Vagus nerve stimulation (VNS) therapy update

The Brain-Heart Network of Syncope

Observed and recorded in various forms since ancient times, 'syncope' is often popularly called 'fainting', such that the two terms are used synonymously. Syncope/fainting can be caused by a variety of conditions, including but not limited to head injuries, vertigo, and oxygen deficiency. Here, we draw on a large body of literature on syncope, including the role of a recently discovered set of specialized mammalian neurons. Although the etiology of syncope still remains a mystery, we have attempted to provide a comprehensive account of what is known and what still needs to be performed. Much of our understanding of syncope is owing to studies in the laboratory mouse, whereas evidence from human patients remains scarce. Interestingly, the cardioinhibitory Bezold-Jarisch reflex, recognized in the early 1900s, has an intriguing similarity to-and forms the basis of-syncope. In this review, we have integrated this minimal model into the modern view of the brain-neuron-heart signaling loop of syncope, to which several signaling events contribute. Molecular signaling is our major focus here, presented in terms of a normal heart, and thus, syncope due to abnormal or weak heart activity is not discussed in detail. In addition, we have offered possible directions for clinical intervention based on this model. Overall, this article is expected to generate interest in chronic vertigo and syncope/fainting, an enigmatic condition that affects most humans at some point in life; it is also hoped that this may lead to a mechanism-based clinical intervention in the future.

The protective role of vagus nerve stimulation in ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) encompasses the damage resulting from the restoration of blood supply following tissue ischemia. This phenomenon commonly occurs in clinical scenarios such as hemorrhagic shock, severe trauma, organ transplantation, and thrombolytic therapy. Despite its prevalence, existing treatments exhibit limited efficacy against IRI. Vagus nerve stimulation (VNS) is a widely utilized technique for modulating the autonomic nervous system. Numerous studies have demonstrated that VNS significantly reduces IRI in various organs, including the heart, brain, and liver. This article reviews the pathological processes during IRI and summarizes the role and possible mechanisms of VNS in IRI of different organs. Furthermore, this review addresses the current challenges of VNS clinical applications, providing a novel perspective on IRI treatment.

The Development of a New Vagus Nerve Simulation Electroceutical to Improve the Signal Attenuation in a Living Implant Environment

An electroceutical is a medical device that uses electrical signals to control biological functions. It can be inserted into the human body as an implant and has several crucial advantages over conventional medicines for certain diseases. This research develops a new vagus nerve simulation (VNS) electroceutical through an innovative approach to overcome the communication limitations of existing devices. A phased array antenna with a better communication performance was developed and applied to the electroceutical prototype. In order to effectively respond to changes in communication signals, we developed the steering algorithm and firmware, and designed the smart communication protocol that operates at a low power that is safe for the patients. This protocol is intended to improve a communication sensitivity related to the transmission and reception distance. Based on this technical approach, the heightened effectiveness and safety of the prototype have been ascertained, with the actual clinical tests using live animals. We confirmed the signal attenuation performance to be excellent, and a smooth communication was achieved even at a distance of 7 m. The prototype showed a much wider communication range than any other existing products. Through this, it is conceivable that various problems due to space constraints can be resolved, hence presenting many benefits to the patients whose last resort to the disease is the VNS electroceutical.

An optoelectronic implantable neurostimulation platform allowing full MRI safety and optical sensing and communication

A novel programmable implantable neurostimulation platform based on photonic power transfer has been developed for various clinical applications with the main focus of being safe to use with MRI scanners. The wires usually conveying electrical current from the neurostimulator to the electrodes are replaced by optical fibers. Photovoltaic cells at the tip of the fibers convert laser light to biphasic electrical impulses together with feedback signals with 54% efficiency. Furthermore, a biocompatible, implantable and ultra-flexible optical lead was developed including custom optical fibers. The neurostimulator platform incorporates advanced signal processing and optical physiological sensing capabilities thanks to a hermetically sealed transparent nonmetallic casing. Skin transparency also allowed the development of a high-speed optical transcutaneous communication channel. This implantable neurostimulation platform was first adapted to a vagus nerve stimulator for the treatment of epilepsy. This neurostimulator has been designed to fulfill the requirements of a class III long-term implantable medical device. It has been proven compliant with standard ISO/TS10974 for 1.5 T and 3 T MRI scanners. The device poses no related threat and patients can safely undergo MRI without specific or additional precautions. Especially, the RF induced heating near the implant remains below 2 °C whatever the MRI settings used. The main features of this unique advanced neurostimulator and its architecture are presented. Its functional performance is evaluated, and results are described with a focus on optoelectronics aspects and MRI safety.

Delayed vagal nerve compressive neuropathy following placement of vagal nerve stimulator: case report

Vagal neuropathy causing vocal fold palsy is an uncommon complication of vagal nerve stimulator (VNS) placement. It may be associated with intraoperative nerve injury or with device stimulation. Here we present the first case of delayed, compressive vagal neuropathy associated with VNS coil placement which presented with progressive hoarseness and vocal cord paralysis. Coil removal and vagal neurolysis was performed to relieve the compression. Larger 3 mm VNS coils were placed for continuation of therapy. Coils with a larger inner diameter should be employed where possible to prevent this complication. The frequency of VNS-associated vagal nerve compression may warrant further investigation.

The role of neuromodulation in the management of drug-resistant epilepsy

Drug-resistant epilepsy (DRE) poses significant challenges in terms of effective management and seizure control. Neuromodulation techniques have emerged as promising solutions for individuals who are unresponsive to pharmacological treatments, especially for those who are not good surgical candidates for surgical resection or laser interstitial therapy (LiTT). Currently, there are three neuromodulation techniques that are FDA-approved for the management of DRE. These include vagus nerve stimulation (VNS), deep brain stimulation (DBS), and responsive neurostimulation (RNS). Device selection, optimal time, and DBS and RNS target selection can also be challenging. In general, the number and localizability of the epileptic foci, alongside the comorbidities manifested by the patients, substantially influence the selection process. In the past, the general axiom was that DBS and VNS can be used for generalized and localized focal seizures, while RNS is typically reserved for patients with one or two highly localized epileptic foci, especially if they are in eloquent areas of the brain. Nowadays, with the advance in our understanding of thalamic involvement in DRE, RNS is also very effective for general non-focal epilepsy. In this review, we will discuss the underlying mechanisms of action, patient selection criteria, and the evidence supporting the use of each technique. Additionally, we explore emerging technologies and novel approaches in neuromodulation, such as closed-loop systems. Moreover, we examine the challenges and limitations associated with neuromodulation therapies, including adverse effects, complications, and the need for further long-term studies. This comprehensive review aims to provide valuable insights on present and future use of neuromodulation.

Preventive noninvasive vagal nerve stimulation reduces insufficient sleep-induced depression by improving the autonomic nervous system

BACKGROUND

Depression is closely linked to an imbalance in the autonomic nervous system (ANS). However, the role of this imbalance in mediating the effects of sleep deprivation (SD) and vagus nerve stimulation (VNS) on emotional well-being is not fully understood.

METHODS

A population-based analysis was conducted to explore the relationship between sleep duration, depression scores, and heart rate variability (HRV). Additionally, the chronic SD mouse model was established to assess the impact of preventive transcutaneous auricular VNS (taVNS) on pathological and behavioral changes.

RESULTS

Our study found a significant link between sleep duration, depression severity, and HRV. Shorter sleep duration was associated with higher depression scores and lower RMSSD (a measure of HRV). In our rat model, insufficient sleep consistently impaired HRV. This effect was mitigated by taVNS, accompanied by corresponding changes in levels of IL-1β and IL-6, astrocyte and microglia activation, and tail suspension times.

CONCLUSIONS

Using VNS as a preventive treatment for depression-risk individuals with insufficient sleep shows promise. It not only broadens the potential applications of VNS but also sheds light on its mechanism-particularly its role in enhancing vagal nerve function and balancing the ANS, as evidenced by HRV measurements.

