An international study to explore the feasibility of collecting standardised outcome data for Complex Regional Pain Syndrome: recommendations for an international clinical research registry.

Introduction: Complex Regional Pain Syndrome (CRPS) is a persistent pain condition with low prevalence. Multi-centre collaborative research is needed to attain sufficient sample sizes for meaningful studies. This international observational study: (1) tested the feasibility and acceptability of collecting outcome data using an agreed core measurement set (2) tested and refined an electronic data management system to collect and manage the data. Methods: Adults with CRPS, meeting the Budapest diagnostic clinical criteria, were recruited to the study from 7 international research centres. After informed consent, a questionnaire comprising the core set outcome measures was completed: on paper at baseline (T1), and at 3 or 6 months (T2) using a paper or e-version. Participants and clinicians provided feedback on the data collection process. Clinicians completed the CRPS severity score at T1 and optionally, at T2. Ethical approval was obtained at each international centre. Results: Ninety-eight adults were recruited (female n=66; mean age 46.6 years, range 19-89), of whom 32% chose to receive the T2 questionnaire in an electronic format. Fifty-five participants completed both T1 and T2. Eighteen participants and nine clinicians provided feedback on their data collection experience. Conclusion: This study confirmed the questionnaire core outcome data are feasible and practicable to collect in clinical practice. The electronic data management system provided a robust means of collecting and managing the data across an international population. The findings have informed the final data collection tools and processes which will comprise the first international, clinical research registry and data bank for CRPS.

'I think it affects every aspect of my life, really': Cancer survivors' experience of living with chronic pain after curative cancer treatment in England, UK.

AIM: To explore cancer survivors' experiences of living with chronic pain after curative cancer treatment in England, UK. METHODS: A qualitative study using telephone interviews with adult cancer survivors experiencing chronic pain after curative cancer treatment. Interview data was analysed using a reflexive thematic approach [1-3]. FINDINGS: Nineteen participants: 14 female, 5 male, mean age 62.4 years, 1.5-48 years since cancer diagnosis, eight tumour groups represented. Six participants (31.6%) developed chronic pain more than ten years after completing cancer treatment (range 0-25 years). Five themes were generated which highlighted the experience of chronic pain after cancer treatment for cancer survivors: 1) 'Hear me… believe me…. Please'. Survivors felt that they had not been listened to when they tried to talk about their chronic pain after cancer treatment, nor at times, believed. 2) 'Expectation versus reality'. Survivors had anticipated returning to pre cancer quality of life yet living in chronic pain prevented them from doing so. 3) 'They don't understand…. We don't understand'. Cancer survivors did not feel informed or prepared for the risk or reality of chronic pain after cancer treatment and this compounded the difficulties of coping with and managing their pain. They felt health care professionals lacked knowledge and understanding of chronic pain after cancer. 4) 'Negotiating the maze'. Cancer survivors encountered unclear and limited pathways for support, often bouncing from one support team to another. Identifying and accessing services was a challenge, and the responsibility of this was often left to the survivor. 5) 'Validate my pain, validate me'. Palpable relief and benefit was felt when health care professionals diagnosed and acknowledged their chronic pain after cancer treatment. CONCLUSIONS: Cancer survivors can feel ill prepared for the risk of chronic pain after cancer treatment and can experience challenges accessing support from healthcare professionals and clinical services.

Resilience in patients with complex regional pain syndrome 1-a cross-sectional analysis of patients participating in a cross-sectional cohort study.

