Correction: Cross-cultural translation and psychometric validation of the French version of the Fear-Avoidance Components Scale (FACS).

[This corrects the article DOI: 10.1371/journal.pone.0288899.].

Examining the Duration of Carryover Effect in Patients With Chronic Pain Treated With Spinal Cord Stimulation (EChO Study): An Open, Interventional, Investigator-Initiated, International Multicenter Study.

OBJECTIVES: Spinal cord stimulation (SCS) is a surgical treatment for severe, chronic, neuropathic pain. It is based on one to two lead(s) implanted in the epidural space, stimulating the dorsal column. It has long been assumed that when deactivating SCS, there is a variable interval before the patient perceives the return of the pain, a phenomenon often termed echo or carryover effect. Although the carryover effect has been problematized as a source of error in crossover studies, no experimental investigation of the effect has been published. This open, prospective, international multicenter study aimed to systematically document, quantify, and investigate the carryover effect in SCS. MATERIALS AND METHODS: Eligible patients with a beneficial effect from their SCS treatment were instructed to deactivate their SCS device in a home setting and to reactivate it when their pain returned. The primary outcome was duration of carryover time defined as the time interval from deactivation to reactivation. Central clinical parameters (age, sex, indication for SCS, SCS treatment details, pain score) were registered and correlated with carryover time using nonparametric tests (Mann-Whitney/Kruskal-Wallis) for categorical data and linear regression for continuous data. RESULTS: In total, 158 patients were included in the analyses. A median carryover time of five hours was found (interquartile range 2.5;21 hours). Back pain as primary indication for SCS, high-frequency stimulation, and higher pain score at the time of deactivation were correlated with longer carryover time. CONCLUSIONS: This study confirms the existence of the carryover effect and indicates a remarkably high degree of interindividual variation. The results suggest that the magnitude of carryover may be correlated to the nature of the pain condition and possibly stimulation paradigms. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT03386058.

Beyond numbers: integrating qualitative analysis into quantitative sensory testing for neuropathic pain.

This article investigates the benefits of adopting qualitative and quantitative sensory testing (QQST) in sensory assessment, with a focus on understanding neuropathic pain. The innovative QQST method combines participant qualitative experiences with quantitative psychophysical measurements, offering a more varied interpretation of sensory abnormalities and normal sensory function. This article also explores the steps for the optimization of the method by identifying qualitative signs of sensory abnormalities and standardizing data collection. By leveraging the inherent subjectivity in the test design and participant responses, the QQST method contributes to a more holistic exploration of both normal and abnormal sensory experiences. This article positions the QQST approach as a foundational element within the Sensory Evaluation Network, uniting international experts to harmonize qualitative and quantitative sensory evaluation methods.

Workers' Worries, Pain, Psychosocial Factors, and Margin of Manoeuvre, in Relation to Outcomes in a Return-to-Work Program: An Exploratory Study.

PURPOSE: To explore the intensity and variation of workers' worries, pain, psychosocial factors, and margin of manoeuvre before and after a return-to-work program, and identified the psychosocial factors associated with non-return to work at the end of the rehabilitation program. METHODS: A pre-post study design was used. A convenience sample of 80 workers starting a return-to-work program and having a compensated musculoskeletal injury that caused an absence of more than three months from their regular work was recruited. Data were collected at baseline and at the end of the rehabilitation program on the nature of the worries and maintenance factors defined in Dugas' generalized anxiety and worry model, using validated questionnaires. The margin of manoeuvre was assessed by the treating occupational therapist. A series of descriptive analyses were performed, as well as Generalized Estimating Equations analyses. RESULTS: Workers' worries were work-related or disability-related 83% of the time at baseline. These worries were essentially based on the situation then occurring at work 90% of the time. For the Generalized Estimating Equations analyses on work status, the final model was significant, explaining 54% of the variance in non-return to work (Pseudo R2 = 0.54; p = 0.0001). Workers were 8.52 times less likely to return to work when the margin of manoeuvre was insufficient, and twice as likely not to return to work in the presence of intense worry. Worries were significantly associated with insufficient margin of manoeuvre. CONCLUSION: A strong association between workers' lack of margin of manoeuvre at work and their worries about their return to work, and poor work outcomes, supports the importance of the worker-environment interaction in rehabilitation programs.

Cross-cultural translation and psychometric validation of the French version of the Fear-Avoidance Components Scale (FACS).

