Stimulation Strategies Research Articles

Subthalamic and Pallidal Stimulations in Patients with Parkinson's Disease: Common and Dissociable Connections.

ObjectiveThe subthalamic nucleus (STN) and internal globus pallidus (GPi) are the most effective targets in deep brain stimulation (DBS) for Parkinson's disease (PD). However, the common and specific effects on brain connectivity of stimulating the 2 nuclei remain unclear.MethodsPatients with PD receiving STN‐DBS (n = 27, 6 women, mean age 64.8 years) or GPi‐DBS (n = 28, 13 women, mean age 64.6 years) were recruited for resting‐state functional magnetic resonance imaging to assess the effects of STN‐DBS and GPi‐DBS on brain functional dynamics.ResultsThe functional connectivity both between the somatosensory‐motor cortices and thalamus, and between the somatosensory‐motor cortices and cerebellum decreased in the DBS‐on state compared with the off state (p < 0.05). The changes in thalamocortical connectivity correlated with DBS‐induced motor improvement (p < 0.05) and were negatively correlated with the normalized intersection volume of tissues activated at both DBS targets (p < 0.05). STN‐DBS modulated functional connectivity among a wider range of brain areas than GPi‐DBS (p = 0.009). Notably, only STN‐DBS affected connectivity between the postcentral gyrus and cerebellar vermis (p < 0.001) and between the somatomotor and visual networks (p < 0.001).InterpretationOur findings highlight common alterations in the motor pathway and its relationship with the motor improvement induced by both STN‐ and GPi‐DBS. The effects on cortico‐cerebellar and somatomotor‐visual functional connectivity differed between groups, suggesting differentiated neural modulation of the 2 target sites. Our results provide mechanistic insight and yield the potential to refine target selection strategies for focal brain stimulation in PD. ANN NEUROL 2021;90:670–682

Design of an FPGA-Based Fuzzy Feedback Controller for Closed-Loop FES in Knee Joint Model.

Functional electrical stimulation (FES) device has been widely used by spinal cord injury (SCI) patients in their rehab exercises to restore motor function to their paralysed muscles. The major challenge of muscle contraction induced by FES is early muscle fatigue due to the open-loop stimulation strategy. To reduce the early muscle fatigue phenomenon, a closed-loop FES system is proposed to track the angle of the limb’s movement and provide an accurate amount of charge according to the desired reference angle. Among the existing feedback controllers, fuzzy logic controller (FLC) has been found to exhibit good control performance in handling complex non-linear systems without developing any complex mathematical model. Recently, there has been considerable interest in the implementation of FLC in hardware embedded systems. Therefore, in this paper, a digital fuzzy feedback controller (FFC) embedded in a field-programmable gate array (FPGA) board was proposed. The digital FFC mainly consists of an analog-to-digital converter (ADC) Data Acquisition and FLC sub-modules. The FFC was designed to monitor and control the progress of knee extension movement by regulating the stimulus pulse width duration to meet the target angle. The knee is expected to extend to a maximum reference angle setting (70°, 40° or 30°) from its normal position of 0° once the stimulus charge is applied to the muscle by the FES device. Initially, the FLC was modelled using MATLAB Simulink. Then, the FLC was hardcoded into digital logic using hardware description language (HDL) Verilog codes. Thereafter, the performance of the digital FLC was tested with a knee extension model using the HDL co-simulation technique in MATLAB Simulink. Finally, for real-time verification, the designed digital FFC was downloaded to the Intel FPGA (DE2-115) board. The digital FFC utilized only 4% of the total FPGA (Cyclone IV E) logic elements (LEs) and required 238 µs to regulate stimulus pulse width data, including 3 µs for the FLC computation. The high processing speed of the digital FFC enables the stimulus pulse width duration to be updated every stimulation cycle. Furthermore, the implemented digital FFC has demonstrated good control performance in accurately controlling the stimulus pulse width duration to reach the desired reference angle with very small overshoot (1.4°) and steady-state error (0.4°). These promising results are very useful for a real-world closed-loop FES application.