OBJECTIVE: To assess the degree of resilience in patients with complex regional pain syndrome (CRPS) 1, to explore the relationship between resilience and patient-related outcome measurements and to describe a pattern of clinical manifestations associated with low resilience. METHODS: This study presents a cross-sectional analysis of baseline information collected from patients enrolled in a single center study between February 2019 and June 2021. Participants were recruited from the outpatient clinic of the Department of Physical Medicine & Rheumatology of the Balgrist University Hospital, Zurich, Switzerland. We used linear regression analysis to explore association of resilience with patient reported outcomes at baseline. Furthermore, we explored the impact of significant variables on the low degree resilience using logistic regression analysis. RESULTS: Seventy-one patients (females 90.1%, mean age 51.2 ± 12.9 years) were enrolled. There was no association between CRPS severity and the level of resilience. Quality of Life was positively correlated with resilience, as was pain self-efficacy. Pain catastrophizing was inversely correlated with the level of resilience. We observed a significant inverse association between anxiety, depression and fatigue and the level of resilience. The proportion of patients with a low resilience increased with higher level of anxiety, depression and fatigue on the PROMIS-29, without reaching statistical significance. CONCLUSION: Resilience seems to be an independent factor in CRPS 1 and is associated with relevant parameters of the condition. Therefore, caretakers may screen the current resilience status of CRPS 1 patients to offer a supplementary treatment approach. Whether specific resilience training modifies CRPS 1 course, requires further investigations.

Optimising management of complex regional pain syndrome to improve clinical outcomes throughout the therapy care pathway in England: Protocol for a qualitative interview and observational study with patients and clinicians.

INTRODUCTION: Complex Regional Pain Syndrome (CRPS) is a disabling and distressing chronic pain condition characterised by a range of sensory, motor, autonomic and trophic symptoms. Guidelines recommend early referral for therapies that promote movement of the painful limb. However, evidence suggests a lack of defined therapy pathways for CRPS. AIMS: The current study aims to explore CRPS therapy management in centres of excellence in England, and outside of these settings, to understand what facilitates and hinders best practice. The overall aim is to develop a draft stratified package of care to expedite patient access to optimal CRPS therapy across the management pathway. METHODS AND ANALYSIS: Semi-structured interviews will be conducted with therapists working in CRPS centres of excellence and with therapists in other settings. Observations of therapy interventions in CRPS centres of excellence and interviews with patients who have received this care, will also help to identify potential key care package components. Interview data will be analysed using thematic analysis, mapped to the Theoretical Domains Framework (TDF), and Intervention Mapping Adapt (IMA) framework. Observations will be described and documented using the TDF headings. CONCLUSION: A triangulation protocol for qualitative health research will be used to integrate all data. Online stakeholder events will be held using consensus methods to agree a draft package of care for future implementation following further refinement, testing and evaluation. CLINICAL TRIAL REGISTRATION: The trial was registered with ISRCTN registry on 24 February 2022 (ISRCTN16917807).

Physical appearance and well-being in adults with incurable cancer: a thematic analysis.

OBJECTIVES: Existing research has established the importance of appearance concerns for individuals with cancer and identified appearance as an important factor in dying with dignity. No research, however, has explored in depth the role of appearance in the experiences of individuals who have incurable cancer. This research aims to explore patients' experiences and perspectives in relation to the role of appearance issues in adults with incurable cancer. METHODS: Semi-structured interviews were conducted with 24 adults with incurable cancer (20 women, 4 men; mean age 54.5, SD 11.32). RESULTS: Thematic analysis generated three themes: 'Identity: Embodying Cancer', 'Communication: Wearing your illness' and 'Support: Holistic Care'. Appearance was felt to be an important element of identity, which was often dominated by cancer, leading to feelings of separation from the participant's previous self. Appearance changes also influenced the way in which individuals communicated with their external world, forcing discussion of their diagnosis, and increasing focus on their cancer, with participants having to manage the emotional impact of this on loved ones, as well as the impact on their legacy. Finally, participants highlighted the positive impact of appearance-related support in their well-being and identified peer connections and refocusing on the self as key elements of such support. CONCLUSIONS: Appearance changes play an important role in the experiences of individuals with incurable cancer with regards to both identity and communication and challenged participants' ability to maintain normalcy. Further psychosocial support relating to appearance concerns was considered necessary to promote dignity and provide truly holistic patient care.

Delphi study to define core clinical outcomes for inclusion in a complex regional pain syndrome international research registry and data bank.

