Using visual illusion to reduce at-level neuropathic pain in paraplegia

Effectiveness of virtual-walking intervention combined with exercise on improving pain and function in incomplete spinal cord injury: a feasibility study

STUDY DESIGN

A feasibility pilot study.

OBJECTIVE

To assess the feasibility a full-scale Randomized Controlled Trial aimed at assessing the beneficial effect of a Virtual Walking (VW)-based (Experimental intervention (EI)) on neuropathic pain and functionality in people with incomplete spinal cord injury (SCI).

SETTING

A hospital service (Hospital Universitario y Politécnico La Fe) and disability associations (TetraSport, CODIFIVA and ASPAYM).

METHODS

Twelve people with chronic incomplete SCI were randomized to EI (VW plus therapeutic exercise program (TE)) -or Control Intervention (CI (placebo VW and TE)) groups. A six-week intervention (3 sessions/week) was carried out. To assess feasibility, the following outcomes were used: level of restriction and validity of inclusion and exclusion criteria, participants' compliance, accessibility and acceptability of the intervention for participants, adequate pre-training time of physiotherapists. To explore therapy effectiveness, pain severity, and interference, mean and maximum isometric strength, walking speed, and walking ability were assessed before (Time 1, T1) and after (Time 2, T2) the intervention.

RESULTS

20% of the participants initially recruited did not meet inclusion criteria. In addition, all participants completed at least 80% of the intervention sessions and none of the participants dropped out before T2. No serious adverse event was found. Moreover, 91.67% of participants were willing to perform the intervention again and all therapists involved were adequately pre-trained. Finally, our preliminary results suggest that the proposed EI is effective.

CONCLUSION

A full-scale RCT is feasible and preliminary results suggest that VW with TE could have a beneficial impact on pain and functionality in this population.

Virtual walking therapy in neuropathic spinal cord injury pain: a feasibility study

STUDY DESIGN

A feasibility study.

OBJECTIVES

Chronic neuropathic pain is a prevalent comorbidity in patients with spinal cord injury (SCI), and current medical treatments remain unsatisfactory. New developments as virtual walking are emerging which has been established and further developed at our centre. This study aims to investigate the feasibility of our virtual walking setup in a small group of SCI patients.

SETTING

The study was conducted at the Swiss Paraplegic Centre in Nottwil, Switzerland.

METHODS

Four patients aged 22 to 60 years were observed during and after therapy. Three had complete paraplegia (levels Th4-Th8) with neuropathic at- and below-level pain, while one had incomplete paraplegia (Th10) with at-level pain. The primary outcome measured was satisfaction with acceptance of and adherence to virtual walking therapy, alongside suggestions for therapy improvements. Additionally, patients kept a pain diary and pain drawings to measure the extent of pain distribution and intensity before and after therapy. Therapy schedules included either two sessions per week for five weeks or five sessions per week for two weeks.

RESULTS

There was a sound satisfaction and good acceptance amongst participants. Support, duration, and number of sessions were perceived well and acceptable. Pain as a secondary outcome did not change during or after therapy in all but one patient which improved in pain intensity, pain quality as well as pain distribution.

CONCLUSION

Results suggest that our virtual walking setting is a feasible tool that should be further studied in patients with SCI-related chronic neuropathic pain.

Neuropathic pain development and maintenance and its association with motor recovery after cervical spinal cord injury

BACKGROUND

In our published randomized controlled trial, we revealed that patients with acute ASIA Grade C incomplete cervical spinal cord injury (SCI) who underwent early surgery (within 24 h post-injury) had accelerated motor recovery at six months than those with delayed surgery (>2 weeks post-injury); however, neuropathic pain (NeP) worsened regardless of surgery timing. Here, we conducted post-hoc analyses to intensively assess NeP development and maintenance.

METHODS

Of 44 patients (median 64.5 years; three female; early intervention, n = 26), NeP was categorized into at-level and below-level pain and evaluated at  two weeks and one year after injury using the Neuropathic Pain Symptom Inventory (NPSI). We compared the two groups based on background characteristics. A mixed-design analysis of variance with sex as a covariate was conducted to analyze motor recovery and Health-related quality of life (HRQOL) in groups with severe (NPSI ≥ 10) or mild (NPSI < 10) pain.

RESULTS

Upper and lower limb motor impairments were comparable between both groups regardless of pain severity. Severe at-level pain remained stable and worsened at one year than mild at-level pain; however, the upper- and lower-limb motor scores and HRQOL had comparable recovery. Background characteristics did not affect severity or time course of NeP. Patients with severe below-level pain demonstrated slower lower-limb motor recovery than those with mild below-level pain, whereas HRQOL improved regardless of pain severity.

CONCLUSIONS

Both at-level and below-level NeP developed and persisted relatively early in the course of traumatic SCI with incomplete motor paralysis; their severities worsened over time or remained severe since onset.

The possible neural mechanism of neuropathic pain evoked by motor imagery in pediatric patients with complete spinal cord injury: A preliminary brain structure study based on VBM

In this study, we observed pediatric complete spinal cord injury (CSCI) patients receiving MI training and divided them into different groups according to the effect of motor imagery (MI) training on neuropathic pain (NP). Then, we retrospectively analysed the differences in brain structure of these groups before the MI training, identifying brain regions that may predict the effect of MI on NP. Thirty pediatric CSCI patients were included, including 12 patients who experienced NP during MI and 18 patients who did not experience NP during MI according to the MI training follow-up. The 3D high-resolution T1-weighted images of all subjects were obtained using a 3.0 T MRI system before MI training. A two-sample t-test was performed to evaluate the differences in gray matter volume (GMV) between patients who experienced NP and those who did not experience NP during MI. Receiver operating characteristic (ROC) analysis was performed to compute the sensitivity and specificity of the imaging biomarkers for the effect of MI on NP in pediatric CSCI patients. MI evoked NP in some of the pediatric CSCI patients. Compared with patients who did not experience NP, patients who experienced NP during MI showed larger GMV in the right primary sensorimotor cortex (PSMC) and insula. When using the GMV of the right PSMC and insula in combination as a predictor, the area under the curve (AUC) reached 0.824. Our study demonstrated that MI could evoke NP in some pediatric CSCI patients, but not in others. The individual differences in brain reorganization of the right PSMC and insula may contribute to the different effects of MI on NP. Moreover, the GMV of the right PSMC and insula in combination may be an effective indicator for screening pediatric CSCI patients before MI training therapy.

Neuropathic pain: From actual pharmacological treatments to new therapeutic horizons

Neuropathic pain, caused by a lesion or disease affecting the somatosensory system, affects between 3 and 17% of the general population. The treatment of neuropathic pain is challenging due to its heterogeneous etiologies, lack of objective diagnostic tools and resistance to classical analgesic drugs. First-line treatments recommended by the Special Interest Group on Neuropathic Pain (NeuPSIG) and European Federation of Neurological Societies (EFNS) include gabapentinoids, tricyclic antidepressants (TCAs) and selective serotonin noradrenaline reuptake inhibitors (SNRIs). Nevertheless these treatments have modest efficacy or dose limiting side effects. There is therefore a growing number of preclinical and clinical studies aim at developing new treatment strategies to treat neuropathic pain with better efficacy, selectivity, and less side effects. In this review, after a brief description of the mechanisms of action, efficacy, and limitations of current therapeutic drugs, we reviewed new preclinical and clinical targets currently under investigation, as well as promising non-pharmacological alternatives and their potential co-use with pharmacological treatments.

Cortical Mechanisms Underlying Immersive Interactive Virtual Walking Treatment for Amelioration of Neuropathic Pain after Spinal Cord Injury: Findings from a Preliminary Investigation of Thalamic Inhibitory Function

BACKGROUND

Neuropathic pain following spinal cord injury (SCI) affects approximately 60% of individuals with SCI. Effective pharmacological and non-pharmacological treatments remain elusive. We recently demonstrated that our immersive virtual reality walking intervention (VRWalk) may be effective for SCI NP. Additionally, we found that SCI NP may result from a decrease in thalamic γ-aminobutyric-acid (GABA), which disturbs central sensorimotor processing.

