Modulation of spinal neuronal excitability by spinal direct currents and locomotion after spinal cord injury

ObjectiveSpinal neuronal function is impaired after a severe spinal cord injury (SCI) and can be assessed by the analysis of spinal reflex (SR) behavior. We applied transcutaneous spinal direct current stimulation (tsDCS) and locomotor activity, to determine whether the excitability of spinal neuronal circuitries underlying locomotion can be modulated after motor complete SCI.MethodSRs were evoked by non-noxious electrical stimulation of the tibial nerve. SR behavior was assessed before, immediately after, and 20 min after four different interventions (anodal, cathodal, sham tsDCS, or locomotion) in subjects with motor complete SCI and healthy subjects.ResultsSR amplitudes in SCI subjects were increased after anodal tsDCS by 84% (p < 0.05). Cathodal, sham tsDCS and locomotion had no influence on SR amplitudes. In addition, reflex threshold was lower after anodal tsDCS and locomotion in SCI subjects (p < 0.05).ConclusionAnodal tsDCS is able to modulate spinal neuronal circuitries after SCI.SignificanceThis novel, noninvasive approach might be used as a tool to excite spinal neuronal circuitries. If applied repetitively within a training approach, anodal tsDCS might prevent adverse alterations in spinal reflex function in severely affected SCI subjects, i.e., a manifestation of a spinal neuronal dysfunction taking part below the level of a spinal lesion.     

Influence of transcutaneous spinal stimulation on human LTP-like pain amplification. A randomized,double-blind study in volunteers

ObjectiveTranscutaneous spinal direct current stimulation (tsDCS) has been proven to affect nociceptive signal processing. We designed a randomized, double-blind, cross-over study to investigate whether tsDCS applied before or after inducing long-term potentiation-(LTP)-like hyperalgesia may decrease nociceptive sensitivity.MethodsIn healthy volunteers, tsDCS (2.5 mA, 15 min) was applied to the thoracic spine prior (n = 14) or immediately following (n = 12) electrical high-frequency stimulation (HFS) to the thigh, inducing hyperalgesia. Mechanical and electrical perception were assessed before HFS stimulation and at three time points following HFS stimulation (all within 90 min of HFS). Subjects took part in three separate sessions to test effects of anodal, cathodal, or sham tsDCS.ResultsWithin 60 min HFS led to unilateral changes on the conditioned side: mechanical pain thresholds tended to decrease and electrical detection thresholds significantly decreased (p < 0.001); pain ratings measured using the numerical rating scale (NRS) increased for electrical stimuli (p < 0.01) and two categories of mechanical stimuli (“Light(8–64 mN)”: p = ns; “Heavy(128–512 mN)”: p < 0.01). Irrespective of stimulation order or polarity, tsDCS could not influence nociceptive sensitivity.ConclusionHyperalgesia was adequately induced, but tsDCS had no effect on HFS-induced sensitization.SignificanceWhile tsDCS has been shown to affect pain measures, our results suggest irrespective of time of stimulation or polarity that tsDCS may be less effective in modulating pain in a sensitized state in healthy subjects.     

Effects of Transcutaneous Spinal Direct Current Stimulation in Idiopathic Restless Legs Patients

BackgroundTranscutaneous spinal direct current stimulation (tsDCS) is a new non-invasive technique to modulate spinal cord activity. The pathophysiological concept of primary RLS proposes increased spinal excitability.ObjectiveThis pilot study used tsDCS to reduce pathologically enhanced spinal excitability in RLS patients and to thereby ameliorate clinical symptoms.Methods20 patients with idiopathic RLS and 14 healthy subjects participated in this double-blinded, placebo-controlled study. All participants received one session of cathodal, anodal and sham stimulation of the thoracic spinal cord for 15 min (2.5 mA) each, in randomized order during their symptomatic phase in the evening. The soleus Hoffmann-reflex with Hmax/Mmax-ratio and seven different H2/H1-ratios (of two H-reflex responses to double stimuli) were measured. The RLS symptoms were assessed by a visual analogue scale (VAS). All parameters were measured before and twice after tsDCS.ResultsRLS patients showed increased H2/H1-ratios during their symptomatic phase in the evening. Application of anodal stimulation led to a decreased H2/H1-ratio for 0.2 and 0.3 s interstimulus intervals in patients. Furthermore, application of anodal and cathodal stimulation led to a reduction in restless legs symptoms on the VAS, whereas application of sham stimulation had no effects on either the VAS or on the H2/H1-ratio in patients. VAS changes did not correlate with changes of H2/H1-ratios.ConclusionsThis is the first tsDCS study in idiopathic RLS, which resulted in short-lasting clinical improvement. Furthermore, our results support the pathophysiological concept of spinal cord hyperexcitability in primary RLS and provide the basis for a new non-pharmacological treatment tool.     