Neuromodulation techniques - From non-invasive brain stimulation to deep brain stimulation

Over the past 30 years, the field of neuromodulation has witnessed remarkable advancements. These developments encompass a spectrum of techniques, both non-invasive and invasive, that possess the ability to both probe and influence the central nervous system. In many cases neuromodulation therapies have been adopted into standard care treatments. Transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and transcranial ultrasound stimulation (TUS) are the most common non-invasive methods in use today. Deep brain stimulation (DBS), spinal cord stimulation (SCS), and vagus nerve stimulation (VNS), are leading surgical methods for neuromodulation. Ongoing active clinical trials using are uncovering novel applications and paradigms for these interventions.

Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies

Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies. Given the emergency of accelerating the progress in new neuromodulation treatments (i.e., drug-resistant hypertension, autoimmune and degenerative diseases), collaboration between multiple fields is imperative. This work intends to foster multidisciplinary work and bring together different fields to provide the fundamental basis underlying Bioelectronic Medicine. In this review we will go from the biophysics of the cell membrane, which we consider the inner core of neuromodulation, to patient care. We will discuss the recently discovered mechanism of neurotransmission switching and how it will impact neuromodulation design, and we will provide an update on neuronal and glial basis in health and disease. The advances in biomedical technology have facilitated the collection of large amounts of data, thereby introducing new challenges in data analysis. We will discuss the current approaches and challenges in high throughput data analysis, encompassing big data, networks, artificial intelligence, and internet of things. Emphasis will be placed on understanding the electrochemical properties of neural interfaces, along with the integration of biocompatible and reliable materials and compliance with biomedical regulations for translational applications. Preclinical validation is foundational to the translational process, and we will discuss the critical aspects of such animal studies. Finally, we will focus on the patient point-of-care and challenges in neuromodulation as the ultimate goal of bioelectronic medicine. This review is a call to scientists from different fields to work together with a common endeavor: accelerate the decoding and modulation of the nervous system in a new era of therapeutic possibilities.

Pathophysiology to Risk Factor and Therapeutics to Treatment Strategies on Epilepsy

Epilepsy represents a condition in which abnormal neuronal discharges or the hyperexcitability of neurons occur with synchronicity, presenting a significant public health challenge. Prognostic factors, such as etiology, electroencephalogram (EEG) abnormalities, the type and number of seizures before treatment, as well as the initial unsatisfactory effects of medications, are important considerations. Although there are several third-generation antiepileptic drugs currently available, their multiple side effects can negatively affect patient quality of life. The inheritance and etiology of epilepsy are complex, involving multiple underlying genetic and epigenetic mechanisms. Different neurotransmitters play crucial roles in maintaining the normal physiology of different neurons. Dysregulations in neurotransmission, due to abnormal transmitter levels or changes in their receptors, can result in seizures. In this review, we address the roles played by various neurotransmitters and their receptors in the pathophysiology of epilepsy. Furthermore, we extensively explore the neurological mechanisms involved in the development and progression of epilepsy, along with its risk factors. Furthermore, we highlight the new therapeutic targets, along with pharmacological and non-pharmacological strategies currently employed in the treatment of epileptic syndromes, including drug interventions employed in clinical trials related to epilepsy.

Effects of vagus nerve stimulation on the quality of sleep and sleep apnea in patients with drug-resistant epilepsy: A systematic review

OBJECTIVE

The objective was to systematically evaluate the current evidence surrounding the effect of vagus nerve stimulation (VNS) on quality of sleep and obstructive sleep apnea (OSA) among patients with epilepsy.

METHODS

A literature search was conducted using the Embase and MEDLINE databases. Studies were included if they involved patients with drug-resistant epilepsy treated with VNS and used validated tools to report on quality of sleep or sleep apnea. The literature search yielded 112 citations related to VNS and sleep quality, and 82 citations related to sleep apnea. Twelve articles were included in the review, of which five measured quality of sleep among patients who underwent VNS, six studies measured sleep apnea, and one study measured both outcomes.

RESULTS

Studies measuring quality of sleep used different methods, including sleep quality questionnaires and the percentage of sleep in each cycle. Studies also varied in patient populations, the use of control groups, and whether multiple measurements were taken for each patient. Some studies found improved sleep quality after VNS, whereas others found reductions in deep sleep stages. Additionally, mixed results in sleep quality were found when comparing patients with epilepsy who received VNS treatment versus patients with epilepsy who did not receive VNS treatment. Variables such as VNS intensity and age could potentially confound quality of sleep. Studies measuring sleep apnea consistently found increased proportions of patients diagnosed with OSA or increased sleep index scores after VNS implantation.

SIGNIFICANCE

Overall, the effect of VNS on quality of sleep remains unclear, as studies were very heterogeneous, although the effect on sleep apnea has consistently shown an increase in sleep apnea severity indices after VNS implantation. Future studies with consistent measures and discussions of confounding are required to determine the effect of VNS on quality of sleep, and the effect of VNS parameters should be further explored among patients who develop sleep apnea.

[Evaluation of the relevance of the pharmaceutical educational interview on the knowledge and satisfaction of patients who received a vagus nerve neurostimulator implantation]

INTRODUCTION

Vagal neurostimulation (VNS) medical devices (MDs) are used to treat drug-resistant epilepsy. Using a magnet, the patient can activate on the stimulations in order to stop a seizure or interrupt the adverse effects (AEs) of the device. The objective is to evaluate the improvement of the patients' knowledge about the VNS following a pharmaceutical educational interview (PEI) as well as their satisfaction.

MATERIALS AND METHODS

The pharmaceutical educational interview regarding drugs and DMs was performed by the clinical pharmacist at the patient's bed after VNS implantation. A questionnaire about VNS devices (operation, adverse effects, recommendations) and assessing knowledge was submitted to patients before and after the PEI. Satisfaction was assessed by the Likert scale.

RESULTS

From March 2020 to August 2021, 18 implanted patients were included in the study. In 78% of cases (14/18), the total number of good responses after PEI increased. The mean good response was significantly increased from 16.11/25 (64%) before PEI to 22.33/25 (89%) after PEI (P-value<0.01). The maximum satisfaction score (4/4) was given in 71% of the items.

DISCUSSION-CONCLUSION

The results support the relevance of PEI. Patients feel a need for information and consider the interview useful. An improvement in knowledge was observed, which allows us to hope for an optimization of the effectiveness of the device, in particular, a reduction in seizures and AE. This study shows the feasibility and the interest of the development of clinical pharmacy applied to medical devices in complementarity with the expertise on drugs.

Further advances in epilepsy

In 2017, one of us reviewed advances in epilepsy (Manford in J Neurol 264:1811-1824, 2017). The current paper brings that review up to date and gives a slight change in emphasis. Once again, the story is of evolution rather than revolution. In recognition that most of our current medications act on neurotransmitters or ion channels, and not on the underlying changes in connectivity and pathways, they have been renamed as antiseizure (ASM) medications rather than antiepileptic drugs. Cenobamate is the one newly licensed medication for broader use in focal epilepsy but there have been a number of developments for specific disorders. We review new players and look forward to new developments in the light of evolving underlying science. We look at teratogenicity; old villains and new concerns in which clinicians play a vital role in explaining and balancing the risks. Medical treatment of status epilepticus, long without evidence, has benefitted from high-quality trials to inform practice; like buses, several arriving at once. Surgical treatment continues to be refined with improvements in the pre-surgical evaluation of patients, especially with new imaging techniques. Alternatives including stereotactic radiotherapy have received further focus and targets for palliative stimulation techniques have grown in number. Individuals' autonomy and quality of life continue to be the subject of research with refinement of what clinicians can do to help persons with epilepsy (PWE) achieve control. This includes seizure management but extends to broader considerations of human empowerment, needs and desires, which may be aided by emerging technologies such as seizure detection devices. The role of specialist nurses in improving that quality has been reinforced by specific endorsement from the International League against Epilepsy (ILAE).

