Neuromodulación eléctrica en el tratamiento del dolor neuropático refractario. Colocación del primer estimulador medular en Cuba / Electric neuromodulation in the treatment of refractory pain. Placement of the first spinal stimulator in Cuba

El dolor es una causa importante de sufrimiento físico y emocional. El tratamiento médico de los pacientes con dolor crónico refractario es un gran reto. Se presenta el caso de una paciente de 19 años con un cuadro radicular compresivo secundario a Hernia discal L5-S1 derecha, que se le aplicó una discectomía L5-S1 por técnica de Caspar. Al mes de evolución regresa con igual sintomatología. A pesar de múltiples terapias farmacológicas y procederes intervencionistas, el dolor neuropático no mejora, después de múltiples estudios y discusiones en colectivo se determina la posibilidad de la colocación de un neuroestimulador medular, proceder que se lleva a cabo con mejoría considerable de su cuadro doloroso(AU)

Pain is a major cause of physical and emotional suffering. The management of patients with refractory chronic pain is a great challenge. The case is presented of a 19-year-old female patient with compressive radicular symptoms secondary to right L5-S1 disc herniation, who underwent L5-S1 discectomy with Caspar technique. After one month of evolution, she returned with the same symptoms. Despite multiple pharmacological therapies and interventional procedures, the neuropathic pain did not improve. After multiple studies and collective discussions, the possibility of placing a spinal neurostimulator was decided. After the procedure, the patient improved considerably with respect to her painful symptoms(AU)

Coexistence of deep brain stimulators and cardiac implantable electronic devices: A systematic review of safety.

As the number of patients implanted with deep brain stimulation systems increases, coexistence with cardiac implantable electronic devices (CIEDs) poses questions about safety. We systematically reviewed the literature on coexisting DBS and CIED. Eighteen reports of 34 patients were included. Device-device interactions were reported in 6 patients. Sources of complications were extensively reviewed and cautious measures which could be considered as part of a standard checklist for careful consideration are suggested.

10 kHz High-Frequency Spinal Cord Stimulation for Chronic Thoracic Pain: A Multicenter Case Series and a Guide for Optimal Anatomic Lead Placement.

BACKGROUND: Surgical options for thoracic pain are limited and carry significant risk and morbidity. Spinal cord stimulation has the potential to be used for treatment of thoracic pain, as it has been useful for treating multiple types of chronic pain. Conventional tonic stimulation is limited in the treatment of thoracic pain, as it can produce paresthesia that is difficult to localize. Conversely, high-frequency spinal cord stimulation (HF-SCS) does not activate dorsal column A Beta fibers and does not produce paresthesia, and thus may be more beneficial in treating thoracic back pain not manageable with tonic stimulation. OBJECTIVES: To evaluate (1) the efficacy of 10 kHz HF-SCS for patients with chronic thoracic pain; and (2) appropriate paresthesia-free lead placement and programming targets for 10 kHz HF-SCS for patients with chronic thoracic pain. STUDY DESIGN: Retrospective case series. SETTING: Multisite academic medical center or pain clinic. METHODS: A retrospective chart review was performed on 19 patients with thoracic back pain who underwent HF-SCS implantation. These patients had lead placement and stimulation between the T1-T6 vertebral levels. Outcome measures collected include location of device implant, stimulation settings, and pain scores at baseline, end of trial, and 1, 6, and 12 months postimplant. Follow-up phone calls collected information on if the patient reported functional improvement, improved sleep, or decreased pain medication usage. A Wilcoxon signed-rank test compared differences in mean pain scores across time points. RESULTS: Significantly decreased Visual Analog Scale scores were observed with 17/19 (89.5%) patients demonstrating response to therapy (> 50% reduction in pain scores). These results were sustained relative to baseline at 1, 6, and 12 months postimplant, depending on length of follow-up. Many patients also reported functional improvement (17/19), improved sleep (14/19), and reduction in use of pain medications after implantation (9/19). A total of 15/19 patients reported best relief when contacts over T1 or T2 vertebrae were used for stimulation. LIMITATIONS: This study is limited by its retrospective design. Additionally, including documentation from multiple sites may be prone to selection and abstraction bias. Data were also not available for all patients at all time points. CONCLUSIONS: HF-SCS may be a viable option for significant, long-lasting pain relief for thoracic back pain. There may also be evidence for anatomically based lead placement and programming for thoracic back pain. Randomized, controlled trials with extended follow-up are needed to further evaluate this therapy. KEY WORDS: Thoracic pain, back pain, spinal cord stimulation, high frequency, 10 kHz.