BACKGROUND: The Fear-Avoidance Components Scale (FACS) is a reliable and valid instrument widely used to assess fear-avoidance beliefs related to pain and disability. However, there is a scarcity of validated translations of the FACS in different cultural and linguistic contexts, including the French population. This study aimed to translate and validate the French version of the FACS (FACS-Fr/CF), examining its psychometric properties among French-speaking individuals. METHODS: A cross-cultural translation process-including forward translation, backward translation, expert committee review, and pre-testing-was conducted to develop the FACS-Fr/CF. The translated version was administered to a sample of French-speaking adults (n = 55) with chronic musculoskeletal pain. Internal consistency (including confirmatory analyses of the 2 factors identified in the Serbian version), test-retest reliability and convergent validity were then assessed. RESULTS: The FACS-Fr/CF demonstrated high global internal consistency (α = 0.94, 95% CI: 0.91-0.96) as well as high internal consistency of the 2 factors identified in the Serbian version (α = 0.90, 95% CI: 0.86-0.94 and α = 0.90, 95% CI: 0.85-0.94, respectively). Test-retest analysis revealed a moderate (close to high) reliability (ICC = 0.89; 95% CI: 0.82-0.94 and r = 0.89; p<0.005). Convergent validity was supported by significant correlations between the FACS-Fr/CF scores and the Tampa Scale for Kinesiophobia (r = 0.82; p < 0.005), the Pain Catastrophizing Scale (r = 0.72; p < 0.005) and the Hospital Anxiety and Depression Scale (r = 0.66; p < 0.005). CONCLUSION: The present study provides evidence for the cross-cultural translation and psychometric validation of the FACS-Fr/CF. The FACS-Fr/CF exhibits a high internal consistency, a moderate (close to high) test-retest reliability, and good construct validity, suggesting its utility in assessing fear-avoidance beliefs in the French-speaking population. This validated tool can enhance the assessment and understanding of fear-avoidance behaviors and facilitate cross-cultural research in pain-related studies.

Treatments for kinesiophobia in people with chronic pain: A scoping review.

Kinesiophobia is associated with pain intensity in people suffering from chronic pain. The number of publications highlighting this relationship has increased significantly in recent years, emphasizing the importance of investigating and synthesizing research evidence on this topic. The purpose of this scoping review was to answer the following questions: (1) What types of interventions have been or are currently being studied in randomized controlled trials (RCTs) for the management of kinesiophobia in patients with chronic pain? (2) What chronic pain conditions are targeted by these interventions? (3) What assessment tools for kinesiophobia are used in these interventions? According to the studies reviewed, (1) physical exercise is the most commonly used approach for managing irrational fear of movement, (2) interventions for kinesiophobia have primarily focused on musculoskeletal pain conditions, particularly low back pain and neck pain, and (3) the Tampa Scale of Kinesiophobia is the most commonly used tool for measuring kinesiophobia. Future RCTs should consider multidisciplinary interventions that can help patients confront their irrational fear of movement while taking into account the patient's personal biological, psychological, and social experiences with pain and kinesiophobia.

The Use of Virtual Reality in Back Pain Rehabilitation: A Systematic Review and Meta-Analysis.

This systematic review aimed to synthesize the existing evidence of extended reality (XR) on pain and motor function outcomes in patients with back pain. Following the Cochrane guidelines, relevant articles of any language were selected by 2 independent reviewers from CINAHL, Cochrane, Embase, Medline and Web of Knowledge databases. Of 2,050 unique citations, 24 articles were included in our review. These studies included a total of 900 back pain patients. Despite broader XR search, all interventions were virtual reality (VR) based and involved physical exercises (n = 17, 71%), hippotherapy (n = 4, 17%), motor imagery (n = 1, 4%), distraction (n = 1, 4%), and cognitive-behavior therapy (n = 1, 4%). Sixteen controlled studies were included in a meta-analysis which suggested that VR provides a significant improvement in terms of back pain intensity over control interventions (Mean Difference: -0.67; 95% CI: -1.12 to -0.23; I2 = 85%). Almost all included studies presented high risk of bias, highlighting the need to improve methodology in the examination of VR interventions. While the specific set of studies showed high heterogeneity across several methodological factors, a tentative conclusion could be drawn that VR was effective improving back pain intensity and tends to have a positive effect on improving other pain outcomes and motion function. PERSPECTIVE: Extended reality technologies have appeared as interesting nonpharmacological options for the treatment of back pain, with the potential to minimise the need for opioid medications. Our systematic review summarised existing applications of extended reality for back pain and proposed a few recommendations to direct further studies in the field.

