Spinal Stimulation Research Articles

Different Effect Sizes of Motor Skill Training Combined with Repetitive Transcranial versus Trans-Spinal Magnetic Stimulation in Healthy Subjects.

Repetitive transcranial magnetic stimulation (rTMS) is used to enhance motor training (MT) performance. The use of rTMS is limited under certain conditions, such as after a stroke with severe damage to the corticospinal tract. This raises the question as to whether repetitive trans-spinal magnetic stimulation (rSMS) can also be used to improve MT. A direct comparison of the effect size between rTMS and rSMS on the same MT is still lacking. Before conducting the study in patients, we determined the effect sizes of different stimulation approaches combined with the same motor training in healthy subjects. Two experiments (E1 and E2) with 96 subjects investigated the effect size of combining magnetic stimulation with the same MT. In E1, high-frequency rTMS, rSMS, and spinal sham stimulation (sham-spinal) were applied once in combination with MT, while one group only received the same MT (without stimulation). In E2, rTMS, rSMS, and sham-spinal were applied in combination with MT over several days. In all subjects, motor tests and motor-evoked potentials were evaluated before and after the intervention period. rTMS had the greatest effect on MT, followed by rSMS and then sham-spinal. Daily stimulation resulted in additional training gains. This study suggests that rSMS increases excitability and also enhances MT performance. This current study provides a basis for further research to discover whether patients who cannot be treated effectively with rTMS would benefit from rSMS.

Spinal magnetic stimulation to treat chronic back pain: a feasibility study in veterans.

Aim: Chronic low back pain represents a significant societal problem leading to increased healthcare costs and quality of life. This study was designed to evaluate the feasibility and effectiveness of non-invasive spinal electromagnetic simulation (SEMS) to treat nonspecific chronic low back pain (CLBP). Methods: A single-site prospective study was conducted to evaluate SEMS in reducing pain and improving disability. A total of 17 patients received SEMS two to threesessions a week. The Numeric Rating Scale and the Modified Oswestry Disability Questionnaire were used to assess pain and disability. Results: Participants receiving SEMS exhibited statistically significant reductions in pain and disability. Conclusion: Current results suggest that non-invasive SEMS can be an effective treatment in reducing pain and improving disability associated with CLBP.

From brain to spinal cord: neuromodulation by direct current stimulation and its promising effects as a treatment option for restless legs syndrome

Neuromodulation is a fast-growing field of mostly non-invasive therapies, which includes spinal cord stimulation (SCS), transcranial direct current stimulation (tDCS), vagal nerve stimulation (VNS), peripheral nerve stimulation, transcranial magnetic stimulation (TMS) and transcutaneous spinal direct current stimulation (tsDCS). This narrative review offers an overview of the therapy options, especially of tDCS and tsDCS for chronic pain and spinal cord injury. Finally, we discuss the potential of tsDCS in Restless Legs Syndrome as a promising non-invasive, alternative therapy to medication therapy.

Recovery of Volitional Motor Control and Overground Walking in Participants With Chronic Clinically Motor Complete Spinal Cord Injury: Restoration of Rehabilitative Function With Epidural Spinal Stimulation (RESTORES) Trial-A Preliminary Study.