OBJECTIVE

While we identified GABAergic changes associated with SCI NP, a critical outstanding question is whether a decrease in SCI NP generated by our VRWalk intervention causes GABA content to rise.

METHOD

A subset of participants (n = 7) of our VRWalk trial underwent magnetic resonance spectroscopy pre- and post-VRWalk intervention to determine if the decrease in SCI NP is associated with an increase in thalamic GABA.

RESULTS

The findings revealed a significant increase in thalamic GABA content from pre- to post-VRWalk treatment.

CONCLUSION

While the current findings are preliminary and should be interpreted with caution, pre- to post-VRWalk reductions in SCI NP may be mediated by pre- to post-treatment increases in thalamic GABA by targeting and normalizing maladaptive sensorimotor cortex reorganization. Understanding the underlying mechanisms of pain recovery can serve to validate the efficacy of home-based VR walking treatment as a means of managing pain following SCI. Neuromodulatory interventions aimed at increasing thalamic inhibitory function may provide more effective pain relief than currently available treatments.

Effect of virtual running with exercise on functionality in pre-frail and frail elderly people: randomized clinical trial

BACKGROUND

Virtual mirror therapies could increase the results of exercise, since the mirror neuron system produces an activation of motor execution cortical areas by observing actions performed by others. In this way, pre-frail and frail people could use this system to reach an exercise capacity threshold and obtain health benefits.

AIM

The aim of this study is to evaluate the effects of a virtual running (VR) treatment combined with specific physical gait exercise (PE) compared to placebo VR treatment combined with PE on functionality, pain, and muscular tone in pre-frail and frail older persons.

METHODS

A single blinded, two-arm, randomised controlled trial design was employed. Thirty-eight participants were divided into two intervention arms: Experimental Intervention (EI) group, in which VR and gait-specific physical exercises were administered and Control Intervention (CI) group, in which a placebo virtual gait and the same exercise programme was administered. Functionality, pain, and tone were assessed.

RESULTS

EI group improved in aerobic capacity, functional lower-limb strength, reaction time, and pain, while CI group remained the same. Regarding static balance and muscle tone, no differences were found for either group. Further analysis is needed to asses VR effectiveness for improving gait, stand-up and sit-down performance and velocity.

CONCLUSIONS

Virtual running therapy appears to enhance capacities related with voluntary movements (i.e., aerobic capacity, functional lower-limb strength, and reaction time) and reduce pain.

The role of virtual reality as adjunctive therapy to spinal cord stimulation in chronic pain: A feasible concept?

Spinal cord stimulation and virtual reality therapy are established and promising techniques, respectively, for managing chronic pain, each with its unique advantages and challenges. While each therapy has been the subject of significant research interest, the prospect of combining the two modalities to offer a synergistic effect in chronic pain therapy is still in its infancy. In this narrative review, we assess the state of the field combining virtual reality as an adjunctive therapy to spinal cord stimulation in chronic pain. We also review the broader field of virtual reality therapy for acute and chronic pain, considering evidence related to feasibility in the Canadian healthcare system from cost and patient satisfaction perspectives. While early results show promise, there are unexplored aspects of spinal cord stimulation combined with virtual reality therapy, particularly long-term effects on analgesia, anxiolysis, and implications on the effectiveness and longevity of spinal cord stimulation. The infrastructure for billing virtual reality as a consult service or therapy must also catch up if it is eventually used to supplement spinal cord stimulation for chronic pain.

VR for Pain Relief

The present chapter explores how immersive virtual reality (VR) systems can be used for pain research and treatment. Pain is a universal, yet entirely subjective and multifaceted unpleasant experience. One of the earliest VR studies on pain highlighted the role of attention in pain modulation. However, the role of body representation in pain modulation has also been described as a crucial factor. Through virtual reality systems, it is possible to modulate both attention to pain and body representation. In this chapter, first we define how immersive VR can be used to create the illusion of being present in immersive VR environments and argue why VR can be an effective tool for distracting patients from acute pain. However, distraction seems to be less useful in chronic pain treatment. Chronic pain can be highly disabling and can significantly impact not only the sufferer's quality of life, but also their perceptions of the bodily self. Close neural connections between the body matrix and pain open a chance for influencing pain through bodily illusions. This chapter explores approaches to inducing body ownership illusions in VR and discusses how they have been applied in pain research. The present chapter also covers a set of practical indications and methodological caveats of immersive VR and solutions for overcoming them. Finally, we outline several promising future research directions and highlight several yet unexplored areas.

Altered bodily perceptions in chronic neuropathic pain conditions and implications for treatment using immersive virtual reality

Chronic neuropathic pain is highly disabling and difficult to treat and manage. Patients with such conditions often report altered bodily perceptions that are thought to be associated with maladaptive structural and functional alterations in the somatosensory cortex. Manipulating these altered perceptions using body illusions in virtual reality is being investigated and may have positive clinical implications for the treatment of these conditions. Here, we have conducted a narrative review of the evidence for the types of bodily distortions associated with a variety of peripheral and central neuropathic pain conditions. In addition, we summarize the experimental and clinical studies that have explored embodiment and body transformation illusions in immersive virtual reality for neuropathic pain relief, which are thought to target these maladaptive changes, as well as suggesting directions for future research.

Embodiment Comfort Levels During Motor Imagery Training Combined With Immersive Virtual Reality in a Spinal Cord Injury Patient

Brain-machine interfaces combining visual, auditory, and tactile feedback have been previously used to generate embodiment experiences during spinal cord injury (SCI) rehabilitation. It is not known if adding temperature to these modalities can result in discomfort with embodiment experiences. Here, comfort levels with the embodiment experiences were investigated in an intervention that required a chronic pain SCI patient to generate lower limb motor imagery commands in an immersive environment combining visual (virtual reality -VR), auditory, tactile, and thermal feedback. Assessments were made pre-/ post-, throughout the intervention (Weeks 0-5), and at 7 weeks follow up. Overall, high levels of embodiment in the adapted three-domain scale of embodiment were found throughout the sessions. No significant adverse effects of VR were reported. Although sessions induced only a modest reduction in pain levels, an overall reduction occurred in all pain scales (Faces, Intensity, and Verbal) at follow up. A high degree of comfort in the comfort scale for the thermal-tactile sleeve, in both the thermal and tactile feedback components of the sleeve was reported. This study supports the feasibility of combining multimodal stimulation involving visual (VR), auditory, tactile, and thermal feedback to generate embodiment experiences in neurorehabilitation programs.

Long-term physical therapy for neuropathic pain after cervical spinal cord injury and resting state electroencephalography: a case report

INTRODUCTION

Neuropathic pain after spinal cord injury is difficult to treat, and it is associated with abnormalities in the function of the thalamus-to-cortex neural circuitry. Aerobic exercise provides immediate improvement in neuropathic pain and is associated with abnormal resting electroencephalography (EEG) findings in patients with spinal cord injury. This study aimed to investigate whether physical therapy, including walking, can improve neuropathic pain and EEG peak alpha frequency (PAF) in the long term in a patient with cervical spinal cord injury.

CASE PRESENTATION

A 50-year-old man was admitted with a cervical spinal cord insufficiency injury sustained one week prior. The residual height was C5. Neuropathic pain was observed in the fingers bilaterally. A numerical rating scale (NRS) was evaluated to measure the weekly mean and maximum intensities of pain. Resting EEG was measured, and the PAF was calculated. Each time point was evaluated in 2-week intervals from the time of admission, and the rate of change (Δ) of PAF was calculated based on the initial evaluation. Interventions included 18 weeks of standard physical therapy focusing on gait, with additional intensive gait training (4-10 weeks). The NRS scores for the mean and maximum intensities of pain decreased significantly after 6 weeks, and ΔPAF increased significantly after 4 weeks. Improvement in PAF coincided with the start of intensive gait training.

DISCUSSION

PAF shifts to a high frequency during intensive gait training, suggesting the effectiveness of aerobic exercise. Furthermore, there is a close relationship between PAF, pain, and the quantification of pain changes.

