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Journal ArticleDOI

Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?

15 Jul 2011-BMC Musculoskeletal Disorders (BioMed Central)-Vol. 12, Iss: 1, pp 162-162

TL;DR: COP mean velocity and sway area are closely related to self-reported pain scores and may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.

AbstractIncreased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults (aged 50 or less) with non-specific low back pain. Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11), an equal number of patients (n = 11) was enrolled per pain score. Generally, our results confirmed increased postural instability in pain sufferers compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points. COP mean velocity and sway area are closely related to self-reported pain scores. This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.

Topics: Balance (ability) (68%), Low back pain (56%)

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Citations
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Journal ArticleDOI
TL;DR: A systematic review of the literature shows that postural deficit may be dependent on experimental conditions in which patients with LBP have been assessed, and that between-group differences did not increase with increased complexity of sensory manipulations.
Abstract: A previous review concluded that postural sway is increased in patients with low back pain (LBP). However, more detailed analysis of the literature shows that postural deficit may be dependent on experimental conditions in which patients with LBP have been assessed. The research question to be answered in this review was: "Is there any difference in postural sway between subjects with and without LBP across several sensory manipulation conditions?". A literature search in Pubmed, Scopus, Embase and PsychInfo was performed followed by hand search and contact with authors. Studies investigating postural sway during bipedal stance without applying external forces in patients with specific and non-specific LBP compared to healthy controls were included. Twenty three articles fulfilled the eligibility criteria. Most studies reported an increased postural sway in LBP, or no effect of LBP on postural sway. In a minority of studies, a decreased sway was found in LBP patients. There were no systematic differences between studies finding an effect and those reporting no effect of LBP. The proportion of studies finding between-group differences did not increase with increased complexity of sensory manipulations. Potential factors that may have caused inconsistencies in the literature are discussed in this systematic review.

108 citations


Journal ArticleDOI
TL;DR: The decreased postural stability in people with neck pain appears to be associated with the presence of pain and correlates with the extent of proprioceptive impairment, but appears unrelated to pain duration.
Abstract: Systematic literature review. To assess differences in center of pressure (COP) measures in patients suffering from non-specific neck pain (NSNP) or whiplash-associated disorder (WAD) compared to healthy controls and any relationship between changes in postural sway and the presence of pain, its intensity, previous pain duration and the perceived level of disability. Over the past 20 years, the center of pressure (COP) has been commonly used as an index of postural stability in standing. While several studies investigated COP excursions in neck pain and WAD patients and compared these to healthy individuals, no comprehensive analysis of the reported differences in postural sway pattern exists. Six online databases were systematically searched followed by a manual search of the retrieved papers. Papers comparing COP measures derived from bipedal static task conditions on a force plate of people with NSNP and WAD to those of healthy controls. Two reviewers independently screened titles and abstracts for relevance. Screening for final inclusion, data extraction and quality assessment were carried out with a third reviewer to reconcile differences. Ten papers met the inclusion criteria. Heterogeneity in study designs prevented pooling of the data and no direct comparison of data across the studies was possible. Instead, a qualitative data analysis was conducted. There was broad consensus that patients with either type of neck pain have increased COP excursions compared to healthy individuals, a difference that was more pronounced in people with WAD. An increased sway in antero-posterior direction was observed in both groups. Patients with neck pain (due to either NSNP or WAD) exhibit greater postural instability than healthy controls, signified by greater COP excursions irrespective of the COP parameter chosen. Further, the decreased postural stability in people with neck pain appears to be associated with the presence of pain and correlates with the extent of proprioceptive impairment, but appears unrelated to pain duration.

58 citations


Cites background from "Is there a relationship between pai..."

  • ...We previously described that such a simple static setup is not only highly discriminative for non-specific low back pain [15] but also allowed the observation of a linear relationship between the perceived pain intensity and COP sway velocity [16]....

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  • ...Pain severity has shown to be a determining factor in non-specific low back pain cases [16] where a significant, linear increase in postural sway was observed beginning at a NRS-11 score of 5....