O-075 The association between high birth weight and long-term outcomes-implications for Assisted Reproductive Technologies: a systematic review and meta-analysis

Abstract Study question Do high birth weight or large for gestational age (LGS) increase the risk of serious disease later in life? Summary answer High birth weight and/or LGA were associated with elevated risks for certain child malignancies, breast cancer, psychiatric disorders, childhood hypertension and diabetes type 1. What is known already Previous studies have shown that children born after frozen embryo transfer (FET) have an increased risk of being born LGA or having a high birth weight. In recent years the practice of FET in Assisted Reproductive Technology (ART) has increased rapidly. The perinatal risks of being born LGA or with a high birth weight are well studied, however less is known about the impact on long-term health and morbidity. Study design, size, duration Pubmed, Scopus and Web of Science were searched until December 2020. 11 748 abstracts were screened, 172 publications were selected for systematic review and 63 for meta-analyses. The methodological quality in terms of risk of bias was assessed by pairs of reviewers. Robin-I (www.methods.cochrane.org) was used for assessing risk of bias in original articles. For systematic reviews AMSTAR was used. For certainty of evidence the GRADE system was used. Participants/materials, setting, methods Exposures were LGA and high birth weight. Long-term morbidity outcomes were cancer, metabolic disease, cardiovascular disease and psychiatric disorders. Cancer was focused on breast cancer, child malignancies in the central nervous system (CNS), hematological malignancies and Wilm´s tumor. Metabolic diseases included diabetes type 1 and type 2. Cardiovascular diseases were focused on hypertension and other cardiovascular disorders and psychiatric disorders on schizophrenia/psychosis and cognitive disorders. Main results and the role of chance Pooled Adjusted Odds Ratios (AOR) for outcome variables were compared for birth weights &amp;gt;4000 or &amp;gt; 4500 g versus &amp;lt; 4000 g. For cancer, meta-analyses showed AOR of 1.24 (95% 1.11-1.39) for development of breast cancer, AOR of 1.15 (95% CI 1.05-1.27) for development of CNS tumors, AOR of 1.29 (95% CI 1.20-1.39) for childhood leukemia and AOR 1.68 (95% CI 1.38-2.06 ) for Wilm´s tumor. For metabolic disease a meta-analysis showed AOR of 1.15 (95%CI 1.05-1.26) for the association between high birth weight and type 1 diabetes. For psychiatric diseases an association was found between high birth weight and/or LGA and schizophrenia and depression. For cardiovascular disease, an association was found between high birth weight and hypertension in childhood with an inverse association in adulthood. No difference in the risk of coronary heart disease in adults born with high birth weight compared to normal birth Limitations, reasons for caution The main limitation is that all data are based on observational studies with their inborn risk of selection bias. Our conclusions are however, mainly based on meta-analyses and/or studies with low risk of bias. Wider implications of the findings Even though high birth weight and LGA are associated with an increased risk of serious diseases, both in childhood and in adulthood, the size of these effects seems modest. However, the identified risk associations should be taken into account in stimulation strategies and when considering fresh or frozen embryo transfer. Trial registration number Not applicable

Corticospinal Motor Circuit Plasticity After Spinal Cord Injury: Harnessing Neuroplasticity to Improve Functional Outcomes.

Spinal cord injury (SCI) is a devastating condition that affects approximately 294,000 people in the USA and several millions worldwide. The corticospinal motor circuitry plays a major role in controlling skilled movements and in planning and coordinating movements in mammals and can be damaged by SCI. While axonal regeneration of injured fibers over long distances is scarce in the adult CNS, substantial spontaneous neural reorganization and plasticity in the spared corticospinal motor circuitry has been shown in experimental SCI models, associated with functional recovery. Beneficially harnessing this neuroplasticity of the corticospinal motor circuitry represents a highly promising therapeutic approach for improving locomotor outcomes after SCI. Several different strategies have been used to date for this purpose including neuromodulation (spinal cord/brain stimulation strategies and brain-machine interfaces), rehabilitative training (targeting activity-dependent plasticity), stem cells and biological scaffolds, neuroregenerative/neuroprotective pharmacotherapies, and light-based therapies like photodynamic therapy (PDT) and photobiomodulation (PMBT). This review provides an overview of the spontaneous reorganization and neuroplasticity in the corticospinal motor circuitry after SCI and summarizes the various therapeutic approaches used to beneficially harness this neuroplasticity for functional recovery after SCI in preclinical animal model and clinical human patients' studies.

