Chronic pain and distorted body image: Implications for multisensory feedback interventions

Impaired gastric and urinary but preserved cardiac interoception in women with endometriosis

Endometriosis is a chronic inflammatory gynaecological condition frequently associated with chronic pelvic pain. Visceral hypersensitivity could be present, like in other chronic pain conditions, causing altered levels of interoception. So far, studies have explored interoceptive deficits in chronic pain individuals mainly using questionnaires or cardiac interoceptive accuracy tasks. Here, we explore the cardiac, gastric, and urinary domains to probe interoceptive differences between patients with endometriosis and healthy women. 30 patients and 30 controls underwent three interoceptive tasks for assessing the cardiac domain (using the Heartbeat Counting Task, HCT), the gastric domain (using the Water Load Test-II, WLT-II) and the bladder domain (using a novel Urinary Interoceptive Task, UIT). Participants also completed bladder interoceptive beliefs measures and subjective pain ratings for each endometriosis symptom (dysmenorrhea, dyspareunia, dyschezia, chronic pain). A positive correlation between the WLT-II and the UIT emerged in all participants (R = 0.47, p < 0.001), indicating that the lower the gastric interoceptive abilities, the lower the urinary ones. Moreover, compared to healthy controls, women with endometriosis exhibited lower scores in the WLT-II (t(58) = 4.6814, p < 0.001) and the UIT (t(39.931)= 5.1462, p < 0.001), as well as higher scores in the subjective bladder beliefs questions (t(57.346)= -4.0304, p < 0.001). Results indicate a dissociation between patients' poor objective performance on interoceptive tasks and their high bladder interoceptive beliefs. UIT scores were associated with pain symptoms, suggesting that patients, probably due to sensitisation, struggle to ignore discomfort sensations, resulting in reduced accuracy in detecting physiological signals coming from the pelvic area.

Virtual reality improves pain threshold and recall in healthy adults: A randomized, crossover study

STUDY OBJECTIVE

Virtual reality (VR) is an emerging technology increasingly used to ameliorate acute and chronic pain although controlled, quantifiable data are limited. The purpose of this study is to evaluate VR's effect on heat pain threshold (HPT), pressure pain threshold (PPT), immediate pain and anxiety, and recalled pain and anxiety.

DESIGN

Prospective, randomized, crossover clinical trial.

SETTING

The Stanford Chariot Program conducted this study at the Stanford School of Medicine Health System.

PATIENTS

Healthy participants meeting inclusion criteria were recruited by solicitation from the Stanford School of Medicine Health System.

INTERVENTIONS

Participants were randomized by hand dominance and condition sequence and underwent standardized pain threshold tests with a thermode or an algometer during VR and control conditions.

MEASUREMENTS

Pain threshold, numeric pain scores, and anxiety scores were immediately recorded. Recalled pain and anxiety scores were recorded 24 h later.

MAIN RESULTS

A total of 80 participants were included, 40 who underwent HPT testing and 40 who underwent PPT testing. VR increased pain thresholds for both HPT (P = 0.002) and PPT (P = 0.044). The use of VR resulted in no difference in initial pain scores for HPT (P = 0.432) or PPT (P = 0.24). There was no difference in recalled pain when using VR for HPT (P = 0.851) although there was for PPT (P = 0.003). Initial and recalled anxiety scores for HPT (P = 0.006, P = 0.018, respectively) and PPT (P = 0.014, P = 0.002, respectively) were all reduced when using VR.

CONCLUSIONS

This study demonstrates that VR increased pain thresholds while modulating initial and recalled experiences with anxiety, which has implications for enhancing patient experiences during medical interventions and long-term health outcomes by optimizing memories during stressful events.

CLINICAL TRIAL REGISTRATION

NCT05836649, 4/19/23. IRB registration: Stanford IRB #69330.

Drawing the lines of fibromyalgia: a mixed-methods approach to mapping body image, body schema, and emotions in patient subtypes

Fibromyalgia is characterized by widespread chronic pain and multiple additional symptoms which may result in significant disability. Recent studies have demonstrated disturbances in body image and body schema in people affected by this condition. Importantly, it affects a heterogenous population in which distinct profiles can be identified based on physiological and/or psychological characteristics. The objective of our study was to explore individual differences in experiencing one's own body in fibromyalgia. We applied a mixed methods design and included data from 28 women diagnosed with fibromyalgia. We measured symptom intensity (Fibromyalgia Impact Questionnaire, part 1), disturbances in body schema (adapted Fremantle Back Awareness Questionnaire) and body image (Body Esteem Scale, Multidimensional Assessment of Interoceptive Awareness). Additionally, participants drew their bodies and how they experienced them (Body Drawing task). Next, we asked five experts in chronic pain treatment to evaluate the drawings on a specially designed scale and indicate what kind of emotions these drawings expressed. We found evidence of disturbed body experiences and large individual differences in each of the measured variables which allowed for clustering participants into three groups, named 'Connected body', 'Conflicted body', and 'Disconnected body'. These preliminary results suggest patients with fibromyalgia may have both qualitatively and quantitatively distinct disrupted body experience.