A proposed guideline for vagus nerve stimulator handling in palliative care and after death.

Vagus nerve stimulation (VNS) is often used for patients with drug-resistant epilepsy. Although this intervention may improve seizure control and mood, a number of factors must be considered when patients with VNS near end of life. We reviewed relevant literature to create a proposed guideline for management of patients with VNS in palliative care and after death. VNS has multiple possible side effects, including cough and swallowing difficulties. For patients with neurologic disease in palliative care, such adverse effects can severely affect quality of life and increase the risk for complications such as aspiration pneumonia. Patients with VNS should be screened regularly for such side effects, and VNS parameters should be adjusted if they are identified. If a patient requires urgent cardiac resuscitation involving external defibrillation, the VNS should be interrogated immediately afterwards to evaluate its function. During defibrillation, paddles should be placed perpendicular to the VNS, and as far as possible away from it. The VNS can be acutely turned off by taping the magnet to the patient's chest, thereby preventing any possible interference with restoration of a normal heart rhythm. After death, any staff involved with handling the body should be notified that a VNS is in place. The device must be removed prior to cremation, as it can explode with high heat. If the cause of death is unclear, a full postmortem examination should be undertaken, per sudden unexpected death in epilepsy guidelines. If there is concern about device malfunction, the device should be returned to the manufacturer for evaluation.

Recommendations for Deep Brain Stimulation Device Management During a Pandemic.

Most medical centers are postponing elective procedures and deferring non-urgent clinic visits to conserve hospital resources and prevent spread of COVID-19. The pandemic crisis presents some unique challenges for patients currently being treated with deep brain stimulation (DBS). Movement disorder (Parkinson's disease, essential tremor, dystonia), neuropsychiatric disorder (obsessive compulsive disorder, Tourette syndrome, depression), and epilepsy patients can develop varying degrees of symptom worsening from interruption of therapy due to neurostimulator battery reaching end of life, device malfunction or infection. Urgent intervention to maintain or restore stimulation may be required for patients with Parkinson's disease who can develop a rare but potentially life-threatening complication known as DBS-withdrawal syndrome. Similarly, patients with generalized dystonia can develop status dystonicus, patients with obsessive compulsive disorder can become suicidal, and epilepsy patients can experience potentially life-threatening worsening of seizures as a result of therapy cessation. DBS system infection can require urgent, and rarely emergent surgery. Elective interventions including new implantations and initial programming should be postponed. For patients with existing DBS systems, the battery status and electrical integrity interrogation can now be performed using patient programmers, and employed through telemedicine visits or by phone consultations. The decision for replacement of the implantable pulse generator to prevent interruption of DBS therapy should be made on a case-by-case basis taking into consideration battery status and a patient's tolerance to potential therapy disruption. Scheduling of the procedures, however, depends heavily on the hospital system regulations and on triage procedures with respect to safety and resource utilization during the health crisis.

FDA Perspectives on the Regulation of Neuromodulation Devices.

The United States Food and Drug Administration (FDA) ensures that patients in the United States have access to safe and effective medical devices. The division of neurological and physical medicine devices reviews medical technologies that interface with the nervous system, including many neuromodulation devices. This article focuses on neuromodulation devices and addresses how to navigate the FDA's regulatory landscape to successfully bring devices to patients.

The Importance of the Location of Dorsal Root Ganglion Stimulator Electrodes Within the Nerve Root Exit Foramen.