Immersive interactive virtual walking reduces neuropathic pain in spinal cord injury: findings from a preliminary investigation of feasibility and clinical efficacy

ABSTRACT

Chronic neuropathic pain (NP) is a common and often debilitating secondary condition for persons with spinal cord injury (SCI) and is minimally responsive to existing pharmacological and nonpharmacological treatments. The current preliminary investigation describes the feasibility and initial comparative efficacy of an interactive virtual reality walking intervention, which is a novel extension of visual feedback/illusory walking therapies shown to reduce SCI NP. Virtual reality walking intervention builds on previous research by, for the first time, allowing individuals with SCI NP to volitionally control virtual gait to interact with a fully immersive virtual environment. The current pilot study compared this interactive, virtual walking intervention to a passive, noninteractive virtual walking condition (analogous to previous illusory walking interventions) in 27 individuals with complete paraplegia (interactive condition, n = 17; passive condition, n = 10; nonrandomized design). The intervention was delivered over 2 weeks in individuals' homes. Participants in the interactive condition endorsed significantly greater reductions in NP intensity and NP-related activity interference preintervention to postintervention. Notable improvements in mood and affect were also observed both within individual sessions and in response to the full intervention. These results, although preliminary, highlight the potentially potent effects of an interactive virtual walking intervention for SCI NP. The current study results require replication in a larger, randomized clinical trial and may form a valuable basis for future inquiry regarding the mechanisms and clinical applications of virtual walking therapies.

The Analgesic Effects of Virtual Reality for People with Chronic Pain: A Scoping Review

OBJECTIVE

Although virtual reality is shown to have short-term analgesic effects in acute pain settings, its long-term efficacy in chronic pain conditions has not been established. This scoping review aims to provide a summary of virtual reality approaches explored in chronic primary and secondary pain conditions as defined by the International Association for the Study of Pain.

METHODS

A systematic literature search in Ovid PubMed and Ovid Embase was conducted between January 5 and January 10, 2021, with the use of the Arksey and O'Malley six-step scoping review criteria. Articles were searched via search terms and keywords relating to International Classification of Diseases-defined primary and secondary chronic pain conditions, virtual reality, virtual illusion, distraction, and effects on levels of pain.

RESULTS

Of the 2,118 articles located, 44 were included, which covered a range of primary and secondary chronic pain conditions and used a variety of different computer screen and headset protocols, including gaming, mindfulness, exercise, relaxation, and proprioceptive skills.

CONCLUSIONS

Studies show virtual reality to be an effective analgesic intervention for people with chronic pain. Given user satisfaction, a lack of side effects such as cybersickness, and relief of comorbid symptoms, virtual reality has potential as a worthwhile adjunct to chronic pain management programs, thus enabling patients to take control of their symptoms.

The CanPain SCI clinical practice guidelines for rehabilitation management of neuropathic pain after spinal cord injury: 2021 update

STUDY DESIGN

Clinical practice guidelines.

OBJECTIVES

The objective was to update the 2016 version of the Canadian clinical practice guidelines for the management of neuropathic pain in people with spinal cord injury (SCI).

SETTING

The guidelines are relevant for inpatient, outpatient and community SCI rehabilitation settings in Canada.

METHODS

The guidelines were updated in accordance with the Appraisal of Guidelines for Research and Evaluation II tool. A Steering Committee and Working Group reviewed the relevant evidence on neuropathic pain management (encompassing screening and diagnosis, treatment and models of care) after SCI. The quality of evidence was scored using Grading of Recommendations Assessment, Development and Evaluation (GRADE). A consensus process was followed to achieve agreement on recommendations and clinical considerations.

RESULTS

The working group identified and reviewed 46 additional relevant articles published since the last version of the guidelines. The panel agreed on 3 new screening and diagnosis recommendations and 8 new treatment recommendations. Two key changes to these treatment recommendations included the introduction of general treatment principles and a new treatment recommendation classification system. No new recommendations to model of care were made.

CONCLUSIONS

The CanPainSCI recommendations for the management of neuropathic pain after SCI should be used to inform practice.

Cost-utility analysis of transcranial direct current stimulation therapy with and without virtual illusion for neuropathic pain for adults with spinal cord injury in Canada

OBJECTIVE

To undertake a cost-utility analysis comparing virtual illusion (VI) and transcranial direct current stimulation (tDCS) combination therapy, tDCS alone and standard pharmacological care in Ontario, Canada from a societal perspective over a three-month time horizon.

DESIGN

Cost-utility analysis using Markov model methods.

SETTING

Community setting in Ontario, Canada.

PARTICIPANTS

Individuals with spinal cord injury and neuropathic pain (NP) resistant to pharmacological therapy.

INTERVENTIONS

Virtual illusion and transcranial direct current stimulation, transcranial direct current stimulation alone and standard pharmacological therapy.

OUTCOME MEASURES

Incremental costs, quality adjusted life years (QALY) and incremental cost effectiveness ratio.

RESULTS

The incremental cost effectiveness ratio of VI and tDCS therapy cost is $3,396 per QALY (2020 Canadian dollars) when compared to standard care. The incremental cost per QALY of tDCS therapy alone is $33,167. VI and tDCS therapy had lower incremental costs (-$519) and higher incremental QALYs (0.026) compared to tDCS alone. From a public healthcare payer perspective, there is a 74% probability that VI and tDCS therapy and 54% probability that tDCS alone would be cost effective at a $50,000 per QALY willingness-to-pay threshold. Our findings remained relatively robust in various scenario analyses.

CONCLUSION

Our findings suggest that at three-months after therapy, VI and tDCS combination therapy may be more cost effective than tDCS therapy alone. Based on conventional health technology funding thresholds, VI and tDCS combination therapy merits consideration for the treatment of NP in adults with spinal cord injuries.

Maladaptive reorganization following SCI: The role of body representation and multisensory integration

In this review we focus on maladaptive brain reorganization after spinal cord injury (SCI), including the development of neuropathic pain, and its relationship with impairments in body representation and multisensory integration. We will discuss the implications of altered sensorimotor interactions after SCI with and without neuropathic pain and possible deficits in multisensory integration and body representation. Within this framework we will examine published research findings focused on the use of bodily illusions to manipulate multisensory body representation to induce analgesic effects in heterogeneous chronic pain populations and in SCI-related neuropathic pain. We propose that the development and intensification of neuropathic pain after SCI is partly dependent on brain reorganization associated with dysfunctional multisensory integration processes and distorted body representation. We conclude this review by suggesting future research avenues that may lead to a better understanding of the complex mechanisms underlying the sense of the body after SCI, with a focus on cortical changes.

A Therapeutic Matrix: Virtual Reality as a Clinical Tool for Spinal Cord Injury-Induced Neuropathic Pain

Neuropathic pain (NP) is a chronic, debilitating, and resistant form of pain. The onset rate of NP following spinal cord injuries (SCI) is high and may reduce the quality of life more than the sensorimotor loss itself. The long-term ineffectiveness of current treatments in managing symptoms and counteracting maladaptive plasticity highlights the need to find alternative therapeutic approaches. Virtual reality (VR) is possibly the best way to administer the specific illusory or reality-like experience and promote behavioral responses that may be effective in mitigating the effects of long-established NP. This approach aims to promote a more systematic adoption of VR-related techniques in pain research and management procedures, highlighting the encouraging preliminary results in SCI. We suggest that the multisensory modulation of the sense of agency and ownership by residual body signals may produce positive responses in cases of brain-body disconnection. First, we focus on the transversal role embodiment and how multisensory and environmental or artificial stimuli modulate illusory sensations of bodily presence and ownership. Then, we present a brief overview of the use of VR in healthcare and pain management. Finally, we discus research experiences which used VR in patients with SCI to treating NP, including the most recent combinations of VR with further stimulation techniques.