ABSTRACT: Complex regional pain syndrome (CRPS) clinical trials have historically captured a diverse range of outcomes. A minimum set of CRPS patient-reported outcomes has been agreed for inclusion in a future CRPS international clinical research registry and data bank. This study aimed to identify a complementary set of core clinical outcomes. Clinicians and researchers from the international CRPS community informed the content of a 2-round electronic Delphi study. Participation was invited from members of the International Association for the Study of Pain CRPS Special Interest Group and the International Research Consortium for CRPS. In round 1, participants rated the relevance of 59 clinical outcomes in relation to the question "What is the clinical presentation and course of CRPS, and what factors influence it?" (1 = not relevant and 9 = highly relevant). In round 2, participants rerated each outcome in the light of the round 1 median scores. The criterion for consensus was median score ≥7, agreed by 75% of respondents. The core study team considered the feasibility of data collection of each identified outcome in agreeing final selections. Sixty respondents completed both survey rounds, with responses broadly consistent across professions. Nine outcomes met the consensus criterion. Final outcomes recommended for inclusion in the core clinical set were record of medications, presence of posttraumatic stress disorder, extent of allodynia, and skin temperature difference between limbs. Study findings provide robust recommendations for core clinical outcome data fields in the future CPRS international clinical research registry. Alongside patient-reported outcomes, these data will enable a better understanding of CRPS.

Complex Regional Pain Syndrome: Practical Diagnostic and Treatment Guidelines, 5th Edition.

There have been some modest recent advancements in the research of Complex Regional Pain Syndrome, yet the amount and quality of the work in this complicated multifactorial disease remains low (with some notable exceptions; e.g., the recent work on the dorsal root ganglion stimulation). The semi-systematic (though in some cases narrative) approach to review is necessary so that we might treat our patients while waiting for "better research." This semi-systematic review was conducted by experts in the field, (deliberately) some of whom are promising young researchers supplemented by the experience of "elder statesman" researchers, who all mention the system they have used to examine the literature. What we found is generally low- to medium-quality research with small numbers of subjects; however, there are some recent exceptions to this. The primary reason for this paucity of research is the fact that this is a rare disease, and it is very difficult to acquire a sufficient sample size for statistical significance using traditional statistical approaches. Several larger trials have failed, probably due to using the broad general diagnostic criteria (the "Budapest" criteria) in a multifactorial/multi-mechanism disease. Responsive subsets can often be identified in these larger trials, but not sufficient to achieve statistically significant results in the general diagnostic grouping. This being the case the authors have necessarily included data from less compelling protocols, including trials such as case series and even in some instances case reports/empirical information. In the humanitarian spirit of treating our often desperate patients with this rare syndrome, without great evidence, we must take what data we can find (as in this work) and tailor a treatment regime for each patient.

Peoples' experiences of painful diabetic neuropathy: are pain management programmes appropriate?

OBJECTIVE: Painful diabetic neuropathy (PDN) is a painful complication of diabetes. This study aimed to explore: (1) strategies used by participants to manage impacts of PDN and (2) their perspectives on whether strategies from pain management programmes (PMPs) had applicability for PDN. DESIGN: Participants were recruited through local National Health Service (NHS) diabetes and PDN clinics, and nationally from a diabetes support charity. One-to-one interviews were conducted. The transcribed data were analysed using inductive thematic analysis. RESULTS: Twenty-three people were interviewed who had PDN symptoms for mean 10 years. Four themes emerged from the data: seeking help and advice, pragmatic approach to management, perspectives on physical activity and perspectives on psychological coping strategies. CONCLUSION: Some participants were open to the strategies advised by PMP strategies. There were also strong opinions that no exercise or psychological approach could help with diabetes-related pain. It is possible PMPs as currently delivered need to be adapted to maximise engagement from people with PDN. Research is required to understand the healthcare priorities of people with PDN and whether these priorities can be mapped to existing management strategies.

Visual illusions modulate body perception disturbance and pain in Complex Regional Pain Syndrome: A randomized trial.

