Implantable Neurostimulator Research Articles

A Retrospective, Single-Center Study Investigating the Effects of a Novel Miniature Wireless Spinal Cord Stimulation System for the Treatment of Chronic Back and Leg Pain

BACKGROUND: Tietze syndrome is believed to be a result of recurrent microtrauma and characterized by painful localized inflammation and swelling of the chest wall. Chronic inflammatory changes may infiltrate surrounding tissues, leading to nerve root irritation and subsequent neuralgia. Resultant chronic neuropathy has been historically treated with conservative therapies and local nerve blocks, but the role of implantable neurostimulators have not been well described. CASE REPORT: A 73-year-old woman presented with chronic pain in the left paracentral chest area with episodes of burning and tingling, which radiated to the left shoulder, left arm, and left upper side of the jaw and face. Following the implantation of a permanent neurostimulator, the patient reported a near complete resolution of her pain symptoms. CONCLUSION: The role of implantable neurostimulators in the treatment of chronic neuropathy in the setting of Tietze syndrome is promising and their use may become a mainstay option in the future. KEY WORDS: Tietze Syndrome, neuromodulation, spinal cord nerve stimulation, pain management, neuralgia, implantable spinal cord stimulator

Ultrasound-driven electrical stimulation of peripheral nerves based on implantable piezoelectric thin film nanogenerators

Electrical stimulation of peripheral nerves is a powerful tool in neuroprosthesis and bioelectronic medicines to treat diverse clinical conditions. To achieve minimally invasive bioelectrical interfaces, the new generation of soft implantable neurostimulators with programmable electrical-stimulation functionality is highly demanded, but it remains a big challenge. Owing to the advantages of ultrasound in biomedical applications, such as deep tissue penetration and excellent clinical safety, we explore directly electrical stimulation of peripheral nerves with soft piezoelectric thin film nanogenerator which can be remotely driven by programmable ultrasound pulses. An ultrasound-active thin film nanogenerator with superior output performance was developed on basis of piezoelectric composite thin films containing 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) nanowires and polyvinylidene fluoride (PVDF) polymer. The piezoelectric thin film nanogenerators without accessory rectifiers can directly serve as neurostimulators, and the electrical pulses generated by the implantable piezoelectric thin film nanogenerator can be programmed by remote ultrasound excitation with adjustable input power and waveform. With sciatic nerves of rats as a model, the directly electrical neurostimulation was successfully achieved by subcutaneously implanted piezoelectric thin film nanogenerators with thickness of around 30 µm, and the stimuli controllability was systematically investigated with varied ultrasound parameters, including acoustic pressure, pulse width and pulse interval. Our ultrasound-driven electrical stimulation of peripheral nerves with ultrasound-active implantable thin film nanogenerators demonstrated a novel strategy to construct a programmable battery-free neurostimulator using soft and implantable energy devices which can be real-time-responsive to programmable external energy sources. • Electrical stimulation of peripheral nerves with soft implantable PENG which can be remotely driven by ultrasound. • The ultrasound-active soft PENG composed of 10 µm thick piezoelectric composite has superior electrical output performance. • This battery-free neurostimulator can be programmed by acoustic pressure, pulse width and pulse interval.

Rechargeable Implantable Neurostimulators: How Much Battery Capacity Remains After 10 Years? (1486)

Rechargeable Implantable Neurostimulators: How Much Battery Capacity Remains After 10 Years? (1486)

Long-Term Efficacy of a Novel Spinal Cord Stimulation Clinical Workflow Using Kilohertz Stimulation: Twelve-Month Results From the Vectors Study