Central Post-Stroke Pain: An Integrative Review of Somatotopic Damage, Clinical Symptoms, and Neurophysiological Measures

Introduction: The physiopathology of central post-stroke pain (CPSP) is poorly understood, which may contribute to the limitations of diagnostic and therapeutic advancements. Thus, the current systematic review was conducted to examine, from an integrated perspective, the cortical neurophysiological changes observed via transcranial magnetic stimulation (TMS), focusing on the structural damage, and clinical symptoms in patients with CPSP. Methods: The literature review included the databases EMBASE, PubMed, and ScienceDirect using the following search terms by MeSH or Entree descriptors: [("Cerebral Stroke") AND ("Pain" OR "Transcranial Magnetic Stimulation") AND ("Transcranial Magnetic Stimulation")] (through September 29, 2020). A total of 297 articles related to CPSP were identified. Of these, only four quantitatively recorded cortical measurements. Results: We found four studies with different methodologies and results of the TMS measures. According to the National Institutes of Health (NIH) guidelines, two studies had low methodological quality and the other two studies had satisfactory methodological quality. The four studies compared the motor threshold (MT) of the stroke-affected hemisphere with the unaffected hemisphere or with healthy controls. Two studies assessed other cortical excitability measures, such as cortical silent period (CSP), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF). The main limitations in the interpretation of the results were the heterogeneity in parameter measurements, unknown cortical excitability measures as potential prognostic markers, the lack of a control group without pain, and the absence of consistent and validated diagnosis criteria. Conclusion: Despite the limited number of studies that prevented us from conducting a meta-analysis, the dataset of this systematic review provides evidence to improve the understanding of CPSP physiopathology. Additionally, these studies support the construction of a framework for diagnosis and will help improve the methodological quality of future research in somatosensory sequelae following stroke. Furthermore, they offer a way to integrate dysfunctional neuroplasticity markers that are indirectly assessed by neurophysiological measures with their correlated clinical symptoms.

Illusion-enhanced Virtual Reality Exercise for Neck Pain: A Replicated Single Case Series

OBJECTIVES

Body illusions have shown promise in treating some chronic pain conditions. We hypothesized that neck exercises performed in virtual reality (VR) with visual feedback of rotation amplified would reduce persistent neck pain.

METHODS

In a multiple-baseline replicated single case series, 8 blinded individuals with persistent neck pain completed a 4-phase intervention (initial n=12, 4 dropouts): (1) "baseline"; (2) "VR" during which participants performed rotation exercises in VR with no manipulation of visual feedback; (3) "VR enhanced" during which identical exercises were performed but visual feedback overstated the range of motion being performed; (4) "follow-up." Primary outcomes were twice-daily measures of pain-free range of motion and pain intensity. During the baseline and follow-up phases, measures were taken but no intervention took place.

RESULTS

No differences in primary outcomes were found between VR and baseline, VR enhanced and VR, or VR enhanced and follow-up.

DISCUSSION

Our hypothesis, that neck exercises performed in VR with visual feedback of rotation amplified, would reduce persistent neck pain was not supported. Possible explanations and future directions are discussed.

Go Virtual to Get Real: Virtual Reality as a Resource for Spinal Cord Treatment

Increasingly, refined virtual reality (VR) techniques allow for the simultaneous and coherent stimulation of multiple sensory and motor domains. In some clinical interventions, such as those related to spinal cord injuries (SCIs), the impact of VR on people's multisensory perception, movements, attitudes, and even modulations of socio-cognitive aspects of their behavior may influence every phase of their rehabilitation treatment, from the acute to chronic stages. This work describes the potential advantages of using first-person-perspective VR to treat SCIs and its implications for manipulating sensory-motor feedback to alter body signals. By situating a patient with SCI in a virtual environment, sensorial perceptions and motor intention can be enriched into a more coherent bodily experience that also promotes processes of neural regeneration and plasticity. In addition to the great potential of research, the most significant areas of interest concern is managing neuropathic pain, motor rehabilitation, and psychological well-being.

Virtual reality for the treatment of neuropathic pain in people with spinal cord injuries: A scoping review

Context: Virtual and augmented imagery are emerging technologies with potential to reduce the severity and impact of neuropathic pain in people with spinal cord injury (SCI).Objective: We aimed to identify and discuss studies using virtual and augmented reality applications for the management of neuropathic pain in people with spinal cord injury.Methods (data sources, data extraction): A systematic literature search was conducted using PRISMA scoping review guidelines. Articles were searched in PubMed, Embase and Web of Science databases using search terms relating to SCI, virtual and augmented reality and neuropathic pain. With no strong evidence for visual imagery in the treatment of pain in SCI patients, we selected exploratory, feasibility and more rigorous methodologies such as randomized controlled trials and case-control studies. We only selected studies evaluating the effects of visual imagery on neuropathic pain at or below the spinal cord injury level.Results: Of 60 articles located, we included nine articles involving 207 participants. All studies were exploratory using head-mounted devices or 3D and 2D screens with virtual walking or limb movement imagery. Outcomes included pain sensitivity, motor function and body ownership. Eight of the nine studies reported significant reductions in neuropathic pain intensity. However, given small sample sizes in all studies, results may be unreliable.Conclusion: Although the number of studies and individual sample sizes are small, these initial findings are promising. Given the limited options available for the effective treatment of neuropathic SCI pain and early evidence of efficacy, they provide valuable incentive for further research.

Transcranial Direct Current Stimulation and Mirror Therapy for Neuropathic Pain After Brachial Plexus Avulsion: A Randomized, Double-Blind, Controlled Pilot Study

Introduction: Although transcranial direct current stimulation (tDCS) and mirror therapy (MT) have benefits in combating chronic pain, there is still no evidence of the effects of the simultaneous application of these techniques in patients with neuropathic pain. This study aims to assess the efficacy of tDCS paired with MT in neuropathic pain after brachial plexus injury. Methods: In a sham controlled, double-blind, parallel-group design, 16 patients were randomized to receive active or sham tDCS administered during mirror therapy. Each patient received 12 treatment sessions, 30 min each, during a period of 4 weeks over M1 contralateral to the side of the injury. Outcome variables were evaluated at baseline and post-treatment using the McGill questionnaire, Brief Pain Inventory, and Medical Outcomes Study 36-Item Short-Form Health Survey. Long-term effects of treatment were evaluated at a 3-month follow-up. Results: An improvement in pain relief and quality of life were observed in both groups (p ≤ 0.05). However, active tDCS and mirror therapy resulted in greater improvements after the endpoint (p ≤ 0.02). No statistically significant differences in the outcome measures were identified among the groups at follow-up (p ≥ 0.12). A significant relationship was found between baseline pain intensity and outcome measures (p ≤ 0.04). Moreover, the results showed that state anxiety is closely linked to post-treatment pain relief (p ≤ 0.05). Conclusion: Active tDCS combined with mirror therapy has a short-term effect of pain relief, however, levels of pain and anxiety at the baseline should be considered. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT04385030.

The brain and behavioral correlates of motor-related analgesia (MRA)

The human motor system has the capacity to act as an internal form of analgesia. Since the discovery of the potential influence of motor systems on analgesia in rodent models, clinical applications of targeting the motor system for analgesia have been implemented. However, a neurobiological basis for motor activation's effects on analgesia is not well defined. Motor-related analgesia (MRA) is a phenomenon wherein a decrease in pain symptoms can be achieved through either indirect or direct activation of the motor axis. To date, research has focused on (a) evaluating the pain-motor interaction as one focused on the acute protection from painful stimuli; (b) motor cortex stimulation for chronic pain; or (c) exercise as a method of improving chronic pain in animal and human models. This review evaluates (1) current knowledge surrounding how pain interferes with canonical neurological performance throughout the motor axis; and (2) the physiological basis for motor-related analgesia as a means to reduce pain symptom loads for patients. A proposal for future research directions is provided.

Mental Imagery as a Rehabilitative Therapy for Neuropathic Pain in People With Spinal Cord Injury: A Randomized Controlled Trial

BACKGROUND

Pain of neuropathic origin in spinal cord injury (SCI) is unbearable and challenging to treat. Research studies conducted in the past have shown that mental imagery (MI) techniques have a significant impact on the reduction of symptoms of central neuropathic pain in people with SCI.

OBJECTIVES

The objective of this study was to evaluate the effect of MI training on pain intensity, neuropathic pain symptoms, and interference of pain with function in SCI.

METHODS

A total of 42 SCI participants with central neuropathic pain (duration 6-12 months) were recruited and randomly allocated to MI or control groups. A MI training protocol was administered to MI group and for 30 min/d for 5 days. Outcome measures were assessed at baseline and at the end of 4 weeks.

