Disrupted Self-Perception in People With Chronic Low Back Pain. Further Evaluation of the Fremantle Back Awareness Questionnaire.

UNLABELLED: Several lines of evidence suggest that body perception is altered in people with chronic back pain. Maladaptive perceptual awareness of the back might contribute to the pain experience as well as serve as a target for treatment. The Fremantle Back Awareness Questionnaire (FreBAQ) is a simple questionnaire recently developed to assess back-specific altered self-perception. The aims of this study were to present the outcomes of a comprehensive evaluation of the questionnaire's psychometric properties and explore the potential relationships between body perception, nociceptive sensitivity, distress, and beliefs about back pain and the contribution these factors might play in explaining pain and disability. Two hundred fifty-one people with chronic back pain completed the questionnaire as well as a battery of clinical tests. The Rasch model was used to explore the questionnaires' psychometric properties and correlation and multiple linear regression analyses were used to explore the relationship between altered body perception and clinical status. The FreBAQ appears unidimensional with no redundant items, has minimal ceiling and floor effects, acceptable internal consistency, was functional on the category rating scale, and was not biased by demographic or clinical variables. FreBAQ scores were correlated with sensitivity, distress, and beliefs and were uniquely associated with pain and disability. PERSPECTIVE: Several lines of evidence suggest that body perception might be disturbed in people with chronic low back pain, possibly contributing to the condition and offering a potential target for treatment. The FreBAQ was developed as a quick and simple way of measuring back-specific body perception in people with chronic low back pain. The questionnaire appears to be a psychometrically sound way of assessing altered self-perception. The level of altered self-perception is positively correlated with pain intensity and disability as well as showing associations with psychological distress, pain catastrophization, fear avoidance beliefs, and lumbar pressure pain threshold. In this sample, it appears that altered self-perception might be a more important determinant of clinical severity than psychological distress, pain catastrophization, fear avoidance beliefs, or lumbar pressure pain threshold.

Moving in an environment of induced sensorimotor incongruence does not influence pain sensitivity in healthy volunteers: a randomised within-subject experiment.

OBJECTIVES: It has been proposed that in the same way that conflict between vestibular and visual inputs leads to motion sickness, conflict between motor commands and sensory information associated with these commands may contribute to some chronic pain states. Attempts to test this hypothesis by artificially inducing a state of sensorimotor incongruence and assessing self-reported pain have yielded equivocal results. To help clarify the effect sensorimotor incongruence has on pain we investigated the effect of moving in an environment of induced incongruence on pressure pain thresholds (PPT) and the pain experienced immediately on completion of PPT testing. METHODS: Thirty-five healthy subjects performed synchronous and asynchronous upper-limb movements with and without mirror visual feedback in random order. We measured PPT over the elbow and the pain evoked by testing. Generalised linear mixed-models were performed for each outcome. Condition (four levels) and baseline values for each outcome were within-subject factors. RESULTS: There was no effect of condition on PPT (p = 0.887) or pressure-evoked pain (p = 0.771). A sensitivity analysis using only the first PPT measure after each condition confirmed the result (p = 0.867). DISCUSSION: Inducing a state of movement related sensorimotor incongruence in the upper-limb of healthy volunteers does not influence PPT, nor the pain evoked by testing. We found no evidence that sensorimotor incongruence upregulates the nociceptive system in healthy volunteers.

Assessing self-perception in patients with chronic low back pain: development of a back-specific body-perception questionnaire.