Standardizing postoperative handoffs using the evidence-based IPASS framework through a multidisciplinary initiative improves handoff communication for neurosurgical patients in the neuro-intensive care unit

Errors in communication are a major source of preventable medical errors. Neurosurgical patients frequently present to the neuro-intensive care unit (NICU) postoperatively, where handoffs occur to coordinate care within a large multidisciplinary team. A multidisciplinary working group at our institution started an initiative to improve postoperative neurosurgical handoffs using validated quality improvement methodology. Baseline handoff practices were evaluated through staff surveys and serial observations. A formalized handoff protocol was implemented using the evidence based IPASS format (Illness severity, Patient summary, Action list, Situational awareness and contingency planning, Synthesis by receiver). Cycles of objective observations and surveys were employed to track practice improvements and guide iterative process changes over one year.Surveys demonstrated improved perceptions of handoffs as organized (17.1% vs 69.7%, p < 0.001), efficient (27.0% vs. 72.7%, p < 0.001), comprehensive (17.1% vs. 66.7%, p < 0.001), and safe (18.0% vs. 66.7%, p < 0.001), noting improved teamwork (31.5% vs. 69.7%, p < 0.001). Direct observations demonstrated improved communication of airway concerns (47.1% observed vs. 92.3% observed, p < 0.001), hemodynamic concerns (70.6% vs. 97.1%, p = 0.001), intraoperative events (52.9% vs. 100%, p < 0.001), neurological examination (76.5% vs. 100%, p < 0.001), vital sign goals (70.6% vs. 100%, p < 0.001), and required postoperative studies (76.5% vs. 100%, p < 0.001). Receiving teams demonstrating improved rates of summarization (47.1% vs. 94.2%, p = 0.005) and asking questions (76.5% vs 98.1%, p = 0.004). The mean handoff time during long-term follow-up was 4.4 min (95% confidence interval = 3.9–5.0 min).Standardization of handoff practices yields improvements in communication practices for postoperative neurosurgical patients.     

Long‐lasting modifications of motoneuron firing properties by trans‐spinal direct current stimulation in rats

Trans‐spinal direct current stimulation (tsDCS) is a novel neuromodulatory technique that has been used during neurological rehabilitation and sports to modulate muscle activation. However, the physiological mechanisms that underly the long‐lasting functional effects of polarization are not yet fully understood, nor are their relationships with specific neuronal populations. The acute facilitatory and depressive effects of anodal and cathodal polarization on motoneurons have been recently demonstrated, and the aim of this study was to determine whether tsDCS‐evoked modulations of motoneuron properties are able to persist over several hours. Intracellular recordings from multiple antidromically identified rat motoneurons were performed both before and after the application of tsDCS (0.1 mA for 15 min), at various time points up to 180 min after the offset of anodal or cathodal tsDCS. The examined effects of anodal polarization included decreased rheobase, voltage threshold, the minimum and maximum currents necessary for rhythmic firing, increased rhythmic firing frequencies and the slope of the f–I relationship. The majority of these facilitatory changes to threshold and firing properties were sustained for 30–60 min after polarization. In contrast, the significant effects of cathodal polarization were absent, except the short‐lasting decreased ability for motoneurons to induce rhythmic activity. This study provides direct evidence that a single polarization session can alter the electrophysiological properties of motoneurons for at least one hour and provides a basis for the further use of tsDCS techniques under conditions where the sustained modification of motoneuron firing is desired.     