Aesthetic transaxillary subpectoral placement of vagus nerve stimulator in children and young adults: A technical note

INTRODUCTION

Vagus nerve stimulation (VNS) is a neuromodulation therapy for drug-resistant epilepsy (DRE), refractory status epilepticus, and treatment-resistant depression. The lead is tunneled into the subcutaneous space and connected to the generator, which is usually implanted in a subcutaneous pocket below the clavicle. Surgical complications in the chest region include skin breakdown or infection. An alternative approach is to perform a subclavear subpectoral implantation. In our surgical series, we report a new aesthetic implantation method for VNS generators in children and young patients: the transaxillary subpectoral placement.

MATERIALS AND METHODS

From May 2021 to May 2023, 10 vagus nerve stimulation generators were placed subpectorally with a transaxillary approach by the authors. We considered operative time, surgical complications such as blood loss, infections, device migration, pain, and adverse events at follow-up.

RESULTS

In this surgical series, we reviewed all cases of subpectoral implantation of VNS generators in children and young adults at our institution in the last 2 years. All patients were treated with subpectoral Sentiva 1000 (Livanova PLC) insertion with axillary access by a neurosurgeon and a pediatric surgeon. The operative time was slightly longer compared to the traditional subcutaneous implant. All generators reported impedances within the optimal range. Blood loss was not significant and no other perioperative complications were reported. Patients and families were highly satisfied with the outcomes in terms of comfort and aesthetic results after surgery and at the last follow-up. No cases of infection occurred, and no malfunctions or displacements of the generator were registered at clinical follow-up.

CONCLUSION

The transaxillary subpectoral placement of theVNS generator is an aesthetic and anatomic approach, which provides several benefits to children and young adults.

Synergistic effects of vagus nerve stimulation and antiseizure medication

INTRODUCTION

Vagus nerve stimulation (VNS) is an effective, non-pharmacological therapy for epileptic seizures. Until now, favorable combinations of different groups of antiseizure medication (ASM) and VNS have not been sufficiently addressed. The aim of this study was to identify the synergistic effects between VNS and different ASMs.

METHODS

We performed an observational study of patients with epilepsy who were implanted with VNS and had a stable ASM therapy during the first 2 years after the VNS implantation. Data were collected from the Mainz Epilepsy Registry. The efficacy of VNS depending on the concomitantly used ASM group/individual ASMs was assessed by quantifying the responder rate (≥ 50% seizure reduction compared to the time of VNS implantation) and seizure freedom (absence of seizures during the last 6 months of the observation period).

RESULTS

One hundred fifty one patients (mean age 45.2 ± 17.0 years, 78 females) were included in the study. Regardless of the used ASM, the responder rate in the whole cohort was 50.3% and the seizure freedom was 13.9%. Multiple regression analysis showed that combination of VNS with synaptic vesicle glycoprotein (SV2A) modulators (responder rate 64.0%, seizure freedom 19.8%) or slow sodium channel inhibitors (responder rate 61.8%, seizure freedom 19.7%) was associated with a statistically significant better responder rate and seizure freedom than combinations of VNS and ASM with other mechanism of action. Within these ASM groups, brivaracetam showed a more favorable effect than levetiracetam, whereas lacosamide and eslicarbazepine were comparable in their effects.

CONCLUSION

Our data suggest that the combination of VNS with ASMs belonging to either SV2A modulators or slow sodium channel inhibitors could be optimal to achieve a better seizure control following VNS. However, these preliminary data require further validation under controlled conditions.

Stimulation of vagus nerve for patients with disorders of consciousness: a systematic review

Purpose

The purpose of this study is to evaluate the efficacy and safety of stimulating the vagus nerve in patients with disorders of consciousness (DOCs).

Methods

A comprehensive systematic review was conducted, encompassing the search of databases such as PubMed, CENTRAL, EMBASE and PEDro from their inception until July 2023. Additionally, manual searches and exploration of grey literature were performed. The literature review was conducted independently by two reviewers for search strategy, selection of studies, data extraction, and judgment of evidence quality according to the American Academy of Cerebral Palsy and Developmental Medicine (AACPDM) Study Quality Scale.

Results

A total of 1,269 articles were retrieved, and 10 studies met the inclusion criteria. Among these, there were three case reports, five case series, and only two randomized controlled trials (RCTs). Preliminary studies have suggested that stimulation of vagus nerve can enhance the levels of DOCs in both vegetative state/unresponsive wakefulness state (VS/UWS) and minimally conscious state (MCS). However, due to a lack of high-quality RCTs research and evidence-based medical evidence, no definitive conclusion can be drawn regarding the intervention's effectiveness on consciousness level. Additionally, there were no significant adverse effects observed following stimulation of vagus nerve.

Conclusion

A definitive conclusion cannot be drawn from this systematic review as there was a limited number of eligible studies and low-quality evidence. The findings of this systematic review can serve as a roadmap for future research on the use of stimulation of vagus nerve to facilitate recovery from DOCs.

Vagus nerve stimulation using an endovascular electrode array

Objective. Vagus nerve stimulation (VNS), which involves a surgical procedure to place electrodes directly on the vagus nerve (VN), is approved clinically for the treatment of epilepsy, depression, and to facilitate rehabilitation in stroke. VNS at surgically implanted electrodes is often limited by activation of motor nerve fibers near and within the VN that cause neck muscle contraction. In this study we investigated endovascular VNS that may allow activation of the VN at locations where the motor nerve fibers are not localized.Approach. We used endovascular electrodes within the nearby internal jugular vein (IJV) to electrically stimulate the VN while recording VN compound action potentials (CAPs) and neck muscle motor evoked potentials (MEPs) in an acute intraoperative swine experiment.Main Results. We show that the stimulation electrode position within the IJV is critical for efficient activation of the VN. We also demonstrate use of fluoroscopy (cone beam CT mode) and ultrasound to determine the position of the endovascular stimulation electrode with respect to the VN and IJV. At the most effective endovascular stimulation locations tested, thresholds for VN activation were several times higher than direct stimulation of the nerve using a cuff electrode; however, this work demonstrates the feasibility of VNS with endovascular electrodes and provides tools to optimize endovascular electrode positions for VNS.Significance. This work lays the foundation to develop endovascular VNS strategies to stimulate at VN locations that would be otherwise too invasive and at VN locations where structures such as motor nerve fibers do not exist.

ASCEND: A randomized controlled trial of titration strategies for vagus nerve stimulation in drug-resistant epilepsy

Vagus Nerve Stimulation (VNS) therapy is widely understood to provide clinically meaningful improvements in seizure control to patients with drug-resistant epilepsy, and has been a staple in the clinical armamentaria available to epileptologists for over 25 years. Despite the long history of evidence-based reviews by neurology professional societies, there is still evidence of a practice gap in VNS titration and dosing that aims to maximize clinical benefit. Recent retrospective analyses have strongly argued for a more consistent application of a population-wide target dose of VNS, and further argued the importance of quickly achieving this target dose to hasten the onset of clinical benefits; however, these analyses failed to provide evidence for practical implementation. Herein, we describe a randomized controlled trial assessing the impact of titrating VNS according to three different protocols to achieve the target dose of 1.5 mA at 500µsec, for a 20-Hz signal frequency. The study was registered as NCT02385526 on March 11, 2015. Sixty-two patients were randomized into treatment groups that followed different titration protocols. One protocol (Group A) was designed to align with currently accepted professional guidance for VNS titration and the manufacturer's labeling for VNS in epilepsy (Heck et al., 2002), while the other two protocols were derived from VNS applications in other therapeutic areas. Group A participants were most likely to achieve the target dose parameters in 12 weeks or less (81.8%), with a median time-until-achievement of the target dose of 8.1 weeks, while less than 60% of patients in other groups were able to achieve the same endpoint. Participants in all groups experienced low levels of transient tolerability concerns and adverse events, suggesting titration to the target dose in 12 weeks or less following the Group A protocol is generally acceptable to most patients. These findings indicate that patients receiving VNS for epilepsy can achieve the manufacturer-recommended dose range in 12 weeks or less. A wider implementation of the approach will likely improve the clinical impact of VNS on seizure control and prevent undertreatment.

