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Electrical Brain Stimulation to Treat Neurological Disorders
Published in Bahman Zohuri, Patrick J. McDaniel, Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Bahman Zohuri, Patrick J. McDaniel
Vagus nerve stimulation (VNS) works through a device implanted under the skin that sends electrical pulses through the left vagus nerve, half of a prominent pair of nerves that run from the brainstem through the neck and down to each side of the chest and abdomen. The vagus nerves carry messages from the brain to the body’s major organs (e.g., heart, lungs, and intestines) and to areas of the brain that control mood, sleep, and other functions (see Figure 6.11).
Chaos or Randomness? Effect of Vagus Nerve Stimulation During Sleep on Heart-Rate Variability
Published in IETE Journal of Research, 2022
Karthi Balasubramanian, Nithin Nagaraj, Sandipan Pati
Epilepsy is a chronic neurological illness that is characterized by an “enduring predisposition to generate epileptic seizures and their associated consequences” [4]. Epileptic seizures can lead to changes in the ANS, and these changes have been associated with mortality including sudden unexpected death in epilepsy (SUDEP) [5]. Vagal Nerve Stimulation (VNS) therapy is used to treat seizures that are refractory to antiepileptic medications. Activation of vagal nerve modulates the parasympathetic division of the ANS and hence has the potential to restore the natural chaotic behavior of the heart. In his seminal research on heart beat dynamics, Goldberger points to the fact that the heart rate in healthy individuals is neither constant nor periodic, but shows irregular patterns that are typically associated with a non-linear chaotic system [6]. This chaotic behavior is indicated by a high complexity of HRV. Thus, in the case of VNS application, the effectiveness can be gauged by the transition of HRV to chaos which in-turn is reflected in the increase in the complexity of the HRV. The study aims to show how a temporal correlation analysis (including surrogate analysis) can indicate the restoration of the natural chaotic behavior of the heart rhythm on application of VNS. We have not used conventional methods to characterize chaos such as estimating Lyapunov exponent and/or infotheoretic measures (such as various kinds of entropy-based measures, for eg., topological entropy), as they greatly suffer from the need of enormous amount of data for robust and reliable computation which is a major limitation of those methods.
Noninvasive vagus nerve stimulation in Parkinson’s disease: current status and future prospects
Published in Expert Review of Medical Devices, 2021
Hilmar P. Sigurdsson, Rachael Raw, Heather Hunter, Mark R. Baker, John-Paul Taylor, Lynn Rochester, Alison J. Yarnall
Pharmacological intervention forms the mainstay treatment for many neurodegenerative and neuropsychiatric disorders, but this approach carries unwanted side effects. Non-pharmacological alternatives such as electrical stimulation used mostly as an adjunct therapy, has gained considerable interest. Vagus nerve stimulation (VNS) is a neuromodulation technique involving invasive surgical implantation of a generator subcutaneously, providing direct electrical stimulation of the left cervical vagus nerve [1–3]. Implantable VNS (iVNS) sends intermittent electrical currents through a wire wrapped around the vagus nerve. It is more common that the left vagus nerve is stimulated due to the right vagus nerve having greater connections to the heart [1]. The VNS device conveys signals through neural impulses to the central nervous system (CNS) [1]. iVNS is approved by the U.S. Food and Drug Administration (FDA) as an adjunct treatment for drug-resistant epilepsy [4] and in patients with treatment-resistant depression [5]; iVNS is also approved by the European Medicines Agency (EMA) for the latter. Recent randomized controlled trials have additionally shown the potential benefits of iVNS in upper limb motor recovery after stroke when stimulation is paired with rehabilitation therapy [6].
Recent advances in devices for vagus nerve stimulation
Published in Expert Review of Medical Devices, 2018
Ann Mertens, Robrecht Raedt, Stefanie Gadeyne, Evelien Carrette, Paul Boon, Kristl Vonck
Invasive vagus nerve stimulation (VNS) is a neurostimulation therapy where the vagus nerve is stimulated in the neck region by means of a helical electrode that is wound around the cervical vagus fibers and connected with a lead to a subclavicularly implanted pulse generator. In the past two decades, it has become a valuable option in the therapeutic armamentarium for patients with refractory epilepsy and it is currently routinely available in epilepsy centers worldwide [1]. Extensive evidence is also available for the application of invasive VNS therapy in treatment-resistant depression [2,3]. Small studies and case report series have shown efficacy of invasive VNS for treatment of refractory migraine and cluster headache, Alzheimer’s disease, treatment-resistant anxiety disorders, bipolar disorder, and obesity [3,4].