RESULTS

There was significant reduction in differences of mean [95% CI] scores of numeric rating scale (-2.1 [CI -2.78 to -1.41]; P < .001) between groups. Mean [95% CI] total scores of Neuropathic Pain Symptom Inventory declined in MI group as compared with control group (-4.52 [CI -5.86 to -3.18]; P < .001). Similarly, Brief Pain Inventory interference scale total dropped significantly (P < .001) in MI group. Majority of participants in the MI group (55%) reported improvement in scores of Patients' Global Impression of Change scale as compared with control group where most of the participants (52%) reported no change.

CONCLUSIONS

This study shows the effectiveness of the MI protocol developed as a rehabilitative approach in improving central neuropathic pain in SCI. Trial Registration. Clinical Trials Registry-India under Indian Council of Medical Research; CTRI/2018/07/014884. Registered July 16, 2018.

Methods and strategies of tDCS for the treatment of pain: current status and future directions

INTRODUCTION

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique that has been widely studied for the treatment of chronic pain. It is considered a promising and safe alternative pain therapy. Different targets have been tested, each having their own particular mechanisms for modulating pain perception.

AREAS COVERED

We discuss the current state of the art of tDCS to manage pain and future strategies to optimize tDCS' effects. Current strategies include primary motor cortex tDCS, prefrontal tDCS and tDCS combined with behavioral interventions while future strategies, on the other hand, include high-intensity tDCS, transcutaneous spinal direct current stimulation, cerebellar tDCS, home-based tDCS, and tDCS with extended number of sessions.

EXPERT COMMENTARY

It has been shown that the stimulation of the prefrontal and primary motor cortex is efficient for pain reduction while a few other new strategies, such as high-intensity tDCS and network-based tDCS, are believed to induce strong neuroplastic effects, although the underlying neural mechanisms still need to be fully uncovered. Hence, conventional tDCS approaches demonstrated promising effects to manage pain and new strategies are under development to enhance tDCS effects and make this approach more easily available by using, for instance, home-based devices.

Motor imagery for pain and motor function after spinal cord injury: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVES

To evaluate the therapeutic benefits of motor imagery (MI) for the people with spinal cord injury (SCI).

SETTING

International.

METHODS

We searched electronic bibliographic databases, trial registers, and relevant reference lists. The review included experimental and quasi-experimental study designs as well as observational studies. For the critical appraisal of the 18 studies retrieved (three RCT, seven quasi-RCT, eight observational), we used instruments from the Joanna Briggs Institute. The primary outcome measure was pain. Secondary outcome measures included motor function and neurophysiological parameters. Adverse effects were extracted if reported in the included studies. Because of data heterogeneity, only a qualitative synthesis is offered.

RESULTS

The included studies involved 282 patients. In most, results were an improvement in motor function and decreased pain; however, some reported no effect or an increase in pain. Although protocols of MI intervention were heterogeneous, sessions of 8-20 min were used for pain treatments, and of 30-60 min were used for motor function improvement. Neurophysiological measurements showed changes in brain region activation and excitability imposed by SCI, which were partially recovered by MI interventions. No serious adverse effects were reported.

CONCLUSIONS

High heterogeneity in the SCI population, MI interventions, and outcomes measured makes it difficult to judge the therapeutic effects and best MI intervention protocol, especially for people with SCI with neuropathic pain. Further clinical trials evaluating MI intervention as adjunct therapy for pain in SCI patients are warranted.

Effectiveness of the graded motor imagery to improve hand function in patients with distal radius fracture: A randomized controlled trial

STUDY DESIGN

Single-blinded randomized controlled trial.

INTRODUCTION

Pain management is essential in the early stages of the rehabilitation of distal radius fractures (DRFx). Pain intensity at the acute stage is considered important for determining the individual recovery process, given that higher pain intensity and persistent pain duration negatively affect the function and cortical activity of pain response. Graded motor imagery (GMI) and its components are recent pain management strategies, established on a neuroscience basis.

PURPOSE OF THE STUDY

To investigate the effectiveness of GMI in hand function in patients with DRFx.

METHODS

Thirty-six participants were randomly allocated to either GMI (n = 17; 52.59 [9.8] years) or control (n = 19; 47.16 [10.5] years) groups. The GMI group received imagery treatment in addition to traditional rehabilitation, and the control group received traditional rehabilitation for 8 weeks. The assessments included pain at rest and during activity using the visual analog scale, wrist and forearm active range of motion (ROM) with universal goniometer, grip strength with the hydraulic dynamometer (Jamar; Bolingbrook, IL), and upper extremity functional status using the Disability of the Arm, Shoulder and Hand Questionnaire, and the Michigan Hand Questionnaire. Assessments were performed twice at baseline and at the end of the eighth week.

RESULTS

The GMI group showed greater improvement in pain intensity (during rest, 2.24; activity, 6.18 points), wrist ROM (flexion, -40.59; extension, -45.59; radial deviation, -25.59; and ulnar deviation, -26.77 points) and forearm ROM (supination, -43.82 points), and functional status (Disability of the Arm, Shoulder and Hand Questionnaire, 38.00; Michigan Hand Questionnaire, -32.53 points) when compared with the control group (for all, P < .05).

CONCLUSION

The cortical model of pathological pain suggests new strategies established on a neuroscience basis. These strategies aim to normalize the cortical proprioceptive representation and reduce pain. One of these recent strategies, GMI appears to provide beneficial effects to control pain, improve grip strength, and increase upper extremity functions in patients with DRFx.

Management of pain in individuals with spinal cord injury: Guideline of the German-Speaking Medical Society for Spinal Cord Injury

Introduction: Pain is a prominent complication in spinal cord injury (SCI). It can either occur as a direct or as an indirect consequence of SCI and it often heavily influences the quality of life of affected individuals. In SCI, nociceptive and neuropathic pain can equally emerge at the same time above or below the level of injury. Thus, classification and grading of pain is frequently difficult. Effective treatment of SCI-related pain in general and of neuropathic pain in particular is challenging. Current treatment options are sparse and their evidence is considered to be limited. Considering these aspects, a clinical practice guideline was developed as basis for an optimized, comprehensive and standardized pain management in SCI-related pain.

Methods: The German-Speaking Medical Society for Spinal Cord Injury (Deutschsprachige Medizinische Gesellschaft für Paraplegiologie – DMGP) developed a clinical practice guideline that received consensus from seven further German-speaking medical societies and one patient organization. The evidence base from clinical trials and meta-analyses was summarized and subjected to a structured consensus-process in accordance with the regulations of the Association of Scientific Medical Societies in Germany (AWMF) and the methodological requirements of the “German instrument for methodological guideline appraisal”.

Results: This consensus-based guideline (S2k classification according to the AWMF guidance manual and rules) resulted in seven on-topic statements and 17 specific recommendations relevant to the classification, assessment and therapy of pain directly or indirectly caused by SCI. Recommended therapeutic approaches comprise pharmacological (e.g. nonsteroidal anti-inflammatory drugs or anticonvulsants) and non-pharmacological (e.g. physical activity or psychotherapeutic techniques) strategies for both nociceptive and neuropathic pain.

Discussion: Assessment of SCI-related pain is standardized and respective methods in terms of examination, classification and grading of pain are already in use and validated in German language. In contrast, valid, evidence-based and efficient therapeutic options are limited and ask for further clinical studies, ideally randomized controlled trials and meta-analyses.

EEG Correlates of Self-Managed Neurofeedback Treatment of Central Neuropathic Pain in Chronic Spinal Cord Injury

BACKGROUND

Neurofeedback (NFB) is a neuromodulatory technique that enables voluntary modulation of brain activity in order to treat neurological condition, such as central neuropathic pain (CNP). A distinctive feature of this technique is that it actively involves participants in the therapy. In this feasibility study, we present results of participant self-managed NFB treatment of CNP.

METHODS

Fifteen chronic spinal cord injured (SCI) participants (13M, 2F), with chronic CNP equal or greater than 4 on the Visual Numeric Scale, took part in the study. After initial training in hospital (up to 4 sessions), they practiced NF at home, on average 2-3 times a week, over a period of several weeks (min 4, max 20). The NFB protocol consisted of upregulating the alpha (9-12 Hz) and downregulating the theta (4-8 Hz) and the higher beta band (20-30 Hz) power from electrode location C4, for 30 min. The output measures were pain before and after NFB, EEG before and during NFB and pain questionnaires. We analyzed EEG results and show NFB strategies based on the Power Spectrum Density of each single participant.