Classification of Qualitative Fieldnotes Collected During Quantitative Sensory Testing: A Step Towards the Development of a New Mixed Methods Approach in Pain Research.

PURPOSE: Quantitative sensory testing (QST) is a standardized method to assess somatosensory function. The collection of qualitative information, during the QST procedure, could be an interesting way to facilitate the characterization of altered sensory perception and the identification of different pain phenotypes. The aims of this study were 1) to classify qualitative fieldnotes of sensory abnormalities collected during an independent QST study, and 2) to generate a qualitative interview guide that could be included in the traditional QST procedure as a step towards the implementation of a mixed methods approach. PATIENTS AND METHODS: QST data were collected from 48 chronic neuropathic pain patients treated with spinal cord stimulation (SCS). Three body areas, with or without SCS, were tested: the painful limb targeted by SCS, the contralateral area, and the ipsilateral upper limb. After each trial of each QST modality, patients were encouraged to report any sensory abnormalities they could identify with a pain quality scale or using their own words. RESULTS: Qualitative self-reported sensory abnormalities were dichotomized into two groups: altered sensory intensities and altered sensory perceptions. Altered sensory intensities were classified as sensory loss or sensory gain subgroups. Altered sensory perceptions were classified as paresthesia and dysesthesia subgroups Overall, 630 qualitative fieldnotes of altered sensations were collected: 385 on the painful limb, 173 at the contralateral area, and 72 at the ipsilateral upper limb. Based on these qualitative data, we propose a standardized method to collect qualitative data involving 9 open- and close-ended questions and 21 codes. CONCLUSION: Our findings have highlighted the value of qualitative sensory evaluation during QST and constitute an important milestone in the development of a mixed methods protocol in phenotyping research.

Comparison of Thermal and Electrical Modalities in the Assessment of Temporal Summation of Pain and Conditioned Pain Modulation.

Temporal summation of pain (TSP) and conditioned pain modulation (CPM) can be measured using a thermode and a cold pressor test (CPT). Unfortunately, these tools are complex, expensive, and are ill-suited for routine clinical assessments. Building on the results from an exploratory study that attempted to use transcutaneous electrical nerve stimulation (TENS) to measure CPM and TSP, the present study assesses whether a "new" TENS protocol can be used instead of the thermode and CPT to measure CPM and TSP. The objective of this study was to compare the thermode/CPT protocol with the new TENS protocol, by (1) measuring the association between the TSP evoked by the two protocols; (2) measuring the association between the CPM evoked by the two protocols; and by (3) assessing whether the two protocols successfully trigger TSP and CPM in a similar number of participants. We assessed TSP and CPM in 50 healthy participants, using our new TENS protocol and a thermode/CPT protocol (repeated measures and randomized order). In the TENS protocol, both the test stimulus (TS) and the conditioning stimulus (CS) were delivered using TENS; in the thermode/CPT protocol, the TS was delivered using a thermode and the CS consisted of a CPT. There was no association between the response evoked by the two protocols, neither for TSP nor for CPM. The number of participants showing TSP [49 with TENS and 29 with thermode (p < 0.001)] and CPM [16 with TENS and 30 with thermode (p = 0.01)] was different in both protocols. Our results suggest that response to one modality does not predict response to the other; as such, TENS cannot be used instead of a thermode/CPT protocol to assess TSP and CPM without significantly affecting the results. Moreover, while at first glance it appears that TENS is more effective than the thermode/CPT protocol to induce TSP, but less so to induce CPM, these results should be interpreted carefully. Indeed, TSP and CPM response appear to be modality-dependent as opposed to an absolute phenomenon, and the two protocols may tap into entirely different mechanisms, especially in the case of TSP.

Effects of Tonic Spinal Cord Stimulation on External Mechanical and Thermal Stimuli Perception Using Quantitative Sensory Testing: A Multicenter Stimulation ON-OFF Study on Chronic Pain Patients.