OBJECTIVE: To quantify the relationship between the electrical power requirement to achieve pain relief and the position of the active electrode of dorsal root ganglion stimulators within the spinal nerve root exit foramen. MATERIALS AND METHODS: Retrospective analysis of prospectively collected data of 92 consecutive patients undergoing dorsal root ganglion stimulation (DRGS) for chronic pain in a single center. Cervical and sacral cases, and failed trials/explanted DRGS were excluded, so we report on 57 patients with 78 implanted leads. Anteroposterior and lateral fluoroscopic images of the lead in the exit foramen were examined, and the active electrode positions were put into categories depending on their location relative to fixed anatomical landmarks. The clinical outcome and the power requirements for each of these groups of electrodes were then analyzed. Overall pain outcome was assessed by numeric pain rating scale score pre-operatively and post-operatively. RESULTS: There was no significant relationship between power requirements and mediolateral electrode position, although the lowest average was observed with electrode positions directly below the center of the pedicle. On lateral x-ray, the lowest power requirements were observed in the electrodes positioned superodorsally or dorsally within the foramen. Importantly, power requirements in this location were consistently low, while the power requirements in other locations were not only higher but also much more variable. Electrodes in the superodorsal position required a median output power almost four times lower than electrodes in other positions (p = 0.002). Clinical outcome was not significantly related to power requirement or foraminal position. CONCLUSION: Aiming for a superodorsal electrode position on lateral intraoperative fluoroscopy is desirable, since siting leads in this location reduces the required stimulator output power very substantially and thus will extend battery life. Position within the foramen does not determine clinical outcome, and so the implanter can safely aim for the low power site without detriment to the analgesic efficacy of the system.

Impact of neuroanatomical variations and electrode orientation on stimulus current in a device for migraine: a computational study.

OBJECTIVE: Conventional treatment methods for migraine often have side effects. One treatment involves a wearable neuromodulator targeting frontal nerves. Studies based on this technique have shown limited efficacy and the existing setting can cause pain. These may be associated with neuroanatomical variations which lead to high levels of required stimulus current. The aim of this paper is to study the effect of such variations on the activation currents of the Cefaly neuromodulator. Also, using a different electrode orientation, the possibility of reducing activation current levels to avoid painful side-effects and improve efficacy, is explored. APPROACH: This paper investigates the effect of neuroanatomical variations and electrode orientation on the stimulus current thresholds using a computational hybrid model involving a volume conductor and an advanced nerve model. Ten human head models are developed considering statistical variations of key neuroanatomical features, to model a representative population. MAIN RESULTS: By simulating the required stimulus current level in the head models, it is shown that neuroanatomical variations have a significant impact on the outcome, which is not solely a function of one specific neuroanatomical feature. The stimulus current thresholds based on the conventional Cefaly system vary from 4.4 mA to 25.1 mA across all head models. By altering the electrode orientation to align with the nerve branches, the stimulus current thresholds are substantially reduced to between 0.28 mA and 15 mA, reducing current density near pain-sensitive structures which may lead to a higher level of patient acceptance, further improving the efficacy. SIGNIFICANCE: Computational modeling based on statistically valid neuroanatomical parameters, covering a representative adult population, offers a powerful tool for quantitative comparison of the effect of the position of stimulating electrodes which is otherwise not possible in clinical studies.

Electrical connectors for neural implants: design, state of the art and future challenges of an underestimated component.

Technological advances in electrically active implantable devices have increased the complexity of hardware design. In particular, the increasing number of stimulation and recording channels requires innovative approaches for connectors that interface electrodes with the implant circuitry. OBJECTIVE: This work aims to provide a common theoretical ground for implantable connector development with a focus on neural applications. APPROACH: Aspects and experiences from several disciplines are compiled from an engineering perspective to discuss the state of the art of connector solutions. Whenever available, we also present general design guidelines. MAIN RESULTS: Degradation mechanisms, material stability and design rules in terms of biocompatibility and biostability are introduced. Considering contact physics, we address the design and characterization of the contact zone and review contaminants, wear and contact degradation. For high-channel counts and body-like environments, insulation can be even more crucial than the electrical connection itself. Therefore, we also introduce the requirements for electrical insulation to prevent signal loss and distortion and discuss its impact on the practical implementation. SIGNIFICANCE: A final review is dedicated to the state of the art connector concepts, their mechanical setup, electrical performance and the interface to other implant components. We conclude with an outlook for possible approaches for the future generations of implants.