BACKGROUND: There is considerable interest in the role that disturbance of body-perception may play in long standing pain problems such as chronic low back pain (CLBP), both as a contributor to the clinical condition and as a potential target for treatment. In some chronic pain conditions body-perception has been investigated using self-report questionnaires. There is currently no questionnaire for assessing body-perception in people with CLBP. OBJECTIVE: To describe the development of a back-specific body-perception questionnaire and examine the psychometrics of this new scale. METHODS: Based on available evidence a back-specific body-perception questionnaire was developed. Fifty-one people with CLBP and an equal number of healthy controls completed the questionnaire; a subset of the patient population completed the questionnaire again one-week later. Scale-consistency and test-retest reliability were investigated on the patient sample. Validity was investigated by comparing responses between patients and controls as well as exploring the relationship between the questionnaire and important clinical characteristics. RESULTS: All but one of the patients endorsed items on the questionnaire, which suggests that distorted body-perception may exist in this population. The internal-consistency and test-retest reliability of the scale appear acceptable. The discriminative validity of the questionnaire is supported by the marked differences in the questionnaire responses between patients and healthy controls and the construct validity by the significant association between the questionnaire score and important clinical variables. CONCLUSION: Symptoms of body-perception distortion were endorsed by most CLBP patients, while these symptoms are very infrequent amongst healthy controls. Our results suggest the questionnaire has reasonable psychometric properties.

Illusory touch temporarily improves sensation in areas of chronic numbness: a brief communication.

BACKGROUND: Creating the visual illusion of touch can improve tactile perception in healthy subjects. OBJECTIVE: We were interested in seeing if creating the illusion of touch in an insensate area could improve sensation in that area. METHODS: Fourteen people with chronic numbness participated in a randomized crossover experiment. The 4 conditions were the following: (a) stimulation over the unaffected limb with mirror visual feedback (experimental condition), (b) stimulation over the affected limb with mirror visual feedback, (c) stimulation over the unaffected limb without mirror visual feedback, and (d) stimulation over the affected limb without mirror visual feedback. Participants were assessed before and after each condition using the Ten-Test and mechanical detection thresholds. Data were analyzed using linear mixed models. RESULT: Only the experimental condition produced a change in the Ten-Test (mean difference = -1.1; 95% confidence interval = -1.8 to -0.4; P = .003), corresponding to a 24% improvement in sensation. No differences were observed for any condition in mechanical detection thresholds. CONCLUSION: Creating the illusion of touch may improve sensory function in areas of chronic numbness. This preliminary finding adds to the growing body of evidence supporting the use of techniques that directly target cortical function in people with peripheral nerve injury.

Lumbar tactile acuity is near identical between sides in healthy pain-free participants.

A growing body of literature suggests that alterations in brain structure and function are a feature of chronic back pain. Tactile acuity is considered a clinical signature of primary somatosensory representation and offers a simple measure of cortical reorganisation. Clinical interpretation of test scores from an individual patient is hampered by variance in published normative values and less than ideal inter-rater reliability. These problems might be mitigated in people with unilateral back pain by using the patient as their own control and comparing tactile acuity at the painful site to performance at the corresponding position on the non-painful side. The first step in exploring this approach is to quantify the normal side-to-side difference in healthy populations. We pooled data from three previous studies that measured lumbar tactile acuity bilaterally in healthy controls using similar protocols. We calculated the mean and variance of the absolute error between sides, the standard error of measurement and the reliable change index (RCI). The mean difference between sides was 3.2 mm (±5.2) when assessed vertically and 1.9 mm (±3.2) when assessed horizontally. The standard error of measurement was 4.2 mm when assessed vertically and 2.7 mm when assessed horizontally. The RCI suggests that differences of greater than 13 mm when assessed horizontally and 17 mm when assessed vertically equate to 95% confidence that a difference truly exists. Several assumptions related to the application of this approach need to be investigated further.

Seeing it helps: movement-related back pain is reduced by visualization of the back during movement.

OBJECTIVES: The aim of this study was to determine whether visualization of the back influenced parameters of movement-related pain in people with chronic nonspecific low back pain. METHODS: We used a randomized cross-over experiment in which 25 participants performed repeated lumbar spine movements under 2 conditions. In the visual feedback condition, patients were able to visualize their back as it moved by the use of mirrors. In the control condition, the mirror was covered so no visualization of the back was possible. RESULTS: The average postmovement pain intensity after participants had moved with visual feedback was less (35.5 ± 22.8 mm) than when they moved without visual feedback (44.7 ± 26.0 mm). This difference was statistically significant (mean difference=9.3, 95% confidence interval: 2.8-15.7 F(1,22)=8.82, P=0.007). The average time to ease after participants had moved with visual feedback was shorter (44.5 s ± 53.8) than when they moved without visual feedback (94.4 s ± 80.7). This difference was also statistically significantly (mean difference=49.9, 95% confidence interval: 19.3-80.6, F(1,22)=8.82, P=0.003). DISCUSSION: Patients with chronic nonspecific low back pain reported less increase in pain and faster resolution of pain when moving in an environment that enabled them to visualize their back. This is consistent with emerging research on the use of mirror visual feedback in other long-standing pain problems and suggests that similar lines of inquiry may be worth pursuing in the chronic nonspecific low back pain population.