Spinal cord injury (SCI) is damage to any part of the spinal cord resulting in paralysis, bowel and/or bladder incontinence, and loss of sensation and other bodily functions. Current treatments for chronic SCI are focused on managing symptoms and preventing further damage to the spinal cord with limited neuro-restorative interventions. Recent research and independent clinical trials of spinal cord stimulation (SCS) or intensive neuro-rehabilitation including neuro-robotics in participants with SCI have suggested potential malleability of the neuronal networks for neurological recovery. We hypothesize that epidural electrical stimulation (EES) delivered via SCS in conjunction with mental imagery practice and robotic neuro-rehabilitation can synergistically improve volitional motor function below the level of injury in participants with chronic clinically motor-complete SCI. In our pilot clinical RESTORES trial (RESToration Of Rehabilitative function with Epidural spinal Stimulation), we investigate the feasibility of this combined multi-modal approach in restoring volitional motor control and achieving independent overground locomotion in participants with chronic motor complete thoracic SCI. Secondary aims are to assess the safety of this combination therapy including the off-label SCS usage as well as improving functional outcome measures. To our knowledge, this is the first clinical trial that investigates the combined impact of this multi-modal EES and rehabilitation strategy in participants with chronic motor complete SCI. Two participants with chronic motor-complete thoracic SCI were recruited for this pilot trial. Both participants have successfully regained volitional motor control below their level of SCI injury and achieved independent overground walking within a month of post-operative stimulation and rehabilitation. There were no adverse events noted in our trial and there was an improvement in post-operative truncal stability score. Results from this pilot study demonstrates the feasibility of combining EES, mental imagery practice and robotic rehabilitation in improving volitional motor control below level of SCI injury and restoring independent overground walking for participants with chronic motor-complete SCI. Our team believes that this provides very exciting promise in a field currently devoid of disease-modifying therapies.

Initial feasibility evaluation of the RISES system: An innovative and activity-based closed-loop framework for spinal cord injury rehabilitation and recovery.

Electrical stimulation of the spinal cord may improve rewiring of the affected pathways. Immediate modulation of stimulation parameters, and its effects of it on kinematics and electromyographic variables is unclear. This study piloted the safety and feasibility of the Reynolds Innovative Spinal Electrical Stimulation (RISES) technology with a focus on its novel closed-loop setting. This personalized, task-specific non-invasive stimulation system enables real-time stimulation parameter modulation and supports multi-data acquisition and storage. Four SCI participants underwent a clinical trial coupled with activity-based training. Primary safety outcome measures included adverse events (AEs) and skin integrity; secondary measures were vital signs, pain, and fatigue assessed at the pre, mid, and post-stimulation sessions. The trial included open-loop and closed-loop blocks of transcutaneous spinal cord stimulation (tSCS). Results showed no serious adverse events, with skin integrity unaffected. Vital signs and pain showed no significant differences across session timepoints. Fatigue levels differed significantly with post-session > mid-session > pre-session. Comparisons between open-loop and closed-loop blocks showed no significant differences in setup time, vital signs, pain, or fatigue. Average stimulation duration per task was significantly longer for open-loop (467.6 sec) than Closed-loop (410.8 sec). RISES, demonstrated safety and feasibility. Further work will focus on clinical efficacy.

Neuromodulation in Spinal Cord Injury Using Transcutaneous Spinal Stimulation-Mapping for a Blood Pressure Response: A Case Series.

Spinal cord transcutaneous stimulation (scTS) offers a promising approach to enhance cardiovascular regulation in individuals with a high-level spinal cord injury (SCI), addressing the challenges of unstable blood pressure (BP) and the accompanying hypo- and hypertensive events. While scTS offers flexibility in stimulation locations, it also leads to significant variability and lack of validation in stimulation sites utilized by studies. Our study presents findings from a case series involving eight individuals with chronic cervical SCI, examining the hemodynamic effects of scTS applied in different vertebral locations, spanning from high cervical to sacral regions. Stimulation of the lumbosacral vertebrae region (L1/2, S1/2, and also including T11/12) significantly elevated BP, unlike cervical or upper thoracic stimulation. The observed trend, which remained consistent across different participants, highlights the promising role of lumbosacral stimulation in neuromodulating BP.

Central and Peripheral Motor Conduction Studies by Single-Pulse Magnetic Stimulation.