OBJECTIVES: Tonic spinal cord stimulation (SCS) is currently used to treat neuropathic pain. With this type of stimulation, an implantable pulse generator generates electrical paresthesias in the affected area through 1 or more epidural leads. The goal of this study was to evaluate the impact of tonic SCS on the sensory perception of chronic pain patients using quantitative sensory testing (QST). MATERIALS AND METHODS: Forty-eight patients (mean age: 57 y) with chronic leg pain due to failed back surgery syndrome or complex regional pain syndrome treated with SCS were recruited from 3 research centers. Test procedures included 2 sessions (stimulation On or Off), with measures of detection thresholds for heat, touch, vibration, and of pain thresholds for cold, heat, pressure, the assessment of dynamic mechanical allodynia, and temporal pain summation. Three different areas were examined: the most painful area of the most painful limb covered with SCS-induced paresthesias (target area), the contralateral limb, and the ipsilateral upper limb. Wilcoxon signed-rank tests were used to compare the mean difference between On and Off for each QST parameter at each area tested. P-values <0.05 were considered significant. RESULTS: Regarding the mean difference between On and Off, patients felt less touch sensation at the ipsilateral area (-0.4±0.9 g, P=0.0125) and were less sensitive at the contralateral area for temporal pain summation (-4.9±18.1 on Visual Analog Scale 0 to 100, P=0.0056) with SCS. DISCUSSION: It is not clear that the slight changes observed were clinically significant and induced any changes in patients' daily life. Globally, our results suggest that SCS does not have a significant effect on sensory perception.

Agreement Analysis between Vive and Vicon Systems to Monitor Lumbar Postural Changes.

Immersive virtual reality has recently developed into a readily available system that allows for full-body tracking. Can this affordable system be used for component tracking to advance or replace expensive kinematic systems for motion analysis in the clinic? The aim of this study was to assess the accuracy of position and orientation measures from Vive wireless body trackers when compared to Vicon optoelectronic tracked markers attached to (1) a robot simulating trunk flexion and rotation by repeatedly moving to know locations, and (2) healthy adults playing virtual reality games necessitating significant trunk displacements. The comparison of both systems showed component tracking with Vive trackers is accurate within 0.68 ± 0.32 cm translationally and 1.64 ± 0.18° rotationally when compared with a three-dimensional motion capture system. No significant differences between Vive trackers and Vicon systems were found suggesting the Vive wireless sensors can be used to accurately track joint motion for clinical and research data.

Effects of Tonic Spinal Cord Stimulation on Sensory Perception in Chronic Pain Patients: A Systematic Review.

OBJECTIVES: Even if spinal cord stimulation (SCS) is widely used and effective in treating intractable chronic neuropathic pain conditions, little is known about its possible impacts on sensory perception. Quantitative sensory testing (QST) is a useful tool to assess this issue. The aim of this study was to review the impact of tonic SCS on somatosensory perception quantified by QST in chronic pain patients. MATERIALS AND METHODS: Relevant articles and abstracts were searched in all languages from CINAHL, Cochrane, Embase, MEDLINE, and Web of Knowledge data bases. Data were extracted and included studies were assessed for risk of bias. RESULTS: Out of 5610 records, 15 peer-reviewed articles were eligible and included. The results are heterogeneous due to inadequate comparability among studies for populations (a total of 224 patients diagnosed with more than 13 chronic pain conditions), QST parameters (22 measured with 25 different devices) and experimental procedures (study design, comparator, evaluation time, and area tested). The wide variety of studies, designs, populations, and measures included in this review did not lead to strong evidence on how conventional ("tonic") SCS affects sensory processing in patients with chronic pain. CONCLUSIONS: The data available tend to suggest that conventional SCS does not interfere with perception of external stimuli. New studies that follow a standardized procedure and consider the possible influence of sensory profile, after-effect bias, and confounding factors are required to confirm this observation. Moreover, the impact on sensory perception of other SCS modalities and alternative electrical neuromodulation therapies could also be explored.

