Mislocalization of Sensory Information in People With Chronic Low Back Pain: A Preliminary Investigation

The Fremantle Back Awareness Questionnaire: Cross-cultural adaptation, validity and reliability of the Polish version

BACKGROUND

Body image disturbance is observed in individuals with chronic low back pain (CLBP) and is a potential treatment target. The Fremantle Back Awareness Questionnaire (FreBAQ) is designed to identify disrupted body image specific to the low back. This study aimed to develop and assess the measurement properties of a Polish language version of this questionnaire (FreBAQ-PL).

METHODS

Following the translation process, cognitive interviews were carried out as a qualitative assessment of content validity. Subsequently a quantitative assessment of content validity was undertaken among in a study sample with CLBP and experts. Measurement properties were assessed in 114 participants with CLBP and 53 pain-free participants. The CLBP sample repeated the FreBAQ-PL assessment within 14-days. The measurement properties assessed in this study were content validity, internal consistency, frequency of responses, known-groups validity, convergent validity and test-retest reliability.

RESULTS

Content validity was supported, affirming relevance and comprehensiveness. Known-groups validity was confirmed by significant differences in FreBAQ-PL scores between participants with CLBP and pain-free participants (p < 0.05). Convergent validity was established through moderate associations between FreBAQ-PL scores and pain variables (intensity and duration) (ρ's = 0.24-0.27, p's < 0.01), disability (ρ = 0.34, p < 0.01), kinesiophobia (ρ = 0.37, p < 0.01), depression (ρ = 0.30, p < 0.01) and anxiety (ρ = 0.24, p < 0.01). The scale was internally consistent (Cronbach's alpha 0.81). Test-retest reliability was good (ICC 0.90).

CONCLUSIONS

The FreBAQ-PL is a reliable, internally consistent, and valid measure that can be used in clinical and research settings to assess the presence of body image disturbance in Polish-speaking individuals with CLBP.

Body awareness disturbances in patients with low back pain: a systematic review

BACKGROUND

The pain-neuroscience literature has recently emphasized body perception or awareness. Impaired body perception results have been reported in many different chronic pain problems. Studies have reported that individuals with low back pain (LBP) also have body perception disturbances related to the lumbar spine.

OBJECTIVES

This review aimed to determine the evidence that body awareness alterations in individuals with LBP.

DESIGN

Systematic review.

METHOD

Studies were searched in PubMed, Cochrane Library, and Pedro databases up to January 2021. Each database was searched independently, according to a specific iteration research string. The protocol record of the systematic review was entered into the PROSPERO system.

RESULTS

Nine studies were included in this research. We found evidence to support more perceptual impairments in patients with LBP than healthy counterparts. In addition, the results of the studies showed an association between disrupted body awareness and pain severity, pain catastrophizing, and disability.

CONCLUSIONS

Body perception disturbances in LBP seem to be a promising path that needs to be further explored, with the ultimate goal of developing treatment contents targeting body awareness as a more comprehensive and valid evaluation and therapeutic method.

TRIAL REGISTRATION

The registration number was CRD42021235934.

Hacking the Predictive Mind

According to active inference, constantly running prediction engines in our brain play a large role in delivering all human experience. These predictions help deliver everything we see, hear, touch, and feel. In this paper, I pursue one apparent consequence of this increasingly well-supported view. Given the constant influence of hidden predictions on human experience, can we leverage the power of prediction in the service of human flourishing? Can we learn to hack our own predictive regimes in ways that better serve our needs and purposes? Asking this question rapidly reveals a landscape that is at once familiar and new. It is also challenging, suggesting important questions about scope and dangers while casting further doubt (as if any was needed) on old assumptions about a firm mind/body divide. I review a range of possible hacks, starting with the careful use of placebos, moving on to look at chronic pain and functional disorders, and ending with some speculations concerning the complex role of genetic influences on the predictive brain.

Tactile localization accuracy at the low back

Localizing tactile stimulation is an important capability for everyday function and may be impaired in people with persistent pain. This study sought to provide a detailed description of lumbar spine tactile localization accuracy in healthy individuals. Sixty-nine healthy participants estimated where they were touched at nine different points, labelled in a 3 × 3 grid over the lumbar spine. Mislocalization between the perceived and actual stimulus was calculated in horizontal (x) and vertical (y) directions, and a derived hypotenuse (c) mislocalization was calculated to represent the direct distance between perceived and actual points. In the horizontal direction, midline sites had the smallest mislocalization. Participants exhibited greater mislocalization for left- and right-sided sites, perceiving sites more laterally than they actually were. For all vertical values, stimulated sites were perceived lower than reality. A greater inaccuracy was observed in the vertical direction. This study measured tactile localization for the low back utilizing a novel testing method. The large inaccuracies point to a possible distortion in the underlying perceptual maps informing the superficial schema; however, further testing comparing this novel method with an established tactile localization task, such as the point-to-point method, is suggested to confirm these findings.

Does Active Inference Provide a Comprehensive Theory of Placebo Analgesia?