IC-Based Neuro-Stimulation Environment for Arbitrary Waveform Generation

Electrical stimulation of the nervous system is commonly based on biphasic stimulation waveforms, which limits its relevance for some applications, such as selective stimulation. We propose in this paper a stimulator capable of delivering arbitrary waveforms to electrodes, and suitable for non-conventional stimulation strategies. Such a system enables in vivo stimulation protocols with optimized efficacy or energy efficiency. The designed system comprises a High Voltage CMOS ASIC generating a configurable stimulating current, driven by a digital circuitry implemented on a FPGA. After fabrication, the ASIC and system were characterized and tested; they successfully generated programmable waveforms with a frequential content up to 1.2 MHz and a voltage compliance between [−17.9; +18.3] V. The system is not optimum when compared to single application stimulators, but no embedded stimulator in the literature offers an equivalent bandwidth which allows the wide range of stimulation paradigms, including high-frequency blocking stimulation. We consider that this stimulator will help test unconventional stimulation waveforms and can be used to generate proof-of-concept data before designing implantable and application-dedicated implantable stimulators.

Contralateral C7 Nerve Transfer for Stroke Recovery: New Frontier for Peripheral Nerve Surgery.

Ischemic stroke remains a major cause of disability in the United States and worldwide. Following the large-scale implementation of stroke thrombectomy and the optimization of treatment protocols for acute stroke, the reduction in stroke-associated mortality has resulted in an increased proportion of stroke survivors, many of whom have moderate to severe disability. To date, the treatment of subacute and chronic stroke has remained a challenge. Several approaches, involving pharmacological interventions to promote neuroplasticity, brain stimulation strategies and rehabilitative interventions, are currently being explored at different stages of the translational spectrum, yet level 1 evidence is still limited. In a recent landmark study, surgical intervention using contralateral C7 nerve transfer, an approach used to treat brachial plexus injury, was implemented in patients with chronic stroke, demonstrating an added benefit to standard rehabilitation strategies, leading to improved motor performance and reduced spasticity. The procedure involved the transfer of the C7 nerve root and middle trunk from the uninjured extremity to the injured extremity using a short conduit that allows for faster regeneration and innervation of the injured upper extremity via the ipsilateral (contralesional) hemisphere. In this work, we review the rationale for using contralateral C7 nerve transfer in stroke, describe the surgical intervention with associated variations and limitations, and discuss the current evidence for the efficacy of this technique in ischemic stroke research.

Embedded adaptive deep brain stimulation for cervical dystonia controlled by motor cortex theta oscillations

Dystonia is a disabling movement disorder characterized by excessive muscle contraction for which the underlying pathophysiology is incompletely understood and treatment interventions limited in efficacy. Here we utilize a novel, sensing-enabled, deep brain stimulator device, implanted in a patient with cervical dystonia, to record local field potentials from chronically implanted electrodes in the sensorimotor cortex and subthalamic nuclei bilaterally. This rechargeable device was able to record large volumes of neural data at home, in the naturalistic environment, during unconstrained activity. We confirmed the presence of theta (3–7 Hz) oscillatory activity, which was coherent throughout the cortico-subthalamic circuit and specifically suppressed by high-frequency stimulation. Stimulation also reduced the duration, rate and height of theta bursts. These findings motivated a proof-of-principle trial of a new form of adaptive deep brain stimulation - triggered by theta-burst activity recorded from the motor cortex. This facilitated increased peak stimulation amplitudes without induction of dyskinesias and demonstrated improved blinded clinical ratings compared to continuous DBS, despite reduced total electrical energy delivered. These results further strengthen the pathophysiological role of low frequency (theta) oscillations in dystonia and demonstrate the potential for novel adaptive stimulation strategies linked to cortico-basal theta bursts.

Perception of microstimulation frequency in human somatosensory cortex.