BACKGROUND: Effective treatment of longstanding Complex Regional Pain Syndrome (CRPS) is a challenge, as causal mechanisms remain elusive. People with CRPS frequently report distorted subjective perceptions of their affected limb. Evidence of pain reduction when the affected limb is visually altered in size suggests that visual illusions used to target central processing could restore coherence of this disrupted limb representation. We hypothesized that using virtual reality that alters hand image to match the patient's desired hand appearance would improve body perception disturbance and pain. Also, repeated exposure would maintain any therapeutic effect. METHODS: A blinded randomized controlled trial of 45 participants with refractory upper-limb CRPS and body perception disturbance (BPD) viewed a digital image of their affected hand for 1 min. The image was digitally altered according to the patient's description of how they desired their hand to look in the experimental group and unaltered in the control group. BPD and pain were measured pre- and post-intervention. A subgroup was followed up 2 weeks after a course of repeated interventions. RESULTS: BPD (mean-6, ±SD 7.9, p = 0.036, effect size [ES] = 0.6) and pain intensity (mean-0.43, ±SD 1.3, p = 0.047, ES = 0.5) reduced in 23 participants after single exposure compared to controls (n = 22). At follow-up, the subgroup (experimental n = 21; control n = 18) showed sustained pain reduction only (p = 0.037, ±SD 1.9, ES = 0.7), with an overall 1.2 decrease on an 11-point scale. CONCLUSIONS: Visually changing the CRPS hand to a desired appearance modulates BPD and pain suggesting therapeutic potential for those with refractory CRPS. Further research to optimize this therapeutic effect is required. SIGNIFICANCE: Visual bodily illusions that change the shape and appearance of the painful CRPS hand to that desired by the patient result in a rapid amelioration of pain and body perception disturbance in people with longstanding CRPS. These findings highlight the future potential of this drug-free approach in the treatment of refractory CRPS.

The Contribution of Motor Commands to the Perturbations Induced by Sensorimotor Conflicts in Fibromyalgia.

Individuals with pain report higher sensory disturbances during sensorimotor conflicts compared to pain-free individuals. In the pain field, it is frequently assumed that disturbances arise from a discordance between sensory and efference copies (defined as sensory-motor conflict), while in the sensorimotor control field they are considered to result from the incongruence between sensory modalities (defined as sensory-sensory conflict). The general aim of this study was to disentangle the relative contribution of motor efferences and sensory afferences to the increased sensitivity to sensorimotor conflicts in individual with fibromyalgia (n = 20) compared to controls (n = 20). We assessed sensory and motor disturbances during sensory-sensory and sensory-motor conflicts using a robotized exoskeleton interfaced with a 2D virtual environment. There was a significant interaction between the group and the type of conflict (p = 0.03). Moreover, the increase in conflict sensitivity from sensory-sensory to sensory-motor conflicts in fibromyalgia was related to conflict-induced motor disturbances (r = 0.57; p < 0.01), but did not result from a poorer proprioception (r = 0.12; p = 0.61). Therefore, it appears that higher conflict sensitivity in fibromyalgia is mainly explained by a sensory-motor conflict rather by a sensory-sensory conflict. We suggest this arises due to a deficit in updating predicted sensory feedback rather than in selecting appropriate motor commands.

Bodily changes and sensory sensitivity in complex regional pain syndrome and fibromyalgia.

Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions of unexplained origins. In addition to symptoms in the diagnostic criteria, patients can report changes to vision and other sensations or bodily functions. It is unclear whether these are greater than would be expected due to normal ageing, living with chronic pain generally, or common comorbidities of chronic pain such as depression or anxiety. We administered an on-line survey evaluating the frequencies and types of self-reported somatic symptoms, bodily changes, and sensory sensitivity in respondents with CRPS (n = 390), fibromyalgia (n = 425), and both CRPS and fibromyalgia ("CRPS+fibromyalgia"; n = 88) compared to respondents with other chronic pain conditions (n = 331) and pain-free controls (n = 441). The survey assessed somatic symptoms (Patient Health Questionnaire-15), bodily changes, pain/discomfort/distress triggers, and pain intensifiers. We conducted analysis of covariance's with age, sex, Patient Health Questionnaire-9 (measuring depression), Generalized Anxiety Disorder-7, pain duration in years, hours of pain per day, and number of pain-related medical diagnoses as covariates. After controlling for covariates, respondents with CRPS and/or fibromyalgia reported more somatic symptoms, changes in movement and biological responses, pain/discomfort/distress triggers, and pain intensifiers than pain(-free) control groups. Fibromyalgia specifically related to changes in vision and hearing, urinary/intestinal function, and drinking and eating. Complex regional pain syndrome related to changes in hair, skin, and nails; and infection and healing. The CRPS+fibromyalgia group presented with features of both disorders with minimal additional stressors or symptoms over and above these. Our findings suggest that CRPS and fibromyalgia share underlying pathophysiologies, although specific mechanisms might be different.

The experience of persistent pain in adult cancer survivors: A qualitative evidence synthesis.

OBJECTIVE: This qualitative evidence synthesis aimed to identify, review and synthesise qualitative research describing the experience of persistent pain in adult cancer survivors. METHODS: A systematic literature search was conducted between December 2007 and June 2019. Data synthesis followed Thomas and Harden's (2008) method of thematic synthesis. RESULTS: Four studies were identified, together incorporating findings from 52 female breast cancer survivors. Six themes were generated as follows: (a) interwoven relationship between experience of cancer and persistent pain, (b) lack of preparedness and support for persistent pain, (c) physical impact of persistent pain, (d) employing coping strategies, (e) emotional experience of persistent pain and (f) conceptualisation of persistent pain. CONCLUSIONS: Persistent pain is intrinsically interwoven with women's experiences of cancer. Persistent pain was unexpected, and women did not feel supported. Women need more information about persistent pain after cancer treatment and support with self-management of pain. Ways to best support cancer survivors with persistent pain need exploration and a review of currently available services is required. More research is needed to understand the experiences of men and other cancer groups.

Complex regional pain syndrome: An international survey of clinical practice.

BACKGROUND: Published guidelines promote best practice in complex regional pain syndrome (CRPS) treatment and management; however, these recommendations are not always applied in clinical practice. Understanding existing care internationally will help inform future patient and health professional service delivery, education initiatives and content of clinical guidelines. METHODS: An e-survey was conducted in order to gain an insight into routine CRPS clinical practice. Health professionals and academics, from the field of CRPS, were recruited from an international population. Quantitative and qualitative data were elicited. Data were mapped onto a framework to identify macro-regional factors. RESULTS: Of the 260 survey respondents, 96% (n = 241) provided clinical care for people with CRPS, with academics not involved in patient care also responding. Half of respondents expressed difficulty in recognizing the symptoms of CRPS but treatment aims corresponded with published guidelines. However, a lack of resources and fragmented care were reported as barriers to early intervention. Service constraints were most frequently reported by European respondents. Five themes emerged from the qualitative data: the benefit of interdisciplinary working; the importance of symptom management; need for early diagnosis and intervention; establishing a collaborative partnership with patients; the value of education for patients and health professionals. CONCLUSIONS: Our data suggest that more work is required to raise awareness of the Budapest CRPS diagnostic criteria so as to promote early diagnosis and intervention. Future work to optimize clinical effectiveness should consider enhancing interdisciplinary service delivery that encourages a collaborative patient/clinician partnership; includes excellent patient education; and addresses modifiable patient-related factors. SIGNIFICANCE: Health professionals expressed some level of difficulty recognizing the signs and symptoms of CRPS despite the majority of health professionals having had clinical experience exceeding 6 years in the field of CRPS. More work is required to raise awareness amongst clinicians of the Budapest CRPS diagnostic criteria so as to promote early diagnosis and intervention Health professionals' treatment aims reflected the current clinical guidelines however, a lack of resources and fragmented care were frequently cited as barriers to achieving these.