Preserved tactile distance estimation despite body representation distortions in individuals with fibromyalgia

Our mental representation of our body depends on integrating various sensory modalities, such as tactile information. In tactile distance estimation (TDE) tasks, participants must estimate the distance between two tactile tips applied to their skin. This measure of tactile perception has been linked to body representation assessments. Studies in individuals with fibromyalgia (FM), a chronic widespread pain syndrome, suggest the presence of body representation distortions and tactile alterations, but TDE has never been examined in this population. Twenty participants with FM and 24 pain-free controls performed a TDE task on three Body regions (upper limb, trunk, lower limb), in which they manually estimated the interstimuli distance on a tablet. TDE error, the absolute difference between the estimation and the interstimuli distance, was not different between the Groups, on any Body region. Drawings of their body as they felt it revealed clear and frequent distortions of body representation in the group with FM, compared to negligible perturbations in controls. This contrast between distorted body drawings and unaltered TDE suggests a preserved integration of tactile information but an altered integration of this information with other sensory modalities to generate a precise and accurate body representation. Future research should investigate the relative contribution of each sensory information and prior knowledge about the body in body representation in individuals with FM to shed light on the observed distortions.

Disturbed body schema, perceptual body image, and attitudinal body image in patients with borderline personality disorder

Background

Borderline personality disorder (BPD) is a severe mental disorder that affects attitudes toward the body. However, whether this condition also affects body schema and perceptual body image remains unclear. Previous questionnaire-based studies found dissatisfaction with one's body in patients with BPD. In addition to attitudinal body image, our study investigates whether body schema and perceptual body image are disturbed in patients with BPD.

Method

Our study included 31 patients diagnosed with BPD (25 women) and 30 healthy individuals (19 women) (Mage = 29 for both groups). The SCID-5-PD interview was used to determine personality disorder. Attitudinal body image was measured using the Body Attitude Test (BAT) factors. Body schema and perceptual body image were measured by two conditions of a body representation task, the body portraying method (BPM).

Results

BPD patients achieved higher scores in all three BAT factors and were more susceptible to misinformation in both conditions of BPM. Based on the results, BPD patients appear to have more negative attitudes toward their bodies and worse perceptual body image and body schema.

Conclusion

The novel finding of our study is that, besides the previously found attitudinal dissatisfaction with the body, individuals with BPD also show disturbances at the levels of body schema and perceptual body image. Our findings concerning disturbances in body schema and perceptual body need further research into their etiological factors and provide new therapeutic targets for the treatment of BPD.

Role of Immersive Virtual Reality in Motor Behaviour Decision-Making in Chronic Pain Patients

Primary chronic pain is a major contributor to disability worldwide, with an estimated prevalence of 20-33% of the world's population. The high socio-economic impact of musculoskeletal pain justifies seeking an appropriate therapeutic strategy. Immersive virtual reality (VR) has been proposed as a first-line intervention for chronic musculoskeletal pain. However, the growing literature has not been accompanied by substantial progress in understanding how VR exerts its impact on the pain experience and what neurophysiological mechanisms might be involved in the clinical effectiveness of virtual reality interventions in chronic pain patients. The aim of this review is: (i) to establish the state of the art on the effects of VR on patients with chronic pain; (ii) to identify neuroplastic changes associated with chronic pain that may be targeted by VR intervention; and (iii) to propose a hypothesis on how immersive virtual reality could modify motor behavioral decision-making through an interactive experience in patients with chronic pain.

Relating different Dimensions of Bodily Experiences: Review and proposition of an integrative model relying on phenomenology, predictive brain and neuroscience of the self

How we mentally experience our body has been studied in a variety research domains. Each of these domains focuses in its own ways on different aspects of the body, namely the neurophysiological, perceptual, affective or social components, and proposes different conceptual taxonomies. It is therefore difficult to find one's way through this vast literature and to grasp the relationships between the different dimensions of bodily experiences. In this narrative review, we summarize the existing research directions and present their limits. We propose an integrative framework, grounded in studies on phenomenal consciousness, self-consciousness and bodily self-consciousness, that can provide a common basis for evaluating findings on different dimensions of bodily experiences. We review the putative mechanisms, relying on predictive processes, and neural substrates that support this model. We discuss how this model enables a conceptual assessment of the interrelationships between multiple dimensions of bodily experiences and potentiate interdisciplinary approaches.