Laser-evoked potentials in post-herpetic neuralgia

Objective: We evaluated the reliability of laser-evoked potentials (LEPs) as a diagnostic tool in patients with post-herpetic neuralgia (PHN), i.e. a chronic painful condition that causes small-diameter fibre dysfunction. Furthermore, we sought information on pathophysiology of PHN pain.Methods: We recorded ‘late’ LEPs after stimulation of the supraorbital, upper cervical, lower cervical, upper thoracic, mid thoracic, and lower thoracic territories in 12 control subjects and 40 patients with PHN. We also determined the correlation of LEP data with age, duration of disease, and severity and quality of pain.Results: At all stimulation sites, laser pulses invariably evoked high-amplitude brain potentials related to small-myelinated (A-delta) fibre activation. The laser perceptive threshold and LEP latency correlated with the distance of the dermatome from the brain (P<0.001). In patients, the perceptive threshold was higher and the LEP amplitude was lower in the affected dermatome than on the contralateral side (P<0.001). We found no significant LEP-clinical correlation except for a correlation between LEP abnormality and age.Conclusions: Being sensitive and reliable in assessing sensory function also in proximal dermatomes, LEPs are a promising diagnostic tool in radiculopathies. Although PHN severely impairs small myelinated fibres, the lack of a significant correlation between LEP abnormalities and pain suggests that pain in PHN does not chiefly arise from a dysfunction of small-myelinated afferents.     

Motor cortex rTMS reduces acute pain provoked by laser stimulation in patients with chronic neuropathic pain

ObjectiveTo assess the modulation of acute provoked pain by repetitive transcranial magnetic stimulation (rTMS) of the motor cortex in patients with chronic neuropathic pain.MethodsIn 32 patients with chronic neuropathic pain affecting one upper limb, laser-evoked potentials (LEPs) (N2 and P2 components) were recorded in response to laser stimulation of the painful or painless hand, before and after active or sham rTMS applied at 10 Hz over the motor cortex corresponding to the painful hand. Laser-induced pain was scored on a visual analogue scale.ResultsBoth active and sham rTMS reduced N2–P2 amplitude of the LEPs in response to painful or painless hand stimulation, likely due to the decline of attention during the sessions. However, active rTMS, but not sham rTMS, specifically reduced N2 amplitude and N2/P2 amplitude ratio of the painful hand LEPs. Painful hand LEP attenuation correlated with the magnitude of pain relief produced by active rTMS.ConclusionMotor cortex rTMS delivered at high frequency (10 Hz) was able to reduce LEP amplitude in parallel with laser-induced pain scores in patients with chronic neuropathic pain. The preferential change in the N2 component suggested a modulation of the sensori-discriminative aspect of laser-induced pain.SignificancePrevious studies have shown that rTMS delivered to various cortical targets by different protocols could modulate experimental pain, primarily in healthy subjects. The present results demonstrate the ability of motor cortex rTMS to interfere with the processing of acute provoked pain, even if there is an underlying chronic neuropathic pain.     

Spinal DC stimulation in humans modulates post-activation depression of the H-reflex depending on current polarity

ObjectiveTranscranial direct current stimulation induces long-lasting changes in cortical excitability in humans depending on the current used. Further, transcutaneous spinal application of direct current (tsDCS) induces plastic changes in spinal conduction properties, tested by somatosensory evoked potentials. To verify this thesis on plastic changes in spinal circuitry, we investigated the effects of tsDCS on H-reflex size and post-activation depression.MethodsTen healthy subjects participated in the study. The H_max/M_max ratio and H-reflex post-activation depression were evaluated before, at current offset, and 15 min after anodal, cathodal or sham tsDCS. Stimulation of the spinal cord (2.5 mA, 0.063 mA/cm², 0.056 C/cm²) was applied for 15 min at Th11 level.ResultsAnodal tsDCS induced a lasting decrease in H-reflex post-activation depression, while cathodal stimulation resulted in a sustained increase. Sham stimulation had no significant effects. The H_max/M_max ratio remained unchanged throughout all conditions.ConclusionAnodal and cathodal tsDCS is a non-invasive and painless method that is able to induce lasting changes in the efficacy of the Ia fibre-motoneurone synapse.SignificanceTranscutaneous spinal DC stimulation might be a valuable new tool in modulating spinal motor pathways.     