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  • ...As a linear relationship between pain intensity and COP sway velocity has been demonstrated in patients with non-specific low back pain [16], further research is necessary to investigate whether this also applies to people with neck pain....

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Journal ArticleDOI
TL;DR: Postural control, as evidenced by increased oscillation of COP, is impaired in individuals with cLBP relative to controls, and differences are magnified by visual deprivation and unstable surface conditions.
Abstract: A preliminary case–control study. To assess postural control in individuals with and without non-specific chronic low back pain (cLBP) during quiet standing. cLBP affects 12–33 % of the adult population. Reasons for pain chronicity are yet poorly known. Change in postural control may be a risk factor for cLBP, although available studies are not conclusive. Sample consisted of 21 individuals with cLBP and 23 controls without cLBP. Balance was assessed using a force plate (Balance Master®, NeuroCom) by the modified clinical test of sensory interaction and balance, pain severity by the visual analogue scale, quality of life with the SF-36 Questionnaire, and functional disability with the Roland-Morris Questionnaire. Groups were homogeneous for age, weight, height and body mass index. Relative to controls, participants in the cLBP group had deficits in the postural control, with greater postural sway in the quiet standing condition with closed eyes closed on unstable surfaces (p < 0.05) for the following parameters: total COP oscillation [cLBP 1,432.82 (73.27) vs CG 1,187.77 (60.30)], root mean square sagittal plane [cLBP 1.21 (0.06) vs CG 1.04 (0.04)], COP area [cLBP 24.27 (2.47) vs CG 16.45 (1.79)] and mean speed of oscillation [cLBP 12.97 (0.84) vs CG 10.55 (0.70)]. Postural control, as evidenced by increased oscillation of COP, is impaired in individuals with cLBP relative to controls. Differences are magnified by visual deprivation and unstable surface conditions.

39 citations


Journal ArticleDOI
TL;DR: Alterations in self-reported pain intensities are closely related to changes in postural sway, suggesting that pain interference appears responsible for the altered sway in pain sufferers.
Abstract: Background: Increased postural sway is well documented in patients suffering from non-specific low back pain, whereby a linear relationship between higher pain intensities and increasing postural sway has been described No investigation has been conducted to evaluate whether this relationship is maintained if pain levels change in adults with non-specific low back pain Methods: Thirty-eight patients with non-specific low back pain and a matching number of healthy controls were enrolled Postural sway was measured by three identical static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface The perceived pain intensity was assessed by a numeric rating scale (NRS-11) The patients received three manual interventions (eg manipulation, mobilization or soft tissue techniques) at 3-4 day intervals, postural sway measures were obtained at each occasion Results: A clinically relevant decrease of four NRS scores in associated with manual interventions correlated with a significant decrease in postural sway In contrast, if no clinically relevant change in intensity occurred (≤ 1 level), postural sway remained similar compared to baseline The postural sway measures obtained at follow-up sessions 2 and 3 associated with specific NRS level showed no significant differences compared to reference values for the same pain score Conclusions: Alterations in self-reported pain intensities are closely related to changes in postural sway The previously reported linear relationship between the two variables is maintained as pain levels change Pain interference appears responsible for the altered sway in pain sufferers This underlines the clinical use of sway measures as an objective monitoring tool during treatment or rehabilitation

35 citations


Cites background or result from "Is there a relationship between pai..."

  • ...This is not considered a clinically significant improvement and sway data published in an earlier study did also not identify a significant change in postural sway between those pain scores [1]....

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  • ...In a previous study we outlined that non-specific low back pain (NSLBP) intensity is correlated with the magnitude of postural sway [1]....

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  • ...Previously we were able to demonstrate a linear relationship between COP sway and NRS scores in NSLBP patients [1]....

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  • ...The participants of this study were from a previously enrolled group of 77 NSLBP sufferers [1] that agreed to complete a course of three measurements and interventions....

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  • ...Seventy-seven symptomatic participants enrolled in an earlier study [1] provided baseline data....