Vagus nerve stimulation primes platelets and reduces bleeding in hemophilia A male mice

Deficiency of coagulation factor VIII in hemophilia A disrupts clotting and prolongs bleeding. While the current mainstay of therapy is infusion of factor VIII concentrates, inhibitor antibodies often render these ineffective. Because preclinical evidence shows electrical vagus nerve stimulation accelerates clotting to reduce hemorrhage without precipitating systemic thrombosis, we reasoned it might reduce bleeding in hemophilia A. Using two different male murine hemorrhage and thrombosis models, we show vagus nerve stimulation bypasses the factor VIII deficiency of hemophilia A to decrease bleeding and accelerate clotting. Vagus nerve stimulation targets acetylcholine-producing T lymphocytes in spleen and α7 nicotinic acetylcholine receptors (α7nAChR) on platelets to increase calcium uptake and enhance alpha granule release. Splenectomy or genetic deletion of T cells or α7nAChR abolishes vagal control of platelet activation, thrombus formation, and bleeding in male mice. Vagus nerve stimulation warrants clinical study as a therapy for coagulation disorders and surgical or traumatic bleeding.

Application of Vagus Nerve Stimulation in Spinal Cord Injury Rehabilitation

Spinal cord injury (SCI) is a prevalent devastating condition causing significant morbidity and mortality, especially in developing countries. The pathophysiology of SCI involves ischemia, neuroinflammation, cell death, and scar formation. Due to the lack of definitive therapy for SCI, interventions mainly focus on rehabilitation to reduce deterioration and improve the patient's quality of life. Currently, rehabilitative exercises and neuromodulation methods such as functional electrical stimulation, epidural electrical stimulation, and transcutaneous electrical nerve stimulation are being tested in patients with SCI. Other spinal stimulation techniques are being developed and tested in animal models. However, often these methods require complex surgical procedures and solely focus on motor function. Vagus nerve stimulation (VNS) is currently used in patients with epilepsy, depression, and migraine and is being investigated for its application in other disorders. In animal models of SCI, VNS significantly improved locomotor function by ameliorating inflammation and improving plasticity, suggesting its use in human subjects. SCI patients also suffer from nonmotor complications, including pain, gastrointestinal dysfunction, cardiovascular disorders, and chronic conditions such as obesity and diabetes. VNS has shown promising results in alleviating these conditions in non-SCI patients, which makes it a possible therapeutic option in SCI patients.

Therapeutic Strategies to Ameliorate Neuronal Damage in Epilepsy by Regulating Oxidative Stress, Mitochondrial Dysfunction, and Neuroinflammation

Epilepsy is a central nervous system disorder involving spontaneous and recurring seizures that affects 50 million individuals globally. Because approximately one-third of patients with epilepsy do not respond to drug therapy, the development of new therapeutic strategies against epilepsy could be beneficial. Oxidative stress and mitochondrial dysfunction are frequently observed in epilepsy. Additionally, neuroinflammation is increasingly understood to contribute to the pathogenesis of epilepsy. Mitochondrial dysfunction is also recognized for its contributions to neuronal excitability and apoptosis, which can lead to neuronal loss in epilepsy. This review focuses on the roles of oxidative damage, mitochondrial dysfunction, NAPDH oxidase, the blood-brain barrier, excitotoxicity, and neuroinflammation in the development of epilepsy. We also review the therapies used to treat epilepsy and prevent seizures, including anti-seizure medications, anti-epileptic drugs, anti-inflammatory therapies, and antioxidant therapies. In addition, we review the use of neuromodulation and surgery in the treatment of epilepsy. Finally, we present the role of dietary and nutritional strategies in the management of epilepsy, including the ketogenic diet and the intake of vitamins, polyphenols, and flavonoids. By reviewing available interventions and research on the pathophysiology of epilepsy, this review points to areas of further development for therapies that can manage epilepsy.

Biomechanics Characterization of Autonomic and Somatic Nerves by High Dynamic Closed-Loop MEMS force sensing

The biomechanics of peripheral nerves are determined by the blood-nerve barrier (BNB), together with the epineural barrier, extracellular matrix, and axonal composition, which maintain structural and functional stability. These elements are often ignored in the fabrication of penetrating devices, and the implant process is traumatic due to the mechanical distress, compromising the function of neuroprosthesis for sensory-motor restoration in amputees. Miniaturization of penetrating interfaces offers the unique opportunity of decoding individual nerve fibers associated to specific functions, however, a main issue for their implant is the lack of high-precision standardization of insertion forces. Current automatized electromechanical force sensors are available; however, their sensitivity and range amplitude are limited (i.e. mN), and have been tested only in-vitro. We previously developed a high-precision bi-directional micro-electromechanical force sensor, with a closed-loop mechanism (MEMS-CLFS), that while measuring with high-precision (-211.7μN to 211.5μN with a resolution of 4.74nN), can be used in alive animal. Our technology has an on-chip electrothermal displacement sensor with a shuttle beam displacement amplification mechanism, for large range and high-frequency resolution (dynamic range of 92.9 dB), which eliminates the adverse effect of flexural nonlinearity measurements, observed with other systems, and reduces the mechanical impact on delicate biological tissue. In this work, we use the MEMS-CLFS for in-vivo bidirectional measurement of biomechanics in somatic and autonomic nerves. Furthermore we define the mechanical implications of irrigation and collagen VI in the BNB, which is different for both autonomic and somatic nerves (~ 8.5-8.6 fold density of collagen VI and vasculature CD31+ in the VN vs ScN). This study allowed us to create a mathematical approach to predict insertion forces. Our data highlights the necessity of nerve-customization forces to prevent injury when implanting interfaces, and describes a high precision MEMS technology and mathematical model for their measurements.

Electroceutical and Bioelectric Therapy: Its Advantages and Limitations

Given the long history, the field of electroceutical and bioelectric therapy has grown impressively, recognized as the main modality of mental health treatments along with psychotherapy and pharmacotherapy. Electroceutical and bioelectric therapy comprises electroconvulsive therapy (ECT), vagus nerve stimulation (VNS), repetitive transcranial magnetic stimulation (rTMS), deep brain stimulation (DBS), transcranial electrical stimulation (tES), and other brain stimulation techniques. Much empirical research has been published regarding the application guidelines, mechanism of action, and efficacy of respective brain stimulation techniques, but no comparative study that delineates the advantages and limitations of each therapy exists for a comprehensive understanding of each technique. This review provides a comparison of existing electroceutical and bioelectric techniques, primarily focusing on the therapeutic advantages and limitations of each therapy in the current electroceutical and bioelectric field.

Training and teaching of vagus nerve stimulation surgery: Worldwide survey and future perspectives

OBJECTIVE

Vagus nerve stimulation (VNS) therapy has been used for more than two decades to treat drug resistant epilepsy and depression and most recently received FDA approval for stroke rehabilitation. Expanding indications will renew the interest in the technique and increase the number of surgeons to be trained. The aim of this study was to survey surgeons with substantial expertise on optimal teaching and training approaches.

METHODS

Anonymous forms comprising 16 questions were sent by e-mail to surgeons with substantial expertise. Statistical analyses were used to compare the answers of the most experienced surgeons (>5 years) with the less experienced ones (<5 years).

RESULTS

Fully-completed forms were collected from 57 experts from 20 countries. The placement of the helical coils was deemed to be the most difficult step by 36 (63.2%) experts, and the use of optical magnification during this step was deemed necessary by 39 (68.4%) experts. Vocal cord palsy should be largely avoidable with proper surgical technique according to 44 (77.2%) experts. The teaching tool considered the most useful was mentoring (38, 66.7%). The future of VNS surgery teaching was deemed to be in anatomical workshops (29, 50.9%) and surgical simulation (26, 45.6%). Overall, answers did not vary significantly according to experience.

CONCLUSIONS

VNS surgery should be mastered by actively participating in dedicated practical training courses and by individual mentoring during actual surgery, which is still the best way to learn. This study highlights the need for a formal training course and possible specific accreditation.