RESULTS

Twelve participants achieved statistically significant reduction in pain and in eight participants this reduction was clinically significant (larger than 30%). The most successfully regulated frequency band during NFB was alpha. However, most participants upregulated their individual alpha band, that had an average dominant frequency at αp = 7.6 ± 0.8 Hz (median 8 Hz) that is lower than the average of the general population, which is around 10 Hz. Ten out of fifteen participants significantly upregulated their individual alpha power (αp ± 2 Hz) as compared to 4 participants who upregulated the power in the fixed alpha band (8-12 Hz). Eight out of the twelve participants who achieved a significant reduction of pain, significantly upregulated their individual alpha band power. There was a significantly larger increase in alpha power (p < 0.0001) and decrease of theta power (p < 0.04) in participant specific rather than in fixed frequency bands.

CONCLUSION

Neurofeedback is a neuromodulatory technique that gives participants control over their pain and can be self-administered at home. Regulation of individual frequency band was related to a significant reduction in pain.

Mental imagery training for treatment of central neuropathic pain: a narrative review

Mental imagery is a quasi-perceptual experience in the absence of external stimuli. This concept has intrigued psychologists, sportspersons, neurologists and other scientists for over a decade now. Imagery has been used in rehabilitation and the results have been promising. Researchers refer to this as healing the body through the mind. However, the challenge is lack of standardized protocols, homogeneity and consistency in application of mental imagery in different populations. The purpose of this review is to discuss and understand the role of mental imagery in the treatment of central neuropathic pain (CNP). Treatment options of CNP are inadequate and their benefits are short lived. We conducted an extensive search on various databases using combinations of different keywords and reviewed the available literature in this area. We were able to finalize twelve studies where mental imagery was used for treating CNP in spinal cord injury (SCI), stroke and multiple sclerosis. However, the methodology and techniques of mental imagery training used in these studies were non-homogeneous and inconsistent. This review provides a guiding framework to further explore the different techniques of mental imagery and their roles in treating CNP.

Decreasing Pain Ratings in Chronic Arm Pain Through Changing a Virtual Body: Different Strategies for Different Pain Types

Modifying the visual aspect of a virtual arm that is felt as one's own using immersive virtual reality (VR) modifies pain threshold in healthy subjects, but does it modify pain ratings in chronic pain patients? Our aim was to investigate whether varying properties of a virtual arm co-located with the real arm modulated pain ratings in patients with chronic arm/hand pain because of complex regional pain syndrome (CRPS) type I (without nerve injury) or peripheral nerve injury (PNI). CRPS (n = 9) and PNI (n = 10) patients were immersed in VR and the virtual arm was shown at 4 transparency levels (transparency test) and 3 sizes (size test). We evaluated pain ratings throughout the conditions and assessed the virtual experience, finding that patients with chronic pain can achieve levels of ownership and agency over a virtual arm similar to healthy participants. All 7 conditions globally decreased pain ratings by half. Increasing transparency decreased pain in CRPS but did the opposite in PNI, whereas increasing size slightly increased pain ratings only in CRPS. We conclude that embodiment in VR can decrease pain ratings in chronic arm pain, although the type of pain determines which strategy to decrease pain is most useful. We discuss this through the interactions between body image and pain perception. PERSPECTIVE: "Embodiment" in VR is useful to decrease pain ratings in chronic pain patients, but the best strategy needs to be tuned to the pain etiology. This approach could potentially help patients with chronic pain and clinicians who seek alternatives to pain management for patients.

Embodying functionally relevant action sounds in patients with spinal cord injury

Growing evidence indicates that perceptual-motor codes may be associated with and influenced by actual bodily states. Following a spinal cord injury (SCI), for example, individuals exhibit reduced visual sensitivity to biological motion. However, a dearth of direct evidence exists about whether profound alterations in sensorimotor traffic between the body and brain influence audio-motor representations. We tested 20 wheelchair-bound individuals with lower skeletal-level SCI who were unable to feel and move their lower limbs, but have retained upper limb function. In a two-choice, matching-to-sample auditory discrimination task, the participants were asked to determine which of two action sounds matched a sample action sound presented previously. We tested aural discrimination ability using sounds that arose from wheelchair, upper limb, lower limb, and animal actions. Our results indicate that an inability to move the lower limbs did not lead to impairment in the discrimination of lower limb-related action sounds in SCI patients. Importantly, patients with SCI discriminated wheelchair sounds more quickly than individuals with comparable auditory experience (i.e. physical therapists) and inexperienced, able-bodied subjects. Audio-motor associations appear to be modified and enhanced to incorporate external salient tools that now represent extensions of their body schemas.

Gestural Interaction and Visual Illusion for Lower Limbs' Neuropathic Pain Treatment

Pain caused by a lesion or a disease affecting the somatosensory nervous system is known as Neuropathic pain. It has been shown that neuropathic pain can be treated with the combination of simultaneous transcranial direct current stimulation and the generation of the visual illusion that the patient retains control of the affected limbs. For persons with neuropathic pain in the lower limbs, the visual illusion consists of an image of the patient walking normally. Such a visual illusion has classically been generated by using a physical mirror and a projector. The objective of this paper is to develop and validate a computer-based version of the visual illusion, including Gestural Control. The developed system has been validated in a trial and has been successfully implanted in daily clinical practice in a reference neurorehabilitation hospital. A retrospective statistical analysis shows that the patients treated with the computer-based system reduce their pain level significantly more than the patients treated with the mirror and projector treatment before the introduction of the computer-based version. Furthermore, it also makes possible to bring the therapy to the home of the patients, where the treatment can be self-administered while still being monitored by the clinical staff.

Virtual reality for spinal cord injury-associated neuropathic pain: Systematic review

BACKGROUND

Treatment of spinal cord injury (SCI)-associated neuropathic pain is challenging, with limited efficacy and no definitive options, and SCI patients often show resistance to pharmacologic treatment. Virtual reality (VR) therapy is a non-invasive, non-pharmacologic alternative with minimal adverse effects.

OBJECTIVE

To investigate the effect of VR therapy on SCI-associated neuropathic pain in a systematic review.

METHODS

Articles needed to 1) be written in English; 2) include adult subjects, with at least half the study population with a SCI diagnosis; 3) involve any form of VR therapy; and 4) assess neuropathic pain by quantitative outcome measures. Articles were searched in MEDLINE/PubMed, CINAHL^®, EMBASE, and PsycINFO up to April 2018. Reference lists of retrieved articles were hand-searched. Methodologic quality was assessed by the Physiotherapy Evidence Database Score (PEDro) for randomized controlled trials and Modified Downs and Black Tool (D&B) for all other studies. Level of evidence was determined by using a modified Sackett scale.

RESULTS

Among 333 studies identified, 9 included in this review (n=150 participants) evaluated 4 methods of VR therapy (virtual walking, VR-augmented training, virtual illusion, and VR hypnosis) for treating neuropathic pain in SCI patients. Each VR method reduced neuropathic pain: 4 studies supported virtual walking, and the other 3 VR methods were each supported by a different study. Combined treatment with virtual walking and transcranial direct current stimulation was the most effective. The quality of studies was a major limitation.

CONCLUSION

VR therapy could reduce SCI-associated neuropathic pain, although the clinical significance of this analgesic effect is unclear. Clinical trials evaluating VR therapy as standalone and/or adjunct therapy for neuropathic pain in SCI patients are warranted.

Mental practice for chronic pain in people with spinal cord injury: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The primary objective of this systematic review is to identify the effects of mental practice (MP) interventions on chronic neuropathic and nociceptive pain and motor function recovery in individuals after spinal cord injury (SCI). Where possible, this review will also describe the optimal type and dosage (i.e. frequency, intensity and duration) of MP interventions for patients with SCI.