Placebo interventions generate mismatches between expected pain and sensory signals from which pain states are inferred. Because we lack direct access to bodily states, we can only infer whether nociceptive activity indicates tissue damage or results from noise in sensory channels. Predictive processing models propose to make optimal inferences using prior knowledge given noisy sensory data. However, these models do not provide a satisfactory explanation of how pain relief expectations are translated into physiological manifestations of placebo responses. Furthermore, they do not account for individual differences in the ability to endogenously regulate nociceptive activity in predicting placebo analgesia. The brain not only passively integrates prior pain expectations with nociceptive activity to infer pain states (perceptual inference) but also initiates various types of actions to ensure that sensory data are consistent with prior pain expectations (active inference). We argue that depending on whether the brain interprets conflicting sensory data (prediction errors) as a signal to learn from or noise to be attenuated, the brain initiates opposing types of action to facilitate learning from sensory data or, conversely, to enhance the biasing influence of prior pain expectations on pain perception. Furthermore, we discuss the role of stress, anxiety, and unpredictability of pain in influencing the weighting of prior pain expectations and sensory data and how they relate to the individual ability to regulate nociceptive activity (endogenous pain modulation). Finally, we provide suggestions for future studies to test the implications of the active inference model of placebo analgesia.

The cross-cultural adaptation, validity, and reliability of the Spanish version of the Fremantle Back Awareness Questionnaire

Introduction

In chronic low back pain (CLBP), disturbed body image has been highlighted as a contributor to the condition and a potential target for treatment. The Fremantle Back Awareness Questionnaire (FreBAQ) allows its assessment. Following international guidelines for the cross-cultural translation of questionnaires, we aimed to translate the FreBAQ into Spanish (FreBAQ-S) and validate the new questionnaire in a sample of Spanish-speaking people with CLBP.

Methods

Two hundred and sixty-four adults with CLBP (91 males) and 128 healthy controls (34 males) completed an online form including the FreBAQ-S and questionnaires related to the pain experience. All participants were Spanish and no gender identities differing from biological sex were reported. A week later, 113 CLBP participants and 45 healthy controls (41 and 13 males, respectively), re-answered the FreBAQ-S to evaluate test-retest reliability. Confirmatory factor and multigroup analysis assessed the scale consistency on the patient sample. Discriminant and convergent validity were explored by between-group differences and the relationship with clinical characteristics. Reliability relied on Cronbach's alpha estimates and test-retest (intraclass correlation coefficient, standard error of measurement, minimal detectable change).

Results and discussion

Confirmatory factor analysis showed a one-factor structure of the questionnaire, without supporting evidence for item deletion (CFI = 0.97; TLI = 0.96; RMSEA = 0.06; SRMR = 0.07; SRMRu = 0.064). Multigroup analyses do not support mean invariance between groups regarding health condition or sex. The FreBAQ-S demonstrated good discriminant and convergent validity, internal consistency (α = 0.82), and test-retest reliability (ICC = 0.78; SE = 3.41; MDC = 5.12). The FreBAQ-S is a valid and reliable tool to assess back awareness in clinical and non-clinical samples.

Proprioceptive acuity is core for back awareness in chronic low back pain: Further analysis of the content validity of the Spanish version of the Fremantle Back Awareness Questionnaire

Treatments aimed at increasing self-perception may improve chronic low back pain (CLBP) symptomatology and present novel management approaches. Consequently, it is important to have valid, complete, and reliable tools for its assessment, and to understand which variables influence altered back awareness. We aimed to evaluate the face/content validity of the Spanish version of the Fremantle Back Awareness Questionnaire (FreBAQ-S) among people with and without CLBP, and to explore additional variables suggested to be involved in back awareness. A total of 264 individuals with CLBP and 128 healthy controls (HC) answered an online survey, including the FreBAQ-S, and questions regarding the completeness, comprehensibility, time-to-complete adequacy, and time spent completing it. If participants declared a lack of completeness, they had to report which aspects would be incorporated into the questionnaire to explore additional back-awareness-related variables. A statistically significant difference in completeness emerged between groups (p < 0.01). The questionnaire was comprehensible for more than 85% of participants, regardless of the group (p = 0.45). CLBP participants spent significantly more time in completing the questionnaire than controls (p < 0.01), but no differences were found between groups regarding the time-to-complete adequacy (p = 0.49). Regarding the back-awareness-related variables, 77 suggestions from CLBP group and seven from the HC were received. Most of them were related to proprioceptive acuity such as posture, weight, or movement patterns, among others. The FreBAQ-S demonstrated adequate face/content validity, completeness, comprehensibility, and adequate time of response. The feedback provided will help improve currently available assessment tools.

Somatosensory Impairment and Chronic Pain Following Stroke: An Observational Study

BACKGROUND

Chronic pain and somatosensory impairment are common following a stroke. It is possible that an interaction exists between pain and somatosensory impairment and that a change in one may influence the other. We therefore investigated the presence of chronic pain and self-reported altered somatosensory ability in individuals with stroke, aiming to determine if chronic pain is more common in stroke survivors with somatosensory impairment than in those without.

METHODS

Stroke survivors were invited to complete an online survey that included demographics, details of the stroke, presence of chronic pain, and any perceived changes in body sensations post-stroke.

RESULTS

Survivors of stroke (n = 489) completed the survey with 308 indicating that they experienced chronic pain and 368 reporting perceived changes in somatosensory function. Individuals with strokes who reported altered somatosensory ability were more likely to experience chronic pain than those who did not (OR = 1.697; 95% CI 1.585, 2.446). Further, this difference was observed for all categories of sensory function that were surveyed (detection of light touch, body position, discrimination of surfaces and temperature, and haptic object recognition).