What is the evidence of effectiveness of non-pharmaceutical, non-surgical, biopsychosocial interventions for body image and pain management in individuals with endometriosis? A systematic review

Aim:

To identify and review the success of non-pharmaceutical, non-surgical biopsychosocial interventions in individuals with endometriosis, in managing pain and improving body image.

Methods:

Cochrane, EBSCO, IBSS, NICE, Open Grey, OVID, Proquest, Scopus and Science Direct were searched in April 2021, using inclusion and exclusion criteria.

Data collection and analysis:

Five randomised control trials, and one controlled clinical trial resulted from the search. Study quality was assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool. Studies were synthesised by intervention type, into physical only, and physical and psychological.

Results:

Across the six papers, 323 participants were recruited, through medical records or self-referral, and treatments largely administered by specialist practitioners. From the EPHPP quality assessment,2 weak quality papers, and four moderate quality papers found improvements to pain, with large effect sizes in four papers. No studies used established body image measures to examine intervention effects on body image, and all lacked health psychology theoretical basis. There were common issues in selection bias, confounders and blinding.

Conclusion:

Without gold-standard methodology, evidence of effectiveness cannot be concluded. However, there is promising rationale if these issues are addressed.

Patients' Lived Experience in a Multicomponent Intervention for Fibromyalgia Syndrome in Primary Care: A Qualitative Interview Study

Fibromyalgia syndrome (FMS) disrupts patients' biopsychosocial spheres. A multicomponent intervention (MCI) program, which combined health education, cognitive behavioral therapy, and physical activity, was conducted in South Catalonia's primary care centers with the aim of improving symptom self-management and quality of life. A qualitative interview study was carried out to understand patients' lived experiences during the intervention program. Sampled purposively, 10 patients were interviewed via phone calls and face-to-face. The encounters were audio-recorded, verbatim transcribed, and analyzed through thematic analysis. As a result, four themes emerged: legitimizing fibromyalgia through the MCI, the MCI as a socializing experience, learning how to live with FMS through the MCI, and room for improving the MCI. Participants agreed on the program being an insightful experience that promoted illness knowledge and acceptance and that improved their coping skills and symptom self-management. The inclusion of additional psychological guidance, expressive psychological group therapy, and providing relatives with information were proposed for enhancing the program. Our findings have contributed to gaining insight into the subjective impact of the MCI and identifying new therapeutic targets to tailor the program to patients' needs, which will hopefully increase its effectiveness and improve their quality of life.

The sensorimotor theory of pathological pain revisited

Harris (1999) proposed that pain can arise in the absence of tissue damage because changes in the cortical representation of the painful body part lead to incongruences between motor intention and sensory feedback. This idea, subsequently termed the sensorimotor theory of pain, has formed the basis for novel treatments for pathological pain. Here we review the evidence that people with pathological pain have changes to processes contributing to sensorimotor function: motor function, sensory feedback, cognitive representations of the body and its surrounding space, multisensory processing, and sensorimotor integration. Changes to sensorimotor processing are most evident in the form of motor deficits, sensory changes, and body representations distortions, and for Complex Regional Pain Syndrome (CRPS), fibromyalgia, and low back pain. Many sensorimotor changes are related to cortical processing, pain, and other clinical characteristics. However, there is very limited evidence that changes in sensorimotor processing actually lead to pain. We therefore propose that the theory is more appropriate for understanding why pain persists rather than how it arises.

The chronic disease Self-Management Programme: A phenomenological study for empowering vulnerable patients with chronic diseases included in the EFFICHRONIC project

Introduction

The Chronic Disease Self‐Management Programme (CDSMP) has resulted in improved health outcomes for patients. However, research has focused mainly on those with chronic conditions and has not extensively explored prevention programmes targeting individuals with specific vulnerability profiles.

Aim

This study aimed to understand the effects of the CDSMP on the lived experience of vulnerable patients included in the EFFICHRONIC project in France, based on their needs and expectations before and after participation.

Methods

We conducted a qualitative phenomenological semio‐pragmatic study based on 37 in‐depth interviews with 20 patients (20 before/17 after CDSMP).

Results

By transforming existential dimensions (identity, relationship with others and bodily experience), chronic illness generates new needs in the vulnerable person. By resonating with the expectations and needs of participants, the CDSMP induces motivation and a sense of belonging to a community of peers. It has enabled the participants to become actors of their own health until empowerment. Although some limitations are reported, the programme has awakened a desire in the participants to take better care of their health and to develop personal skills with, for some, a desire to become involved in health education.

Conclusion

Our phenomenological approach highlighted the resonance between the programme (its design and implementation) and the lived experience of patients, as an effective element of empowerment. This necessitates training the facilitators to elicit the lived experience of patients. Furthermore, as a patient‐centred approach is required, the facilitators need to learn how to adapt the design of the programme to the singularity of the patient.