A multi-centre study to explore the feasibility and acceptability of collecting data for complex regional pain syndrome clinical studies using a core measurement set: Study protocol.

OBJECTIVES: This international, multicentre study will inform the final data collection tools and processes which will comprise the first international, clinical research registry for complex regional pain syndrome (CRPS). This study will: (a) test the feasibility and acceptability of collecting outcome measurement data using a patient reported, questionnaire core measurement set (COMPACT [Core Outcome Measurement set for complex regional PAin syndrome Clinical sTudies]); and (b) test and refine an electronic data management system to collect and manage the data. METHODS: A maximum of 240 adults, meeting the Budapest diagnostic clinical criteria for CRPS type I or II, will be recruited across eight countries. The COMPACT questionnaire will be completed on two occasions: at baseline (T1) and 6 months later (T2). At T2, participants will choose to complete COMPACT using a paper or electronic version. Participants will be asked to feed back on their experience of completing COMPACT via a questionnaire. A separate questionnaire will ask clinicians to feed back their experience of data collection. ANALYSIS: The study is not aiming to derive statistically significant data but to ascertain the practicalities of collecting data, using the COMPACT questionnaire set, across a range of different cultures and populations. At the end of the study, a single workshop will be convened to review the findings and agree the final documents and processes for the international registry.

Maintained physical activity and physiotherapy in the management of distal arm pain: a randomised controlled trial.

Objectives: The epidemiology of distal arm pain and back pain are similar. However, management differs considerably: for back pain, rest is discouraged, whereas patients with distal arm pain are commonly advised to rest and referred to physiotherapy. We hypothesised that remaining active would reduce long-term disability and that fast-track physiotherapy would be superior to physiotherapy after time on a waiting list. Methods: Adults referred to community-based physiotherapy with distal arm pain were randomised to: advice to remain active while awaiting physiotherapy (typically delivered after 6-8 weeks); advice to rest while awaiting physiotherapy, or immediate treatment. Intention-to-treat analysis determined whether the probability of recovery at 26 weeks was greater among the active advice group, compared with those advised to rest and/or among those receiving immediate versus usually timed physiotherapy. Results: 538 of 1663 patients invited between February 2012 and February 2014 were randomised (active=178; rest=182; immediate physiotherapy=178). 81% provided primary outcome data, and complete recovery was reported by 60 (44%), 46 (32%) and 53 (35%). Those advised to rest experienced a lower probability of recovery (OR: 0.54; 95% CI 0.32 to 0.90) versus advice to remain active. However, there was no benefit of immediate physiotherapy (0.64; 95% CI 0.39 to 1.07). Conclusions: Among patients awaiting physiotherapy for distal arm pain, advice to remain active results in better 26-week functional outcome, compared with advice to rest. Also, immediate physiotherapy confers no additional benefit in terms of disability, compared with physiotherapy delivered after 6-8 weeks waiting time. These findings question current guidance for the management of distal arm pain.

An exploration of the experiences of women treated with radiotherapy for breast cancer: Learning from recent and historical cohorts to identify enduring needs.

PURPOSE: Recent decades have seen improvements in UK breast cancer services and treatments. Despite this, it is recognised that a range of patients' psychological and emotional needs remain unmet, both at the time of treatment and into survivorship. Using data from two distinct cohorts of women: those treated with radiotherapy for breast cancer historically, and women treated more recently, this study sought to identify and explore those needs and concerns that have continued to persist, despite advances in treatment and care. METHOD: Data from N = 13 semi-structured interviews were analysed using Interpretative Phenomenological Analysis. An heuristic framework was applied to extract themes common to both participant cohorts. RESULTS: Participants' data evidenced an enduring vulnerability amongst cancer patients that has not diminished with new treatment pathways. Themes common to both cohorts highlighted the ongoing importance of personal factors such as resilience, and strategies to help retain a sense of normality. Extrinsic support was important too, especially high quality communication by healthcare professionals and having access to ongoing emotional support from others, particularly when active treatment ends. Participants' suggestions for future service development included the provision of ongoing continuity of care and greater access to emotional support services. CONCLUSIONS: This study highlights the psychological needs and concerns of breast cancer patients that have persisted, despite the many advances in patient-centred care. Findings are of value to nurses and other healthcare professionals in highlighting the ongoing importance of recognising, acknowledging and addressing patients' concerns and needs, even within current cancer care pathways.