Background and ObjectivesMultiple variables play a role in spinal cord stimulation (SCS) treatment outcomes, including patient anatomy, pain pattern, lead location, stimulation parameters, and so on. A wide range of stimulation parameters are considered safe and on-label, and as a result a growing number of new frequencies and frequency-combinations are being incorporated into standard practice. A standardized approach to therapy delivery may provide more consistent outcomes for more patients. The Vectors study evaluated whether there is significant sustained improvement in pain and functional outcomes when therapy is delivered using a standardized approach. Materials and MethodsVectors, a post-market, single-arm study evaluated the safety and efficacy of SCS with an implantable neurostimulator starting with 1 kHz stimulation, targeting the T9–T10 disc space following paresthesia mapping. Subjects with chronic intractable low back and leg pain (visual analogue scale [VAS] ≥ 50 mm) were enrolled. The primary endpoint was change in overall pain (VAS) at the three-month visit compared to baseline. Subjects were followed through 12 months. Secondary endpoints included changes in low back and leg pain, quality of life (European Quality of Life – Five Dimensions, EQ-5D-5L), disability (Oswestry Disability Index, ODI), individual subject goals, and subject satisfaction. ResultsThere was a significant reduction in overall pain (VAS; 45.4 mm) through the three-month visit, which was sustained through 12 months. At 12 months, 79% of subjects had ≥50% improvement in at least one pain domain (overall, lowback or leg) with 85% of subjects reporting therapy satisfaction. There was a decrease in disability and an improvement in quality of life with 70% of subjects achieving a personal activity goal by the three-month visit. ConclusionsLong-term pain relief and improvement in quality of life and function were achieved when following a standardized workflow. Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT03345472.

Magnetic Control of a Flexible Needle in Neurosurgery.

Minimally invasive neurosurgery does not require large incisions and openings in the skull to access the desired brain region, which often results in a faster recovery with fewer complications than traditional open neurosurgery. For disorders treated by the implantation of neurostimulators and thermocoagulation probes, current procedures incorporate a straight rigid needle, which restricts surgical trajectories and limits the number of possible targets and degrees of freedom at the respective target. A steerable needle with a flexible body could overcome these limitations. In this paper, we present a flexible needle steering system with magnetic and fluoroscopic guidance for neurosurgical procedures. A permanent magnet at the proximal end of a flexible needle is steered by an external magnetic field, and the resultant tip-deflection angle bends the flexible body like a bevel-tip needle. We implemented a kinematic model for the magnetic needle derived from a nonholonomic bicycle model and a closed-loop control strategy with feed-forward and feed-back components using a chained-form transformation. The proposed needle steering method was investigated through in vitro and ex vivo experiments.

Dental considerations in obstructive sleep apnea – Retrieving current status

Obstructive sleep apnea (OSA) is a sleep disorder caused by partial or complete upper airway collapse with hallmark features of repetitive breathing cessation resulting in reduced oxygen saturation. India ranks third among countries worst hit by OSA. OSA is linked with elevated morbidity and mortality with various modifiable/nonmodifiable predisposing factors. Different medical approaches such as polysomnography, home sleep testing, dynamic magnetic resonance imaging, drug-induced sleep endoscopy, and neutrophil-to-lymphocyte ratio assist in diagnosis. Depending on disease severity, various treatment lines have been advocated, including behavioral modifications, continuous positive airway pressure, oral appliances (OAs), and surgical intervention. The role of pharmacotherapy in OSA remains controversial and demands extensive study. OA case selection and titration need to be done with utmost care. Definite protocols for the selection of suitable candidates for OA therapy need to be established. Various invasive and non-invasive surgical interventions such as bariatric surgeries, uvulopalatopharyngoplasty and Mandibular advancement appliances (MAA) have been advocated for OSA treatment. However, MMA requires a detailed diagnosis, including hard and soft tissue examination and an adequate recovery strategy to avoid any resulting adverse facial aesthetics. Implantable upper airway neurostimulators serve as a hope for newer therapeutic approaches. The need for the hour is a multidisciplinary solution to OSA.