Microstimulation in the somatosensory cortex can evoke artificial tactile percepts and can be incorporated into bidirectional brain-computer interfaces (BCIs) to restore function after injury or disease. However, little is known about how stimulation parameters themselves affect perception. Here, we stimulated through microelectrode arrays implanted in the somatosensory cortex of two human participants with cervical spinal cord injury and varied the stimulus amplitude, frequency, and train duration. Increasing the amplitude and train duration increased the perceived intensity on all tested electrodes. Surprisingly, we found that increasing the frequency evoked more intense percepts on some electrodes but evoked less-intense percepts on other electrodes. These different frequency-intensity relationships were divided into three groups, which also evoked distinct percept qualities at different stimulus frequencies. Neighboring electrode sites were more likely to belong to the same group. These results support the idea that stimulation frequency directly controls tactile perception and that these different percepts may be related to the organization of somatosensory cortex, which will facilitate principled development of stimulation strategies for bidirectional BCIs.

A wireless spinal stimulation system for ventral activation of the rat cervical spinal cord

Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.

WS5.4. EMG Monitoring: Free-Run and Triggered

The recording of compound muscle action potentials (CMAPs) in response to spontaneous or electrically stimulation of the cranial, spinal, peripheral nerves or nerve root activation is known as intraoperative electromyography (EMG). EMG monitoring is widely used in surgeries when the aforementioned neural structures might be at risk. It allows early detection of surgery- related nerve injury so that proper intervention can be accordingly adopted; it also allows confirmation of the functional status of the nerve. The intraoperative monitoring team must thoroughly understand the nervous pathways that require monitoring and mapping in order to develop optimal stimulation and recording strategies for each surgical procedure. Intraoperative EMG testing includes triggered EMG (tEMG) for mapping and free-run EMG (fEMG) for monitoring purposes. Triggered EMG is used to identify the nerves and nerve root, to define a safe entry pathway to access the lesion, or to assess the functional integrity of the nerve so that the surgical plan can be modified accordingly. Clinical applications of tEMG also include confirmation of the placement of pedicle screws during spine surgery and guiding the sectioning of the lumbosacral rootlets during selective dorsal rhizotomy. The following three kinds of stimulation electrodes are available: monopolar, bipolor, and tripolar electrode. Each of the aforementioned electrodes are associated with certain strengths and weakness; thus, they can be used under different circumstances and meets most of our clinical needs. fEMG involves recording spontaneous or evoked muscle activity without interfering with the surgery. It is used as a monitoring tool to detect surgically driven mechanical irritation of the peripheral nerves and motor cranial nerves, hopefully before permanent damage occurs. It also can be applied to detect muscle activity evoked by mechanical irritation of the corticospinal tract and/or alpha motor neurons during brain tumor or intramedullary spinal cord tumor resection. There are three types of fEMG activity, referred to as the A, B and C train. Among them, the A train has been more associated with poor postoperative outcomes, although false-positive and false-negative findings do exist. Thus, the concomitant use of somatosensory and motor evoked potentials will certainly increase the sensitivity and specificity of fEMG.

Evaluating proxies for the drivers of natural gas productivity using machine-learning models

The extensive development of unconventional reservoirs using horizontal drilling and multistage hydraulic fracturing has generated large volumes of reservoir characterization and production data. The analysis of this abundant data using statistical methods and advanced machine-learning (ML) techniques can provide data-driven insights into well performance. Most predictive modeling studies have focused on the impact that different well completion and stimulation strategies have on well production but have not fully exploited the available in situ rock property data to determine its role in reservoir productivity. We have used machine-learning techniques to rank rock mechanical properties, microseismic attributes, and stimulation parameters in the order of their significance for predicting natural gas production from an unconventional reservoir. The data for this study came from a hydraulically fractured well in the Marcellus Shale in Monongalia County, West Virginia. The data classes included measurements aggregated by well completion stage that included (1) gas production, (2) well-log-derived measurements including bulk density, elastic moduli, shear impedance, compressional impedance, brittleness, and gamma measurements, (3) microseismic attributes, (4) long-period long-duration (LPLD) event counts, (5) fracture counts, and (6) stimulation parameters that included the fluid injection volume and average pumping pressure. To identify observable proxies for the drivers of gas production, we evaluated five commonly used ML approaches including multivariate adaptive regression spline, Gaussian mixture model, random forest, gradient boosting, and neural network. We selected five variables including LPLD event count, seismogenic b-value, hydraulic diffusivity, cumulative moment, and fluid volume as the features most likely to impact gas productivity at the stage level in the study area. The data-driven selection of these parameters for their importance in determining gas production can help reservoir engineers design more effective hydraulic-fracture treatments in the Marcellus Shale and other similar unconventional reservoirs. Plain language summary: We use machine-learning methods and data-driven selection of reservoir parameters to rank and better understand their importance in determining gas production, which can help reservoir engineers design more effective hydraulic-fracture treatments in the Marcellus Shale and other similar unconventional reservoirs.