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Journal ArticleDOI
TL;DR: A model for control of postural sway is proposed that suggests that subjects with LBP use more co-contraction and less cognitive control, to maintain a standing balance when compared to subjects without LBP.
Abstract: Patients with non-specific low back pain (LBP) may use postural control strategies that differ from healthy subjects. To study these possible differences, we measured the amount and structure of postural sway, and the response to muscle vibration in a working cohort of 215 subjects. Subjects were standing on a force plate in bipedal stance. In the first trial the eyes were open, no perturbation applied. In the following 6 trials, vision was occluded and subjects stood under various conditions of vibration/no vibration of the lumbar spine or m. Triceps Surae (TSM) on firm surface and on foam surface. We performed a factor analysis to reduce the large amount of variables that are available to quantify all effects. Subjects with LBP showed the same amount of sway as subjects without LBP, but the structure of their sway pattern was less regular with higher frequency content. Subjects with LBP also showed a smaller response to TSM vibration, and a slower balance recovery after cessation of vibration when standing on a solid surface. There was a weak but significant association between smaller responses to TSM vibration and an irregular, high frequency sway pattern, independent from LBP. A model for control of postural sway is proposed. This model suggests that subjects with LBP use more co-contraction and less cognitive control, to maintain a standing balance when compared to subjects without LBP. In addition, a reduced weighting of proprioceptive signals in subjects with LBP is suggested as an explanation for the findings in this study.

30 citations


References
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Journal ArticleDOI
Abstract: Reliability coefficients often take the form of intraclass correlation coefficients. In this article, guidelines are given for choosing among six different forms of the intraclass correlation for reliability studies in which n target are rated by k judges. Relevant to the choice of the coefficient are the appropriate statistical model for the reliability and the application to be made of the reliability results. Confidence intervals for each of the forms are reviewed.

19,527 citations


"Is there a relationship between pai..." refers methods in this paper

  • ...To test the reliability of the COP measures for this experimental setup for both controls and pain sufferers, the two-way random-effect intra-class correlation coefficient (ICC2,k) as described by Shrout and Fleiss [18] was computed using absolute agreement....

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  • ...Shrout PE, Fleiss JL: Intraclass correlations: uses in assessing rater reliability....

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Journal ArticleDOI
TL;DR: In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC and how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.
Abstract: Reliability, the consistency of a test or measurement, is frequently quantified in the movement sciences literature. A common metric is the intraclass correlation coefficient (ICC). In addition, the SEM, which can be calculated from the ICC, is also frequently reported in reliability studies. However, there are several versions of the ICC, and confusion exists in the movement sciences regarding which ICC to use. Further, the utility of the SEM is not fully appreciated. In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC. The primary distinction between ICC equations is argued to be one concerning the inclusion (equations 2,1 and 2,k) or exclusion (equations 3,1 and 3,k) of systematic error in the denominator of the ICC equation. Inferential tests of mean differences, which are performed in the process of deriving the necessary variance components for the calculation of ICC values, are useful to determine if systematic error is present. If so, the measurement schedule should be modified (removing trials where learning and/or fatigue effects are present) to remove systematic error, and ICC equations that only consider random error may be safely used. The use of ICC values is discussed in the context of estimating the effects of measurement error on sample size, statistical power, and correlation attenuation. Finally, calculation and application of the SEM are discussed. It is shown how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.

3,542 citations


"Is there a relationship between pai..." refers background or methods in this paper

  • ...Weir JP: Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM....

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  • ...Secondly, given the linear relationship between pain intensity and, for example, mVel, a clinically significant decrease of two points on a pain NRS [20] is equivalent to a reduction in mean sway velocity of 3....

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  • ...In addition, the 95% confidence intervals (CI) and the standard error of measurement (SEM) [20] were calculated....