CONCLUSIONS

The results point to a new characteristic of chronic pain in strokes, regardless of nature or region of the pain experienced, and raises the potential of somatosensory impairment being a rehabilitation target to improve pain-related outcomes for stroke survivors.

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 effect of visually manipulating back size and morphology on back perception, body ownership, and attitudes towards self-capacity during a lifting task

Body re-sizing illusions can profoundly alter perception of our own body. We investigated whether creating the illusion of a muscled and fit-looking back (Strong) influenced perceived back size, body ownership, and attitudes towards self-capacity during a lifting task. Twenty-four healthy male volunteers performed a standardised lifting task while viewing real-time (delay < 20 ms) video of their own back through a head-mounted display under four different conditions (Normal size, Strong, Reshaped, Large; order randomised). The MIRAGE-mediated reality system was used to modify the shape, size, and morphology of the back. Participants were poor at recognizing the correct appearance of their back, for both implicit (perceived width of shoulders and hips) and explicit (questionnaire) measures of back size. Visual distortions of body shape (Reshaped condition) altered implicit back size measures. However, viewing a muscled back (Strong condition) did not result in a sense of agency or ownership and did not update implicit perception of the back. No conditions improved perceptions/attitudes of self-capacity (perceived back strength, perceived lifting confidence, and perceived back fitness). The results lend support for the importance of the embodiment of bodily changes to induce changes in perception. Further work is warranted to determine whether increased exposure to illusory changes would alter perceptions and attitudes towards self-capacity or whether different mechanisms are involved.

Perception of Tactile Distance on the Back

The perceived distance between two touches is anisotropic on many parts of the body. Generally, tactile distances oriented across body width are perceived as larger than distances oriented along body length, though the magnitude of such biases differs substantially across the body. In this study, we investigated tactile distance perception on the back. Participants made verbal estimates of the perceived distance between pairs of touches oriented either across body width or along body length on (a) the left hand, (b) the left upper back, and (c) the left lower back. There were clear tactile distance anisotropies on the hand and upper back, with distances oriented across body width overestimated relative to those along body length/height, consistent with previous results. On the lower back, however, an anisotropy in exactly the opposite direction was found. These results provide further evidence that tactile distance anisotropies vary systematically across the body and suggest that the spatial representation of touch on the lower back may differ qualitatively from that on other regions of the body.

Body perception disturbances in women with pregnancy-related lumbopelvic pain and their role in the persistence of pain postpartum

Background

Lumbopelvic pain (LPP) is common during pregnancy and can have long-lasting negative consequences in terms of disability and reduced quality of life. Therefore, it is crucial to identify women at risk of having pregnancy-related LPP after childbirth. This study aimed to investigate the association between body perception, pain intensity, and disability in women with pregnancy-related LPP during late pregnancy and postpartum, and to study whether a disturbed body perception during late pregnancy predicted having postpartum LPP.

Methods

A prospective cohort study in 130 primiparous women (median age = 30 years) was performed. Pain intensity, disability, and lumbopelvic body perception during the last month of pregnancy and 6 weeks postpartum were assessed with the Numerical Pain Rating Scale (NPRS), Oswestry Disability Index, and Fremantle Back Awareness Questionnaire, respectively. Having pregnancy-related LPP was defined as an NPRS score ≥ 1/10. At both timepoints, women were categorized into three groups; pain-free, LPP with low disability, and LPP with high disability (based on Oswestry Disability Index scores). At each timepoint, body perception was compared between groups, and correlations between body perception, pain intensity, and disability were evaluated in women with LPP by using non-parametric tests. Logistic regression analysis was used to determine whether body perception during the last month of pregnancy predicted the presence of LPP 6 weeks postpartum.

Results

Women with LPP at the end of pregnancy, and 6 weeks postpartum reported a more disturbed body perception compared to pain-free women (p ≤ 0.005). Greater body perception disturbance correlated with higher pain intensity (σ = 0.266, p = 0.008) and disability (σ = 0.472, p < 0.001) during late pregnancy, and with pain intensity 6 weeks postpartum (σ = 0.403, p = 0.015). A disturbed body perception during late pregnancy nearly significantly predicted having postpartum LPP (Odds Ratio = 1.231, p = 0.052).

Conclusions

Body perception disturbance was greater in women experiencing LPP during late pregnancy and postpartum compared to pain-free women, and correlated with pain intensity and disability. Though non-significant (p = 0.052), the results of the regression analysis suggest that greater body perception disturbance during late pregnancy might predict having LPP postpartum. However, future studies should follow up on this.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03704-w.

Description and psychometric properties of a prototype to test tactile acuity in the neck

BACKGROUND

Clinical tools assessing tactile acuity in people with persistent pain have limitations. Therefore, a novel and semi-automated tool was developed: The Imprint Tactile Acuity Device (iTAD).

AIM

To describe the iTAD prototype and present the psychometric properties of its tactile acuity assessments: the localisation test, the orientation test and the overall score (mean of both tests).