Peripheral Nerve Stimulation Inhibits Nociceptive Processing: An Electrophysiological Study in Healthy Volunteers

Objectives. Electric peripheral nerve stimulation (PNS) is a neuromodulatory therapy in pain patients. The efficacy of this neurosurgical pain treatment is controversial because its antinociceptive effect in humans has not been objectively proven so far. Materials and Methods. Noxious infrared laser stimulation of the left hand dorsum evoked cortical potentials (LEP) by selective excitation of Aδ‐fiber nociceptors in 15 healthy volunteers under control and PNS conditions. LEP were recorded before, during, and after electric Aβ‐fiber stimulation (PNS) of the left superficial radial nerve. In the control session LEP were recorded without PNS. Laser stimulus intensity ratings, LEP latencies, and amplitudes were statistically analyzed (anova ). Results. During PNS, LEP amplitudes (p < 0.001) and laser intensity ratings (p < 0.05) significantly decreased, and LEP latencies significantly increased (p < 0.05). Under control conditions LEP and intensity ratings remained unchanged. Conclusions. The electrophysiologic data provide evidence that electric stimulation of peripheral Aβ‐fibers reliably suppresses Aδ‐fiber nociceptive processing in human volunteers.     

Dissociation between cutaneous silent period and laser evoked potentials in assessing neuropathic pain

In this study we investigate whether the cutaneous silent period (CSP)—an inhibitory response evoked in hand muscles by painful digital nerve stimulation—is useful for assessing nociceptive pathway function in patients with neuropathic pain. In 40 patients with peripheral neuropathy (21 without and 19 with neuropathic pain) we recorded the CSP in the abductor digiti minimi after fifth digit stimulation and also recorded laser evoked potentials (LEPs) after stimulation applied to the ulnar territory of the hand. Although the LEP amplitude was significantly lower in patients with pain than in those without (P < 0.005), the CSP duration did not differ between groups (P > 0.50). Pain intensity correlated significantly with LEP amplitudes (P < 0.005) but not with CSP duration (P > 0.5). Our findings indicate that the CSP is not useful for assessing nociceptive pathway function in patients with neuropathic pain. Muscle Nerve, 2008     

The auditory startle response in relation to outcome in functional movement disorders

BackgroundThe auditory startle reflex (ASR) is enlarged in patients with functional movement disorders (FMD).ObjectivesTo study whether the ASR relates to symptom reduction in FMD patients, who participated in a placebo controlled double blind treatment trial with Botulinum Neurotoxin (BoNT).MethodsResponse to treatment in the BoNT study was assessed using the Clinical Global Impression – Improvement scale (CGI-I). The electromyography (EMG) muscle activity of 7 muscles following 110 dB tones was measured in 14 FMD patients before and after one-year treatment and compared to 11 matched controls. The early and a late (behaviorally affected) component of the ASR and the sympathetic skin response (SSR) were assessed.Results10 of 14 patients (71.4%) showed symptom improvement, which was believed to be mainly caused by placebo effects. The early total response probability of the ASR at baseline tended to be larger in patients compared to controls (p = 0.08), but normalized at follow-up (p = 0.84). The late total response probability was larger in patients vs. controls at baseline (p < 0.05), a trend that still was present at follow-up (p = 0.08). The SSR was higher in patients vs. controls at baseline (p < 0.01), and normalized at follow-up (p = 0.71).ConclusionsOn a group level 71.4% of the patients showed clinical symptom improvement after treatment. The early part of the ASR, most likely reflecting anxiety and hyperarousal, normalized in line with the clinical improvement. Interestingly, the augmented late component of the ASR remained enlarged suggesting persistent altered behavioral processing in functional patients despite motor improvement.     

Neuromodulation of lower limb motor responses with transcutaneous lumbar spinal cord direct current stimulation

Objective

Trans-spinal direct current stimulation (tsDCS) is a promising technique to modulate spinal circuits. Combining clinical with modelling studies can improve effectiveness of tsDCS protocols. The aim of this study is to measure the effects of lumbar tsDCS on motor spinal responses and observe if these are consistent with the electric field (E-field) predicted from a computational model.