Clinical Benefit of Vagus Nerve Stimulation for Epilepsy: Assessment of Randomized Controlled Trials and Prospective Non-Randomized Studies

We examined the efficacy of vagal nerve stimulation (VNS) for patients suffering from medically intractable epilepsy. Four randomized controlled trials (RCTs - 3 adult RCTs and 1 pediatric RCT) were identified in our comprehensive literature search. Across the 4 studies, high frequency VNS stimulation (frequency >20 Hz) consistently achieved a greater seizure frequency reduction (23.4-33.1%) relative to low frequency VNS stimulation (1 Hz, .6-15.2%). We identified 2 RCTs examining whether the parameters of stimulation influenced seizure control. These studies reported that VNS achieved seizure control comparable to those reported by the first 4 RCTs (22-43% seizure frequency reduction), irrespective of the parameters utilized for VNS stimulation. In terms of VNS associated morbidity, these morbidities were consistently higher in adults who underwent high frequency VNS stimulation (eg dysphonia 37-66%, dyspnea 6-25.3%). However, no such differences were observed in the pediatric population. Moreover, <2% of patients withdrew from the RCTs/prospective studies due to intolerable symptoms. To provide an assessment of how the risks and benefits of VNS impact the patient experience, 1 study assessed the well-being of enrolled patients (as a secondary end point) and found VNS was associated with an overall improvement in well-being. Consistent with this observation, we identified a prospective, non-randomized study that demonstrated improved quality of life for epilepsy patients managed with VNS and best medical practice relative to best medical practice alone. In aggregate, these RCT studies support the efficacy and benefit of VNS as a neuro-modulatory platform in the management of a subset of medically refractory epilepsy patients.

Pediatric Vagus Nerve Stimulation: Case Series Outcomes and Future Directions

BACKGROUND

Vagus nerve stimulation (VNS) is a neuromodulatory procedure most extensively studied as an adjunct to medically refractory epilepsy. Despite widespread adoption and decades of clinical experience, clinical predictors of response to VNS remain unclear.

OBJECTIVE

To evaluate a retrospective cohort of pediatric patients undergoing VNS at our institution to better understand who may benefit from VNS and identify factors which may predict response to VNS.

METHODS

We conducted a retrospective cohort study examining pediatric patients undergoing VNS over nearly a 20-year span at a single institution. Presurgical evaluation, including demographics, clinical history, and diagnostic electroencephalogram, and imaging findings were examined. Primary outcomes included VNS response.

RESULTS

Two hundred ninety-seven subjects were studied. The mean age at surgery was 10.1 (SD = 4.9, range = 0.8-25.3) years; length of follow-up was a mean of 4.6 years (SD = 3.5, median = 3.9 years, range 1 day-16.1 years). There was no association between demographic factors, epilepsy etiology, or genetic basis and VNS outcomes. There was an association between reduction in main seizure type with positive MRI finding. Of all MRI findings analyzed, brain atrophy was significantly associated with worse VNS outcomes, whereas dysplastic hippocampus and chronic periventricular leukomalacia findings were found to be associated with improved outcomes. Increased seizure semiology variability and seizure type were also associated with improved seizure outcomes.

CONCLUSION

Predicting response to VNS remains difficult, leading to incompletely realized benefits and suboptimal resource utilization. Specific MRI findings and increased seizure semiology variability and type can help guide clinical decision making and patient counseling.

Epilepsy and Autism Spectrum Disorder (ASD): The Underlying Mechanisms and Therapy Targets Related to Adenosine

Epilepsy and autism spectrum disorder (ASD) are highly mutually comorbid, suggesting potential overlaps in genetic etiology, pathophysiology, and neurodevelopmental abnormalities. Adenosine, an endogenous anticonvulsant and neuroprotective neuromodulator of the brain, has been proved to affect the process of epilepsy and ASD. On the one hand, adenosine plays a crucial role in preventing the progression and development of epilepsy through adenosine receptordependent and -independent ways. On the other hand, adenosine signaling can not only regulate core symptoms but also improve comorbid disorders in ASD. Given the important role of adenosine in epilepsy and ASD, therapeutic strategies related to adenosine, including the ketogenic diet, neuromodulation therapy, and adenosine augmentation therapy, have been suggested for the arrangement of epilepsy and ASD. There are several proposals in this review. Firstly, it is necessary to further discuss the relationship between both diseases based on the comorbid symptoms and mechanisms of epilepsy and ASD. Secondly, it is important to explore the role of adenosine involved in epilepsy and ASD. Lastly, potential therapeutic value and clinical approaches of adenosine-related therapies in treating epilepsy and ASD need to be emphasized.

Development of localized interictal epileptiform discharges following vagus nerve stimulation for lennox-gastaut syndrome: a case report

Background

Lennox-gastaut syndrome (LGS) is an epileptic encephalopathy often associated with behavioral and psychiatric disorders. Vagus nerve stimulation (VNS) has been approved effective for LGS treatment. Surgical resection is also an option for LGS patients with focal pathology, offering a high probability of seizure control. However, it is challenging to accurately localize the seizure focus.

Case presentation

The case presented here is a 19-year-old male with a 16-year history of epilepsy with comorbid severe cognitive and psychiatric disorders. He was diagnosed with LGS due to generalized slow spike-wave discharges and multiple seizure types. He was treated with VNS in 2017 at the age of 15. After that, the frequency of the short tonic seizures decreased from 4–5 times per day to 2–5 times per year, and the generalized tonic–clonic seizure pattern did not recur, which had a frequency of 2–4 times per month before the surgery. In 2019, the generalized abnormal interictal epileptiform discharges changed to be localized in the right frontal–temporal lobe at the age of 17 years (2019).

Conclusions

This case report suggested that the generalized epileptiform discharges evolve into localized discharges after VNS treatment, which may help reveal the primary seizure focus for resection surgery in patients with LGS.

Safety and Management of Implanted Epilepsy Devices for Imaging and Surgery

Permanently implanted devices that deliver electrical stimulation are increasingly used to treat patients with drug-resistant epilepsy. Primary care physicians, neurologists, and epilepsy clinicians may encounter patients with a variety of implanted neuromodulation devices in the course of clinical care. Due to the rapidly changing landscape of available epilepsy-related neurostimulators, there may be uncertainty related to how these devices should be handled during imaging procedures and perioperative care. We review the safety and management of epilepsy-related implanted neurostimulators that may be encountered during imaging and surgery. We provide a summary of approved device labeling and recommendations for the practical management of these devices to help guide clinicians as they care for patients treated with bioelectronic medicine.

Neuromodulation in drug-resistant epilepsy: A review of current knowledge

Nearly 1% of the global population suffers from epilepsy. Drug-resistant epilepsy (DRE) affects one-third of epileptic patients who are unable to treat their condition with existing drugs. For the treatment of DRE, neuromodulation offers a lot of potential. The background, mechanism, indication, application, efficacy, and safety of each technique are briefly described in this narrative review, with an emphasis on three approved neuromodulation therapies: vagus nerve stimulation (VNS), deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS), and closed-loop responsive neurostimulation (RNS). Neuromodulatory approaches involving direct or induced electrical currents have been developed to lessen seizure frequency and duration in patients with DRE since the notion of electrical stimulation as a therapy for neurologic diseases originated in the early nineteenth century. Although few people have attained total seizure independence for more than 12 months using these treatments, more than half have benefitted from a 50% drop in seizure frequency over time. Although promising outcomes in adults and children with DRE have been achieved, challenges such as heterogeneity among epilepsy types and etiologies, optimization of stimulation parameters, a lack of biomarkers to predict response to neuromodulation therapies, high-level evidence to aid decision-making, and direct comparisons between neuromodulatory approaches remain. To solve these existing gaps, authorize new kinds of neuromodulation, and develop personalized closed-loop treatments, further research is needed. Finally, both invasive and non-invasive neuromodulation seems to be safe. Implantation-related adverse events for invasive stimulation primarily include infection and pain at the implant site. Intracranial hemorrhage is a frequent adverse event for DBS and RNS. Other stimulation-specific side-effects are mild with non-invasive stimulation.