METHOD

A test-retest design with fifty healthy participants was used to assess intra-rater reliability (ICC_(2.1)), internal consistency (ICC_(2.4)) and measurement error (SEM) of the three assessments (0-100% accuracy scores each) performed at the neck. Using a known-group comparison design, balanced by age and sex, scores of thirty individuals with persistent neck pain were compared to thirty healthy controls to determine construct validity.

RESULTS

The ICC_(2,1) and ICC_(2,4) were 0.60 and 0.78 for the localisation test, 0.66 and 0.77 for the orientation test, and 0.73 and 0.84 for the overall score. The SEMs were 9.0%, 8.1% and 6.0%, respectively. No fixed or proportional bias, or signs of heteroscedasticity were observed. Overall, no between group differences were observed (p = 0.49). In the male subgroup, however, the overall score was lower for people with neck pain than for healthy participants (mean difference (SE); 7.6% (2.5); p = 0.008).

DISCUSSION

The tactile acuity assessments of the iTAD demonstrate moderate reliability and good internal consistency. Measurement errors appear comparable to currently preferred methods. Clear construct validity was not established, but results may be biased by design issues of the prototype. Taken together, the iTAD shows promise but further fine-tuning is needed.

Translation and Cross-cultural Adaptation of the Fremantle Back Awareness Questionnaire into Persian language and the assessment of reliability and validity in patients with chronic low back pain

Background:

Chronic low back pain (LBP) causes some neuroplastic changes in the brain, which result in body perception impairment. The Fremantle Back Awareness Questionnaire (FreBAQ) is a suggested tool for the diagnosis and evaluation of back perception in people with LBP. The aim of this study is to translate and cross culturally adapt the FreBAQ into Persian language and to assess its reliability and validity in patients with chronic LBP (CLBP).

Materials and Methods:

Fifty people with CLBP and fifty healthy people participated in this study. To evaluate the discriminant validity, we assessed the ability of the FreBAQ to discriminate between people with and without LBP. After an interval of 1 week, 25 patients with CLBP completed the questionnaire in the retest session. Data obtained from the first test administration were used for internal consistency and data obtained from repeated testing were used for test–retest reliability. Construct validity was assessed by investigating a correlation between the FreBAQ with the Roland–Morris Disability Questionnaire (RDQ), Visual Analog Scale, Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale, and Tampa Scale of Kinesiophobia. In addition, the construct validity of Persian FreBAQ was measured by factor analysis.

Results:

The test–retest reliability of the questionnaire was confirmed by intraclass correlation coefficient = 0.96. Cronbach's alpha was 0.74 for Persian FreBAQ. The standard error of measurement and minimal detectable change were 0.91 and 2.52, respectively. Construct validity was demonstrated by statistically significant relationship between the Persian FreBAQ and questionnaires of PCS (P < 0.001) and RDQ (P = 0.01).

Conclusion:

The Persian version of FreBAQ is a valid and reliable measurement tool for evaluating back perception changes in Persian-speaking patients with LBP.

A Distorted Body Schema and Susceptibility to Experiencing Anomalous Somatosensory Sensations in Fibromyalgia Syndrome

OBJECTIVE

Evidence suggests that there is an association between chronic pain and disruption of the body schema. We tested the hypothesis in fibromyalgia syndrome (FMS).

MATERIALS AND METHODS

We investigated distinct perceptual aspects of the body schema both in a sample of patients with FMS and in pain-free controls. Performances on the left/right judgment task were measured; tactile acuity was assessed by using the 2-point discrimination test. Furthermore, we evaluated sensations evoked by tactile stimulation with von Frey filaments to body parts that were experiencing pain. Anomalous sensations elicited by sensory-motor conflict (SMC) were also investigated.

RESULTS

Patients with FMS showed inferior performance on the right/left judgment task, both in terms of correct matches (75.38% vs. 89.67%, respectively; P<0.05) and response time (2.58 s vs. 1.89 s, respectively; P<0.05). Effect sizes were large and very large, respectively. Two-point discrimination thresholds were significantly higher (P<0.05) in participants from the FMS sample (mean of 49.71 mm, SD: 12.09 mm) relative to controls (mean of 37.36 mm, SD: 7.81 mm). Nine of 14 participants with FMS, but no control participants, reported referred sensations upon tactile stimulation, including tingling, pins and needles, weight, and cramps. Referral sites included regions both adjacent and remote to stimulated sites. Patients with FMS scored across all items within the administered questionnaire addressing anomalous sensations on the mirror setup (Cohen d=1.04 to 2.42 across all items), and FMS patients perceived pain during the SMC (the required statistical power for it to be statistically significant was 96% and for it to be recognized as a difference of means in pain item).

CONCLUSION

Our present findings suggest a disrupted body schema and propensity to experiencing anomalous somatosensory sensations during SMC in people with FMS.

Interrogating cortical representations in elite athletes with persistent posterior thigh pain - New targets for intervention?

OBJECTIVES

Hamstring injuries in athletes can lead to significant time away from competition as a result of persistent posterior thigh pain. These cases are often difficult to treat as the state of the tissues alone cannot explain symptoms. In non-athletic populations with persistent pain, disruptions to tactile, proprioceptive, and spatial cortical representations exist, which has led to promising brain-based treatments. Here, we explored whether athletes with persistent posterior thigh pain also display impairments in these cortical representations.