Acoustic Power Transfer Using Self-Focused Transducers for Miniaturized Implantable Neurostimulators

An emerging neurostimulation therapy utilizes electroceuticals to treat numerous neurological disorders. With the aim to discover novel clinical applications of neural stimulation, device miniaturization has been a key challenge for successful clinical translation of implantable stimulators. The battery size has been a limiting factor in further miniaturization, so wireless power transfer without the use of an implanted battery has gained interest. Among various power transfer techniques, acoustic power transfer (APT) provides substantial benefits for powering implantable devices due to its proven safety and efficiency for human body penetration. In this study, we proposed an APT-based neurostimulator with an integrated self-focused 3.6 MHz acoustic transducer and a receiver circuit composed of a power management module and pulse generator. The size of the entire device was 8 mm $\times$ 8 mm $\times8.6$ mm, which is small enough to be implanted with a small incision. A focused beam generated by an external transmitter was received by another focused beam from a receiver transducer, and this optimized pair of transducers with a receiver circuit generated 1.5 V, 1.3 ms pulse trains, which successfully transmitted stimulation pulses. We adopted a 1–3 composite with a piezolayer to implement a curved aperture, which enabled less-attenuated, focused, and matched beams for maximization of power transfer efficiency. We evaluated APT performance through rigorous bench-top and phantom tests and demonstrated the feasibility of stimulation through an in vivo experiment of sciatic nerve stimulation using a rat model.

Operative Technique and Lessons Learned From Surgical Implantation of the NeuroPace Responsive Neurostimulation® System in 57 Consecutive Patients.

The Responsive Neurostimulation (RNS)® System (NeuroPace, Inc) is an implantable device designed to improve seizure control in patients with medically refractory focal epilepsy. Because it is relatively new, surgical pearls and operative techniques optimized from experience beyond a small case series have yet to be described. To provide a detailed description of our operative technique and surgical pearls learned from implantation of the RNS System in 57 patients at our institution. We describe our method for frame-based placement of amygdalo-hippocampal depth leads, open implantation of cortical strip leads, and open installation of the neurostimulator. We outline considerations for patient selection, preoperative planning, surgical positioning, incision planning, stereotactic depth lead implantation, cortical strip lead implantation, craniotomy for neurostimulator implantation, device testing, closure, and intraoperative imaging. The median reduction in clinical seizure frequency was 60% (standard deviation 63.1) with 27% of patients achieving seizure freedom at last follow up (median 23.1 mo). No infections, intracerebral hemorrhages, or lead migrations were encountered. Two patients experienced lead fractures, and four lead exchanges have been performed. The techniques set forth here will help with the safe and efficient implantation of these new devices.

MagNI: A Magnetoelectrically Powered and Controlled Wireless Neurostimulating Implant.

This paper presents the first wireless and programmable neural stimulator leveraging magnetoelectric (ME) effects for power and data transfer. Thanks to low tissue absorption, low misalignment sensitivity and high power transfer efficiency, the ME effect enables safe delivery of high power levels (a few milliwatts) at low resonant frequencies ( ∼250kHz) to mm-sized implants deep inside the body (30-mm depth). The presented MagNI (Magnetoelectric Neural Implant) consists of a 1.5-mm 2 180-nm CMOS chip, an in-house built 4×2mm ME film, an energy storage capacitor, and on-board electrodes on a flexible polyimide substrate with a total volume of 8.2mm 3. The chip with a power consumption of 23.7 μW includes robust system control and data recovery mechanisms under source amplitude variations (1-V variation tolerance). The system delivers fully-programmable bi-phasic current-controlled stimulation with patterns covering 0.05-to-1.5-mA amplitude, 64-to-512- μs pulse width, and 0-to-200-Hz repetition frequency for neurostimulation.

Miniaturised Wireless Power Transfer Systems for Neurostimulation: A Review.