Delivering transcutaneous auricular neurostimulation (tAN) to improve symptoms associated with opioid withdrawal: results from a prospective clinical trial

Background

As pharmacological treatments are the primary option for opioid use disorder, neuromodulation has recently demonstrated efficacy in managing opioid withdrawal syndrome (OWS). This study investigated the safety and effectiveness of transcutaneous auricular neurostimulation (tAN) for managing OWS.

Methods

This prospective inpatient trial included a 30-minute randomized, sham-controlled, double-blind period followed by a 5-day open-label period. Adults with physical dependence on opioids were randomized to receive active or sham tAN following abrupt opioid discontinuation. The Clinical Opiate Withdrawal Scale (COWS) was used to determine withdrawal level, and participants were required to have a baseline COWS score ≥ 13 before enrollment. The double-blind period of the study occurred during the first 30-minutes to assess the acute effects of tAN therapy compared to a sham control. Group 1 received active tAN during both the 30-minute double-blind period and the 5-day open-label period. Group 2 received passive sham tAN (no stimulation) during the double-blind period, followed by active tAN during the 5-day open-label period. The primary outcome was change in COWS from baseline to 60-minutes of active tAN (pooled across groups, accounting for 30-minute delay). Secondary outcomes included difference in change in COWS scores between groups after 30-minutes of active or sham tAN, change in COWS scores after 120-minutes of active tAN, and change in COWS scores on Days 2–5. Non-opioid comfort medications were administered during the trial.

Results

Across all thirty-one participants, the mean (SD) COWS scores relative to baseline were reduced by 7.0 (4.7) points after 60-minutes of active tAN across both groups (p < 0.0001; Cohen’s d = 2.0), demonstrating a significant and clinically meaningful reduction of 45.9%. After 30-minutes of active tAN (Group 1) or sham tAN (Group 2), the active tAN group demonstrated a significantly greater COWS score reduction than the sham tAN group (41.7% vs. 24.1%; p = 0.036). Participants across both groups achieved an average COWS reduction up to 74.7% on Days 2–5.

Conclusion

Results demonstrate tAN is a safe and effective non-opioid approach for reducing symptoms of OWS. This study supported an FDA clearance.

Clinical trial registration

clinicaltrials.gov/ct2/show/NCT04075214, Identifier: NCT04075214, Release Date: August 28, 2019.

Vagus nerve stimulation for super-refractory status epilepticus in febrile infection-related epilepsy syndrome: a pediatric case report and literature review

Febrile infection-related epilepsy syndrome (FIRES) is a devastating epileptic encephalopathy with limited treatment options and unclear etiology. Vagus nerve stimulation (VNS) is an FDA-approved therapy for refractory epilepsy that has been shown to decrease the frequency and severity of seizures. There is a growing interest in alternate non-pharmaceutical therapies for managing super-refractory status epilepticus (SRSE). We present a 29-month-old case, diagnosed with FIRES, whose seizures were successfully controlled by utilization of VNS after ineffective response to intensive pharmacotherapy and ketogenic diet treatment. The VNS was planted after 14 days of refractory seizure activity with a following rapid parameter titration for 42 days without evident side effect, which finally controlled the seizure in the acute phase. VNS may be a potential candidate for the treatment of SRSE in FIRES.

Prediction of the Responsiveness to Vagus-Nerve Stimulation in Patients with Drug-Resistant Epilepsy via Directed-Transfer-Function Analysis of Their Perioperative Scalp EEGs

This study aims to compare directed transfer function (DTF), which is an effective connectivity analysis, derived from scalp EEGs between responder and nonresponder groups implanted with vagus-nerve stimulation (VNS). Twelve patients with drug-resistant epilepsy (six responders and six nonresponders) and ten controls were recruited. A good response to VNS was defined as a reduction of ≥50% in seizure frequency compared with the presurgical baseline. DTF was calculated in five frequency bands (delta, theta, alpha, beta, and broadband) and seven grouped electrode regions (left and right frontal, temporal, parieto-occipital, and midline) in three different states (presurgical, stimulation-on, and stimulation-off states). Responders showed presurgical nodal strength close to the control group in both inflow and outflow, whereas nonresponders exhibited increased inward and outward connectivity measures. Nonresponders also had increased inward and outward connectivity measures in the various brain regions and various frequency bands assessed compared with the control group when the stimulation was on or off. Our study demonstrated that the presurgical DTF profiles of responders were different from those of nonresponders. Moreover, a presurgical normal DTF profile may predict good responsiveness to VNS.

Surgical Treatment of Drug-Resistant Generalized Epilepsy

PURPOSE OF REVIEW

To summarize current evidence and recent developments in the surgical treatment of drug-resistant generalized epilepsy.

RECENT FINDINGS

Current surgical treatments of drug-resistant generalized epilepsy include vagus nerve stimulation (VNS), deep brain stimulation (DBS) and corpus callosotomy (CC). Neurostimulation with VNS and/or DBS has been shown to be effective in reducing seizure frequency in patients with generalized epilepsy. DBS for generalized epilepsy is primarily consisted of open-loop stimulation directed at the centromedian (CM) nucleus in the thalamus, though closed-loop stimulation and additional targets are being explored. CC can be effective in treating some seizure types and can be performed using traditional surgical techniques or with the less invasive methods of laser ablation and radiosurgery. This current literature supports the use of VNS, DBS and CC, alone or in combination, as palliative treatments of drug-resistant generalized epilepsy.

Neurostimulation as a Method of Treatment and a Preventive Measure in Canine Drug-Resistant Epilepsy: Current State and Future Prospects

Modulation of neuronal activity for seizure control using various methods of neurostimulation is a rapidly developing field in epileptology, especially in treatment of refractory epilepsy. Promising results in human clinical practice, such as diminished seizure burden, reduced incidence of sudden unexplained death in epilepsy, and improved quality of life has brought neurostimulation into the focus of veterinary medicine as a therapeutic option. This article provides a comprehensive review of available neurostimulation methods for seizure management in drug-resistant epilepsy in canine patients. Recent progress in non-invasive modalities, such as repetitive transcranial magnetic stimulation and transcutaneous vagus nerve stimulation is highlighted. We further discuss potential future advances and their plausible application as means for preventing epileptogenesis in dogs.

Transcutaneous Cervical Vagus Nerve Stimulation Induces Changes in the Electroencephalogram and Heart Rate Variability of Healthy Dogs, a Pilot Study

Transcutaneous cervical vagus nerve stimulation (tcVNS) has been used to treat epilepsy in people and dogs. Objective electroencephalographic (EEG) and heart rate variability (HRV) data associated with tcVNS have been reported in people. The question remained whether EEG and electrocardiography (ECG) would detect changes in brain activity and HRV, respectively, after tcVNS in dogs. Simultaneous EEG and Holter recordings, from 6 client-owned healthy dogs were compared for differences pre- and post- tcVNS in frequency band power analysis (EEG) and HRV. The feasibility and tolerance of the patients to the tcVNS were also noted. In a general linear mixed model, the average power per channel per frequency band was found to be significantly different pre- and post-stimulation in the theta (p = 0.02) and alpha bands (p = 0.04). The pooled power spectral analysis detected a significant decrease in the alpha (p < 0.01), theta (p = 0.01) and beta (p = 0.035) frequencies post-stimulation. No significant interaction was observed between dog, attitude, and stimulation in the multivariate model, neither within the same dog nor between individuals. There was a significant increase in the HRV measured by the standard deviation of the inter-beat (SDNN) index (p < 0.01) and a decrease in mean heart rate (p < 0.01) after tcVNS. The tcVNS was found to be well-tolerated. The results of this pilot study suggest that EEG and ECG can detect changes in brain activity and HRV associated with tcVNS in healthy dogs. Larger randomized controlled studies are required to confirm the results of this study and to assess tcVNS potential therapeutic value.