Changes in daily energy expenditure and movement behavior in unilateral vestibular hypofunction: Relationships with neuro-otological parameters

The vestibular system has been found to affect energy homeostasis and body composition, due to its extensive connections to the brainstem and melanocortin nuclei involved in regulating the metabolism and feeding behavior. The aim of this study was to evaluate – by means of a wrist-worn physical activity tracker and bioelectrical impedance analysis (BIA) – the energy expenditure (EE) in resting (REE) and free-living conditions and movement behavior in a group of chronic unilateral vestibular hypofunction (UVH) patients when compared with a control group (CG) of healthy participants. Forty-six chronic UVH and 60 CG participants underwent otoneurological (including video-Head Impulse Test [vHIT] for studying vestibulo-ocular reflex [VOR] and static posturography testing [SPT]), and EE and movement measurements and self–report (SRM) and performance measures (PM). As well as significant (p < 0.001) changes in SPT variables (area and path length) and SRM/PM, UVH participants also demonstrated significantly (p < 0.001) lower values in REE, movement EE, hours/day spent upright, number of strides and distance covered and total daily EE (p = 0.007) compared to the CG. UVH patients consumed significantly lower Kcal/min in sweeping (p = 0.001) and walking upstairs and downstairs (p < 0.001) compared to the CG. Multiple correlations were found between free-living and resting EE and neuro-otological parameters in UVH participants. Since the melanocortin system could be affected along the central vestibular pathways as a consequence of chronic vestibular deafferentation, data collected by reliable wearables could reflect the phenomena that constitute an increased risk of falls and sedentary lifestyle for patients affected by UVH, and could improve rehabilitation stages.     

(VISIION-S): Viz.ai Implementation of Stroke augmented Intelligence and communications platform to improve Indicators and Outcomes for a comprehensive stroke center and Network – Sustainability

ObjectivesAs Comprehensive Stroke Centers (CSCs) strive to improve neuro-intervention (NIR) times, process improvements are put in place to streamline workflows. Our prior publication (VISIION) demonstrated improvements in key performance indicators (KPIs). The purpose VISIION-S was to analyze whether those results were sustainable.Materials and methodsConsecutive Direct Arriving LVO (DALVO) and telemedicine transfer LVO (BEMI) stroke NIR cases were assessed, including subgroups of DALVO-OnHours, DALVO-OffHours, BEMI-OnHours, and BEMI-OffHours. We analyzed times for the original 6 months pre (6/10/20-1/15/21) and compared them to a 17 month post-implementation period (1/16/21- 6/25/22) to evaluate for sustainability. Mann-Whitney U was utilized.Results150 NIR cases were analyzed pre (n = 47) v. post (n = 103) implementation (DALVO-OnHours 7 v. 20, DALVO-OffHours 10 v. 25, BEMI-OnHours 13 v. 20, BEMI-OffHours 17 v. 38). For Door-to-groin (DTG), improvement was noted for DALVO-OffHours 39%(157 min,96 min;p < 0.001), DALVO-ALL 25%(127 min,95 min;p = 0.006), BEMI-OffHours 46%(45 min,25 min;p = 0.023), and BEMI-ALL 40%(42 min,25 min;p = 0.005). Activation-to-groin (ATG), door-to-device (DTD), and door-to-recanalization (DTR) also showed statistical improvements. For DALVO-OffHours, there were reductions in door to CT (DTC) 80%(26 min,5 min;p < 0.001), ATG 32%(90 min,61 min;p = 0.036), DTG 39%(157 min,96 min;p < 0.001), DTD 31%(178 min,123 min;p = 0.002), and DTR 32%(197 min,135 min;p = 0.003).ConclusionsWe noted sustainability over a 17 month period with sustained reduction in KPIs for even more NIR time interval comparisons. In the greatest opportunity subgroup (DALVO-OffHours), we noted a reduction in all 5 time interval metrics. Our sustainability finding is important to show that process improvements continued even after the immediate period, adding credibility to the results. Models such as this could be useful for other centers striving to optimize workflow and improve times.     

Altered cortical gray matter volume and functional connectivity after transcutaneous spinal cord direct current stimulation in idiopathic restless legs syndrome