ReStore: A wireless peripheral nerve stimulation system.

BACKGROUND: The growing use of neuromodulation techniques to treat neurological disorders has motivated efforts to improve on the safety and reliability of implantable nerve stimulators. NEW METHOD: The present study describes the ReStore system, a miniature, implantable wireless nerve stimulator system that has no battery or leads and is constructed using commercial components and processes. The implant can be programmed wirelessly to deliver charge-balanced, biphasic current pulses of varying amplitudes, pulse widths, frequencies, and train durations. Here, we describe bench and in vivo testing to evaluate the operational performance and efficacy of nerve recruitment. Additionally, we also provide results from a large-animal chronic active stimulation study assessing the long-term biocompatibility of the device. RESULTS: The results show that the system can reliably deliver accurate stimulation pulses through a range of different loads. Tests of nerve recruitment demonstrate that the implant can effectively activate peripheral nerves, even after accelerated aging and post-chronic implantation. Biocompatibility and hermeticity tests provide an initial indication that the implant will be safe for use in humans. COMPARISON WITH EXISTING METHOD(S): Most commercially available nerve stimulators include a battery and wire leads which often require subsequent surgeries to address failures in these components. Though miniaturized battery-less stimulators have been prototyped in academic labs, they are often constructed using custom components and processes that hinder clinical translation. CONCLUSIONS: The results from testing the performance and safety of the ReStore system establish its potential to advance the field of peripheral neuromodulation.

Abdominal Versus Standard Placement of the Sacral Nerve Stimulator Implantable Pulse Generator.

OBJECTIVES: To determine patient factors prompting anterior abdominal wall placement of the sacral nerve stimulator implantable pulse generator and investigate revision and infection rates for buttock (standard) and abdominal placement. METHODS: We retrospectively reviewed records of consecutive sacral nerve stimulation procedures by a single surgeon from 2012 to 2017 at a single institution. RESULTS: 75 patients underwent sacral nerve stimulation--60 with standard and 15 with abdominally placed implantable pulse generators. The mean age and body mass index of the standard group was higher than that of the abdominal group and the majority was female. A greater proportion of patients in the abdominal group had a neurological diagnosis and was wheelchair-dependent. Overall, a total of 20 patients underwent 38 revision surgeries. The indications for revision surgery were pain, loss of efficacy, or lead migration. The standard group accounted for more revisions than the abdominal group (34vs 4 cases, P = .048), with no revisions due to pain in the abdominal group. The infection rate (2% vs 13%, P = .10), average time from implantation to revision, and operative duration were not statistically different between groups. CONCLUSION: In a subset of patients who were wheelchair-dependent or lacked gluteal fat, placement of the implantable pulse generator in the anterior abdominal wall resulted in no revisions due to pain. Operative duration and infection rates were similar between abdominal and standard placement. Abdominal placement with extended length leads could be considered as a primary or revision option in these select patients.

Behavioral validation of a wireless low-power neurostimulation technology in a conditioned place preference task.

OBJECTIVE: Neurostimulation technologies are important for studying neural circuits and the connections that underlie neurological and psychiatric disorders. However, current methods come with limitations such as the restraint on movement imposed by the wires delivering stimulation. The objective of this study was to assess whether the e-Particle (EP), a novel wireless neurostimulator, could sufficiently stimulate the brain to modify behavior without these limitations. APPROACH: Rats were implanted with the EP and a commercially available stimulating electrode. Animals received rewarding brain stimulation, and performance in a conditioned place preference (CPP) task was measured. To ensure stimulation-induced neuronal activation, immediate early gene c-fos expression was also measured. MAIN RESULTS: The EP was validated in a commonly used CPP task by demonstrating that (1) wireless stimulation via the EP induced preference behavior that was comparable to that induced by standard wired electrodes and (2) neuronal activation was observed in projection targets of the stimulation site. SIGNIFICANCE: The EP may help achieve a better understanding of existing brain stimulation methods while overcoming their limitations. Validation of the EP in a behavioral model suggests that the benefits of this technology may extend to other areas of animal research and potentially to human clinical applications.