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Journal ArticleDOI
01 Oct 1986-Pain
TL;DR: The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity, however, when considering the remaining 3 criteria, the 101‐point numerical rating scale appears to be the most practical index.
Abstract: The measurement of subjective pain intensity continues to be important to both researchers and clinicians. Although several scales are currently used to assess the intensity construct, it remains unclear which of these provides the most precise, replicable, and predictively valid measure. Five criteria for judging intensity scales have been considered in previous research: ease of administration of scoring; relative rates of incorrect responding; sensitivity as defined by the number of available response categories; sensitivity as defined by statistical power; and the magnitude of the relationship between each scale and a linear combination of pain intensity indices. In order to judge commonly used pain intensity measures, 75 chronic pain patients were asked to rate 4 kinds of pain (present, least, most, and average) using 6 scales. The utility and validity of the scales was judged using the criteria listed above. The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity. However, when considering the remaining 3 criteria, the 101-point numerical rating scale appears to be the most practical index.

2,686 citations


"Is there a relationship between pai..." refers methods in this paper

  • ...The NSLBP participants were further asked to describe their pain intensity at the time of recording by means of an NRS-11, a rating scale ranging from 0 (no pain) to 10 (worst possible pain) [15]....

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Journal Article
TL;DR: A set of criteria based upon biostatistical considerations for determining the interrater reliability of specific adaptive behavior items in a given setting was presented and guidelines for differentiating type of adaptive behavior that are statistically reliable from those that are reliable in a clinical or practical sense were delineated.
Abstract: A set of criteria based upon biostatistical considerations for determining the interrater reliability of specific adaptive behavior items in a given setting was presented. The advantages and limitations of extant statistical assessment procedures were discussed. Also, a set of guidelines for differentiating type of adaptive behavior that are statistically reliable from those that are reliable in a clinical or practical sense was delineated. Data sets were presented throughout in order to illustrate the advantages of recommended statistical procedures over other available ones.

1,829 citations


Journal ArticleDOI
TL;DR: Care should be taken when quantifying postural sway through stabilometric parameters, and it is suggested as a good practice to include some anthropometric measurements in the experimental protocol, and to standardize or trace foot position.
Abstract: Objective. To recognize and quantify the influence of biomechanical factors, namely anthropometry and foot placement, on the more common measures of stabilometric performance, including new-generation stochastic parameters. Design. Fifty normal-bodied young adults were selected in order to cover a sufficiently wide range of anthropometric properties. They were allowed to choose their preferred side-by-side foot position and their quiet stance was recorded with eyes open and closed by a force platform. Background. Biomechanical factors are known to influence postural stability but their impact on stabilometric parameters has not been extensively explored yet. Methods. Principal component analysis was used for feature selection among several biomechanical factors. A collection of 55 stabilometric parameters from the literature was estimated from the center-of-pressure time series. Linear relations between stabilometric parameters and selected biomechanical factors were investigated by robust regression techniques. Results. The feature selection process returned height, weight, maximum foot width, base-of-support area, and foot opening angle as the relevant biomechanical variables. Only eleven out of the 55 stabilometric parameters were completely immune from a linear dependence on these variables. The remaining parameters showed a moderate to high dependence that was strengthened upon eye closure. For these parameters, a normalization procedure was proposed, to remove what can well be considered, in clinical investigations, a spurious source of between-subject variability. Conclusion. Care should be taken when quantifying postural sway through stabilometric parameters. It is suggested as a good practice to include some anthropometric measurements in the experimental protocol, and to standardize or trace foot position. Relevance Although the role of anthropometry and foot placement has been investigated in specific studies, there are no studies in the literature that systematically explore the relationship between such BF and stabilometric parameters. This knowledge may contribute to better defining the experimental protocol and improving the functional evaluation of postural sway for clinical purposes, e.g. by removing through normalization the spurious effects of body properties and foot position on postural performance. � 2002 Elsevier Science Ltd. All rights reserved.

454 citations


"Is there a relationship between pai..." refers background or result in this paper

  • ...As outlined in our systematic literature review [1], several factors such as age [9-11], gender, weight [12], and height [13] have been shown to exhibit a significant effect on postural sway....

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  • ...In contrast to other studies [9-13], we could not demonstrate any significant effect of age, height, weight or gender on COP excursions in the patient group....

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