DESIGN

Cross-sectional study.

METHODS

Fourteen male professional athletes with persistent posterior thigh pain ('Patients') and 14 pain-free age, sport, body mass index and level-matched controls ('Controls') participated. The tactile cortical representation was assessed using two-point discrimination (TPD) threshold and accuracy of tactile localisation; the proprioceptive cortical representation was assessed using a left/right judgement task; spatial processing was assessed using an auditory detection task.

RESULTS

TPD thresholds were similar for Patients and Controls (p=0.70). Patients were less accurate at localising tactile stimuli delivered to their affected leg, slower to make left/right judgements when the lower limb image corresponded to the side of their affected leg, and less accurate at detecting auditory stimuli delivered near their affected leg, when compared to their healthy leg or to the leg of Controls (p<0.01 for all).

CONCLUSIONS

Leg-specific tactile, proprioceptive, and spatial processing deficits exist in athletes with persistent posterior thigh pain. That these processing deficits exist despite rehabilitation and normal tissue healing time suggests they may play a role in the persistence of posterior thigh pain.

Explicit and Implicit Own's Body and Space Perception in Painful Musculoskeletal Disorders and Rheumatic Diseases: A Systematic Scoping Review

Background: Pain and body perception are essentially two subjective mutually influencing experiences. However, in the field of musculoskeletal disorders and rheumatic diseases we lack of a comprehensive knowledge about the relationship between body perception dysfunctions and pain or disability. We systematically mapped the literature published about the topics of: (a) somatoperception; (b) body ownership; and (c) perception of space, analysing the relationship with pain and disability. The results were organized around the two main topics of the assessment and treatment of perceptual dysfunctions. Methods: This scoping review followed the six-stage methodology suggested by Arksey and O'Malley. Ten electronic databases and grey literature were systematically searched. The PRISMA Extension for Scoping Reviews was used for reporting results. Two reviewers with different background, independently performed study screening and selection, and one author performed data extraction, that was checked by a second reviewer. Results: Thirty-seven studies fulfilled the eligibility criteria. The majority of studies (68%) concerned the assessment methodology, and the remaining 32% investigated the effects of therapeutic interventions. Research designs, methodologies adopted, and settings varied considerably across studies. Evidence of distorted body experience were found mainly for explicit somatoperception, especially in studies adopting self-administered questionnaire and subjective measures, highlighting in some cases the presence of sub-groups with different perceptual features. Almost half of the intervention studies (42%) provided therapeutic approaches combining more than one perceptual task, or sensory-motor tasks together with perceptual strategies, thus it was difficult to estimate the relative effectiveness of each single therapeutic component. Conclusions: To our knowledge, this is the first attempt to systematically map and summarize this research area in the field of musculoskeletal disorders and rheumatic diseases. Although methodological limitations limit the validity of the evidence obtained, some strategies of assessment tested and therapeutic strategies proposed represent useful starting points for future research. This review highlights preliminary evidence, strengths, and limitations of the literature published about the research questions, identifying key points that remain opened to be addressed, and make suggestions for future research studies. Body representation, as well as pain perception and treatment, can be better understood if an enlarged perspective including body and space perception is considered.

Embodying the illusion of a strong, fit back in people with chronic low back pain. A pilot proof-of-concept study

OBJECTIVE

This proof-of-concept pilot study aimed to investigate if a visual illusion that altered the size and muscularity of the back could be embodied and alter perception of the back.

METHODS

The back visual illusions were created using the MIRAGE multisensory illusion system. Participants watched real-time footage of a modified version of their own back from behind. Participants undertook one experimental condition, in which the image portrayed a muscled, fit-looking back (Strong), and two control conditions (Reshaped and Normal) during a lifting task. Embodiment, back perception as well as pain intensity and beliefs about the back during lifting were assessed.

RESULTS

Two participants with low back pain were recruited for this study: one with altered body perception and negative back beliefs (Participant A) and one with normal perception and beliefs (Participant B). Participant A embodied the Strong condition and pain and fear were less and both perceived strength and confidence were more than for the Normal or the Reshaped condition. Participant B did not embody the Strong condition and reported similar levels of pain, fear strength and confidence across all three conditions.

DISCUSSION

An illusion that makes the back look strong successfully induced embodiment of a visually modified back during a lifting task in a low back pain patient with altered body perception. Both participants tolerated the illusion, there were no adverse effects, and we gained preliminary evidence that the approach may have therapeutic potential.

Preliminary Validation of a Two-Point Estimation Task for the Measurement of Sensory Dissociation in Patients with Chronic Low Back Pain

Objectives

Sensory dissociation (SEDI), the discrepancy between perception and actual size or shape of a painful body part, is a frequently observed finding in patients with chronic low back pain. However, the current methods of evaluating SEDI have several limitations, such as a qualitative nature and weak evidence supporting their reliability. In the current study, the reliability of two versions (manual and verbal) of a novel test, a two-point estimation task (TPE), was investigated.

Methods

To perform the manual version of the task, patients estimated the distance between two tactile stimuli delivered to their back using callipers, whereas in the verbal version they verbally reported the estimated distance.

