Rubber Hands Feel Touch, but Not in Blind Individuals

Psychology and neuroscience have a long-standing tradition of studying blind individuals to investigate how visual experience shapes perception of the external world. Here, we study how blind people experience their own body by exposing them to a multisensory body illusion: the somatic rubber hand illusion. In this illusion, healthy blindfolded participants experience that they are touching their own right hand with their left index finger, when in fact they are touching a rubber hand with their left index finger while the experimenter touches their right hand in a synchronized manner (Ehrsson et al. 2005). We compared the strength of this illusion in a group of blind individuals (n = 10), all of whom had experienced severe visual impairment or complete blindness from birth, and a group of age-matched blindfolded sighted participants (n = 12). The illusion was quantified subjectively using questionnaires and behaviorally by asking participants to point to the felt location of the right hand. The results showed that the sighted participants experienced a strong illusion, whereas the blind participants experienced no illusion at all, a difference that was evident in both tests employed. A further experiment testing the participants' basic ability to localize the right hand in space without vision (proprioception) revealed no difference between the two groups. Taken together, these results suggest that blind individuals with impaired visual development have a more veridical percept of self-touch and a less flexible and dynamic representation of their own body in space compared to sighted individuals. We speculate that the multisensory brain systems that re-map somatosensory signals onto external reference frames are less developed in blind individuals and therefore do not allow efficient fusion of tactile and proprioceptive signals from the two upper limbs into a single illusory experience of self-touch as in sighted individuals

A Behavioral Medicine Perspective on Pain Disability in a Work Context : Prevention, Assessment, and Tailored Physiotherapy

Chronic pain (>3 months) is associated with work limitations and sick leave. This thesis aimed to evaluate assessments and interventions targeting work disability for individuals at risk of or with chronic pain. Specific aims for studies I and II were to compare the preventive effects of a brief psychosocial program with an active educational control. Study III aimed to evaluate the construct validity and internal consistency of the Work Ability Index (WAI). Study IV aimed to systematically replicate a behavioral medicine physiotherapy intervention within a return-to-work context and evaluate its effects on an individual level.   Methods: Studies I and II were based on a cluster-randomized controlled trial, including 191 employees with reported pain and/or stress-related ill-health and 53 supervisors. Study I reported on the primary outcome of sick leave and secondary health-related outcomes on employees at 6-months follow-up; study II reported on the supervisors’ communication behavior and perceived stress. Study III was a cross-sectional study including 118 patients with chronic pain referred to specialized care. Study IV was a single case experimental design study including five participants with chronic pain on long-term sick leave.  Results: In studies I and II, no effects of the brief psychosocial program were found on outcomes on employees or supervisors. In study III, the construct validity and internal consistency of the WAI were supported. In study IV, the physiotherapy protocol was successfully replicated, and the results indicated an effect on task-specific self-efficacy for target activities at work, but not on experience of target activities or work ability. Conclusion: The results highlight the importance of selecting participants for preventive workplace interventions based on their assessed risk profiles for long-term pain disability, and that targeting mainly the supervisors might be insufficient. The WAI appears to be a valid measurement of work ability for patients with chronic pain in specialized care. Accordingly, behavioral medicine physiotherapy can be successfully adapted to work disability needs for patients with chronic pain. Large-scale trials are needed to evaluate its effects on return-to-work. A behavioral medicine perspective on pain disability in a work context motivates a focus on target activities at work, which can be seen to mediate the incorporation of behavioral knowledge in assessments and interventions for individuals with pain

A Behavioral Medicine Perspective on Pain Disability in a Work Context : Prevention, Assessment, and Tailored Physiotherapy

Chronic pain (>3 months) is associated with work limitations and sick leave. This thesis aimed to evaluate assessments and interventions targeting work disability for individuals at risk of or with chronic pain. Specific aims for studies I and II were to compare the preventive effects of a brief psychosocial program with an active educational control. Study III aimed to evaluate the construct validity and internal consistency of the Work Ability Index (WAI). Study IV aimed to systematically replicate a behavioral medicine physiotherapy intervention within a return-to-work context and evaluate its effects on an individual level.   Methods: Studies I and II were based on a cluster-randomized controlled trial, including 191 employees with reported pain and/or stress-related ill-health and 53 supervisors. Study I reported on the primary outcome of sick leave and secondary health-related outcomes on employees at 6-months follow-up; study II reported on the supervisors’ communication behavior and perceived stress. Study III was a cross-sectional study including 118 patients with chronic pain referred to specialized care. Study IV was a single case experimental design study including five participants with chronic pain on long-term sick leave.  Results: In studies I and II, no effects of the brief psychosocial program were found on outcomes on employees or supervisors. In study III, the construct validity and internal consistency of the WAI were supported. In study IV, the physiotherapy protocol was successfully replicated, and the results indicated an effect on task-specific self-efficacy for target activities at work, but not on experience of target activities or work ability. Conclusion: The results highlight the importance of selecting participants for preventive workplace interventions based on their assessed risk profiles for long-term pain disability, and that targeting mainly the supervisors might be insufficient. The WAI appears to be a valid measurement of work ability for patients with chronic pain in specialized care. Accordingly, behavioral medicine physiotherapy can be successfully adapted to work disability needs for patients with chronic pain. Large-scale trials are needed to evaluate its effects on return-to-work. A behavioral medicine perspective on pain disability in a work context motivates a focus on target activities at work, which can be seen to mediate the incorporation of behavioral knowledge in assessments and interventions for individuals with pain

