Relationship between quantitative sensory testing and pain or disability in people with spinal pain-a systematic review and meta-analysis

Changes in Cytokines, Sensory Tests, and Self-reported Pain Levels After Manual Treatment of Low Back Pain

STUDY DESIGN

Unbalanced 3-factor design with repeated measures on 1 factor.

OBJECTIVE

To determine the effect of manual treatment (MT) on cytokine and pain sensations in those with and without low back pain (LBP).

SUMMARY OF BACKGROUND DATA

Evidence suggests that MT reduces LBP but by unknown mechanisms. Certain cytokines have been elevated in patients with LBP and may be affected by MT.

METHODS

Participants aged 20-60 years with chronic LBP or without LBP were recruited and randomly assigned to MT, sham ultrasound treatment, or no treatment groups. Venous blood samples were collected and pain levels assessed at baseline, 1 hour later, and 24 hours later. Blood was analyzed for interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and C-reactive protein. Pain levels were measured by pressure pain threshold (PPT), mechanical detection threshold (MDT), dynamic mechanical allodynia, and self-report.

RESULTS

Forty (30 women, age 36±11 y) participants completed the study, 33 with LBP (13 MT, 13 sham ultrasound treatment, and 7 no treatment) and 7 without LBP. Participants with or without LBP could not be differentiated on the basis of serum cytokine levels, PPT, or MDT (P≥0.08). There were no significant differences between the groups at 1 hour or 24 hours on serum cytokines, PPT, or MDT (P≥0.07). There was a significant decrease from baseline in IL-6 for the no treatment (LBP) group (P=0.04), in C-reactive protein for the sham ultrasound treatment group (P=0.03), in MDT for all 3 LBP groups (P≤0.02), and in self-reported pain for the MT and sham ultrasound treatment groups (P=0.03 and 0.01).

CONCLUSIONS

Self-reported pain was reduced with MT and sham ultrasound treatment 24 hours after treatment, but inflammatory markers within venous circulation and quantitative sensory tests were unable to differentiate between study groups. Therefore, we were unable to characterize mechanisms underlying chronic LBP.

Assessment of deep dynamic mechanical sensitivity in individuals with tension-type headache: The dynamic pressure algometry

BACKGROUND

To explore the validity of dynamic pressure algometry for evaluating deep dynamic mechanical sensitivity by assessing its association with headache features and widespread pressure sensitivity in tension-type headache (TTH).

METHODS

One hundred and eighty-eight subjects with TTH (70% women) participated. Deep dynamic sensitivity was assessed with a dynamic pressure algometry set (Aalborg University, Denmark^© ) consisting of 11 different rollers including fixed levels from 500 g to 5300 g. Each roller was moved at a speed of 0.5 cm/s over a 60-mm horizontal line covering the temporalis muscle. Dynamic pain threshold (DPT-level of the first painful roller) was determined and pain intensity during DPT was rated on a numerical pain rate scale (NPRS, 0-10). Headache clinical features were collected on a headache diary. As gold standard, static pressure pain thresholds (PPT) were assessed over temporalis, C5/C6 joint, second metacarpal, and tibialis anterior muscle.

RESULTS

Side-to-side consistency between DPT (r = 0.843, p < 0.001) and pain evoked (r = 0.712; p < 0.001) by dynamic algometer was observed. DPT was moderately associated with widespread PPTs (0.526 > r > 0.656, all p < 0.001). Furthermore, pain during DPT was negatively associated with widespread PPTs (-0.370 < r < -0.162, all p < 0.05).

DISCUSSION

Dynamic pressure algometry was a valid tool for assessing deep dynamic mechanical sensitivity in TTH. DPT was associated with widespread pressure sensitivity independently of the frequency of headaches supporting that deep dynamic pressure sensitivity within the trigeminal area is consistent with widespread pressure sensitivity. Assessing deep static and dynamic somatic tissue pain sensitivity may provide new opportunities for differentiated diagnostics and possibly a new tool for assessing treatment effects.

SIGNIFICANCE

The current study found that dynamic pressure algometry in the temporalis muscle was associated with widespread pressure pain sensitivity in individuals with tension-type headache. The association was independent of the frequency of headaches. Assessing deep static and dynamic somatic tissue pain sensitivity may provide new opportunities for differentiated diagnostics and possibly a tool for assessing treatment effects.