Gut Microbial Dysbiosis and Cognitive Impairment in Bipolar Disorder: Current Evidence

Recent studies have reported that the gut microbiota influences mood and cognitive function through the gut-brain axis, which is involved in the pathophysiology of neurocognitive and mental disorders, including Parkinson’s disease, Alzheimer’s disease, and schizophrenia. These disorders have similar pathophysiology to that of cognitive dysfunction in bipolar disorder (BD), including neuroinflammation and dysregulation of various neurotransmitters (i.e., serotonin and dopamine). There is also emerging evidence of alterations in the gut microbial composition of patients with BD, suggesting that gut microbial dysbiosis contributes to disease progression and cognitive impairment in BD. Therefore, microbiota-centered treatment might be an effective adjuvant therapy for BD-related cognitive impairment. Given that studies focusing on connections between the gut microbiota and BD-related cognitive impairment are lagging behind those on other neurocognitive disorders, this review sought to explore the potential mechanisms of how gut microbial dysbiosis affects cognitive function in BD and identify potential microbiota-centered treatment.

Single-interface bioelectronic medicines - concept, clinical applications and preclinical data

Presently, large groups of patients with various diseases are either intolerant, or irresponsive to drug therapies and also intractable by surgery. For several diseases, one option which is available for such patients is the implantable neurostimulation therapy. However, lacking closed-loop control and selective stimulation capabilities, the present neurostimulation therapies are not optimal and are therefore used as only "third" therapeutic options when a disease cannot be treated by drugs or surgery. Addressing those limitations, a next generation class of closed-loop controlled and selective neurostimulators generically named bioelectronic medicines seems within reach. A sub-class of such devices is meant to monitor and treat impaired functions by intercepting, analyzing and modulating neural signals involved in the regulation of such functions using just one neural interface for those purposes. The primary objective of this review is to provide a first broad perspective on this type of single-interface devices for bioelectronic therapies. For this purpose, the concept, clinical applications and preclinical studies for further developments with such devices are here analyzed in a narrative manner.

The role of vagus nerve stimulation in genetic etiologies of drug-resistant epilepsy: a meta-analysis

OBJECTIVE

Drug-resistant epilepsy (DRE) affects many children. Vagus nerve stimulation (VNS) may improve seizure control; however, its role in children with genetic etiologies of epilepsy is not well described. The authors systematically reviewed the literature to examine the effectiveness of VNS in this cohort.

METHODS

In January 2021, the authors performed a systematic review of the PubMed/MEDLINE, SCOPUS/Embase, Cochrane, and Web of Science databases to investigate the impact of VNS on seizure outcomes in children with genetic etiologies of epilepsy. Primary outcomes included seizure freedom rate, ≥ 90% seizure reduction rate, and ≥ 50% seizure reduction rate. Secondary outcomes were seizure severity and quality of life (QOL), including cognitive, functional, and behavioral outcomes. A random-effects meta-analysis was performed.

RESULTS

The authors identified 125 articles, of which 47 with 216 nonduplicate patients were analyzed. Common diagnoses were Dravet syndrome (DS) (92/216 patients [42.6%]) and tuberous sclerosis complex (TSC) (63/216 [29.2%]). Seizure freedom was not reported in any patient with DS; the pooled proportion (95% CI) of patients with ≥ 50% seizure reduction was 41% (21%-58%). Secondary cognitive outcomes of VNS were variable in DS patients, but these patients demonstrated benefits in seizure duration and status epilepticus. In TSC patients, the pooled (95% CI) seizure freedom rate was 40% (12%-71%), ≥ 90% seizure reduction rate was 31% (8%-56%), and ≥ 50% reduction rate was 68% (48%-91%). Regarding the secondary outcomes of VNS in TSC patients, several studies reported decreased seizure severity and improved QOL outcomes. There was limited evidence regarding the use of VNS to treat patients with other genetic etiologies of epilepsy, such as mitochondrial disease, Rett syndrome, Doose syndrome, Landau-Kleffner syndrome, Aicardi syndrome, Angelman syndrome, ring chromosome 20 syndrome, and lissencephaly; variable responses were reported in a limited number of cases.

CONCLUSIONS

The authors conducted a systematic review of VNS outcomes in children with genetic etiologies of DRE. Among the most studied conditions, patients with TSC had substantial seizure reduction and improvements in QOL, whereas those with DS had less robust seizure reduction. Increased testing, diagnosis, and long-term follow-up studies are necessary to better characterize VNS response in these children.

Evaluating vagus nerve stimulation treatment with heart rate monitoring in pediatric patients with intractable epilepsy

PURPOSE

Vagus nerve stimulators (VNS) have emerged as an effective treatment modality for pediatric patients suffering from intractable, drug-resistant epilepsy. Newer devices, AspireSR™ Model 106 and the SenTiva™ Model 1000 (VNS TherapyⓇ, LivaNova™), contain an "auto-stimulation" feature that detects ictal tachycardia and transmits pulsations to attenuate seizures. However, the exact benefits of auto-stimulation compared to its risks still merit further exploration. This study evaluates the utility of these specific devices in a heterogeneous population of pediatric and young adult patients with intractable epilepsy.

METHODS

This is a retrospective chart review of 55 patients who underwent either VNS insertion with or without an auto-stimulation-enabled VNS device at a single level four epilepsy center. Seizure frequency, seizure subtype, side effects, and change in anti-seizure medication load both before and after VNS implantations were collected from patient self-reporting at the time of VNS insertion and 12 months following implantation. Information regarding output current, auto-stimulation current, duty cycling, and auto-stimulation threshold of the device was obtained from documented VNS interrogation for patients with auto-stimulation-enabled VNS devices.

RESULTS

Patients with auto-stimulation-enabled VNS devices had a mean 56.0% (SD = 0.414) seizure frequency reduction 12 months post-VNS insertion, while patients without auto-stimulation-enabled VNS devices had a mean 41.6% (SD = 0.456) seizure frequency reduction during the same interval. The mean seizure frequency reduction 12 months post-VNS insertion for patients with a SenTiva™ 1000 model was 66.0% (SD = 0.426). For patients with auto-stimulation-enabled VNS devices, post-treatment seizure reduction was significantly correlated with daily auto-stimulation activation (R = 0.432, p = 0.025).

CONCLUSION

This study supports the clinical safety and utility of auto-stimulation-enabled VNS models, specifically the SenTiva™ 1000, in treating pediatric patients with intractable epilepsy of various subtypes and etiologies. Further research is needed to evaluate the sustained impact of auto-stimulation on long-term outcomes (≥ 2 years follow-up post-VNS).

Genetic variations of adenosine kinase as predictable biomarkers of efficacy of vagus nerve stimulation in patients with pharmacoresistant epilepsy

OBJECTIVE

Vagus nerve stimulation (VNS) is an alternative treatment option for individuals with refractory epilepsy, with nearly 40% of patients showing no benefit after VNS and only 6%-8% achieving seizure freedom. It is presently unclear why some patients respond to treatment and others do not. Therefore, identification of biomarkers to predict efficacy of VNS is of utmost importance. The objective of this study was to explore whether genetic variations in genes involved in adenosine kinase (ADK), ecto-5'-nucleotidase (NT5E), and adenosine A1 receptor (A1R) are linked to outcome of VNS in patients with refractory epilepsy.

METHODS

Thirty single-nucleotide polymorphisms (SNPs), including 9 in genes encoding ADK, 3 in genes encoding NT5E, and 18 in genes encoding A1R, were genotyped in 194 refractory epilepsy patients who underwent VNS. The chi-square test and binary logistic regression were used to determine associations between genetic differences and VNS efficacy.

RESULTS

A significant association between ADK SNPs rs11001109, rs7899674, and rs946185 and seizure reduction with VNS was found. Regardless of sex, age, seizure frequency and type, antiseizure drug use, etiology, and prior surgical history, all patients (10/10 patients [100%]) with minor allele homozygosity at rs11001109 (genotype AA) or rs946185 (AA) achieved > 50% seizure reduction and 4 patients (4/10 [40%]) achieved seizure freedom. VNS therapy demonstrated higher efficacy among carriers of minor allele rs7899674 (CG + GG) (68.3% vs 48.8% for patients with major allele homozygosity).

CONCLUSIONS

Homozygous ADK SNPs rs11001109 (AA) and rs946185 (AA), as well as minor allele rs7899674 (CG + GG), may serve as useful biomarkers for prediction of VNS therapy outcome.