Single-pulse magnetic stimulation is the simplest type of transcranial magnetic stimulation (TMS). Muscle action potentials induced by applying TMS over the primary motor cortex are recorded with surface electromyography electrodes, and they are called motor-evoked potentials (MEPs). The amplitude and latency of MEPs are used for various analyses in clinical practice and research. The most commonly used parameter is the central motor conduction time (CMCT), which is measured using motor cortical and spinal nerve stimulation. In addition, stimulation at the foramen magnum or the conus medullaris can be combined with conventional CMCT measurements to evaluate various conduction parameters in the corticospinal tract more precisely, including the cortical-brainstem conduction time, brainstem-root conduction time, cortical-conus motor conduction time, and cauda equina conduction time. The cortical silent period is also a useful parameter for evaluating cortical excitability. Single-pulse magnetic stimulation is further used to analyze not only the central nervous system but also the peripheral nervous system, such as for detecting lesions in the proximal parts of peripheral nerves. In this review article we introduce four types of single-pulse magnetic stimulation-of the motor cortex, spinal nerve, foramen magnum, and conus medullaris-that are useful for the diagnosis, elucidation of pathophysiology, and evaluation of clinical conditions and therapeutic effects. Single-pulse magnetic stimulation is a clinically useful technique that all neurologists should learn.

Assessing the Effect of Cervical Transcutaneous Spinal Stimulation With an Upper Limb Robotic Exoskeleton and Surface Electromyography.

Transcutaneous spinal stimulation (TSS) is a promising rehabilitative intervention to restore motor function and coordination for individuals with spinal cord injury (SCI). The effects of TSS are most commonly assessed by evaluating muscle response to stimulation using surface electromyography (sEMG). Given the increasing use of robotic devices to deliver therapy and the emerging potential of hybrid rehabilitation interventions that combine neuromodulation with robotic devices, there is an opportunity to leverage the on-board sensors of the robots to measure kinematic and torque changes of joints in the presence of stimulation. This paper explores the potential for robotic assessment of the effects of TSS delivered to the cervical spinal cord. We used a four degree-of-freedom exoskeleton to measure the torque response of upper limb (UL) joints during stimulation, while simultaneously recording sEMG. We analyzed joint torque and electromyography data generated during TSS delivered over individual sites of the cervical spinal cord in neurologically intact participants. We show that site-specific effects of TSS are manifested not only by modulation of the amplitude of spinally evoked motor potentials in UL muscles, but also by changes in torque generated by individual UL joints. We observed preferential resultant action of proximal muscles and joints with stimulation at the rostral site, and of proximal joints with rostral-lateral stimulation. Robotic assessment can be used to measure the effects of TSS, and could be integrated into complex control algorithms that govern the behavior of hybrid neuromodulation-robotic systems.

Ab. No. 95 Integrated Effect of Photobiomodulation Therapy Along With Surface Spinal Stimulation and Activity-Based Therapy on Locomotion in an Individual With Traumatic Incomplete Spinal Cord Injury - Single Case Study

Introduction: The purpose of the study was to examine the integrated effect of photobiomodulation therapy (PBMT) along with surface spinal stimulation (SSS) and activity-based therapy (ABT) on the locomotion in an individual with traumatic incomplete spinal cord injury (SCI). The study aims to provide an insight for advanced non-invasive treatment approach useful in activating central pattern generator by bio-modulating the state of spinal cord. Methods: Individual diagnosed with traumatic spinal cord injury, Motor incomplete ASIA grade B. A 36-year-old male pre-diagnosed with D12-L1 vertebrae fracture and anterolisthesis of D11 over D12 vertebra had undergone surgical management in august 2023. Physiotherapy management was given with PBMT using Class IV LASER (2000 joules at 7 watts) on lesion site, SSS (2500 Hz carrier frequency, 80 Hz beat frequency for 20 minutes) on paravertebral area and activity-based therapy (trunk control exercises, body weight supported treadmill training, overground walking for 45 minutes) for 6 sessions per week for duration of 5 weeks. Pre and Post intervention assessment was done using International Standards for Neurological Classification of Spinal cord injury- ASIA Impairment Scale, Walking Index for spinal cord injury-II (WISCII-II) and Spinal cord independence measure-III (SCIM-III) at day 0, 15 and 30. Results: ASIA motor score of right lower limb, SCIM-III and WISCI-II had shown significant improvement. ASIA motor score of right lower limb improved from 0 to 1, SCIM-III from 42 to 54 and WISCI-II from 0 to 6 between day 0 and day 30. Conclusion: The study concluded that combined photobiomodulation therapy using class IV LASER along with surface spinal stimulation and activity-based therapy has positive effect in enhancing the locomotion in an individual with traumatic incomplete SCI. Implications: This integrated non-invasive treatment approach can be used as management guideline for enhancing locomotion in individuals with incomplete SCI.