Fixed-Life or Rechargeable Battery for Deep Brain Stimulation: Which Do Patients Prefer?

BACKGROUND: Deep brain stimulation (DBS) is increasingly used to treat a wide variety of neurological and psychiatric disorders. Implantable pulse generators (implantable pulse generators/batteries) for DBS were originally only available as a nonrechargeable option. However, there is now a choice between fixed-life and rechargeable batteries, with each having their own advantages and disadvantages. The extent of patient involvement in the choice of battery and the factors that matter to them have not been well studied. METHODS: Thirty consecutive adult patients with movement disorders attending a pre-DBS clinic were offered a choice of fixed-life or rechargeable battery and completed a questionnaire after the consultation on which factors influenced their decision. RESULTS: Nineteen patients (63%) chose the fixed-life battery and 11 patients (37%) chose the rechargeable battery. There were no significant differences in age, sex, underlying disease, disease duration or Unified Parkinson's Disease Rating Scale (UPDRS) (part 3) score (for patients with Parkinson disease) between those who chose the fixed-life vs. rechargeable battery. Most patients were not concerned about the size of the battery. Equal numbers were concerned about surgery to replace the battery, and less than half were concerned about the need to recharge the battery. More than half of patients felt that an acceptable charging frequency was monthly or yearly, and all patients felt that an acceptable charging duration was less than 1 hour, with half of all patients choosing less than 30 min. The main reasons cited for choosing the fixed-life battery were convenience and concern about forgetting to recharge the battery. The main reason for choosing the rechargeable battery was the avoidance of further surgery. DISCUSSION: Most patients in this adult cohort with movement disorders chose the fixed-life battery. The better lifestyle associated with a fixed-life battery is a major factor influencing their choice. Rechargeable batteries may be more acceptable if the recharging process is improved, more convenient, and discreet. CONFLICT OF INTEREST: The authors' institution has received educational grants from Medtronic, Abbott, and Boston Scientific companies.

[A Torso Simulator Design for Implantable Nerve Stimulator Test].

This paper introduces ISO 14708-3:2017, the new edition of the international standard for implantable neurostimulator, and emphasizes the new requirements in the clause of protection from RF electromagnetic interference. To meet this new requirements, this paper presents a design of torso simulator for the testing of implantable neurostimulator. The design includes volume conductor, electrodes and grids, which can simulate the actual operating environment of implantable neurostimulator in RF electromagnetic interference testing. The torso simulator is verified by performance in the last part of the paper.

[Interpretation of the International Standard 2017 Version of Implantable Neurostimulators].

ISO 14708-3 "Implants for surgery-active implantable medical devices-Part 3:implantable neurostimulators" 2017 version and 2008 version are compared, and changes in the standard are interpreted combined with the characteristics of the neurostimulator. The new version of the standard for the first time in the introduction mentioned a new type of non-electrode or extension's neurostimulator. Key issues that have significant impact on safety concerns such as wireless charging temperature rise, MRI acceptance criteria, etc., are given for the first time in the new version. New requirements to the wireless communication section are added, and the electromagnetic compatibility part is greatly adjusted. With more miniature non-electrode or extension's neurostimulator entering the market, standards such as electromagnetic compatibility and MRI, there will be greater adjustments.

Neurostimulation Devices for the Treatment of Neurologic Disorders.