ObjectiveTo explore the neurophysiological mechanism of clinically effective transcutaneous spinal cord direct current stimulation (tsDCS) on idiopathic restless legs syndrome (RLS), structural magnetic resonance imaging (sMRI), and resting-state functional MRI (rs-fMRI) were applied to reveal the structural and functional changes in idiopathic RLS patients after tsDCS.MethodsThirty idiopathic RLS patients and 20 gender- and age-matched healthy controls (HC) were enrolled. All patients were randomly divided into anodal treatment group and sham treatment group and were treated with tsDCS for 2 weeks. The international RLS Rating Scale (IRLS-RS) and Pittsburgh Sleep Quality Index (PSQI) were used to evaluate the severity of RLS and sleep quality respectively. The sMRI and rs-fMRI data of anodal treatment group and HC were collected. Voxel-based morphology (VBM) and resting-state functional connectivity analysis were used to assess the change of cortical gray matter volume (GMV) and corresponding functional connectivity (FC) respectively in anodal treatment group after tsDCS treatment.ResultsSham treatment group showed no significant change in IRLS-RS and PSQI scores after tsDCS, while significant decrease scores were observed in anodal treatment group, and the improvement sustained up to 2 weeks. Anodal treatment group showed significant regional decrease of GMV in bilateral cuneus compared to the HC. After tsDCS treatment, the GMV in the bilateral cuneus and left ventral post central gyrus (PoCG_L) decreased significantly. The FC between bilateral cuneus and left primary visual cortex (V1_L), and between right cuneus (Cune_R) and right lingual gyrus (LG_R) increased significantly after tsDCS, whereas the FC between PoCG_L and supplementary motor area (SMA) decreased significantly. The changed FC between PoCG_L and SMA, between Cune_R and V1_L were correlated with the changed IRLS-RS.ConclusionDisturbance of sensorimotor network and visual processing network may be involved in the pathogenesis of RLS. tsDCS probably can regulate FC in the sensorimotor cortex and visual processing cortex to relieve the symptom of RLS. Continuous tsDCS may improve the symptoms of RLS patients for a long time. tsDCS probably could provide a potential non-pharmacologic treatment for idiopathic RLS patients.     

Modulatory effects of anodal transcranial direct current stimulation on perception and pain thresholds in healthy volunteers

Background and purpose: We aimed to evaluate whether transcranial direct current stimulation (tDCS) is effective in modulating sensory and pain perception thresholds in healthy subjects as to further explore mechanisms of tDCS in pain relief. Methods: Twenty healthy subjects received stimulation with tDCS under four different conditions of stimulation: anodal tDCS of the primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), occipital cortex (V1), and sham tDCS. The order of conditions was randomized and counterbalanced across subjects. Perception threshold and pain threshold to peripheral electrical stimulation of the right index finger were evaluated by a blinded rater. Results: The results showed a significant effect of the interaction time versus stimulation condition for perception (P = 0.046) and pain threshold (P = 0.015). Post hoc comparisons revealed that anodal stimulation of M1 increased both perception (P < 0.001, threshold increase of 6.5%) and pain (P = 0.001, threshold increase of 8.3%) thresholds significantly, whilst stimulation of the DLPFC increased pain threshold only (P = 0.046, threshold increase of 10.0%). There were no significant effects for occipital or sham stimulation. Conclusions: These results show that both M1 and DLFPC anodal tDCS can be used to modulate pain thresholds in healthy subjects; thus, the mechanism of tDCS in modulating pain involves pathways that are independent of abnormal pain‐related neural activity.     

Theta-burst versus 20 Hz repetitive transcranial magnetic stimulation in neuropathic pain: A head-to-head comparison

ObjectiveHigh-frequency repetitive transcranial magnetic stimulation (rTMS) has been shown to reduce neuropathic pain, but intermittent “theta-burst” stimulation (iTBS) could be a better alternative because of shorter duration and greater ability to induce cortical plasticity. Here we compared head-to-head the pain-relieving efficacy of the two modalities when applied daily for 5 days to patients with neuropathic pain.MethodsForty-six patients received 20 Hz-rTMS and/or iTBS protocols and 39 of them underwent the full two procedures in a random cross-over design. They rated pain intensity, sleep quality, fatigue and general health status daily during 5 consecutive weeks.ResultsPain relief during the month following stimulation was superior after 20 Hz-rTMS relative to iTBS (F(1,38) = 4.645; p = 0.037). Correlation between respective levels of maximal relief showed a significant deviation toward the 20 Hz-rTMS effect. A greater proportion of individuals responded to 20 Hz-rTMS (52% vs 32%, 95 %CI[0.095–3.27]; p = 0.06), and reports of fatigue significantly improved after 20 Hz-rTMS relative to iTBS (p = 0.01). General health and sleep quality scores did not differentiate both techniques.ConclusionsHigh-frequency rTMS appeared superior to iTBS for neuropathic pain relief.SignificanceAdequate matching between the oscillatory activity of motor cortex and that of rTMS may increase synaptic efficacy, thus enhancing functional connectivity of motor cortex with distant structures involved in pain regulation.     