Results

The manual version of TPE showed greater interexaminer reliability than the verbal version, and the mean of the two repeated measurements was sufficient for reaching excellent reliability for the pain-free (intraclass correlation coefficient [ICC] = 0.91, 95% confidence interval [CI] = 0.77–0.97) and painful (ICC = 0.86, 95% CI = 0.65–0.94) sides. Intra-examiner reliability was moderate to excellent (ICC = 0.66–0.96) for the manual version performed at the pain-free and painful sides. Distribution, duration, and intensity of pain significantly predicted SEDI and accounted for 42% of the total variance (corrected R2 = 0.42, P &lt; 0.01).

Conclusions

TPE showed higher reliability coefficients compared with tools previously suggested in the literature and can therefore be used clinically and experimentally by one or more examiners. Further research is required to investigate the validity of this new test.

The development of the Dutch version of the Fremantle Back Awareness Questionnaire

BACKGROUND

Disturbed body perception may play a role in the aetiology of chronic low back pain (LBP). The Fremantle Back Awareness Questionnaire (FreBAQ) is currently the only self-report questionnaire to assess back-specific body perception in individuals with LBP.

OBJECTIVES

To perform a cross-cultural adaptation of the FreBAQ into Dutch.

DESIGN

Psychometric study.

METHODS

A Dutch version of the FreBAQ was generated through forward-backward translation, and was completed by 73 patients with LBP and 73 controls to assess discriminant validity. Structural validity was assessed by principal component analysis. Internal consistency was assessed by the Cronbach's alpha coefficient. Construct validity was assessed by examining the relationship with clinical measures (Numerical Rating Scale pain, Oswestry Disability Index (ODI), Tampa Scale for Kinesiophobia). Test-retest reliability was assessed in a subgroup (n = 48 with LBP and 48 controls) using intraclass correlation coefficients (ICC), standard error of measurement (SEM) and minimal detectable change (MDC 95%) RESULTS: The Dutch FreBAQ showed one component with eigenvalue >2. Cronbach's alpha values were respectively 0.82 and 0.73 for the LBP and control group. ICC values were respectively 0.69 and 0.70 for the LBP and control group. In the LBP group, the SEM was 3.9 and the MDC (95%) was 10.8. The LBP group (ODI 22 ± 21%) scored significantly higher on the Dutch FreBAQ than the control group (ODI 0%) (11 ± 7 vs. 3 ± 9, p < 0.001). Within the LBP group, higher Dutch FreBAQ scores correlated significantly with higher ODI scores (rho = 0.30, p = 0.010), although not with pain (rho = 0.10, p = 0.419) or kinesiophobia (r = 0.14, p = 0.226).

CONCLUSIONS

The Dutch version of the FreBAQ can be considered as unidimensional and showed adequate internal consistency, sufficient test-retest reliability and adequate discriminant and construct validity in individuals with and without LBP. It can improve our understanding on back-specific perception in the Dutch-speaking population with LBP.

Disrupted body-image and pregnancy-related lumbopelvic pain. A preliminary investigation

BACKGROUND

Recent investigations have suggested that disrupted body-image may contribute to the lumbopelvic pain experience. The changes in body shape and size associated with pregnancy suggest that pregnancy-related lumbopelvic pain might be a problem in which alterations in body-image are particularly relevant.

OBJECTIVES

To investigate if self-reported body-image is related to lumbopelvic pain status in women during pregnancy and explore the factors that might contribute to changes in body-image in women experiencing pregnancy-related lumbopelvic pain.

DESIGN

Cross-sectional cohort study.

METHOD

Forty-two women in the third trimester of pregnancy were recruited regardless of clinical status. Pain intensity and disability were measured to estimate clinical severity. The Fremantle Back Awareness Questionnaire was used to assess body-image. Participants also completed a series of questionnaires and physical tests to explore factors that might be associated with altered body-image.

RESULTS

The median Fremantle Back Awareness Questionnaire score for the pain free women was 1 (IQR 0-1.5) and the median score for those in pain was 3.5 (IQR 2-8). This difference was statistically significant (p = 0.005). The questionnaire score was significantly correlated with pain intensity but not with disability. Of the measured variables only pain catastrophisation was significantly associated with disrupted body-image.

CONCLUSIONS

Self-reported disruption of body-image was significantly greater in pregnant women who were experiencing lumbopelvic pain than those who weren't and the extent of body-image disruption was associated with pain intensity. Only pain related catastrophisation was related to disrupted body-image.

Validation of the Japanese Version of the Fremantle Back Awareness Questionnaire in Patients with Low Back Pain

BACKGROUND

There is a growing interest in the role of disturbed body perception in people with persistent pain problems such as chronic low back pain (CLBP). A questionnaire, the Fremantle Back Awareness Questionnaire (FreBAQ), was recently developed as a simple and quick way of assessing disturbed perceptual awareness of the back in people with CLBP and appears to have acceptable psychometric properties. The aim of the present study was to develop a Japanese version of the FreBAQ (FreBAQ-J) and evaluate its psychometric properties in a sample of Japanese people with low back pain (LBP).

METHODS

Translation of the FreBAQ into Japanese was conducted using a forward-backward method. One hundred participants with LBP completed the resultant FreBAQ-J. A subset of the participants completed the FreBAQ-J again 2 weeks later. Validity was investigated by examining the relationship between the FreBAQ-J and clinical valuables. Rasch analysis was used to assess targeting, category ordering, unidimensionality, person fit, internal consistency, and differential item functioning.