In neurostimulation, wireless power transfer is an efficient technology to overcome several limitations affecting medical devices currently used in clinical practice. Several methods were developed over the years for wireless power transfer. In this review article, we report and discuss the three most relevant methodologies for extremely miniaturised implantable neurostimulators: ultrasound coupling, inductive coupling and capacitive coupling. For each powering method, the discussion starts describing the physical working principle. In particular, we focus on the challenges given by the miniaturisation of the implanted integrated circuits and the related ad-hoc solutions for wireless power transfer. Then, we present recent developments and progresses in wireless power transfer for biomedical applications. Last, we compare each technique based on key performance indicators to highlight the most relevant and innovative solutions suitable for neurostimulation, with the gaze turned towards miniaturisation.

Treatment of Multi-Focal Epilepsy With Resective Surgery Plus Responsive Neurostimulation (RNS): One Institution's Experience

Objective: Patients with medically refractory focal epilepsy can be difficult to treat surgically, especially if invasive monitoring reveals multiple ictal onset zones. Possible therapeutic options may include resection, neurostimulation, laser ablation, or a combination of these surgical modalities. To date, no study has examined outcomes associated with resection plus responsive neurostimulation (RNS, Neuropace, Inc., Mountain View, CA) implantation and we describe our initial experience in patients with multifocal epilepsy undergoing this combination therapy.Methods: A total of 43 responsive neurostimulation (RNS) devices were implanted at UCI from 2015 to 2019. We retrospectively reviewed charts of patients from the same time period who underwent both resection and RNS implantation. Patients were required to have independent or multifocal onset, undergo resection and RNS implantation, and have a minimum of six-months for follow-up to be included in the study. Demographics, location of ictal onset, location of surgery, complications, and seizure outcome were collected.Results: Ten patients met inclusion criteria for the study, and seven underwent both procedures in the same setting. The average age was 36. All patients had multifocal ictal onset on video electroencephalogram or invasive EEG with four patients undergoing subdural grid placement and four patients undergoing bilateral sEEG prior to the definitive surgery. Five patients underwent resection plus ipsilateral RNS placement and the remainder underwent resection with contralateral RNS placement. Two minor complications were encountered in this group. At six months follow up, there was an average of 81% ± 9 reduction in seizures, while four patients experienced complete seizure freedom at 1 year.Conclusion: Patients with multifocal epilepsy can be treated with partial resection plus RNS. The complication rates are low with potential for worthwhile seizure reduction.

Brain-responsive corticothalamic stimulation in the centromedian nucleus for the treatment of regional neocortical epilepsy

ObjectiveThe aim of the study was to determine if corticothalamic responsive stimulation targeting the centromedian nucleus of the thalamus (CMT) is a potential treatment for neocortical epilepsies with regional onsets. MethodsWe assessed efficacy and safety of CMT and neocortical responsive stimulation, detection, and stimulation programming, methods for implantation, and location and patterns of electrographic seizure onset and spread in 7 patients with medically intractable focal seizures with a regional neocortical onset. ResultsThe median follow-up duration was 17 months (average: 17 months, range: 8–28 months). The median % reduction in disabling seizures (excludes auras) in the 7 patients was 88% (mean: 80%, range: 55–100%). The median % reduction in all seizure types (disabling + auras) was 73% (mean: 67%, range: 15–94%). There were no adverse events related to implantation of the responsive neurostimulator and leads or related to the delivery of responsive stimulation. Stimulation-related contralateral paresthesias were addressed by adjusting stimulation parameters in the clinic during stimulation testing.Electrographic seizures were detected in the CMT and neocortex in all seven patients. Four patients had simultaneous or near simultaneous seizure onsets in the neocortex and CMT and three had onsets in the neocortex with spread to the CMT. ConclusionIn this small series of patients with medically intractable focal seizures and regional neocortical onset, responsive neurostimulation to the neocortex and CMT improved seizure control and was well tolerated. SignificanceResponsive corticothalamic neurostimulation of the CMT and neocortex is a potential treatment for patients with regional neocortical epilepsies.

