Arnaud Dupeyron

BACKGROUND Complex regional pain syndrome (CRPS) is a chronic, debilitating condition involving sensory, motor, and neuroplastic dysfunctions. Although movement representation therapies, such as mirror therapy, are recommended for CRPS patients, there is limited evidence for augmented reality mirror therapy (ARMT), particularly within personalized rehabilitation programs.This study aimed to evaluate the efficacy of ARMT as an adjunct to conventional, multidisciplinary rehabilitation programs for adult patients with upper limb CRPS. The primary outcome was hand dexterity. Secondary outcomes included motor imagery, CRPS severity, quality of life, pain intensity, proprioception, and global impression of change. OBJECTIVE This study aimed to evaluate the efficacy of ARMT as an adjunct to conventional, multidisciplinary rehabilitation programs for adult patients with upper limb CRPS. The primary outcome was hand dexterity. Secondary outcomes included motor imagery, CRPS severity, quality of life, pain intensity, proprioception, and global impression of change. METHODS A single-case experimental design (SCED) with an A-B-A multiple baseline design was conducted with six participants. Patients underwent a 10-week outpatient rehabilitation program consisting of three phases: Phase A (conventional therapy), Phase B (conventional therapy + ARMT), and Phase A’ (withdrawal of ARMT). Assessments were performed 20 times per patient (twice weekly). The primary outcome was hand dexterity, which was measured using the Box and Block Test (BBT). Secondary outcomes included mental motor chronometry, CRPS severity score, EuroQol-5D (EQ-5D), patient global impression of change, Rivermead assessment of somatosensory performance (proprioception), and pain intensity (visual analog scale [VAS]). Statistical analyses included Kendall’s tau and tau-U for individual data and mixed linear regression models for group-level data. RESULTS Six patients completed the study (96% of the expected number of assessment sessions). At the group level, adding ARMT to conventional rehabilitation produced a statistically significant improvement in hand function (+3.5 blocks/min, 95% CI: 1.2–5.9; p < 0.001), though this improvement was below the minimal clinically important difference (MCID) of 5.5–6.46 blocks/min. The CRPS Severity Score improved modestly throughout the program (p = 0.02), yet no clinically significant group-level changes were observed in motor imagery, quality of life, pain intensity, proprioception, or global impression of change. High individual variability was observed, with some patients experiencing worsened outcomes. No adverse events were reported. CONCLUSIONS Adding ARMT to conventional rehabilitation produced statistically significant, yet clinically modest, improvements in hand function with no meaningful effects on other outcomes. The high variability in responses underscores the heterogeneous nature of CRPS and suggests that personalized rehabilitation programs must evolve beyond considering pain intensity alone. Future trials should prioritize predefined repetitive movement protocols, graded pain exposure, and the incorporation of body perception disturbance assessments to better target neuroplastic mechanisms and improve clinical efficacy. Given its safety and tolerability, ARMT warrants further investigation with optimized, mechanism-driven protocols to improve CRPS outcomes. CLINICALTRIAL NCT05787119

Le rachis lombaire est à la fois capable de répondre à des exigences de stabilité pour protéger les structures neurologiques ou ostéo-ligamentaires et de mouvement pour assumer les gestes de la vie quotidienne, professionnelle et sportive. La lombalgie, pathologie multifactorielle, s'accompagne de perturbations musculaires, réflexes ou comportementales. La complexité de ces adaptations explique pourquoi il est encore difficile de savoir comment un sujet devient lombalgique ou pourquoi il le reste. Ce travail de recherche s'est focalisé sur l'étude de certaines adaptations du rachis lombaire en situation aiguës ou chroniques. Les objectifs étaient d'analyser l'influence (i) des tissus de soutien sur le comportement musculaire lombaire (ii) du gainage abdominal sur l'efficience des membres inférieurs, (iii) de la fatigue des érecteurs spinaux sur la réponse réflexe chez le sujet sain et (iv) d'un programme de rééducation chez le lombalgique. Les résultats obtenus soulignent le rôle central de l'effecteur neuromusculaire lombaire. Le maintien de certaines postures entraîne des adaptations mécaniques (pression intramusculaire) et métaboliques (oxygénation musculaire) limitant l'efficience des érecteurs spinaux. Le renforcement abdominal, probablement par son action stabilisatrice lombaire, modifie la raideur du système tronc -membres inférieurs et peut-être l'aptitude au saut vertical. Une fatigue lombaire induite provoque une adaptation réflexe chez le sujet sain (gain d'amplitude et peut-être de latence) pour compenser la perte de force. Enfin, un programme de restauration fonctionnelle permettrait, chez le lombalgique chronique, de modifier les capacités d'anticipation en limitant les activations musculaires exagérées et la réponse réflexe à une perturbation, évoquant l'émergence de nouvelles stratégies d'adaptation. Ce travail suggère la possibilité de nouvelles approches dans un cadre sportif ou médical.