RESULTS

The FreBAQ-J was significantly correlated with pain in motion, disability, pain-related catastrophizing, fear of movement, and anxiety symptomatology. The FreBAQ-J had acceptable internal consistency, a minor departure from unidimensionality, and good test-retest reliability, and was functional on the category rating scale.

CONCLUSIONS

The FreBAQ-J has acceptable psychometric properties and is suitable for use in people with LBP. Participants with high levels of disturbed body perception are well targeted by the scale. The functioning of one item (item 8) was poor. Further study is warranted to confirm if this item should be excluded.

Cortical Sensorimotor Processing of Painful Pressure in Patients with Chronic Lower Back Pain-An Optical Neuroimaging Study using fNIRS

In this study we investigated sensorimotor processing of painful pressure stimulation on the lower back of patients with chronic lower back pain (CLBP) by using functional near-infrared spectroscopy (fNIRS) to measure changes in cerebral hemodynamics and oxygenation. The main objectives were whether patients with CLBP show different relative changes in oxy- and deoxyhemoglobin ([O2Hb] and [HHb]) in the supplementary motor area (SMA) and primary somatosensory cortex (S1) compared to healthy controls (HC). Twelve patients with CLBP (32 ± 6.1 years; range: 24-44 years; nine women) and 20 HCs (33.5 ± 10.7 years; range 22-61 years; eight women) participated in the study. Painful and non-painful pressure stimulation was exerted with a thumb grip perpendicularly to the spinous process of the lumbar spine. A force sensor was attached at the spinous process in order to control pressure forces. Tactile stimulation was realized by a one-finger brushing. Hemodynamic changes in the SMA and S1 were measured bilaterally using a multi-channel continuous wave fNIRS imaging system and a multi-distant probe array. Patients with CLBP showed significant stimulus-evoked hemodynamic responses in [O2Hb] only in the right S1, while the HC exhibited significant [O2Hb] changes bilaterally in both, SMA and S1. However, the group comparisons revealed no significant different hemodynamic responses in [O2Hb] and [HHb] in the SMA and S1 after both pressure stimulations. This non-significant result might be driven by the high inter-subject variability of hemodynamic responses that has been observed within the patients group. In conclusion, we could not find different stimulus-evoked hemodynamic responses in patients with CLBP compared to HCs. This indicates that neither S1 nor the SMA show a specificity for CLBP during pressure stimulation on the lower back. However, the results point to a potential subgrouping regarding task-related cortical activity within the CLBP group; a finding worth further research.

Listening is therapy: Patient interviewing from a pain science perspective

The interview of a patient attending physical therapy is the cornerstone of the physical examination, diagnosis, plan of care, prognosis, and overall efficacy of the therapeutic experience. A thorough, skilled interview drives the objective tests and measures chosen, as well as provides context for the interpretation of those tests and measures, during the physical examination. Information from the interview powerfully influences the treatment modalities chosen by the physical therapist (PT) and thus also impacts the overall outcome and prognosis of the therapy sessions. Traditional physical therapy focuses heavily on biomedical information to educate people about their pain, and this predominant model focusing on anatomy, biomechanics, and pathoanatomy permeates the interview and physical examination. Although this model may have a significant effect on people with acute, sub-acute or postoperative pain, this type of examination may not only gather insufficient information regarding the pain experience and suffering, but negatively impact a patient's pain experience. In recent years, physical therapy treatment for pain has increasingly focused on pain science education, with increasing evidence of pain science education positively affecting pain, disability, pain catastrophization, movement limitations, and overall healthcare cost. In line with the ever-increasing focus of pain science in physical therapy, it is time for the examination, both subjective and objective, to embrace a biopsychosocial approach beyond the realm of only a biomedical approach. A patient interview is far more than "just" collecting information. It also is a critical component to establishing an alliance with a patient and a fundamental first step in therapeutic neuroscience education (TNE) for patients in pain. This article highlights the interview process focusing on a pain science perspective as it relates to screening patients, establishing psychosocial barriers to improvement, and pain mechanism assessment.

Differential Neural Processing during Motor Imagery of Daily Activities in Chronic Low Back Pain Patients

Chronic low back pain (chronic LBP) is both debilitating for patients but also a major burden on the health care system. Previous studies reported various maladaptive structural and functional changes among chronic LBP patients on spine- and supraspinal levels including behavioral alterations. However, evidence for cortical reorganization in the sensorimotor system of chronic LBP patients is scarce. Motor Imagery (MI) is suitable for investigating the cortical sensorimotor network as it serves as a proxy for motor execution. Our aim was to investigate differential MI-driven cortical processing in chronic LBP compared to healthy controls (HC) by means of functional magnetic resonance imaging (fMRI). Twenty-nine subjects (15 chronic LBP patients, 14 HC) were included in the current study. MI stimuli consisted of randomly presented video clips showing every-day activities involving different whole-body movements as well as walking on even ground and walking downstairs and upstairs. Guided by the video clips, subjects had to perform MI of these activities, subsequently rating the vividness of their MI performance. Brain activity analysis revealed that chronic LBP patients exhibited significantly reduced activity compared to HC subjects in MI-related brain regions, namely the left supplementary motor area and right superior temporal sulcus. Furthermore, psycho-physiological-interaction analysis yielded significantly enhanced functional connectivity (FC) between various MI-associated brain regions in chronic LBP patients indicating diffuse and non-specific changes in FC. Current results demonstrate initial findings about differences in MI-driven cortical processing in chronic LBP pointing towards reorganization processes in the sensorimotor network.