Patient or Public Contribution

Patients provided the data that were collected through in‐depth interviews, and their experiences before and after the programme were analysed.

"But it feels swollen!": the frequency and clinical characteristics of people with knee osteoarthritis who report subjective knee swelling in the absence of objective swelling

Supplemental Digital Content is Available in the Text.

The present results support the coexistence of altered body image (subjective without objective swelling) and pain, disability, and maladaptive beliefs in people with knee osteoarthritis.

Introduction:

There are complex interactions between pain and perceptions of the painful body part in musculoskeletal disorders, and disruption of various body representations in people with chronic pain.

Objectives:

The purpose of this study was to investigate how frequently people with knee osteoarthritis (OA) complain of swelling without objective evidence of swelling, and describe the clinical characteristics of this population.

Methods:

Forty-six people with knee OA (68.1 ± 8.8 years) participated in this cross-sectional study. Subjective and objective swelling was evaluated by knee-specific body perception questionnaire and ultrasonography, respectively. Pain intensity, disability, pain-related beliefs, 2-point discrimination threshold, and quadriceps muscle strength were also evaluated.

Results:

Approximately 1/3 of participants (n = 15) had subjective feelings of knee swelling in the absence of objective swelling (S only). Fifteen participants had both subjective and objective knee swelling (S + O group) and 16 had neither subjective nor objective knee swelling (No S/O group). Participants in the S only group had similar pain or disability as those in the S + O group but had more severe pain or disability than those with in the No S/O group. Those in the S only group also had larger 2-point discrimination distance threshold at the medial knee (impaired tactile acuity) than those in the S + O group and had more dysfunctional pain catastrophizing and pain-related self-efficacy than both other groups.

Conclusion:

Our results suggest that about 30% of people with knee OA perceive swelling of the knee in the absence of any objective swelling and that this is accompanied by severe pain and functional disability. Considering altered body image of the knee may reveal relevant treatment-based subgroups in people with knee OA.

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.

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.

Looking beyond the binary: an extended paradigm for focus of attention in human motor performance

Focus of attention (FOA) has been shown to affect human motor performance. Research into FOA has mainly posited it as either external or internal to-the-body (EFOA and IFOA, respectively). However, this binary paradigm overlooks the dynamic interactions among the individual, the task, and the environment, which are core to many disciplines, including dance. This paper reviews the comparative effects of EFOA and IFOA on human motor performance. Next, it identifies challenges within this EFOA-IFOA binary paradigm at the conceptual, definitional, and functional levels, which could lead to misinterpretation of research findings thus impeding current understanding of FOA. Building on these challenges and in effort to expand the current paradigm into a non-binary one, it offers an additional FOA category-dynamic interactive FOA-which highlights the dynamic interactions existing between EFOA and IFOA. Mental imagery is then proposed as a suitable approach for separately studying the different FOA subtypes. Lastly, clinical and research applications of a dynamic interactive FOA perspective for a wide range of domains, from motor rehabilitation to sports and dance performance enhancement, are discussed.

A Novel Method to Understand Neural Oscillations During Full-Body Reaching: A Combined EEG and 3D Virtual Reality Study

Virtual reality (VR) can be used to create environments that are not possible in the real-world. Producing movements in VR holds enormous promise for rehabilitation and offers a platform from which to understand the neural control of movement. However, no study has examined the impact of a 3D fully immersive head-mounted display (HMD) VR system on the integrity of neural data. We assessed the quality of 64-channel EEG data with and without HMD VR during rest and during a full-body reaching task. We compared resting EEG while subjects completed three conditions: No HMD (EEG-only), HMD powered off (VR-off), and HMD powered on (VR-on). Within the same session, EEG were collected while subjects completed full-body reaching movements in two conditions (EEG-only, VR-on). During rest, no significant differences in data quality and power spectrum were observed between EEG-only, VR-off, and VR-on conditions. During reaching movements, the proportion of components attributed to the brain was greater in the EEG-only condition compared to the VR-on condition. Despite this difference, neural oscillations in source space were not significantly different between conditions, with both conditions associated with decreases in alpha and beta power in sensorimotor cortex during movements. Our findings demonstrate that the integrity of EEG data can be maintained while individuals execute full-body reaching movements within an immersive 3D VR environment. Clinical impact: Integrating VR and EEG is a viable approach to understanding the cortical processes of movement. Simultaneously recording movement and brain activity in combination with VR provides the foundation for neurobiologically informed rehabilitation therapies.

Perceived Sensitivity to Pain and Responsiveness to Non-noxious Sensation in Substance Use Disorder

OBJECTIVE

This comparative cross-sectional study aimed to characterize individuals with substance use disorder (SUD) in self-perception of pain sensitivity, experimental auditory aversiveness, and non-noxious sensory responsiveness, as well as examine the associations with SUD.