Synergistic effects of transcutaneous spinal stimulation and neuromuscular electrical stimulation on lower limb force production: Time to deliver.

Transcutaneous spinal stimulation (TSS) and neuromuscular electrical stimulation (NMES) can facilitate self-assisted standing in individuals with paralysis. However, individual variability in responses to each modality may limit their effectiveness in generating the necessary leg extension force for full body weight standing. To address this challenge, we proposed combining TSS and NMES to enhance leg extensor muscle activation, with optimizing timing adjustment to maximize the interaction between the two modalities. To assess the effects of TSS and NMES on knee extension and plantarflexion force, ten neurologically intact participants underwent three conditions: (1) TSS control, (2) NMES control, and (3) TSS + NMES. TSS was delivered between the T10 and L2 vertebrae, while NMES was delivered to the skin over the right knee extensors and plantarflexors. TSS and NMES were administered using a 15 Hz train of three 0.5 ms biphasic pulses. During the TSS + NMES condition, the timing between modalities was adjusted in increments of ¼ the interval within a 15 Hz frequency, i.e., 66, 49.5, 33, 16.5, and 1 ms. NMES combined with TSS, produced synergistic effects even on non-targeted muscle groups, thereby promoting leg extension across multiple joints in the kinematic chain. The sequence of NMES or TSS trains relative to each other did not significantly impact motor output. Notably, a delay of 16.5 to 49.5 ms between interleaved TSS and NMES pulses, each delivered at 15 Hz, results in more robust and synergistic responses in knee extensors and plantarflexors. By adjusting the timing between TSS and NMES, we can optimize the combined use of these modalities for functional restoration. Our findings highlight the potential of integrated TSS and NMES protocols to enhance motor function, suggesting promising avenues for therapeutic applications, particularly in the rehabilitation of individuals with SCI.

The impact of spinal cord stimulation on a chronic model of atrial fibrillation in a mini-pig experiment

Introduction: Despite the advancement interventional methods for treating atrial fibrillation, the effectiveness of catheter ablation remains poor, especially in patients with persistent and long-persistent atrial fibrillation. Thus, experts continue to explore new treatments for this arrhythmia. The issue of experimental studies investigating the association between spinal cord stimulation and atrial fibrillation is mainly attributed to the lack of optimal algorithms for spinal cord stimulation in animal experiments. Therefore, it is important to develop adequate algorithms for spinal cord stimulation in the chronic model of atrial fibrillation.Objective: To evaluate the impact of spinal cord stimulation on the model of atrial fibrillation in mini-pigs.Methods: In a series of experiments, 6 (100%) successful implantations of electrodes and pacemakers, and spinal cord stimulation electrodes were performed. The electrodes were used to stimulate the atria, creating a model of atrial fibrillation, while the spinal cord stimulation was carried out using an electrode implanted into the spinal canal. During the experiment, an electrophysiological study was performed using an implanted pacemaker. The inducibility of atrial fibrillation was assessed before and after the experiment using various spinal cord stimulation algorithms.Results: There were no complications associated with surgery or stimulation of the atria and spinal cord. Spinal stimulation had a modeling effect on the autonomic nervous system, significantly changing the average heart rate, Wenckebach point, and effective refractory period. When comparing spinal stimulation algorithms, algorithm 1 was found to significantly reduce the atrial fibrillation inducibility.Conclusion: Spinal cord stimulation had a modeling effect on the autonomic nervous system, significantly changing the average heart rate, Wenckebach point, and effective refractory period. Inducibility of atrial fibrillation decreases with changes in the spinal pacing algorithm. Received 15 September 2023. Revised 30 October 2023. Accepted 31 October 2023. Funding: The study was supported by Russian Science Foundation (project No. 22-25-00672). Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: A.G. Filippenko, V.V. Shabanov, V.I. MurtazinData collection and analysis: A.G. Filippenko, T.U. Khalkhoghaev, V.V. BeloborodovStatistical analysis: A.G. Filippenko, V.V. ShabanovDrafting the article: A.G. Filippenko, V.V. BeloborodovCritical revision of the article: V.V. ShabanovFinal approval of the version to be published: V.V. Shabanov, A.G. Filippenko, V.V. Beloborodov, T.U. Khalkhoghaev, V.I. Murtazin