Prognostic Value of S-100ß Protein for Prediction of Post-Concussion Symptoms after a Mild Traumatic Brain Injury: Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to determine the prognostic value of S-100ß protein to identify patients with post-concussion symptoms after a mild traumatic brain injury (mTBI). A search strategy was submitted to seven databases from their inception to October 2016. Individual patient data were requested. Cohort studies evaluating the association between S-100ß protein level and post-concussion symptoms assessed at least seven days after the mTBI were considered. Outcomes were dichotomized as persistent (≥3 months) or early (≥7 days <3 months). Our search strategy yielded 23,298 citations of which 29 studies including between seven and 223 patients (n = 2505) were included. Post-concussion syndrome (PCS) (16 studies) and neuropsychological symptoms (9 studies) were the most frequently assessed outcomes. The odds of having persistent PCS (odds ratio [OR] 0.62, 95% confidence interval [CI]: 0.34-1.12, p = 0.11, I2 0% [n = five studies]) in patients with an elevated S-100ß protein serum level were not significantly different from those of patients with normal values while the odds of having early PCS (OR 1.67, 95% CI: 0.98-2.85, p = 0.06, I2 38% [n = five studies]) were close to statistical significance. Similarly, having an elevated S-100ß protein serum level was not associated with the odds of returning to work at six months (OR 2.31, 95% CI: 0.50-10.64, p = 0.28, I2 22% [n = two studies]). Overall risk of bias was considered moderate. Results suggest that the prognostic biomarker S-100ß protein has a low clinical value to identify patients at risk of persistent post-concussion symptoms. Variability in injury to S-100ß protein sample time, mTBI populations, and outcomes assessed could potentially explain the lack of association and needs further evaluation.

Effects of ipratropium on exercise-induced cough in winter athletes: a hypothesis-generating study.

BACKGROUND: Exercise-induced cough (EIC) is frequently reported by winter athletes, but this symptom is not always associated with exercise-induced bronchoconstriction (EIB). The aims of this study were to determine if EIC can be inhibited or reduced with the inhalation of ipratropium, and if EIC in winter athletes is associated with EIB. METHODS: On 2 visits, 24 cross-country skiers (10 males and 12 females, mean age 17 ± 3 years) performed an outdoor exercise in the winter (30-minute warm-up, followed by a 3-minute sprint), randomly preceded by the inhalation of ipratropium or a placebo. A spirometry was done at baseline and 20 minutes after inhalation of ipratropium or placebo. Exercise was then performed, followed by the measurement of forced expiratory volume in 1 second and the recording of the number of coughs until 60 minutes after exercise. Before and after exercise, the perception of cough intensity was evaluated using a modified Borg scale. RESULTS: Twelve of 16 athletes who completed the study (75%) were symptomatic following exercise with placebo (number of coughs ≥ 5), but none developed EIB. For these athletes, the number of coughs after exercise (mean number of coughs ± standard deviation: placebo, 26 ± 14; ipratropium, 25 ± 23; P value, nonsignificant) and the maximal perception score for cough intensity (mean Borg score ± standard deviation: placebo, 1.9 ± 1.2; ipratropium, 2.0 ± 1.1; P value, nonsignificant) were not significantly different between ipratropium and placebo. A decrease in the number of coughs was observed in 6 of the symptomatic athletes and an increase was observed in the other 6, resulting in a nonsignificant mean effect. CONCLUSIONS: Ipratropium does not appear to significantly influence the number and the perception of cough following exercise. Moreover, these results suggest that EIC is not mainly associated with EIB. However, a subgroup of athletes seems to show a beneficial response to ipratropium, suggesting different cough responses in this population.

From expression pattern to genetic association in asthma and asthma-related phenotypes.

BACKGROUND: Asthma is a complex disease characterized by hyperresponsiveness, obstruction and inflammation of the airways. To date, several studies using different approaches as candidate genes approach, genome wide association studies, linkage analysis and genomic expression leaded to the identification of over 300 genes involved in asthma pathophysiology. Combining results from two studies of genomic expression, this study aims to perform an association analysis between genes differently expressed in bronchial biopsies of asthmatics compared to controls and asthma-related phenotypes using the same French-Canadian Caucasian population. RESULTS: Before correction, 31 of the 85 genes selected were associated with at least one asthma-related phenotype. We found four genes that survived the correction for multiple testing. The rs11630178 in aggrecan gene (AGC1) is associated with atopy (p=0.0003) and atopic asthma (p=0.0001), the rs1247653 in the interferon alpha-inducible protein 6 (IFI6), the rs1119529 in adrenergic, alpha-2A-, receptor (ADRA2A) and the rs13103321 in the alcohol dehydrogenase 1B (class I), beta polypeptide (ADH1B), are associated with asthma (p=0.019; 0.01 and 0.002 respectively). CONCLUSION: To our knowledge, this is the first time those genes are associated with asthma and related traits. Consequently, our study confirms that genetic and expression studies are complementary to identify new candidate genes and to investigate their role to improve the comprehension of the complexity of asthma pathophysiology.