Bilateral double beta peaks in a PD patient with STN electrodes

Subthalamic local field potentials in the beta band are considered as potential biomarkers for closed-loop deep brain stimulation. To investigate the subthalamic beta band peak amplitudes in a Parkinson’s disease patient over an extended period of time by using a novel and commercially available neurostimulator with permanent sensing capability. We recorded local field potentials of the subthalamic nucleus using the Medtronic Percept™ implantable neurostimulator at rest and during physical activity (gait) with and in response to deep brain stimulation. We found a double-peaked beta activity on both sides. Increasing stimulation and physical activity resulted in a decreased beta band amplitude, but was accompanied by the appearance of a second, and previously unrecognized peak at 13 Hz in the right hemisphere. Our results will support the investigation of distinct different peaks in the beta band and their relevance and usefulness as closed-loop biomarkers.

P935Can we predict the occurrence of persistent atrial fibrillation in large animal models to improve study efficiency?

Abstract Funding Acknowledgements British Heart Foundation Project Grant FS/17/54/33126 Background A key consideration when using animals in research is maximising experimental efficiency to minimise the number of animals required. Large animal models have proven an invaluable tool for establishing pathophysiological mechanisms underpinning atrial fibrillation (AF) and testing novel therapeutics, however animals may be resistant to developing the arrhythmias required. While the relationships between atrial refractory periods, conduction velocity, surface area, and vulnerability to fibrillation have been established in clinical practice, these parameters are not regularly used to design animal studies of persistent AF (PsAF). Purpose We investigated whether routinely collected baseline parameters could be used to improve experimental efficiency in an ovine model, by predicting the development of PsAF as opposed to arrhythmia resistance. The aims were to: reduce the number of animals used in future studies, and avoid prolonged experiments in animals likely to be resistant to AF. Methods All procedures were conducted with respect to the Animals [Scientific Procedures] Act, UK, 1986; and were approved by the local ethical review board. The ovine model consisted of healthy adult Welsh mountain sheep that underwent implantation of a neurostimulator connected via an endocardial pacing lead to the right atrial appendage. The device was programmed to deliver intermittent 30 second bursts of 50Hz and sheep were monitored over an eight week period for PsAF. Eight variables were collected at time of implant including weight (kg), left atrial diameter (LAD; cm), P wave duration (msec), PR interval (msec), atrial effective refractory period (ERP; msec), atrial conduction velocity (CV; m/s), AF inducibility with 50Hz bursts (secs), and rate threshold of atrial action potential alternans (msec). Analysis of the data was performed using multiple logistic regression and receiver-operator characteristic (ROC) curves. Regression coefficients are presented as natural logarithm of odds ratios (OR) with 95% confidence intervals (CI). Results Seventeen sheep were included in this study. Five (29%) developed PsAF whereas twelve (71%) were resistant (non-sustained or no AF). Univariate analysis found none of the parameters alone could predict PsAF, however ERP (OR -0.05, CI -.01 to 0.01, p = 0.089) and LAD (OR 8.1, CI -1.6 to 17.5, p = 0.095) suggested a combination may be predictive. A multivariate analysis using Fibrillation number (calculated as LAD / [ERP X CV]) was predictive (OR 26.9, CI 1.1 to 52.7; p = 0.04], with an area under ROC curve of 0.85 (p = 0.027). Conclusions Fibrillation number can predict the development of PsAF in healthy sheep. Practically speaking, this means animals with: a larger LAD, shorter ERP and slower CV are more likely to develop PsAF. These findings can be used to optimise the design of future studies, particularly by reducing the number of animals required.