Feasibility of Interferential and Pulsed Transcranial Electrical Stimulation for Neuromodulation at the Human Scale

Transcranial electrical stimulation (tES) is a promising tool for modulating neural activity, but tES has poor penetrability and spatiotemporal resolution compared to invasive techniques like deep brain stimulation (DBS). Interferential strategies for alternating-current stimulation (IF-tACS) and pulsed/intersectional strategies for transcranial direct-current stimulation (IS-tDCS) address some of the limitations of tES, but the comparative advantages and disadvantages of these new techniques is not well understood. This study's objective was to evaluate the suprathreshold and subthreshold membrane dynamics of neurons in response to IF-tACS and IS-tDCS. We analyzed the biophysics of IF-tACS and IS-tDCS using a bioelectric field model of tES. Neural responses were quantified for suprathreshold generation of action potentials in axons and for subthreshold modulation of membrane dynamics in spiking pyramidal neurons. IF-tACS and IS-tDCS could not directly activate axons at or below 10mA, but within this current range, these fields were able to modulate, albeit indirectly, spiking activity in the neuron model. IF-tACS facilitated phase synchronization similar to tACS, and IS-tDCS enhanced and suppressed spiking activity similar to tDCS; however, in either case, the modulatory effects of these fields were less potent than their standard counterparts at a matched field intensity. Moreover, neither IF-tACS nor IS-tDCS improved the spatial selectivity of their parent strategies. Enhancing the spatiotemporal precision and penetrability of tES with interferential and intersectional strategies is possible at the human scale. However, IF-tACS or IS-tDCS will likely require spatial multiplexing with multiple simultaneous sources to counteract their reduced potency, compared to standard techniques, to maintain stimulation currents at tolerable levels.

Discrete element modelling of multi-stage hydroshearing stimulation in Enhanced Geothermal System

In contrast to the conventional single stage hydraulic stimulation carried out simultaneously on the whole open hole section, the multi-stage stimulation, applying fluid injection on a selected interval of open hole for each stage, may provide an alternative for better reservoir permeability improvement while reducing the maximum seismic event magnitude and preventing short circulation during the production. We presented coupled hydro-mechanical modellings of the hydroshearing process on natural fractures for both the single stage and multi-stage stimulation strategies. The modellings have demonstrated that the single stage stimulation commonly caused the concentration of slip on the fracture with a higher initial aperture, potentially leading to large magnitude events. Adopting the strategy of multi-stage stimulation, it was able to develop the slip zone on multiple fractures and avoid. to induce large slip zone on specific fractures with a high initial aperture. It has been demonstrated there is general effectiveness of the multi-stage stimulation on homogenizing and enlarging the stimulated reservoir area with the lowering of possible maximum seismic event magnitude.

A Comparison of 1000Hz to 30Hz Spinal Cord Stimulation Strategies in Patients with Unilateral Neuropathic Leg Pain Due to Failed Back Surgery Syndrome: A Multicenter, Randomized, Double-Blinded, Crossover Clinical Study (HALO).