Effect of non-invasive spinal cord stimulation in unmedicated adults with major depressive disorder: a pilot randomized controlled trial and induced current flow pattern

Converging theoretical frameworks suggest a role and a therapeutic potential for spinal interoceptive pathways in major depressive disorder (MDD). Here, we aimed to evaluate the antidepressant effects and tolerability of transcutaneous spinal direct current stimulation (tsDCS) in MDD. This was a double-blind, randomized, sham-controlled, parallel group, pilot clinical trial in unmedicated adults with moderate MDD. Twenty participants were randomly allocated (1:1 ratio) to receive “active” 2.5 mA or “sham” anodal tsDCS sessions with a thoracic (anode; T10)/right shoulder (cathode) electrode montage 3 times/week for 8 weeks. Change in depression severity (MADRS) scores (prespecified primary outcome) and secondary clinical outcomes were analyzed with ANOVA models. An E-Field model was generated using the active tsDCS parameters. Compared to sham (n = 9), the active tsDCS group (n = 10) showed a greater baseline to endpoint decrease in MADRS score with a large effect size (−14.6 ± 2.5 vs. −21.7 ± 2.3, p = 0.040, d = 0.86). Additionally, compared to sham, active tsDCS induced a greater decrease in MADRS “reported sadness” item (−1.8 ± 0.4 vs. −3.2 ± 0.4, p = 0.012), and a greater cumulative decrease in pre/post tsDCS session diastolic blood pressure change from baseline to endpoint (group difference: 7.9 ± 3.7 mmHg, p = 0.039). Statistical trends in the same direction were observed for MADRS “pessimistic thoughts” item and week-8 CGI-I scores. No group differences were observed in adverse events (AEs) and no serious AEs occurred. The current flow simulation showed electric field at strength within the neuromodulation range (max. ~0.45 V/m) reaching the thoracic spinal gray matter. The results from this pilot study suggest that tsDCS is feasible, well-tolerated, and shows therapeutic potential in MDD. This work also provides the initial framework for the cautious exploration of non-invasive spinal cord neuromodulation in the context of mental health research and therapeutics. The underlying mechanisms warrant further investigation. Clinicaltrials.gov registration: NCT03433339 URL: https://clinicaltrials.gov/ct2/show/NCT03433339.

Standing Reactive Postural Responses of Lower Limbs With and Without Self-Balance Assistance in Individuals With Spinal Cord Injury Receiving Epidural Stimulation.