0691 Comparison Of Odds Ratio Product And Other Polysomnographic Metrics Among Responders And Non-responders To Upper Airway Stimulation Treatment Of Obstructive Sleep Apnea

Abstract Introduction Upper airway stimulation (UAS) is a surgical method of treating obstructive sleep apnea (OSA). UAS involves an implantable neuro-stimulator that stimulates the hypoglossal nerve to protrude the tongue during sleep. OSA fails to improve in 22% of patients who receive UAS as defined by a > 50% reduction in Apnea-Hypopnea Index (AHI) and an AHI <20 events/hour. Light sleep may predict UAS failure in that it may limit the stimulus strength that can be applied. The odds ratio product (ORP) is a novel polysomnographic (PSG) metric of sleep depth. We hypothesized that ORP values prior to surgery will be higher (lighter sleep) in non-responders. Having markers that predict surgical success can help reduce unnecessary surgeries. Methods This is a retrospective cohort study of 126 patients (83 responders vs. 43 non-responders) who received UAS implantation for the treatment of OSA. PSG data was obtained from the Stimulation for Apnea Reduction (STAR) trial. Raw baseline PSG data were analyzed and ORP values calculated using Michele Sleep Scoring Software (Cerebra Medical, Winnipeg, CA). In addition, 13 PSG metrics that were considered possibly relevant to surgical outcome were calculated as an exploratory analysis. The measurements included: spindle density, spindle power, spindle frequency, alpha intrusion, Right/Left sleep depth correlation coefficient, respiratory duty cycle, respiratory flow limitation, and arousal intensity. Statistical Analysis: Comparisons between responders and non-responders used parametric t-tests for continuous data and chi-squared or Fisher’s exact tests for categorical data. Statistical significance was based on a Bonferroni-corrected p<0.00357. Results Differences in ORP values and other PSG metrics between responders and non-responders were not statistically significant. Of all PSG metrics only differences in spindle density approached statistical significance (Responders = 2.33 spindles/minute vs Non-Responders = 1.39 spindles/minute, p=0.00360). Conclusion The findings suggest that differences in sleep depth and several other sleep characteristics do not play a significant role in determining response to UAS therapy. Support This project was supported by a Sleep Research Society Career Development Award #023-JP-19

Surgical Outcomes in Post-Traumatic Epilepsy: A Single Institutional Experience.

Post-traumatic epilepsy (PTE) is a debilitating sequela of traumatic brain injury (TBI), occurring in up to 20% of severe cases. This entity is generally thought to be more difficult to treat with surgical intervention. To detail our experience with the surgical treatment of PTE. Patients with a history of head injury undergoing surgical treatment for epilepsy were retrospectively enrolled. Engel classification at the last follow-up was used to assess outcome of patients that underwent surgical resection of an epileptic focus. Reduction in seizure frequency was assessed for patients who underwent vagal nerve stimulator (VNS) or responsive neurostimulator (RNS) implantation. A total of 23 patients met inclusion criteria. Nineteen (82.6%) had mesial temporal sclerosis, 3 had lesional neocortical epilepsy (13.0%), and 1 had nonlesional neocortical epilepsy (4.3%). Fourteen patients (60.9%) underwent temporal lobectomy (TL), 2 underwent resection of a cortical focus (8.7%), and 7 underwent VNS implantation (30.4%). Three patients underwent RNS implantation after VNS failed to reduce seizure frequency more than 50%. In the patients treated with resection, 11 (68.8%) were Engel I, 3 (18.8%) were Engel II, and 2 (12.5%) were Engel III at follow-up. Average seizure frequency reduction in the VNS group was 30.6%±25.6%. RNS patients had reduction of seizure severity but seizure frequency was only reduced 9.6%±13.6%. Surgical outcomes of PTE patients treated with TL were similar to reported surgical outcomes of patients with nontraumatic epilepsy treated with TL. Patients who were not candidates for resection demonstrated variable response rates to VNS or RNS implantation.

Restorative Neurostimulation for Chronic Mechanical Low Back Pain and Multifidus Motor Control Impairment

Introduction: ReActiv8-B is an international, multicenter, prospective, randomized, sham-controlled, blinded clinical trial with one-way crossover. The FDA trial, performed at 26 investigational sites in Australia, the United States, and Europe, is intended to evaluate safety and efficacy of a new implantable Restorative Neurostimulation system which targets multifidus motor control in people with Chronic Mechanical Low Back Pain (CMLBP).