IntroductionMulticenter, randomized, double-blinded crossover study. The Netherlands (ClinicalTrials.gov NCT02112474). We hypothesized that the pain suppressive effects of 1000 Hz and 30 Hz spinal cord stimulation (SCS) strategies are equally effective in patients with chronic, neuropathic, unilateral leg pain after back surgery.MethodsThirty-two patients (18–70 years, minimum leg pain 50 mm on 100 mm visual analog scale (VAS), minimal back pain) were randomized (1:1) to start 1000 Hz or 30 Hz neurostimulation for 9 days. After a 5-day washout, they crossed over, for another 9 days. Primary outcome was pain suppression (mean of VAS scores 4×/day) during the crossover period. The main investigators were blinded to strategy allocation, patients were blinded to the outcome, a blinded assessor analyzed the primary outcome.ResultsThe primary outcome was analyzed in 26 patients. There was no period effect (delta 4 mm, p = 0.42, 95% CI [− 5, 13]), allowing direct intrapatient comparison of the treatment effect (delta 1 mm, p = 0.92, 95% CI [− 13, 14]). Ninety-two percent of patients in both periods experienced greater than 34% pain suppression (minimal clinically important difference, MCID). Secondary outcomes (22 patients): pain suppression and improved quality of life were sustained at 12 months; both were statistically significant and clinically relevant. Fifty percent of patients had greater than 80% pain suppression (p < 0.001).At study termination, all events were resolved; no unanticipated events were reported. Medtronic provided a grant for additional study costs.ConclusionWe conclude that our hypothesis regarding the effect of 1000 Hz and 30 Hz stimulation strategies on pain suppression was confirmed. Both stimulation strategies led to a large, sustainable, clinically relevant pain suppression and improvement in quality of life.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40122-021-00268-7.

Lessons Learned From Clinical Trials of a Neurorehabilitation Therapy Based on tDCS, BMI, and Pedaling Systems

This article shows the lessons learned from clinical trials of a new neurorehabilitation therapy for cerebro-vascular accident (CVA) patients. The new therapy is based on the combination of a transcranial direct current stimulation (tDCS) strategy, a brain-machine interface (BMI) based on electroencephalographic signals, and a pedaling system. The new therapy was applied during five consecutive days to six CVA patients with motor limitations in their right lower limb that are in the subacute phase. In this article, not only the clinical results are presented, but also the experiences and challenges of performing clinical trials with patients are described, which can be of great interest for future researchers that are planning to evaluate BMIs and tDCS systems with patients.

Intramuscular Stimulation of Muscle Afferents Attains Prolonged Tremor Reduction in EssentialTremor Patients.

This study proposes and clinically tests intramuscular electrical stimulation below motor threshold to achieve prolonged reduction of wrist flexion/extension tremor in Essential Tremor (ET) patients. The developed system consisted of an intramuscular thin-film electrode structure that included both stimulation and electromyography (EMG) recording electrodes, and a control algorithm for the timing of intramuscular stimulation based on EMG (closed-loop stimulation). Data were recorded from nine ET patients with wrist flexion/extension tremor recruited from the Gregorio Marañón Hospital (Madrid, Spain). Patients participated in two experimental sessions comprising: 1) sensory stimulation of wrist flexors/extensors via thin-film multichannel intramuscular electrodes; and 2) surface stimulation of the nerves innervating the same target muscles. For each session, four of these patients underwent random 60-s trials of two stimulation strategies for each target muscle: 1) selective and adaptive timely stimulation (SATS) - based on EMG of the antagonist muscle; and 2) continuous stimulation (CON) of target muscles. Two patients underwent SATS stimulation trials alone while the other three underwent CON stimulation trials alone in each session. Kinematics of wrist, elbow, and shoulder, together with clinical scales, were used to assess tremor before, right after, and 24 h after each session. Intramuscular SATS achieved, on average, 32% acute (during stimulation) tremor reduction on each trial, while continuous stimulation augmented tremorgenic activity. Furthermore, tremor reduction was significantly higher using intramuscular than surface stimulation. Prolonged reduction of tremor amplitude (24 h after the experiment) was observed in four patients. These results showed acute and prolonged (24 h) tremor reduction using a minimally invasive neurostimulation technology based on SATS of primary sensory afferents of wrist muscles. This strategy might open the possibility of an alternative therapeutic approach for ET patients.

Differential Modulation of Dorsal Horn Neurons by Various Spinal Cord Stimulation Strategies.