Spinal cord epidural stimulation can promote the recovery of motor function in individuals with severe spinal cord injury (SCI) by enabling the spinal circuitry to interpret sensory information and generate related neuromuscular responses. This approach enables the spinal cord to generate lower limb extension patterns during weight bearing, allowing individuals with SCI to achieve upright standing. We have shown that the human spinal cord can generate some standing postural responses during self-initiated body weight shifting. In this study, we investigated the ability of individuals with motor complete SCI receiving epidural stimulation to generate standing reactive postural responses after external perturbations were applied at the trunk. A cable-driven robotic device was used to provide constant assistance for pelvic control and to deliver precise trunk perturbations while participants used their hands to grasp onto handlebars for self-balance support (hands-on) as well as when participants were without support (free-hands). Five individuals with motor complete SCI receiving lumbosacral spinal cord epidural stimulation parameters specific for standing (Stand-scES) participated in this study. Trunk perturbations (average magnitude: 17 ± 3% body weight) were delivered randomly in the four cardinal directions. Participants attempted to control each perturbation such that upright standing was maintained and no additional external assistance was needed. Lower limb postural responses were generally more frequent, larger in magnitude, and appropriately modulated during the free-hands condition. This was associated with trunk displacement and lower limb loading modulation that were larger in the free-hands condition. Further, we observed discernible lower limb muscle synergies that were similar between the two perturbed standing conditions. These findings suggest that the human spinal circuitry involved in postural control retains the ability to generate meaningful lower limb postural responses after SCI when its excitability is properly modulated. Moreover, lower limb postural responses appear enhanced by a standing environment without upper limb stabilization that promotes afferent inputs associated with a larger modulation of ground reaction forces and trunk kinematics. These findings should be considered when developing future experimental frameworks aimed at studying upright postural control and activity-based recovery training protocols aimed at promoting neural plasticity and sensory-motor recovery.

Multi-site lumbar transcutaneous spinal cord stimulation: When less is more

BackgroundTranscutaneous spinal stimulation (TSS) has become a valuable tool for facilitating rehabilitation in individuals with neurological deficits. A significant constraint arises from the need for precise knowledge of stimulation locations to effectively apply TSS for targeted functional enhancement. MethodsIn this study, we investigate whether single-site or simultaneous multi-site stimulation over the lumbar spinal cord is advantageous for recruitment of specific motor pools projecting to lower limb muscles and generates higher leg extensor forces in neurologically intact individuals. Tests were performed in a supine position. TSS was delivered at T10-T11, T11-T12, T12-L1, and L1-L2 intervertebral spaces individually, then through all four locations simultaneously. The peak-to-peak amplitude of spinally evoked motor potentials and the forces generated by lower limb muscles were compared at the common motor threshold intensity level across all stimulation conditions. ResultsRecruitment of motor pools projecting to proximal and distal lower limb muscles followed their topographical rostro-caudal arrangement along the lumbosacral enlargement. Single-site stimulation, apart from the T10-T11 location, resulted in larger responses in both proximal and distal muscles while also generating higher knee-extension and plantarflexion forces when compared to multi-site stimulation. ConclusionsBoth motor response and force generation were reduced when using multi-site TSS when compared to single-site stimulation. This demonstrates that the segmental effects of TSS are important to consider when performing multi-site TSS.

Characterizing neurological status in individuals with tetraplegia using transcutaneous spinal stimulation

Transcutaneous spinal stimulation (TSS) is emerging as a valuable tool for electrophysiological and clinical assessment. This study had the objective of examining the recruitment patterns of upper limb (UL) motor pools through the delivery of TSS above and below a spinal lesion. It also aimed to explore the connection between the recruitment pattern of UL motor pools and the neurological and functional status following spinal cord injury (SCI). In eight participants with tetraplegia due to cervical SCI, TSS was delivered to the cervical spinal cord between the spinous processes of C3–C4 and C7–T1 vertebrae, and spinally evoked motor potentials in UL muscles were characterized. We found that responses observed in UL muscles innervated by motor pools below the level of injury demonstrated relatively reduced sensitivity to TSS compared to those above the lesion, were asymmetrical in the majority of muscles, and were dependent on the level, extent, and side of SCI. Overall, our findings indicate that electrophysiological data acquired through TSS can offer insights into the extent of UL functional asymmetry, disruptions in neural pathways, and changes in motor control following SCI. This study suggests that such electrophysiological data can supplement clinical and functional assessment and provide further insight regarding residual motor function in individuals with SCI.