METHODS

Therapeutic community (TC) individuals with SUD (N = 63, male 88.9%) and healthy controls (N = 60, male 86.7%) completed the Pain Sensitivity Questionnaire (PSQ) and the Sensory Responsiveness Questionnaire-Intensity Scale (SRQ-IS), followed by a psychophysical auditory battery, the Battery of Averseness to Sounds (BAS)-Revised.

RESULTS

The SUD group scored higher on the PSQ (P < 0.0001), BAS-R aversiveness (P < 0.0001), BAS-R-unpleasantness (P < 0.0001), and on the aftersensation of auditory aversiveness (P < 0.0001) and unpleasantness (P < 0.000). Fifty-four percent of the SUD group vs 11.7% of the control group were identified as having sensory modulation dysfunction (SMD; P < 0.0001). Logistic regression modeling revealed that the SRQ-IS-Aversive score had a stronger relationship, indicating a 12.6-times odds ratio for SUD (P = 0.0002). Finally, a risk score calculated from a linear combination of the logistic regression model parameters is presented based on the PSQ and SRQ.

CONCLUSIONS

This is the first study to explore sensory and aversive domains using experimental and self-reporting in situ, revealing pain perception alteration that co-occurs with high prevalence of SMD, specifically of the over-responsive type. Findings may be significant in clinical practice for treating pain, and for expanding therapeutic modalities as part of broader rehabilitation in TC and beyond, to better meet personalized therapy.

Behavioral and neurophysiological evidence for altered interoceptive bodily processing in chronic pain

Whereas impaired multisensory processing of bodily stimuli and distorted body representation are well-established in various chronic pain disorders, such research has focused on exteroceptive bodily cues and neglected bodily signals from the inside of the body (or interoceptive signals). Extending existing basic and clinical research, we investigated for the first time interoception and its neurophysiological correlates in patients with complex regional pain syndrome (CRPS). In three different experiments, including a total of 36 patients with CRPS and 42 aged-gender matched healthy controls, we measured interoceptive sensitivity (heart beat counting task, HBC) and neural responses to heartbeats (heartbeat evoked potentials, HEPs). As hypothesized, we observed reduced sensitivity in perceiving interoceptive bodily stimuli, i.e. their heartbeat, in two independent samples of CRPS patients (studies 1 and 2). Moreover, the cortical processing of their heartbeat, i.e. the HEP, was reduced compared to controls (study 3) and reduced interoceptive sensitivity and HEPs were related to CRPS patients' motor impairment and pain duration. By providing consistent evidence for impaired processing of interoceptive bodily cues in CRPS, this study shows that the perceptual changes occurring in chronic pain include signals originating from the visceral organs, suggesting changes in the neural body representation, that includes next to exteroceptive, also interoceptive bodily signals. By showing that impaired interoceptive processing is associated with clinical symptoms, our findings also encourage the use of interoceptive-related information in future rehabilitation for chronic pain.

Body image experiences in the context of chronic pain: An examination of associations among perceptions of pain, body dissatisfaction, and positive body image

Although body image research has recently begun to examine positive body image and ways to improve body image, it remains unclear the extent to which these findings generalize to individuals who experience chronic pain. With this in mind, this study examined individuals with chronic pain conditions (N = 278, M_age = 36.75, SD = 11.56), including their reports of their ability to control, manage, and accept their pain. Participants also completed assessments of four facets of body image: perceptions of body functionality, body appreciation, appearance evaluation, and body satisfaction. Results indicated that pain acceptance was the most consistent, unique predictor of these body image constructs, after controlling for the other pain facets, as well as body mass index, gender, and age. These findings have implications for improving body image among people with chronic pain; it appears that controlling or altering pain may be less relevant to body image than is how individuals cope with pain.

Psychological, social and biological correlates of body perception disturbance in complex regional pain syndrome

Body Perception Disturbance (BPD) in Complex Regional Pain Syndrome (CRPS) still represents a poorly understood phenomenon. Research has shown that knowledge about changes in body perception can yield relevant information for understanding and treating the disease. This study addressed possible connections between BPD and psychological and social factors, pain intensity, and disease duration. Sixty patients with chronic CRPS Type I of the hand were recruited. Body Perception Disturbance was assessed using the Galer and Jensen Neurobehavioral Questionnaire (GJ) and the BATH CRPS Body Perception Disturbance Scale (BATH). Depression, anxiety, stress, childhood trauma and other life events were assessed using standardized and validated questionnaires. This study found that BPD in CRPS was significantly correlated with measures of depression, anxiety, current stress, quality of life, and pain intensity, but not with stress experienced in the twelve months preceding onset of illness, childhood trauma, or duration of illness. Future research needs to identify which patients are most likely to develop these psychological conditions of CRPS, so that early, preventive intervention is possible. This study establishes a relationship between depression, anxiety, current stress, quality of life, pain intensity, and BPD severity. It also supports literature suggesting that preexisting stress, childhood trauma, and disease duration have no influence on BPD. The findings suggest that there is a bidirectional influence between brain alterations, psychological symptoms, and illness severity.