New strategies for spinal cord stimulation (SCS) for chronic pain have emerged in recent years, which may work better via different analgesic mechanisms than traditional low-frequency (e.g., 50 Hz) paresthesia-based SCS. To determine if 10 kHz and burst SCS waveforms might have a similar mechanistic basis, we examined whether these SCS strategies at intensities ostensibly below sensory thresholds would modulate spinal dorsal horn (DH) neuronal function in a neuron type-dependent manner. By using an in vivo electrophysiological approach in rodents, we found that low-intensity 10 kHz SCS, but not burst SCS, selectively activates inhibitory interneurons in the spinal DH. This study suggests that low-intensity 10 kHz SCS may inhibit pain-sensory processing in the spinal DH by activating inhibitory interneurons without activating DC fibers, resulting in paresthesia-free pain relief, whereas burst SCS likely operates via other mechanisms.

The Expanding Horizon of Neural Stimulation for Hyperkinetic Movement Disorders.

Novel methods of neural stimulation are transforming the management of hyperkinetic movement disorders. In this review the diversity of approach available is showcased. We first describe the most commonly used features that can be extracted from oscillatory activity of the central nervous system, and how these can be combined with an expanding range of non-invasive and invasive brain stimulation techniques. We then shift our focus to the periphery using tremor and Tourette's syndrome to illustrate the utility of peripheral biomarkers and interventions. Finally, we discuss current innovations which are changing the landscape of stimulation strategy by integrating technological advances and the use of machine learning to drive optimization.

Risk of Infection after Deep Brain Stimulation Surgery with Externalization and Local-Field Potential Recordings: Twelve-Year Experience from a Single Institution

Introduction: Deep brain stimulation (DBS) has been an established surgical procedure in the field of functional neurosurgery for many years. The experimental electrophysiological method of local field potential (LFP) recordings in postsurgically externalized patients has made substantial contributions to the better understanding of pathophysiologies underlying movement disorders. As interest in LFP recordings for the development of improved stimulation strategies increases, this study’s aim was to provide evidence concerning safety of this research method, in a major DBS center. Methods: We retrospectively analyzed incidence and infection characteristics in adult patients who underwent two-staged DBS surgery with temporary externalization of leads in our center between January 2008 and November 2019. We focused on whether patients had participated in LFP recordings, and evaluated incidence of infections at 3 months and 1 year after the surgery based on medical records. Infection rates were compared to major DBS studies and reports focusing on the risk of infection due to externalization of DBS leads. Results were visualized using descriptive statistics. Results: Between January 2008 and November 2019, DBS surgery was performed in 528 patients (389/139 patients in the LFP/non-LFP group), mainly for movement disorders such as Parkinson’s disease (308), dystonia (93), and essential tremor (86). Of the patients, 72.9% participated in LFP recordings. The incidence of infections in the acute postsurgical phase (3 months) was 2.46% and did not differ significantly between the LFP group (1.8%) and the non-LFP group (4.32%). The overall incidence after 1 year amounted to 3.6% (19 patients) with no difference between LFP/non-LFP groups. Incidence rates reported in the literature show a large variety (2.6–10%), and the incidence reported here is within the lower range of reported incidences. Discussion/Conclusion: This study demonstrates that DBS is a surgical procedure with a low risk of infection in a large patient cohort. Importantly, it shows that LFP recordings do not have a significant effect on the incidence of infections in patients with externalization. With a representative cohort of more than 380 patients participating in LFP-recordings, this underlines LFP as a safe method in research and supports further use of this method, for example, for the development of adaptive stimulation protocols.

Increasing autonomy through improved care: effects of a professional care-giver training programme on the functional status of older adults

AbstractThe aim of the present research was to evaluate the effectiveness of a care-giver training programme that trains professional care-givers in cognitive stimulation strategies for functional maintenance in care-dependent older adults. The sample contained 69 older adults (37 in the treatment group, 32 control group) assessed with the Barthel Index, the Mini-Mental State Examination and the Clifton Assessment Procedure for the Elderly (Cognitive Scale). Participants in the treatment group were treated by professional care-givers who were trained with the programme CUIDA-2 in communication and cognitive stimulation strategies. The results from the Barthel Index showed significant differences in the post-intervention assessment and in the follow-up assessment, where the treatment group obtained higher scores, and there were significant differences within the treatment group between the initial assessment and the post-treatment assessment, as well as between the initial assessment and the follow-up. The data obtained reflect that a training programme to train professional care-givers produced functional benefits in the older adults, and these improvements persisted over time. Moreover, the care-givers saw themselves as more competent and more satisfied with their work.