Fully implanted battery-free high power platform for chronic spinal and muscular functional electrical stimulation

Electrical stimulation of the neuromuscular system holds promise for both scientific and therapeutic biomedical applications. Supplying and maintaining the power necessary to drive stimulation chronically is a fundamental challenge in these applications, especially when high voltages or currents are required. Wireless systems, in which energy is supplied through near field power transfer, could eliminate complications caused by battery packs or external connections, but currently do not provide the harvested power and voltages required for applications such as muscle stimulation. Here, we introduce a passive resonator optimized power transfer design that overcomes these limitations, enabling voltage compliances of ± 20 V and power over 300 mW at device volumes of 0.2 cm2, thereby improving power transfer 500% over previous systems. We show that this improved performance enables multichannel, biphasic, current-controlled operation at clinically relevant voltage and current ranges with digital control and telemetry in freely behaving animals. Preliminary chronic results indicate that implanted devices remain operational over 6 weeks in both intact and spinal cord injured rats and are capable of producing fine control of spinal and muscle stimulation.

Contraction intensity modulates spinal excitability during transcranial magnetic stimulation-evoked silent period in rectus femoris muscle

PurposeReduced spinal excitability during the transcranial magnetic stimulation (TMS) silent period (SP) has recently been shown to last longer than previously thought in the upper limbs, as assessed via spinal electrical stimulation. Further, there is reason to expect that contraction intensity affects the duration of the reduced spinal excitability.MethodsThis study investigated spinal excitability at different time delays within the TMS-evoked SP in m.rectus femoris. Fifteen participants performed non-fatiguing isometric knee extensions at 25%, 50% and 75% of maximum voluntary contraction (MVC). Lumbar stimulation (LS) induced a lumbar-evoked potential (LEP) of 50% resting M-max. TMS stimulator output induced a SP lasting ~ 200 ms. In each contraction, a LEP (unconditioned) was delivered ~ 2–3 s prior to TMS, which was followed by a second LEP (conditioned) 60, 90, 120 or 150 ms into the silent period. Five contractions were performed at each contraction intensity and for each time delay in random order.ResultsCompared to the unconditioned LEP, the conditioned LEP amplitude was reduced (− 28 ± 34%, p = 0.007) only at 60 ms during 25% of MVC. Conditioned LEP amplitudes during 50% and 75% of MVC were reduced at 60 ms (− 37 ± 47%, p = 0.009 and − 37 ± 42%, p = 0.005, respectively) and 150 ms (− 30% ± 37%, p = 0.0083 and − 37 ± 43%, p = 0.005, respectively). LEP amplitude at 90 ms during 50% of MVC also reduced (− 25 ± 35%, p = 0.013).ConclusionReduced spinal excitability is extended during 50% and 75% of MVC. In future, paired TMS-LS could be a potential method to understand changes in spinal excitability during SP (at different contraction intensities) when testing various neurophysiological phenomena.

Anodal transcutaneous spinal direct current stimulation influences the amplitude of pain-related evoked potentials in healthy subjects