Exploring the Relationships Between Altered Body Perception, Limb Position Sense, and Limb Movement Sense in Complex Regional Pain Syndrome.

Chronic pain is often accompanied by patient-reported distorted body perception and an altered kinesthesia (referring to the senses of limb position and limb movement), but the association between these deficits is unknown. The objectives of this study were to assess body perception and the senses of limb position and limb movement in complex regional pain syndrome (CRPS) and to test whether these variables are related to each other and to pain intensity. Thirteen patients with upper limb CRPS (mean pain intensity, 4.2 ± 2.4 out of 10) and 13 controls were recruited. Body perception was self-reported with a questionnaire, and the senses of limb position (task 1) and of limb movement (task 2) were assessed with a robotic system combined with a 2D virtual reality display. The results showed altered kinesthesia in the patients with CRPS compared with controls (all P < .05). Moreover, in the CRPS group, greater pain intensity was associated with lower performance on task 2 (r = -.60; P < .05). Although alterations in participants' sense of limb position and limb movement were associated with each other (r = -.70, P < .01), they were not related to the altered body perception (all P > .26). Therefore, the results suggest that kinesthesia and body perception should be considered and evaluated separately in patients with CRPS. PERSPECTIVE: Senses of limb position and movement rely on sensorimotor integration. Both are altered in complex regional pain syndrome. However, they are not related to the subjective perception of the painful limb, and thus they should be assessed separately in rehabilitation.

Sensory disturbances induced by sensorimotor conflicts are higher in complex regional pain syndrome and fibromyalgia compared to arthritis and healthy people, and positively relate to pain intensity.

BACKGROUND: Sensorimotor conflicts are well known to induce sensory disturbances. However, explanations as to why patients with chronic pain are more sensitive to sensorimotor conflicts remain elusive. The main objectives of this study were (a) to assess and compare the sensory disturbances induced by sensorimotor conflict in complex regional pain syndrome (n = 38), fibromyalgia (n = 36), arthritis (n = 34) as well as in healthy volunteers (HV) (n = 32); (b) to assess whether these disturbances were related to the intensity and duration of pain, or to other clinical variables assessed using questionnaires (abnormalities in sensory perception, depression and anxiety); and (c) to categorize different subgroups of conflict-induced sensory disturbances. METHODS: One hundred and forty participants performed in phase or anti-phase movements with their arms while viewing a reflection of one arm in a mirror (and the other arm obscured). They were asked to report changes in sensory disturbances using a questionnaire. RESULTS: First, results showed that patients with complex regional pain syndrome and fibromyalgia were more prone to report sensory disturbances than arthritis patients and HV in response to conflicts (small effect size). Second, conflict-induced sensory disturbances were correlated with pain intensity (large effect size) and abnormalities in sensory perception (only in the CRPS group) but were not related to the duration of the disease or psychological factors. Finally, we identified two distinct subgroups of conflict-induced sensory disturbances. CONCLUSIONS: Our results suggest that pain lowers the threshold for the detection of sensorimotor conflicts, a phenomenon that could contribute to the maintenance of pain in clinical populations. SIGNIFICANCE: Individuals with complex regional pain syndrome and fibromyalgia were more sensitive to sensorimotor conflicts than arthritis patients and controls. Moreover, conflict-induced sensory disturbances were specific to higher pain intensity and higher sensory abnormalities in all groups, suggesting that pain lowers the threshold for the detection of sensorimotor conflicts.