Cortical changes in chronic low back pain: current state of the art and implications for clinical practice.

There is increasing evidence that chronic pain problems are characterised by alterations in brain structure and function. Chronic back pain is no exception. There is a growing sentiment, with accompanying theory, that these brain changes contribute to chronic back pain, although empirical support is lacking. This paper reviews the structural and functional changes of the brain that have been observed in people with chronic back pain. We cast light on the clinical implications of these changes and the possibilities for new treatments but we also advise caution against concluding their efficacy in the absence of solid evidence to this effect.

Self-reported assessment of disability and performance-based assessment of disability are influenced by different patient characteristics in acute low back pain.

For an individual, the functional consequences of an episode of low back pain is a key measure of their clinical status. Self-reported disability measures are commonly used to capture this component of the back pain experience. In non-acute low back pain there is some uncertainty of the validity of this approach. It appears that self-reported assessment of disability and direct measurements of functional status are only moderately related. In this cross-sectional study, we investigated this relationship in a sample of 94 acute low back pain patients. Both self-reported disability and a performance-based assessment of disability were assessed, along with extensive profiling of patient characteristics. Scale consistency of the performance-based assessment was investigated using Cronbach's alpha, the relationship between self-reported and performance-based assessment of disability was investigated using Pearson's correlation. The relationship between clinical profile and each of the disability measures were examined using Pearson's correlations and multivariate linear regression. Our results demonstrate that the battery of tests used are internally reliable (Cronbach's alpha = 0.86). We found only moderate correlations between the two disability measures (r = 0.471, p < 0.001). Self-reported disability was significantly correlated with symptom distribution, medication use, physical well-being, pain intensity, depression, somatic distress and anxiety. The only significant correlations with the performance-based measure were symptom distribution, physical well-being and pain intensity. In the multivariate analyses no psychological measure made a significant unique contribution to the prediction of the performance-based measure, whereas depression made a unique contribution to the prediction of the self-reported measure. Our results suggest that self-reported and performance-based assessments of disability are influenced by different patient characteristics. In particular, it appears self-reported measures of disability are more influenced by the patient's psychological status than performance-based measures of disability.

Chronic non-specific low back pain - sub-groups or a single mechanism?

BACKGROUND: Low back pain is a substantial health problem and has subsequently attracted a considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions for chronic non-specific low back pain indicate limited effectiveness for most commonly applied interventions and approaches. DISCUSSION: Many clinicians challenge the results of clinical trials as they feel that this lack of effectiveness is at odds with their clinical experience of managing patients with back pain. A common explanation for this discrepancy is the perceived heterogeneity of patients with chronic non-specific low back pain. It is felt that the effects of treatment may be diluted by the application of a single intervention to a complex, heterogeneous group with diverse treatment needs. This argument presupposes that current treatment is effective when applied to the correct patient. An alternative perspective is that the clinical trials are correct and current treatments have limited efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important that the sub-grouping paradigm is closely examined. This paper argues that there are numerous problems with the sub-grouping approach and that it may not be an important reason for the disappointing results of clinical trials. We propose instead that current treatment may be ineffective because it has been misdirected. Recent evidence that demonstrates changes within the brain in chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of cortical reorganisation and degeneration. This perspective offers interesting insights into the chronic low back pain experience and suggests alternative models of intervention. SUMMARY: The disappointing results of clinical research are commonly explained by the failure of researchers to adequately attend to sub-grouping of the chronic non-specific low back pain population. Alternatively, current approaches may be ineffective and clinicians and researchers may need to radically rethink the nature of the problem and how it should best be managed.