Direct evidence of EEG coherence in alleviating phantom limb pain by virtual referred sensation: Case report

Virtual reality (VR) systems have been integrated into rehabilitation techniques for phantom limb pain (PLP). In this case report, we used electroencephalography (EEG) to analyze corticocortical coherence between the bilateral sensorimotor cortices during vibrotactile stimulation in conjunction with VR rehabilitation in two PLP patients. As a result, we observed PLP alleviation and increased alpha wave coherence during VR rehabilitation when stimulation was delivered to the cheek and shoulder (referred sensation areas) of the affected side. Vibrotactile stimulation with VR rehabilitation may enhance the awareness and movement of the phantom hand.

Manipulating the Perceived Shape and Color of a Virtual Limb Can Modulate Pain Responses

Changes in body representation may affect pain perception. The effect of a distorted body image, such as the telescoping effect in amputee patients, on pain perception, is unclear. This study aimed to investigate whether distorting an embodied virtual arm in virtual reality (simulating the telescoping effect in amputees) modulated pain perception and anticipatory responses to pain in healthy participants. Twenty-seven right-handed participants were immersed in virtual reality and the virtual arm was shown with three different levels of distortion with a virtual threatening stimulus either approaching or contacting the virtual hand. We evaluated pain/discomfort ratings, ownership, and skin conductance responses (SCRs) after each condition. Viewing a distorted virtual arm enhances the SCR to a threatening event with respect to viewing a normal control arm, but when viewing a reddened-distorted virtual arm, SCR was comparatively reduced in response to the threat. There was a positive relationship between the level of ownership over the distorted and reddened-distorted virtual arms with the level of pain/discomfort, but not in the normal control arm. Contact with the threatening stimulus significantly enhances SCR and pain/discomfort, while reduced SCR and pain/discomfort were seen in the simulated-contact condition. These results provide further evidence of a bi-directional link between body image and pain perception.

Virtual reality and chronic low back pain

AIM

Chronic low back pain (CLBP) is a highly prevalent and significant cause of disability which is often resistant to pharmacological management. Virtual reality (VR) is an emerging technology with the potential to influence CLBP, and has been suggested as an alternative to opioids for pain management. VR is a goalfocused, computer-simulated reality allowing modification of the user's experience of their perceived world.

MATERIALS/METHODS

A narrative review of peer-reviewed literature using a systematic search strategy, and sole reviewer for data extraction.

CONCLUSIONS

VR has demonstrated effectiveness in reducing acute, experimental and chronic pain. This review describes the theoretical basis of the therapeutic effects of VR on CLBP via three distinct mechanisms: distraction, neuromodulation and graded exposure therapy. Furthermore, clinical application will be considered, including discussion of ethical issues associated with the technology.Implications for rehabilitationVirtual reality (VR) is suggested as an alternative for opioids in the management of acute and chronic pain.The therapeutic mechanisms of VR in chronic low back pain (CLBP) are equivocal but include distraction, neuromodulation of body perception and graded exposure therapy.VR may show greater efficacy in patients with CLBP with associated kinesiophobia.VR may show greater effect with increased immersion.

Immersive Virtual Reality and Virtual Embodiment for Pain Relief

A significant body of experimental evidence has demonstrated that it is possible to induce the illusion of ownership of a fake limb or even an entire fake body using multisensory correlations. Recently, immersive virtual reality has allowed users to experience the same sensations of ownership over a virtual body inside an immersive virtual environment, which in turn allows virtual reality users to have the feeling of being "embodied" in a virtual body. Using such virtual embodiment to manipulate body perception is starting to be extensively investigated and may have clinical implications for conditions that involve altered body image such as chronic pain. Here, we review experimental and clinical studies that have explored the manipulation of an embodied virtual body in immersive virtual reality for both experimental and clinical pain relief. We discuss the current state of the art, as well as the challenges faced by, and ideas for, future research. Finally, we explore the potentialities of using an embodied virtual body in immersive virtual reality in the field of neurorehabilitation, specifically in the field of pain.