Human locomotion relies on a proximal–distal organization of joint mechanical work that adapts to task constraints, such as those imposed by inclined walking. In individuals with transtibial amputation, loss of the biological ankle disrupts this organization, leading to proximal alterations and inter-limb asymmetries. Active mechatronic prosthetic feet have been developed within a biomechanical biomimicry framework to restore distal positive mechanical work. This exploratory study quantified the effects of an active mechatronic prosthetic foot on joint mechanical work during inclined walking. Four individuals with transtibial amputation performed instrumented treadmill walking at −3°, 0°, and +3° using their habitual passive foot and a powered foot. Positive and negative mechanical work at the ankle, knee, and hip were computed using inverse dynamics and compared with a normative reference database (n = 20). The powered foot induced modest, task-dependent modifications, mainly at the ankle and knee. In downhill walking, it promoted a more symmetrical redistribution of negative mechanical work, particularly at the knee, suggesting a partial reduction in contralateral overload. In uphill walking, distal assistance increased prosthetic-side positive work, reflecting slope-dependent reallocation rather than normalization. Although a multivariate deviation score indicated reduced deviation under the powered condition, full convergence toward the asymptomatic organization was not achieved.

Musculoskeletal pain, particularly low back and neck pain, is associated with maladaptive changes in spinal motor behaviour (SMB). Psychological factors such as pain-related fear play a role in driving these adaptations. While previous research found weak associations between general psychological measures and SMB, task-specific measures may provide more precise insights into movement avoidance. This systematic review and meta-analysis aimed to compare the relative associations of general and task-specific pain-related fear measures with SMB. Following PRISMA guidelines, we included 13 studies (651 participants) assessing both general (Tampa Scale of Kinesiophobia and Pain Anxiety Symptoms Scale) and task-specific measures alongside objective spinal motor outcomes (eg, amplitude, velocity, muscle activity, coordination, variability). A three-level meta-analytic model revealed a weak but significant association between general measures and SMB (r = 0.12, 95% CI: 0.04-0.21, P = 0.007), whereas task-specific measures showed a stronger association (r = 0.29, 95% CI: 0.18-0.40, P < 0.001). The difference between these correlations (Δr _{(task-specific – general)} = 0.16, 95% CI: 0.04 to 0.27, P = 0.008) was statistically significant, indicating that task-specific measures better capture the relationship between perceived fear and movement alterations. Despite methodological heterogeneity, our findings highlight the importance of task-specific assessments in understanding motor impairments associated with pain-related fear. These results support the integration of task-specific evaluations in clinical and research settings. To further elucidate the mechanisms linking psychological factors to SMB, future studies should use longitudinal designs, improve the contextual validity of the motor tasks studied, and explore new approaches of movement analysis.

Background: Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by peripheral, central sensory and motor dysfunction. Implicit motor imagery is known to be impaired in CRPS patients, but evidence for explicit motor imagery is still lacking. Using a self-rated questionnaire, this study aims to compare explicit motor imagery abilities between individuals with CRPS, with chronic limb pain (CLP), and healthy controls, and to also examine differences between affected and unaffected limbs. We hypothesize that both CRPS and CLP patients will show a decrease in motor imagery abilities compared to healthy controls and in their affected limb compared to their own contralateral, unaffected side. Patients and Methods: In this single-center observational study, 123 participants were recruited (CRPS = 40, chronic limb pain, CLP = 40, and healthy individuals = 43). Participants completed the Movement Imagery Questionnaire-Revised Second (MIQ-RS) once for each side of the body. The total MIQ-RS score, and the kinesthetic and visual subscores were compared between groups and between the affected and unaffected sides. Results: A high degree of heterogeneity was observed in the explicit motor imagery scores and subscores, regardless of whether the participants were healthy or individuals with chronic pain. The MIQ-RS did not reveal any significant differences in explicit motor imagery abilities, neither between groups nor between the affected and unaffected side. Bayesian testing of the null hypothesis for kinesthetic motor imagery abilities indicated a sevenfold likelihood of no differences between groups and a more than a fivefold likelihood of no differences between sides. Conclusion: Individuals with CRPS and chronic limb pain displayed preserved explicit motor imagery abilities, notably on the pain side. The preservation of these abilities supports the recommendation of mental imagery therapy to improve motor function and relieve pain in chronic pain patients.

Background/Objectives: Chronic low back pain (CLBP) is a common condition with limited long-term treatment options. Vagus nerve stimulation (VNS) has shown potential for pain improvement, but its use in CLBP remains underexplored. Our aim was to evaluate the efficacy, feasibility and tolerability of transcutaneous auricular vagus nerve stimulation (taVNS) in reducing pain and improving functional outcomes in CLBP patients. Methods: Thirty adults with CLBP (VAS ≥ 40/100) participated in this open-label pilot study (NCT05639270). Patients were treated with a taVNS device on the left ear for 30 min daily over a period of 3 months. The primary outcome was a reduction in pain intensity (VAS) at 1 month. Secondary outcomes included pain intensity at 3 months, disability (Oswestry Disability Index, ODI), quality of life (EQ-5D-5L), catastrophizing and psychological distress. In addition, compliance and adverse events were monitored. Results: After 1 month, 27 patients were evaluated. VAS scores decreased significantly by 16.1 (SD = 17.9) mm (p < 0.001) and by 22.5 (25) mm (p < 0.001) after 3 months (24 patients were analyzed). Functional disability improved with an average reduction in ODI of 11.9 (11.1) points (p < 0.001) after 3 months. Other patient-reported outcomes also improved significantly over the 3-month period. Overall, 51.9% of the patients achieved clinically meaningful pain reduction (≥20 mm), and no serious adverse events were reported. Treatment adherence was good, with half of the patients achieving 80% adherence. Conclusions: This pilot study suggests that taVNS is a feasible, safe and potentially effective treatment for CLBP that warrants further investigation in a randomized controlled trial compared to sham stimulation.