Tactile and proprioceptive sensory stimulation modifies estimation of walking distance but not upright gait stability: a pilot study

[Purpose] Recently, there has been growing interest in the somatosensory system, but little data exist on the interaction between dynamic postural control and the somatosensory system. The purpose of this study was to determine whether a training program, based on tactile and proprioceptive sensory stimulation of the trunk with the use of perceptual surfaces, improved the estimation of walking distance by healthy subjects, the ability to walk toward a memorized distance without vision, and whether it increases upright gait stability. [Subjects and Methods] Ten healthy subjects with a mean age of 31.9 ± 2.5 years were enrolled and participated in 10 daily sessions of perceptive training using perceptual surfaces, for 45 minutes each session. An experimental indoor test measured the subjects' ability to perceive walking distances to a memorized target in an indoor environment. [Results] After treatment, the distances that were traversed were closer to the target than before treatment. Trunk acceleration did not differ significantly between pre- and post-training and did not increase significantly after training. [Conclusion] Treatment with perceptual surfaces stimulating the trunk midline improves the estimation of walking distance and modifies proprioceptive gait patterns, allowing various corrective strategies to be implemented during ambulation.

Real-time modulation of visual feedback on human full-body movements in a virtual mirror: development and proof-of-concept

Background

Virtual reality (VR) provides interactive multimodal sensory stimuli and biofeedback, and can be a powerful tool for physical and cognitive rehabilitation. However, existing systems have generally not implemented realistic full-body avatars and/or a scaling of visual movement feedback. We developed a “virtual mirror” that displays a realistic full-body avatar that responds to full-body movements in all movement planes in real-time, and that allows for the scaling of visual feedback on movements in real-time. The primary objective of this proof-of-concept study was to assess the ability of healthy subjects to detect scaled feedback on trunk flexion movements.

Methods

The “virtual mirror” was developed by integrating motion capture, virtual reality and projection systems. A protocol was developed to provide both augmented and reduced feedback on trunk flexion movements while sitting and standing. The task required reliance on both visual and proprioceptive feedback. The ability to detect scaled feedback was assessed in healthy subjects (n = 10) using a two-alternative forced choice paradigm. Additionally, immersion in the VR environment and task adherence (flexion angles, velocity, and fluency) were assessed.

Results

The ability to detect scaled feedback could be modelled using a sigmoid curve with a high goodness of fit (R² range 89-98%). The point of subjective equivalence was not significantly different from 0 (i.e. not shifted), indicating an unbiased perception. The just noticeable difference was 0.035 ± 0.007, indicating that subjects were able to discriminate different scaling levels consistently. VR immersion was reported to be good, despite some perceived delays between movements and VR projections. Movement kinematic analysis confirmed task adherence.

Conclusions

The new “virtual mirror” extends existing VR systems for motor and pain rehabilitation by enabling the use of realistic full-body avatars and scaled feedback. Proof-of-concept was demonstrated for the assessment of body perception during active movement in healthy controls. The next step will be to apply this system to assessment of body perception disturbances in patients with chronic pain.

Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex

Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the primary somatosensory cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20-60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit's contralateral primary somatosensory cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral primary somatosensory cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = -0.31, P < 0.05), and number of pinch/release cycles (r = -0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral primary somatosensory cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, primary somatosensory cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients.

Acupuncture applied as a sensory discrimination training tool decreases movement-related pain in patients with chronic low back pain more than acupuncture alone: a randomised cross-over experiment

BACKGROUND

High-quality clinical evidence suggests that although acupuncture appears superior to usual care in the management of chronic low back pain, there is little meaningful difference between true and sham acupuncture. This suggests that the benefits of acupuncture are mediated by the placebo response. An alternative explanation is that sham acupuncture is an active treatment and shares a mechanism of action with traditionally applied acupuncture. One plausible candidate for this mechanism is improvement in self-perception mediated through the sensory discrimination-like qualities of acupuncture. We aimed to compare the effects of acupuncture with a sensory discrimination training component to acupuncture without.

METHODS

25 people with chronic low back pain were enroled in a randomised cross-over experiment. We compared the effect of acupuncture delivered when sensory discrimination is optimised to acupuncture delivered when it is not, on movement-related back pain immediately after each intervention.

RESULTS

We found that the average pain intensity after participants had received acupuncture with sensory discrimination training (2.8±2.5) was less than when they received acupuncture without sensory discrimination training (3.6±2.0). This difference was statistically significant (after adjustment; mean difference=-0.8, 95% CI -1.4 to -0.3; p=0.011).

CONCLUSIONS

Our findings are consistent with the idea that acupuncture may offer specific benefit that is not dependent on precisely where the needles are inserted so much as that the patient attends to where they are inserted. If so, the location of the needles might be better focused on the painful area and the need for penetration of the skin may be mitigated.