Selective distortion of body image by asynchronous visuotactile stimulation

In the rubber hand illusion (RHI), a rubber hand is felt as being part of one's body. This illusion is evoked by providing synchronous visuotactile stimulation to the fake and real hands. Asynchronous visuotactile stimulation is known not to produce such an illusion of ownership, being commonly used as the control condition. Here we explored the impact of synchronous and asynchronous visuotactile stimulation on the body image. We combined the induction of the RHI with a quantitative test for the internal representation of body metrics (i.e., the positions of key fiducial points on the body relative to each other). We found a significant recalibration of the upper/lower arm lengths following asynchronous visuotactile stimulation. In particular, we observed a selective elongation of the lower arm, a distortion typical of deafferentation. Conversely, synchronous visuotactile stimulation did not alter the estimation of the arm segments' length. Our findings are consistent with a dynamic internal representation of body image that is continuously updated based on incoming multisensory information. Furthermore, the use of asynchronous multisensory stimulation as a neutral condition should be reconsidered since it introduces changes in the body image.

Enhanced Reality Showing Long-Lasting Analgesia after Total Knee Arthroplasty: Prospective, Randomized Clinical Trial

To overcome the limitation of short-term efficacy of virtual reality (VR), an enhanced reality (ER) analgesia, (combination of the VR, real-time motion capture, mirror therapy [MT]) involving a high degree of patients’ presence or embodiment was explored. Patients, who underwent unilateral total knee arthroplasty (TKA), received ER analgesia. The duration was 5 times a week, for 2 weeks for one group and 5 times a week, for 1 week in the other. Visual Analogue Scale (VAS) at rest and during movement, active knee range of motion (ROM) for flexion and extension were measured repeatedly. After screening 157 patients, 60 were included. Pre-interventional evaluation was performed at 6.7 days and ER was initiated at 12.4 days after surgery. Evaluation was performed at 5, 12, 33 days after the initiation of ER. Analgesia in the 2 week therapy group was effective until the third evaluation (p = 0.000), whereas in the other group, it was effective only until the second evaluation (p = 0.010). Improvement in ROM in the 2 week group was also maintained until the third evaluation (p = 0.037, p = 0.009). It could lay the foundations for the development of safe and long-lasting analgesic tools.

The Bodily Illusion in Adverse Conditions: Virtual Arm Ownership During Visuomotor Mismatch

Classically, body ownership illusions are triggered by cross-modal synchronous stimulations, and hampered by multisensory inconsistencies. Nonetheless, the boundaries of such illusions have been proven to be highly plastic. In this immersive virtual reality study, we explored whether it is possible to induce a sense of body ownership over a virtual body part during visuomotor inconsistencies, with or without the aid of concomitant visuo-tactile stimulations. From a first-person perspective, participants watched a virtual tube moving or an avatar's arm moving, with or without concomitant synchronous visuo-tactile stimulations on their hand. Three different virtual arm/tube speeds were also investigated, while all participants kept their real arms still. The subjective reports show that synchronous visuo-tactile stimulations effectively counteract the effect of visuomotor inconsistencies, but at slow arm movements, a feeling of body ownership might be successfully induced even without concomitant multisensory correspondences. Possible therapeutical implications of these findings are discussed.

Home-Based Tactile Discrimination Training Reduces Phantom Limb Pain

BACKGROUND

Phantom limb pain (PLP) affects a high percentage of amputees. Since treatment options are limited, low quality of life and addiction to pain medication frequently occur. New treatments, such as mirror therapy or electrical sensory discrimination training, make use of the brain's plasticity to alleviate this centrally derived pain.

AIM

This pilot study assessed the question of whether home-based tactile discrimination training (TDT) leads to a stronger decrease in PLP levels compared to standard massage treatment.

DESIGN

Controlled study.

SETTING

Outpatient.

POPULATION

Amputees (upper/lower extremity) with a PLP score of 4 or higher out of a possible 10 points on the visual analog scale.

METHODS

Eight patients participated in the study. The treatment phase comprised 2 weeks (15 minutes daily). Subjects were examined at baseline, after treatment, 2 weeks after completing treatment, and 4 weeks after completing treatment. Pain was assessed using the West Haven-Yale Multidimensional Pain Inventory.

RESULTS

There was a significantly stronger reduction in PLP in the treatment group receiving TDT. PLP intensity ratings were significantly reduced at the end of therapy, and at 2 and 4 weeks after completing treatment compared to pretreatment.

CONCLUSIONS

TDT seems to be an easy, cheap, time-effective, and safe method to achieve sustained alleviation of PLP and also brings about a positive change in body image.

REHABILITATION IMPACT

Home-based TDT could achieve a sustained reduction in PLP and should be considered as a possible alternative to established treatment methods.

Imagine There Is No Plegia. Mental Motor Imagery Difficulties in Patients with Traumatic Spinal Cord Injury

In rehabilitation of patients with spinal cord injury (SCI), imagination of movement is a candidate tool to promote long-term recovery or to control futuristic neuroprostheses. However, little is known about the ability of patients with spinal cord injury to perform this task. It is likely that without the ability to effectively perform the movement, the imagination of movement is also problematic. We therefore examined, whether patients with SCI experience increased difficulties in motor imagery (MI) compared to healthy controls. We examined 7 male patients with traumatic spinal cord injury (aged 23–70 years, median 53) and 20 healthy controls (aged 21–54 years, median 30). All patients had incomplete SCI, with AIS (ASIA Impairment Scale) grades of C or D. All had cervical lesions, except one who had a thoracic injury level. Duration after injury ranged from 3 to 314 months. We performed the Movement Imagery Questionnaire Revised as well as the Beck Depression Inventory in all participants. The self-assessed ability of patients to visually imagine movements ranged from 7 to 36 (Md = 30) and tended to be decreased in comparison to healthy controls (ranged 16–49, Md = 42.5; W = 326.5, p = 0.055). Also, the self-assessed ability of patients to kinesthetically imagine movements (range = 7–35, Md = 31) differed significantly from the control group (range = 23–49, Md = 41; W = 337.5, p = 0.0047). Two patients yielded tendencies for depressive mood and they also reported most problems with movement imagination. Statistical analysis however did not confirm a general relationship between depressive mood and increased difficulty in MI across both groups. Patients with spinal cord injury seem to experience difficulties in imagining movements compared to healthy controls. This result might not only have implications for training and rehabilitation programs, but also for applications like brain-computer interfaces used to control neuroprostheses, which are often based on the brain signals exhibited during the imagination of movements.

[Cognitive-perceptive approaches in the treatment of chronic pain]

In the treatment of difficult chronic pain conditions, cognitive-perceptive approaches offer an alternative to conventional therapies. Especially phantom limb pain and complex regional pain syndrome (CRPS) are frequently treated with these promising modalities. This article provides an overview of the most important cognitive-perceptive therapies and the research results concerning their clinical efficacy. In addition, we discuss their neurobiological foundation and clinical perspectives.

3D augmented reality mirror visual feedback therapy applied to the treatment of persistent, unilateral upper extremity neuropathic pain: a preliminary study

Objective: We assessed whether or not pain relief could be achieved with a new system that combines 3D augmented reality system (3DARS) and the principles of mirror visual feedback. Methods: Twenty-two patients between 18 and 75 years of age who suffered of chronic neuropathic pain. Each patient performed five 3DARS sessions treatment of 20 mins spread over a period of one week. The following pain parameters were assessed: (1) visual analogic scale after each treatment session (2) McGill pain scale and DN4 questionnaire were completed before the first session and 24 h after the last session. Results: The mean improvement of VAS per session was 29% (p < 0.001). There was an immediate session effect demonstrating a systematic improvement in pain between the beginning and the end of each session. We noted that this pain reduction was partially preserved until the next session. If we compare the pain level at baseline and 24 h after the last session, there was a significant decrease (p < 0.001) of pain of 37%. There was a significant decrease (p < 0.001) on the McGill Pain Questionnaire and DN4 questionnaire (p < 0.01). Conclusion: Our results indicate that 3DARS induced a significant pain decrease for patients who presented chronic neuropathic pain in a unilateral upper extremity. While further research is necessary before definitive conclusions can be drawn, clinicians could implement the approach as a preparatory adjunct for providing temporary pain relief aimed at enhancing chronic pain patients' tolerance of manual therapy and exercise intervention. Level of Evidence: 4.