Rapid advancements in neurostimulation technologies are providing relief to an unprecedented number of patients affected by debilitating neurologic and psychiatric disorders. Neurostimulation therapies include invasive and noninvasive approaches that involve the application of electrical stimulation to drive neural function within a circuit. This review focuses on established invasive electrical stimulation systems used clinically to induce therapeutic neuromodulation of dysfunctional neural circuitry. These implantable neurostimulation systems target specific deep subcortical, cortical, spinal, cranial, and peripheral nerve structures to modulate neuronal activity, providing therapeutic effects for a myriad of neuropsychiatric disorders. Recent advances in neurotechnologies and neuroimaging, along with an increased understanding of neurocircuitry, are factors contributing to the rapid rise in the use of neurostimulation therapies to treat an increasingly wide range of neurologic and psychiatric disorders. Electrical stimulation technologies are evolving after remaining fairly stagnant for the past 30 years, moving toward potential closed-loop therapeutic control systems with the ability to deliver stimulation with higher spatial resolution to provide continuous customized neuromodulation for optimal clinical outcomes. Even so, there is still much to be learned about disease pathogenesis of these neurodegenerative and psychiatric disorders and the latent mechanisms of neurostimulation that provide therapeutic relief. This review provides an overview of the increasingly common stimulation systems, their clinical indications, and enabling technologies.

Patient perspectives on the efficacy of a new kind of rechargeable deep brain stimulators(1).

PURPOSE/AIM OF THE STUDY: Rechargeable deep brain stimulation (DBS) system with longer battery life has become available for treating movement disorders. However, little information exists about the safety and management after implantation. Therefore, there is an urgent need to evaluate the recharging performance through long-term observations. MATERIALS AND METHODS: Fifty-three Parkinson's disease (PD) patients were implanted with a new rechargeable device (G102R, PINS Medical). They were observed at the baseline and 3 months, 6 months and 12 months after surgery, with measurement of the acceptance, frequency, recharging time and feeling during recharging. RESULTS: The patients with the ages between 34 and 70 (57.64 ± 7.34) years thought the system was very easy to recharge. The favorite time interval for recharging was 1 week, and 10 days and half a month also chosen. Most of the patients spent around 1 hour recharging, with no unacceptable hot feelings reported. CONCLUSIONS: The PD patients could easily and safely recharge this new rechargeable implantable neurostimulators. Thus, these neurostimulators might be an excellent choice for PD patients.

Implantation of a new Vagus Nerve Stimulation (VNS) Therapy® generator, AspireSR®: considerations and recommendations during implantation and replacement surgery--comparison to a traditional system.

INTRODUCTION: The most widely used neuro-stimulation treatment for drug-resistant epilepsy is Vagus Nerve Stimulation (VNS) Therapy®. Ictal tachycardia can be an indicator of a seizure and, if monitored, can be used to trigger an additional on-demand stimulation, which may positively influence seizure severity or duration. A new VNS Therapy generator model, AspireSR®, was introduced and approved for CE Mark in February 2014. In enhancement of former models, the AspireSR has incorporated a cardiac-based seizure-detection (CBSD) algorithm that can detect ictal tachycardia and automatically trigger a defined auto-stimulation. To evaluate differences in preoperative, intraoperative and postoperative handling, we compared the AspireSR to a conventional generator model (Demipulse®). METHOD: Between February and September 2014, seven patients with drug-resistant epilepsy and ictal tachycardia were implanted with an AspireSR. Between November 2013 and September 2014, seven patients were implanted with a Demipulse and served as control group. Operation time, skin incision length and position, and complications were recorded. Handling of the new device was critically evaluated. RESULTS: The intraoperative handling was comparable and did not lead to a significant increase in operation time. In our 14 operations, we had no significant short-term complications. Due to its larger size, patients with the AspireSR had significantly larger skin incisions. For optimal heart rate detection, the AspireSR had to be placed significantly more medial in the décolleté area than the Demipulse. The preoperative testing is a unique addition to the implantation procedure of the AspireSR, which may provide minor difficulties, and for which we provide several recommendations and tips. The price of the device is higher than for all other models. CONCLUSIONS: The new AspireSR generator offers a unique technical improvement over the previous Demipulse. Whether the highly interesting CBSD feature will provide an additional benefit for the patients, and will rectify the additional costs, respectively, cannot be answered in the short-term. The preoperative handling is straightforward, provided that certain recommendations are taken into consideration. The intraoperative handling is equivalent to former models-except for the placement of the generator, which might cause cosmetic issues and has to be discussed with the patient carefully. We recommend the consideration of the AspireSR in patients with documented ictal tachycardia to provide a substantial number of patients for later seizure outcome analysis.