Sensory Modulation Disorder (SMD) and Pain: A New Perspective

Sensory modulation disorder (SMD) affects sensory processing across single or multiple sensory systems. The sensory over-responsivity (SOR) subtype of SMD is manifested clinically as a condition in which non-painful stimuli are perceived as abnormally irritating, unpleasant, or even painful. Moreover, SOR interferes with participation in daily routines and activities (Dunn, 2007; Bar-Shalita et al., 2008; Chien et al., 2016), co-occurs with daily pain hyper-sensitivity, and reduces quality of life due to bodily pain. Laboratory behavioral studies have confirmed abnormal pain perception, as demonstrated by hyperalgesia and an enhanced lingering painful sensation, in children and adults with SMD. Advanced quantitative sensory testing (QST) has revealed the mechanisms of altered pain processing in SOR whereby despite the existence of normal peripheral sensory processing, there is enhanced facilitation of pain-transmitting pathways along with preserved but delayed inhibitory pain modulation. These findings point to central nervous system (CNS) involvement as the underlying mechanism of pain hypersensitivity in SOR. Based on the mutual central processing of both non-painful and painful sensory stimuli, we suggest shared mechanisms such as cortical hyper-excitation, an excitatory-inhibitory neuronal imbalance, and sensory modulation alterations. This is supported by novel findings indicating that SOR is a risk factor and comorbidity of chronic non-neuropathic pain disorders. This is the first review to summarize current empirical knowledge investigating SMD and pain, a sensory modality not yet part of the official SMD realm. We propose a neurophysiological mechanism-based model for the interrelation between pain and SMD. Embracing the pain domain could significantly contribute to the understanding of this condition’s pathogenesis and how it manifests in daily life, as well as suggesting the basis for future potential mechanism-based therapies.

Experimentally induced pain does not influence updating of peripersonal space and body representations following tool-use

Representations of the body and peripersonal space can be distorted for people with some chronic pain conditions. Experimental pain induction can give rise to similar, but transient distortions in healthy individuals. However, spatial and bodily representations are dynamic, and constantly update as we interact with objects in our environment. It is unclear whether induced pain disrupts the mechanisms involved in updating these representations. In the present study, we sought to investigate the effect of induced pain on the updating of peripersonal space and body representations during and following tool-use. We compared performance under three conditions (pain, active placebo, neutral) on a visuotactile crossmodal congruency task and a tactile distance judgement task to measure updating of peripersonal space and body representations, respectively. Consistent with previous findings, the difference in crossmodal interference from visual distractors in the same compared to opposite visual field to the tactile target was less when tools were crossed than uncrossed. This suggests an extension of peripersonal space to incorporate the tips of the tools. Also consistent with previous findings, estimates of the felt tactile distance judgements decreased after active tool-use. In contrast to our predictions, however, we found no evidence that pain interfered with performance on either task when compared to the control conditions. Our findings suggest that the updating of peripersonal space and body representations is not disrupted by induced pain. That is, experiencing acute pain does not give rise to distorted representations of the body and peripersonal space that can be present in people with chronic pain conditions.

The Stochastic Entanglement and Phantom Motor Execution Hypotheses: A Theoretical Framework for the Origin and Treatment of Phantom Limb Pain

Phantom limb pain (PLP) is a debilitating condition common after amputation that can considerably hinder patients' quality of life. Several treatments have reported promising results in alleviating PLP. However, clinical evaluations are usually performed in small cohorts and rigorous clinical trials are scarce. In addition, the underlying mechanisms by which novel interventions alleviate PLP are often unclear, potentially because the condition itself is poorly understood. This article presents a theoretical framework of PLP that can be used as groundwork for hypotheses of novel treatments. Current hypotheses on the origins of PLP are discussed in relation to available clinical findings. Stochastic entanglement of the pain neurosignature, or connectome, with impaired sensorimotor circuitry is proposed as an alternative hypothesis for the genesis of PLP, and the implications and predictions this hypothesis entails are examined. In addition, I present a hypothesis for the working mechanism of Phantom Motor Execution (PME) as a treatment of PLP, along with its relation to the aforementioned stochastic entanglement hypothesis, which deals with PLP's incipience. PME aims to reactivate the original central and peripheral circuitry involved in motor control of the missing limb, along with increasing dexterity of stump muscles. The PME hypothesis entails that training of phantom movements induces gradual neural changes similar to those of perfecting a motor skill, and these purposefully induced neural changes disentangle pain processing circuitry by competitive plasticity. This is a testable hypothesis that can be examined by brain imaging and behavioral studies on subjects undergoing PME treatment. The proposed stochastic entanglement hypothesis of PLP can be generalized to neuropathic pain due to sensorimotor impairment, and can be used to design suitable therapeutic treatments.