A neurobiologist's attempt to understand persistent pain

This topical review starts with a warning that despite an impressive wealth of neuroscientific data, a reductionist approach can never fully explain persistent pain. One reason is the complexity of clinical pain (in contrast to experimentally induced pain). Another reason is that the "pain system" shows degeneracy, which means that an outcome can have several causes. Problems also arise from lack of conceptual clarity regarding words like nociceptors, pain, and perception. It is, for example, argued that "homeoceptor" would be a more meaningful term than nociceptor. Pain experience most likely depends on synchronized, oscillatory activity in a distributed neural network regardless of whether the pain is caused by tissue injury, deafferentation, or hypnosis. In experimental pain, the insula, the second somatosensory area, and the anterior cingulate gyrus are consistently activated. These regions are not pain-specific, however, and are now regarded by most authors as parts of the so-called salience network, which detects all kinds of salient events (pain being highly salient). The networks related to persistent pain seem to differ from the those identified experimentally, and show a more individually varied pattern of activations. One crucial difference seems to be activation of regions implicated in emotional and body-information processing in persistent pain. Basic properties of the "pain system" may help to explain why it so often goes awry, leading to persistent pain. Thus, the system must be highly sensitive not to miss important homeostatic threats, it cannot be very specific, and it must be highly plastic to quickly learn important associations. Indeed, learning and memory processes play an important role in persistent pain. Thus, behaviour with the goal of avoiding pain provocation is quickly learned and may persist despite healing of the original insult. Experimental and clinical evidence suggest that the hippocampal formation and neurogenesis (formation of new neurons) in the dentate gyrus are involved in the development and maintenance of persistent pain. There is evidence that persistent pain in many instances may be understood as the result of an interpretation of the organism's state of health. Any abnormal pattern of sensory information as well as lack of expected correspondence between motor commands and sensory feedback may be interpreted as bodily threats and evoke pain. This may, for example, be an important mechanism in many cases of neuropathic pain. Accordingly, many patients with persistent pain show evidence of a distorted body image. Another approach to understanding why the "pain system" so often goes awry comes from knowledge of the dynamic and nonlinear behaviour of neuronal networks. In real life the emergence of persistent pain probably depends on the simultaneous occurrence of numerous challenges, and just one extra (however small) might put the network into a an inflexible state with heightened sensitivity to normally innocuous inputs. Finally, the importance of seeking the meaning the patient attributes to his/her pain is emphasized. Only then can we understand why a particular person suffers so much more than another with very similar pathology, and subsequently be able to help the person to alter the meaning of the situation.

Changing the size of a mirror-reflected hand moderates the experience of embodiment but not proprioceptive drift: a repeated measures study on healthy human participants

Mirror visual feedback is used for reducing pain and visually distorting the size of the reflection may improve efficacy. The findings of studies investigating size distortion are inconsistent. The influence of the size of the reflected hand on embodiment of the mirror reflection is not known. The aim of this study was to compare the effect of magnifying and minifying mirror reflections of the hand on embodiment measured using an eight-item questionnaire and on proprioceptive drift. During the experiment, participants (n = 45) placed their right hand behind a mirror and their left hand in front of a mirror. Participants watched a normal-sized, a magnified and a minified reflection of the left hand while performing synchronised finger movements for 3 min (adaptive phase). Measurements of embodiment were taken before (pre) and after (post) synchronous movements of the fingers of both hands (embodiment adaptive phase). Results revealed larger proprioceptive drift post-adaptive phase (p = 0.001). Participants agreed more strongly with questionnaire items associated with location, ownership and agency of the reflection of the hand post-adaptive phase (p < 0.001) and when looking at the normal-sized reflection (p < 0.001). In conclusion, irrespective of size, watching a reflection of the hand while performing synchronised movements enhances the embodiment of the reflection of the hand. Magnifying and minifying the reflection of the hand has little effect on proprioceptive drift, but it weakens the subjective embodiment experience. Such factors need to be taken into account in future studies using this technique, particularly when assessing mirror visual feedback for pain management.

Interactive virtual feedback improves gait motor imagery after spinal cord injury: An exploratory study

Purpose: Motor imagery can improve motor function and reduce pain. This is relevant to individuals with spinal cord injury (SCI) in whom motor dysfunction and neuropathic pain are prevalent. However, therapy efficacy could be dependent on motor imagery ability, and a clear understanding of how motor imagery might be facilitated is currently lacking. Thus, the aim of the present study was to assess the immediate effects of interactive virtual feedback on motor imagery performance after SCI.

Methods: Nine individuals with a traumatic SCI participated in the experiment. Motor imagery tasks consisted of forward (i.e. simpler) and backward (i.e. more complex) walking while receiving interactive versus static virtual feedback. Motor imagery performance (vividness, effort and speed), neuropathic pain intensity and feasibility (immersion, distraction, side-effects) were assessed.

Results: During interactive feedback trials, motor imagery vividness and speed were significantly higher and effort was significantly lower as compared static feedback trials. No change in neuropathic pain was observed. Adverse effects were minor, and immersion was reported to be good.

Conclusions: This exploratory study showed that interactive virtual walking was feasible and facilitated motor imagery performance. The response to motor imagery interventions after SCI might be improved by using interactive virtual feedback.

The effect of bodily illusions on clinical pain: a systematic review and meta-analysis

This systematic review and meta-analysis critically examined the evidence for bodily illusions to modulate pain. Six databases were searched; 2 independent reviewers completed study inclusion, risk of bias assessment, and data extraction. Included studies evaluated the effect of a bodily illusion on pain, comparing results with a control group/condition. Of the 2213 studies identified, 20 studies (21 experiments) were included. Risk of bias was high due to selection bias and lack of blinding. Consistent evidence of pain decrease was found for illusions of the existence of a body part (myoelectric/Sauerbruch prosthesis vs cosmetic/no prosthesis; standardized mean differences = -1.84, 95% CI = -2.67 to -1.00) and 4 to 6 weeks of mirror therapy (standardized mean differences = -1.11, 95% CI = -1.66 to -0.56). Bodily resizing illusions had consistent evidence of pain modulation (in the direction hypothesized). Pooled data found no effect on pain for 1 session of mirror therapy or for incongruent movement illusions (except for comparisons with congruent mirrored movements: incongruent movement illusion significantly increased the odds of experiencing pain). Conflicting results were found for virtual walking illusions (both active and inactive control comparisons). Single studies suggest no effect of resizing illusions on pain evoked by noxious stimuli, no effect of embodiment illusions, but a significant pain decrease with synchronous mirrored stroking in nonresponders to traditional mirror therapy. There is limited evidence to suggest that bodily illusions can alter pain, but some illusions, namely mirror therapy, bodily resizing, and use of functional prostheses show therapeutic promise.

Dysesthesia symptoms produced by sensorimotor incongruence in healthy volunteers: an electroencephalogram study

Objectives

Pathological pain such as phantom limb pain is caused by sensorimotor incongruence. Several studies with healthy participants have clearly indicated that dysesthesia, which is similar to pathological pain, is caused by incongruence between proprioception and/or motor intention and visual feedback. It is not clear to what extent dysesthesia may be caused by incongruence between motor intention and visual feedback or by incongruence between proprioception and visual feedback. The aim of this study was to clarify the neurophysiology of these factors by analyzing electroencephalograms (EEGs).

Methods

In total, 18 healthy participants were recruited for this study. Participants were asked to perform repetitive flexion/extension exercises with their elbows in a congruent/incongruent position while viewing the activity in a mirror. EEGs were performed to determine cortical activation during sensorimotor congruence and incongruence.

Results

In the high-frequency alpha band (10–12 Hz), numeric rating scale scores of a feeling of peculiarity were significantly correlated with event-related desynchronization/synchronization under the incongruence and proprioception conditions associated with motor intention and visual feedback (right inferior parietal region; r=−0.63, P<0.01) and between proprioception and visual feedback (right temporoparietal region; r=−0.49 and r=−0.50, P<0.05). In these brain regions, there was a region in which incongruence between proprioception and visual feedback and between motor intention and visual feedback caused an increase in activity.

Conclusion

The present findings suggest that neural mechanisms of dysesthesia are caused by incongruence between proprioception associated with motor intention and visual feedback and, in particular, are a result of incongruence between proprioception only and visual feedback.