Epilepsy in patients with schizophrenia: Pathophysiology and basic treatments

Schizophrenia is a chronic psychiatric disorder that may lead to epilepsy. However, there are limited findings on the issues. This narrative review aimed to provide a practical perspective on epilepsy in patients with schizophrenia using the current treatment systems for epilepsy. While there has been a debate on the relationship between epilepsy and schizophrenia, i.e., antagonism, affinity, and coincidence, recent large cohort studies have revealed a high frequency of epilepsy in patients with schizophrenia (4-5 times higher than that of general population). The high incidence observed is likely to be due to the bidirectionality between epilepsy and schizophrenia and additional schizophrenia-related conditions, e.g., antipsychotic drugs (APD), substance abuse, and head injury. As for symptomatology of epilepsy, only one small-size study showed that seizures of patients with schizophrenia are equivalent to those of patients without schizophrenia. Patients with schizophrenia exhibit the first seizure in their twenties or later, which are mostly focal seizures. Most of seizures in patients with schizophrenia can be controlled with conventional antiepileptic drugs. Few patients with schizophrenia develop treatment-resistant epilepsy. However, since drug interactions can be more complicated due to multiple conditions, such as pre-existing polypharmacy, heavy smoking, irregular eating, and comorbid metabolic disorders, cautious monitoring for clinical symptoms is required. To improve seizure control and adherence, non-pharmacological approaches are also recommended. Thus far, for seizure treatments in patients with schizophrenia, we have to use many empirical findings or substitute certain findings from population without schizophrenia because evidence is insufficient. The accumulation of clinical findings may contribute to the development of efficient treatment systems.

Links between the brain and body during sleep: implications for memory processing

Sleep is intimately related to memory processes. The established view is that the transformation of experiences into long-term memories is linked to sleep-related CNS function. However, there is increasing evidence that the autonomic nervous system (ANS), long recognized to modulate cognition during waking, can impact memory processing during sleep. Here, we review human research that examines the role of autonomic activity and sleep in memory formation. We argue that autonomic activity during sleep may set the stage for the CNS dynamics associated with sleep and memory stability and integration. Further, we consider how the link between ANS activity and polysomnographic markers of sleep may help elucidate both healthy and pathological cognitive aging in humans.

Efficacy and safety of transcutaneous auricular vagus nerve stimulation combined with conventional rehabilitation training in acute stroke patients: a randomized controlled trial conducted for 1 year involving 60 patients

Transcutaneous auricular vagus nerve stimulation (ta-VNS) is a novel noninvasive treat-ment for stroke that directly stimulates the peripheral auricular branch of the vagus nerve. There have been recent reports that ta-VNS combined with conventional rehabilitation training promotes the recovery of neurological function of patients with acute stroke. However, these were small-sample-sized studies on the recovery of neurological function in patients after percutaneous vagus nerve stimulation in the subacute and chronic phases after stroke. This double-blinded randomized controlled trial involved 60 acute ischemic or hemorrhagic stroke patients aged 18–80 years who received treatment in the Second Affiliated Hospital of Chongqing Medical University. The subjects were randomly assigned to receive ta-VNS or sham ta-VNS combined with conventional rehabilitation training. The follow-up results over 1 year revealed that ta-VNS combined with conventional rehabilitation training greatly improved the recovery of motor and sensory functions and emotional responses compared with sham ta-VNS combined with conventional rehabilitation training. There were no obvious side effects. These findings suggest that ta-VNS combined with conventional rehabilitation training for the treatment of acute ischemic or hemorrhagic stroke patients is safe and effective.

Vagus nerve stimulation: a 20-year Australian experience

BACKGROUND

Vagus nerve stimulation (VNS) therapy was first approved in the mid-1990s in the USA, Europe and Australia, with demonstrable efficacy in paediatric populations. Benefit in seizure frequency reduction can be observed up to 2 years post-intervention; however, few studies assess outcomes beyond this period. Furthermore, paediatric cohort sizes are small, limiting generalisability of outcome assessments. We evaluate VNS insertion outcomes and complications or side-effects in a large paediatric cohort, over a 20-year period from Queensland's first VNS insertion.

METHODS

A retrospective review was conducted of all paediatric VNS insertions at the Queensland Children's Hospital (QCH) and the Mater Children's Hospital/Mater Children's Private Hospital (MCH/MCPH) Brisbane. A minimum of 1-year follow-up from 1999 to 2020 was required for inclusion. Patients were assessed on demographics, epilepsy details, seizure outcomes and complications or side-effects.

RESULTS

In this extended follow-up cohort (76 patients, 7.2 ± 5.3 years), 51.3% of patients had ≥ 50% seizure frequency reduction, while 73.7% experienced an Engel III outcome (worthwhile benefit) or better. Eleven patients (14.9%) were seizure-free at follow-up, and 81.6% retained long-term therapy. Stimulation-related side-effects are common (17.1%) but rarely result in stimulation cessation (3.9%). Cessation occurred in 14 patients (18.4%) and most commonly related to minimal benefit (13.2%). Demographics, aetiology, seizure nature and surgical factors did not influence outcomes.

CONCLUSION

Over extended treatment periods, a large proportion of patients will benefit significantly from VNS therapy. Approximately 4 of 5 patients will retain VNS therapy, and in cases of cessation, this is most commonly related to minimal benefit. Underlying demographics, aetiology or seizure nature do not influence outcomes. This 20-year Queensland assessment of VNS therapy outcomes informs long-term expectation of VNS therapy.

The effects of electroacupuncture and laser acupuncture therapy for patients with major trauma: A study protocol

BACKGROUND

Major trauma is the leading cause of death in the young population. The inflammatory and anti-inflammatory responses are associated with posttraumatic morbidity and mortality; however, it is not fully clear how to reestablish the homeostasis in patients with major trauma.

METHODS

This study will be a prospective, randomized, placebo-controlled, partially double-blinded, three-armed trial. One hundred eighty participants diagnosed with major trauma will be randomly assigned to an electroacupuncture (EA), a laser acupuncture (LA), or a sham laser acupuncture group in a 1:1:1 ratio. All participants will undergo EA, LA, or sham laser acupuncture intervention once a day on 5 acupoints (LI4, PC6, ST36, SP6, and EX-HN1) for 14 consecutive days after enrollment. The primary outcome measure will be the length of hospital stay. Secondary outcomes will be inflammatory mediators, including serum C-reactive protein, interleukin (IL)-6, tumor necrosis factor-α, IL-1β, and IL-10. Clinical outcomes will be numeric rating scale scores for pain, sequential organ failure assessment, ICU length of stay, 30-day mortality, and WHO Disability Assessment Schedule. Data will be analyzed by chi-square test or t test for pairwise comparisons, as well as one-way ANOVA followed by post hoc Tukey method between groups.

OBJECTIVES

The aim of this protocol is to investigate the clinical effects of EA and LA on major trauma.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04970433. Registered on July 21, 2021.

Five weeks of intermittent transcutaneous vagus nerve stimulation shape neural networks: a machine learning approach

Invasive and transcutaneous vagus nerve stimulation [(t)-VNS] have been used to treat epilepsy, depression and migraine and has also shown effects on metabolism and body weight. To what extent this treatment shapes neural networks and how such network changes might be related to treatment effects is currently unclear. Using a pre-post mixed study design, we applied either a tVNS or sham stimulation (5 h/week) in 34 overweight male participants in the context of a study designed to assess effects of tVNS on body weight and metabolic and cognitive parameters resting state (rs) fMRI was measured about 12 h after the last stimulation period. Support vector machine (SVM) classification was applied to fractional amplitude low-frequency fluctuations (fALFF) on established rs-networks. All classification results were controlled for random effects and overfitting. Finally, we calculated multiple regressions between the classification results and reported food craving. We found a classification accuracy (CA) of 79 % in a subset of four brainstem regions suggesting that tVNS leads to lasting changes in brain networks. Five of eight salience network regions yielded 76,5 % CA. Our study shows tVNS’ post-stimulation effects on fALFF in the salience rs-network. More detailed investigations of this effect and their relationship with food intake seem reasonable for future studies.