Psychological Factors Associated with Phantom Limb Pain: A Review of Recent Findings

Phantom limb pain (PLP) is a common phenomenon occurring after the amputation of a limb and can be accompanied by serious suffering. Psychological factors have been shown to play an important role in other types of chronic pain, where they are pivotal in the acquisition and maintenance of pain symptoms. For PLP, however, the interaction between pain and psychological variables is less well documented. In this review, we summarize research on the role of emotional, motivational, cognitive, and perceptual factors in PLP. The reported findings indicate that emotional factors modulate PLP but might be less important compared to other types of chronic pain. Additional factors such as the amount of disability and adjustment to the amputation appear to also play a role. Bidirectional relationships between stress and PLP have been shown quite consistently, and the potential of stress and tension reduction in PLP treatment could be further exploited. Little is known about the role of cognitive variables such as attention or expectation. Catastrophizing seems to aggravate PLP and could be targeted in treatment. Body perception is altered in PLP and poses a potential target for novel mechanistic treatments. More research on psychological factors and their interactions in PLP is needed.

A two-dimensional model of disrupted body integrity: initial evaluation in head and neck cancer

PURPOSE

This cross-sectional study presents an initial psychometric evaluation of a two-dimensional (perceptual and evaluative) conceptualization and measure of disrupted body integrity (DBI)-illness-related disruption of the sense of the body as an integrated, smoothly functioning whole.

METHODS

Male and female head and neck cancer (HNC) outpatients (N = 98) completed a questionnaire package prior to outpatient visits.

MAIN OUTCOME MEASURES

The Disrupted Body Integrity Scale (DBIS) was developed to measure the perceptual and evaluative facets of DBI. Self-report measures of disfigurement, stigma, depressive symptoms, and negative affect were also completed.

RESULTS

Almost all DBIS subscales demonstrated good internal consistency. Results largely supported the DBIS's construct validity. The majority of subscales correlated within the predicted range of r's = .40-.70. Almost all DBIS constructs were positively linked with either depressive symptoms or disfigurement. None correlated with positive affect, and only two subscales, abnormal sensations (perceptual) and physical vulnerability (evaluative), correlated with negative affect. DBIS constructs showed little relation with stigma, once disfigurement effects were controlled for.

CONCLUSIONS

Findings offer preliminary evidence for the DBIS and the relevance of DBI in HNC. Further evaluation of DBI in disease adaptation and the DBIS's factor structure is warranted.

Immersive Virtual Reality for Pediatric Pain

Children must often endure painful procedures as part of their treatment for various medical conditions. Those with chronic pain endure frequent or constant discomfort in their daily lives, sometimes severely limiting their physical capacities. With the advent of affordable consumer-grade equipment, clinicians have access to a promising and engaging intervention for pediatric pain, both acute and chronic. In addition to providing relief from acute and procedural pain, virtual reality (VR) may also help to provide a corrective psychological and physiological environment to facilitate rehabilitation for pediatric patients suffering from chronic pain. The special qualities of VR such as presence, interactivity, customization, social interaction, and embodiment allow it to be accepted by children and adolescents and incorporated successfully into their existing medical therapies. However, the powerful and transformative nature of many VR experiences may also pose some risks and should be utilized with caution. In this paper, we review recent literature in pediatric virtual reality for procedural pain and anxiety, acute and chronic pain, and some rehabilitation applications. We also discuss the practical considerations of using VR in pediatric care, and offer specific suggestions and information for clinicians wishing to adopt these engaging therapies into their daily clinical practice.

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.

Using visuo-kinetic virtual reality to induce illusory spinal movement: the MoOVi Illusion

Background

Illusions that alter perception of the body provide novel opportunities to target brain-based contributions to problems such as persistent pain. One example of this, mirror therapy, uses vision to augment perceived movement of a painful limb to treat pain. Since mirrors can’t be used to induce augmented neck or other spinal movement, we aimed to test whether such an illusion could be achieved using virtual reality, in advance of testing its potential therapeutic benefit. We hypothesised that perceived head rotation would depend on visually suggested movement.

Method

In a within-subjects repeated measures experiment, 24 healthy volunteers performed neck movements to 50^o of rotation, while a virtual reality system delivered corresponding visual feedback that was offset by a factor of 50%–200%—the Motor Offset Visual Illusion (MoOVi)—thus simulating more or less movement than that actually occurring. At 50^o of real-world head rotation, participants pointed in the direction that they perceived they were facing. The discrepancy between actual and perceived direction was measured and compared between conditions. The impact of including multisensory (auditory and visual) feedback, the presence of a virtual body reference, and the use of 360^o immersive virtual reality with and without three-dimensional properties, was also investigated.

Results

Perception of head movement was dependent on visual-kinaesthetic feedback (p = 0.001, partial eta squared = 0.17). That is, altered visual feedback caused a kinaesthetic drift in the direction of the visually suggested movement. The magnitude of the drift was not moderated by secondary variables such as the addition of illusory auditory feedback, the presence of a virtual body reference, or three-dimensionality of the scene.

Discussion

Virtual reality can be used to augment perceived movement and body position, such that one can perform a small movement, yet perceive a large one. The MoOVi technique tested here has clear potential for assessment and therapy of people with spinal pain.