested by a number of simple physical tests (e.g., exercise), these tests still provide us with no visual information on vessel size or orientation. For planning distal reconstructive surgery in cases of severe arteriosclerosis, a vital role could be played by the combination of functional information (e.g., blood flow velocity) and complementary 3D images of individual vessels. Such information could also be helpful in staging general and/or microangiopathy of distal body parts. To our knowledge, we performed the first MR blood flow velocity measurements in human peripheral vessels with diameters as low as 800 m without the need to correct for partial volume effects. MATERIALS AND METHODSBlood flow velocities were measured in the index fingers of five healthy male s...