"My life is under control with these medications" : an interpretative phenomenological analysis of managing chronic pain with opioids

Background: The use of opioids to relieve chronic pain has increased during the last decades, but experiences of chronic opioid therapy (COT) (> 90 days) point at risks and loss of beneficial effects. Still, some patients report benefits from opioid medication, such as being able to stay at work. Guidelines for opioid use in chronic pain do not consider the individual experience of COT, including benefits and risks, making the first person perspective an important scientific component to explore. The aim of this study was to investigate the lived experience of managing chronic pain with opioids in a sample who have severe chronic pain but are able to manage their pain sufficiently to remain at work. Methods: We used a qualitative research design: interpretative phenomenological analysis. Ten individuals with chronic pain and opioid therapy were purposively sampled in Swedish tertiary care. Results: Three super-ordinate themes emerged from the analyses: Without opioids, the pain becomes the boss; Opioids as a salvation and a curse, and Acknowledgement of the pain and acceptance of opioid therapy enables transition to a novel self. The participants used opioids to regain control over their pain, thus reclaiming their wanted life and self, and sense of control over one's life-world. Using opioids to manage pain was not unproblematic and some of the participants had experienced a downward spiral of escalating pain and uncontrollable opioid use, and stigmatisation. Conclusions: All participants emphasised the importance of control, regarding both pain and opioid use. To accomplish this, trust between participants and health care providers was essential for satisfactory treatment. Regardless of the potential sociocultural benefits of staying at work, participants had experiences of balancing positive and negative effects of opioid therapy, similar to what previous qualitative research has found. Measurable improvement of function and quality of life, may justify the long-term use of opioids in some cases. However, monitoring of adverse events should be mandatory. This requires close cooperation and a trusting relationship between the patients and their health care provider

Neural and Nonneural Contributions to Wrist Rigidity in Parkinson's Disease : An Explorative Study Using the NeuroFlexor

Objective. The NeuroFlexor is a novel method incorporating a biomechanical model for the measurement of neural and nonneural contributions to resistance induced by passive stretch. In this study, we used the NeuroFlexor method to explore components of passive movement resistance in the wrist and finger muscles in subjects with Parkinson's disease (PD). Methods. A cross-sectional comparison was performed in twenty-five subjects with PD with clinically identified rigidity and 14 controls. Neural (NC), elastic (EC), and viscous (VC) components of the resistance to passive extension of the wrist were calculated using the NeuroFlexor. Measurements were repeated during a contralateral activation maneuver. Results. PD subjects showed greater total resistance (P < 0.001) and NC (P = 0.002) compared to controls. EC and VC did not differ significantly between groups. Contralateral activation maneuver resulted in increased NC in the PD group but this increase was due to increased resting tension. Total resistance and NC correlated with clinical ratings of rigidity and with bradykinesia. Conclusions. The findings suggest that stretch induced reflex activity, but not nonneural resistance, is the major contributor to rigidity in wrist muscles in PD. The NeuroFlexor is a potentially valuable clinical and research tool for quantification of rigidity

Psychometric assessment of the Swedish version of the injustice experience questionnaire among patients with chronic pain

Objectives: The use of the Injustice Experience Questionnaire (IEQ) in psychological assessment of individuals with chronic pain is supported by research. The psychometric properties of the Swedish version, the IEQ-S, has not yet been evaluated. Hence, the aim was to investigate structural validity, and concurrent criterion validity of the IEQ-S against the Work Ability Index (WAI), the Pain Catastrophizing Scale (PCS-SW), the Patient Health Questionnaire 9-item depression module (PHQ-9), and the Generalized anxiety disorder 7-item scale (GAD-7). Internal consistency and test-retest reliability were also studied. Methods: Sixty-five participants, referred to a University hospital, with a pain duration over three months were consecutively sampled. They completed the IEQ-S at admission and again within six weeks. A confirmatory factor analysis was performed for the study of structural validity. Concurrent criterion validity was evaluated using Spearman's correlation coefficient. Internal consistency reliability for the full IEQ-S was calculated using the Cronbach's alpha. Test-retest reliability was calculated using an Intraclass Correlation Coefficient (ICC). Results: The median total score (0-48, where high scores indicate high levels of injustice) at admission (test 1) was 27.0 (n=64), 25th percentile=15.3, 75th percentile=37.8, range=3-48 points. A one-factor model was supported with item-loadings between 0.67-0.92. Spearman's correlation coefficient between the IEQ-S and the WAI (n=56) was r(s)=-0.46; the PCS-SW (n=63) was r(s)=0.68, the PHQ-9 (n=64) was r(s)=0.50 and the GAD-7 (n=64) was r(s)=0.57, p<0.01. Cronbach's alpha was 0.94 (n=64). The ICC was 0.80 (n=55), with a 95% confidence interval, ranging between 0.69-0.88. Conclusions: Our study supported structural validity and concurrent criterion validity of the IEQ-S against other measures of psychological constructs and work ability. It also supported the internal consistency reliability of the IEQ-S and the test-retest reliability with a retest interval up to six weeks, was good. These findings support the use of the IEQ-S as an adjunct tool to assess appraisals of injustice in patients with chronic pain who are referred to tertiary care in Sweden. The added value might be identification of those who are at risk for slow or no improvement in their pain condition over time, and sick-leave, but this has to be confirmed in future studies