Surgical Back Risk Syndrome and Spinal Cord Stimulation: Better Safe Than Sorry

Recurrent and chronic low back pain, caused by degenerative lumbar spondylosis, commonly affects elderly patients, even those with no previous low back surgery. These patients, like those affected by failed back surgery syndrome (FBSS), may become unresponsive to medical conservative treatment and their quality of life could be easily compromised. Moreover, general comorbidities, obesity, and other typical conditions of the elderly may make surgery under general anesthesia riskier than the natural history of the disease. These patients could be considered affected by surgical back risk syndrome (SBRS). In this article, we report our preliminary observational prospective study on the role of spinal cord stimulation (SCS) in 3 groups of patients: the FBSS group, the SBRS group, and the "other" group. Selection criteria, treatment modality, and outcomes for each patient group are described and discussed. Moreover, a potentially useful diagnostic and therapeutic flowchart on the management options for lumbar back diseases is discussed. The FBSS group included 25 patients, the SBRS group included 10 patients, and the other group included 3 patients. In 22/25 patients with FBSS (88% of the total), the implantation of a definitive neurostimulator was successful. In almost all patients in both the SBRS and the other groups, the implantation of a definitive neurostimulator was successful. In our opinion, SCS could be considered as a valid alternative treatment not only in selected patients affected by FBSS but also in selected patients affected by SBRS, in whom back surgery under general anesthesia may be challenging and overcome the potential benefit of the surgery itself. SBRS could be considered a new disease entity to be managed through SCS.

The First in Russia Experience of Successful Implementation of Constant Neurostimulation of the Spinal Cord in the Complex Treatment of a Patient with Permanent Form of Atrial Fibrillation Combined with Spinal Stenosis

This article describes for the first time in the domestic literature a clinical case of the therapeutic effect of neuromodulation on the permanentform of atrial fibrillation and chronic heart failure in an elderly patient with spinal stenosis which led to the developmentof pain syndrome and movement disorders. For the treatment of neurological pathology, at the beginning epidural administrationof drugs was applied, followed by spinal cord stimulation trial and implantation of permanent neurostimulator. At each stage of treatment conducted by a functional neurosurgeon the patient had a spontaneous restoration of sinus rhythm, and during continuous neurostimulation a stable retention of sinus rhythm and regression of heart failure symptoms have been observed throughout a long observation period. The article also presents the data of a few experimental and clinical studies on the use of neuromodulation in cardiology, describes the method of implantation of spinal electrodes and analyzes possible mechanisms of modulation of the autonomic innervation of the heart, implemented by spinal cord stimulation.

Tunable magnetic skyrmions in spintronic nanostructures for cellular-level magnetic neurostimulation

Electrical probes and arrays are currently ruling the market in treating neurodegenerative, sensory and cardiovascular diseases. Despite the accomplishments, their performance is limited by high power of operation, tissue inflammation, biofouling, inefficient control of electric fields and significant incompatibility for patients who are qualified to take magnetic resonance imaging tests only. Another alternative is magnetic stimulation. In this paper, we have proposed an implantable, highly tunable skyrmion-based neurostimulator (SkyNS). The displacement of magnetic skyrmions in a metallic bilayer generates a time varying magnetic field which induces an electric field gradient large enough to trigger neuron stimulation. SkyNS operates with a current of 2.71 µA and consumes a power of 1.434 nW. The effects of Dzyaloshinskii–Moriya interaction, perpendicular magnetic anisotropy and device dimensions on stable skyrmion nucleation and smooth skyrmion dynamics in a heavy metal/ferromagnetic metal bilayer have been extensively studied by micromagnetic simulation on mumax3. This work provides a proof-of-concept to exploit the material tunability of skyrmion-based spintronic nanodevices as cellular-level, ultra-low power, implantable magnetic neurostimulators.