Effects of curved-walking training on curved-walking performance and freezing of gait in individuals with Parkinson's disease: A randomized controlled trial

IntroductionThe purpose of this study was to investigate the effects of curved-walking training (CWT) on curved-walking performance and freezing of gait (FOG) in people with Parkinson's disease (PD).MethodsTwenty-four PD subjects were recruited and randomly assigned to the CWT group or control exercise (CE) group and received 12 sessions of either CWT with a turning-based treadmill or general exercise training for 30 min followed by 10 min of over-ground walking in each session for 4–6 weeks. The primary outcomes included curved-walking performance and FOG. All measurements were assessed at baseline, after training, and at 1-month follow-up.ResultsOur results showed significant improvements in curved-walking performance (speed, p = 0.007; cadence, p = 0.003; step length, p < 0.001) and FOG, measured by a FOG questionnaire (p = 0.004). The secondary outcomes including straight-walking performance (speed, cadence and step length, p < 0.001), timed up and go test (p = 0.014), functional gait assessment (p < 0.001), Unified Parkinson's disease Rating Scale III (p = 0.001), and quality of life (p < 0.001) were also improved in the experimental group. We further noted that the improvements were maintained for at least one month after training (p < 0.05).ConclusionA 12-session CWT program can improve curved-walking ability, FOG, and other measures of functional walking performance in individuals with PD. Most of the improvements were sustained for at least one month after training.     

Selective augmentation of corticospinal motor drive with trans-spinal direct current stimulation in the cat

BackgroundA key outcome for spinal cord stimulation for neurorehabilitation after injury is to strengthen corticospinal system control of the arm and hand. Non-invasive, compared with invasive, spinal stimulation minimizes risk but depends on muscle-specific actions for restorative functions.ObjectiveWe developed a large-animal (cat) model, combining computational and experimental techniques, to characterize neuromodulation with transcutaneous spinal direct current stimulation (tsDCS) for facilitation of corticospinal motor drive to specific forelimb muscles.MethodsAcute modulation of corticospinal function by tsDCS was measured using motor cortex-evoked muscle potentials (MEPs). The effects of current intensity, polarity (cathodal, anodal), and electrode position on specific forelimb muscle (biceps vs extensor carpi radialis, ECR) MEP modulation were examined. Locations of a key target, the motoneuron pools, were determined using neuronal tracing. A high-resolution anatomical (MRI and CT) model was developed for computational simulation of spinal current flow during tsDCS.ResultsEffects of tsDCS on corticospinal excitability were robust and immediate, therefore supporting MEPs as a sensitive marker of tsDCS targeting. Varying cathodal/anodal current intensity modulated MEP enhancement/suppression, with higher cathodal sensitivity. Muscle-specificity depended on cathode position; the rostral position preferentially augmented biceps responses and the caudal position, ECR responses. Precise anatomical current-flow modeling, supplemented with target motor pool distributions, can explain tsDCS focality on muscle groups.ConclusionAnatomical current-flow modeling with physiological validation based on MEPs provides a framework to optimize muscle-specific tsDCS interventions. tsDCS targeting of representative motor pools enables muscle- and response-specific neuromodulation of corticospinal motor drive.     

Inhibition of Cortical Laser‐Evoked Potentials by Transcutaneous Electrical Nerve Stimulation

Objectives. This study attempts to confirm the hypothesis that transcutaneous electrical stimulation (TENS) of peripheral Aβ fibers inhibits nociceptive processing, by quantifying the change of laser‐evoked potential (LEP) components, using a 980‐nm diode laser. Materials and Methods. Cutaneous heat stimuli were delivered to the dorsum of the right hand in 13 volunteers. LEPs and pain intensity ratings were recorded before, during, and after the use of TENS (110 Hz) at the dorsolateral forearm. Area under the curve (AUC), LEP amplitudes (N2P2), and peak latencies (N2, P2) were calculated. The paired samples t‐test was used for statistical analysis. Results. A significant reduction of LEP amplitudes and AUC was found during and after the use of TENS (p < 0.05). After 10 min of TENS this was associated with a clinically relevant decrease of pain intensity. Conclusions. Our data suggest that TENS inhibits nociceptive processing. Ten minutes of TENS exerts a clinically relevant pain reduction.