The "future" pain clinician : Competencies needed to provide psychologically informed care

Background & objective Psychologically informed care has been proposed to improve treatment outcomes for chronic pain and aligns with a person-centered approach. Yet implementation lags behind, and studies suggest that a lack of competency leads to poor results. It is unclear what training clinicians require to deliver this care. We examine how we might improve psychologically informed care guided by the needs of the patient and in congruence with the scientific literature with a particular focus on how competencies might be upgraded and implementation enhanced. Methods We selectively review the literature for psychologically informed care for pain. The patient’s view on what is needed is contrasted with the competencies necessary to meet these needs and how treatment should be evaluated. Results Patient needs and corresponding competencies are delineated. A number of multi-professional skills and competencies are required to provide psychologically informed care. Single-subject methodologies can determine whether the care has the desired effect for the individual patient and facilitate effectiveness. We argue that becoming a competent “pain clinician” requires a new approach to education that transcends current professional boundaries. Conclusions Providing person-centered care guided by the needs of the patient and in line with the scientific literature shows great potential but requires multiple competencies. We propose that training the pain clinician of the future should focus on psychologically informed care and the competencies required to meet the individual’s needs. Single-subject methodology allows for continual evaluation of this care

Psychometric Assessment of the Swedish version of the Work Ability Index in Patients with Chronic Pain in Specialized Care

Objective: To evaluate the construct validity and internal consistency of the Work Ability Index (WAI) in patients with chronic pain in secondary and tertiary care. Methods: Cross-sectional study based on 200 patients with chronic pain (> 3 months), with a final sample of 118 participants, 18–64-years-old. Construct validity was assessed by exploratory factor analysis for the structural validity of the WAI, and by correlating the WAI with EuroQol EQ-5D, Brief Pain Inventory pain severity and interference, Patient Health Questionnaire and Generalized Anxiety Disorder scales. The study also assessed the discriminant validity of the WAI for occupational status, and the validity of the single-item work ability score. Reliability was assessed by internal consistency. Results: A single-factor model of WAI was supported. Internal consistency was good. Moderate correlations were found, except for Brief Pain Inventory pain severity, where the correlation was weak; hence, both convergent and divergent validity of the WAI were supported. The work ability score correlated strongly with the total WAI, and the discriminant validity for both was good. Conclusion: In patients with chronic pain in specialized care, the WAI and the work ability score displayed acceptable construct validity and internal consistency, supporting their use in a clinical context and research

Figure 1

<p><b>A</b>. The setup used to induce the somatic rubber hand illusion. The experimenter moves the blindfolded participant's left index finger so that it touches the rubber right hand while simultaneously touching the corresponding site on the participant's right hand. <b>B</b>. The procedure used to register the proprioceptive drift as an objective measure of the illusion (Experiment #2). The participant indicates the felt location of the right index finger by moving the left index finger along a ruler. <b>C</b>. The procedure used to measure the basic ability to locate the right index finger in space (proprioception; Experiment #3). The blindfolded participants indicate the felt location of the right index finger resting on the tabletop by moving the left hand under the table to match the positions of both index fingers. The position of the left index finger under the table is registered with a transmitter and the Polhemus Fastrak Magnetic motion-capturing system (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035912#s2" target="_blank">Methods</a>).</p

The results from the proprioceptive drift test, which served as an objective measure of the illusion (Experiment #2).

<p>As expected, the sighted individuals showed a significantly greater drift in the perceived location of their right hand towards the location of the rubber hand in the synchronous condition than in the asynchronous condition (<i>p</i><0.05). This illusion-specific drift towards the rubber hand was absent in the blind group, which did not show any drift in the synchronous condition (mixed ANOVA showed a significant difference between groups, <i>p</i><0.05). For details about the statistical analysis, see the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035912#s3" target="_blank">Results</a> section. Synchronous conditions are color-coded dark gray (sighted) and dark purple (blind), and the asynchronous conditions light gray (sighted) and light purple (blind).</p