It has already been described that transcutaneous spinal direct current stimulation (tsDCS) can selectively influence nociceptive evoked potentials. This study is the first aiming to prove an influence of tsDCS on pain-related evoked potentials (PREP) using concentric surface electrodes (CE), whose nociceptive specificity is still under discussion. 28 healthy subjects participated in this sham-controlled, double-blind cross-over study. All subjects underwent one session of anodal and one session of sham low-thoracic tsDCS. Before and after the intervention, PREP using CE, PREP-induced pain perception and somatosensory evoked potentials (SEP) were assessed on the right upper and lower limb. We found a decrease in PREP amplitude at the lower limb after sham stimulation, but not after anodal tsDCS, while SEP remained unchanged under all studied conditions. There was no difference between the effects of anodal tsDCS and sham stimulation on the studied parameters assessed at the upper limb. PREP-induced pain of the upper and lower limb increased after anodal tsDCS. The ability of influencing PREP using a CE at the spinal level in contrast to SEP suggests that PREP using CE follows the spinothalamic pathway and supports the assumption that it is specifically nociceptive. However, while mainly inhibitory effects on nociceptive stimuli have already been described, our results rather suggest that anodal tsDCS has a sensitizing effect. This may indicate that the mechanisms underlying the elicitation of PREP with CE are not the same as for the other nociceptive evoked potentials. The effects on the processing of different types of painful stimuli should be directly compared in future studies.

Combinatorial Effects of Transcutaneous Spinal Stimulation and Task-Specific Training to Enhance Hand Motor Output after Paralysis.

Despite the positive results in upper limb (UL) motor recovery after using electrical neuromodulation in individuals after cervical spinal cord injury (SCI) or stroke, there has been limited exploration of potential benefits of combining task-specific hand grip training with transcutaneous electrical spinal stimulation (TSS) for individuals with UL paralysis. This study investigates the combinatorial effects of task-specific hand grip training and noninvasive TSS to enhance hand motor output after paralysis. Four participants with cervical SCI classified as AIS A and B and two participants with cerebral stroke were recruited in this study. The effects of cervical TSS without grip training and during training with sham stimulation were contrasted with hand grip training with TSS. TSS was applied at midline over cervical spinal cord. During hand grip training, 5 to 10 seconds of voluntary contraction were repeated at a submaximum strength for approximately 10 minutes, three days per week for 4 weeks. Signals from hand grip dynamometer along with the electromyography (EMG) activity from UL muscles were recorded and displayed as visual feedback. Our case study series demonstrated that combined task-specific hand grip training and cervical TSS targeting the motor pools of distal muscles in the UL resulted in significant improvements in maximum hand grip strength. However, TSS alone or hand grip training alone showed limited effectiveness in improving grip strength. Task-specific hand grip training combined with TSS can result in restoration of hand motor function in paralyzed upper limbs in individuals with cervical SCI and stroke.

Abstract 13000: Twiddler’s Syndrome - A Rare Cause of Pacemaker Malfunction

Description of Case: A 76-year-old female with a past medical history of chronic atrial fibrillation and symptomatic tachycardia and bradycardia status-post dual-chamber pacemaker with right atrial and ventricular leads who presented with dyspnea on exertion. TTE showed normal biventricular function and no significant valvular abnormalities. Upon further evaluation of her pacemaker, she was found to have a very high ventricular capture threshold suggesting RV lead failure. The patient underwent RV lead replacement. The inspection of the pacemaker pocket during the procedure showed manual dislodgement of both tie-down sleeves and the pacemaker leads required untangling. A new RV lead was subsequently placed. Upon further imaging review, displacement of the previous RV lead was evident from initial placement. In addition, the patient had previously had a history of interval diaphragmatic stimulation as well. Overall, the presentation was felt to be consistent with Twiddler’s Syndrome. Discussion: Twiddler’s or Reel Syndrome occurs when conscious or subconscious self-manipulation and spinning of the pulse generator result in lead dislodgement and loss of pacing and pacemaker malfunction. The reeling of the leads around the generator can also cause stimulation of the brachial plexus or phrenic nerve stimulation and subsequent rhythmic arm twitching or diaphragmatic pacing, respectively. It has previously been reported in cases of single- and dual-chamber ICDs, deep brain stimulators, and spinal nerve stimulators with varying presentation. The diagnosis requires clinical suspicion based on history, physical exam, imaging, or surgical inspection suggesting the displacement of leads with evidence of coiling of the wires around the pacemaker. Treatment often requires revision and focus should be maintained on patient education for both primary and secondary prevention of Twiddler’s Syndrome.