Clinical classification in low back pain: best-evidence diagnostic rules based on systematic reviews

Background

Clinical examination findings are used in primary care to give an initial diagnosis to patients with low back pain and related leg symptoms. The purpose of this study was to develop best evidence Clinical Diagnostic Rules (CDR] for the identification of the most common patho-anatomical disorders in the lumbar spine; i.e. intervertebral discs, sacroiliac joints, facet joints, bone, muscles, nerve roots, muscles, peripheral nerve tissue, and central nervous system sensitization.

Methods

A sensitive electronic search strategy using MEDLINE, EMBASE and CINAHL databases was combined with hand searching and citation tracking to identify eligible studies. Criteria for inclusion were: persons with low back pain with or without related leg symptoms, history or physical examination findings suitable for use in primary care, comparison with acceptable reference standards, and statistical reporting permitting calculation of diagnostic value. Quality assessments were made independently by two reviewers using the Quality Assessment of Diagnostic Accuracy Studies tool. Clinical examination findings that were investigated by at least two studies were included and results that met our predefined threshold of positive likelihood ratio ≥ 2 or negative likelihood ratio ≤ 0.5 were considered for the CDR.

Results

Sixty-four studies satisfied our eligible criteria. We were able to construct promising CDRs for symptomatic intervertebral disc, sacroiliac joint, spondylolisthesis, disc herniation with nerve root involvement, and spinal stenosis. Single clinical test appear not to be as useful as clusters of tests that are more closely in line with clinical decision making.

Conclusions

This is the first comprehensive systematic review of diagnostic accuracy studies that evaluate clinical examination findings for their ability to identify the most common patho-anatomical disorders in the lumbar spine. In some diagnostic categories we have sufficient evidence to recommend a CDR. In others, we have only preliminary evidence that needs testing in future studies. Most findings were tested in secondary or tertiary care. Thus, the accuracy of the findings in a primary care setting has yet to be confirmed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1549-6) contains supplementary material, which is available to authorized users.

Biopsychosocial influence on shoulder pain: Rationale and protocol for a pre-clinical trial

BACKGROUND

Chronic musculoskeletal pain conditions are a prevalent and disabling problem. Preventing chronic musculoskeletal pain requires multifactorial treatment approaches that address its complex etiology. Prior cohort studies identified a high risk subgroup comprised of variation in COMT genotype and pain catastrophizing. This subgroup had increased chance of heightened pain responses (in a pre-clinical model) and higher 12month post-operatives pain intensity ratings (in a clinical model). This pre-clinical trial will test mechanisms and efficacy of personalized pain interventions matched to the genetic and psychological characteristics of the high-risk subgroup.

METHODS

Potential participants will be screened for high risk subgroup membership, appropriateness for exercise-induced muscle injury protocol, and appropriateness for propranolol administration. Eligible participants that consent to the study will then be randomized into one of four treatment groups; 1) personalized pharmaceutical and psychological education; 2) personalized pharmaceutical and general education; 3) placebo pharmaceutical and psychological education; 4) placebo pharmaceutical and psychological education. Over the 5-day study period participants will complete an exercise-induced muscle injury protocol and receive study interventions. Pain and disability assessments will be completed daily, with primary outcomes being duration of shoulder pain (number of days until recovery), peak shoulder pain intensity, and peak shoulder disability. Secondary outcomes include inflammatory markers, psychological mediators, and measures of pain sensitivity regulation.

CONCLUSION

This pre-clinical trial builds on prior cohort studies and its completion will provide foundational data supporting efficacy and mechanisms of personalized interventions for individuals that may be at increased risk for developing chronic shoulder pain.

TRIAL REGISTRATION

ClinicalTrials.gov registry, NCT02620579 (Registered on November 13, 2015).

Effectiveness of manual therapy versus surgery in pain processing due to carpal tunnel syndrome: A randomized clinical trial

BACKGROUND

People with carpal tunnel syndrome (CTS) exhibit widespread pressure pain and thermal pain hypersensitivity as a manifestation of central sensitization. The aim of our study was to compare the effectiveness of manual therapy versus surgery for improving pain and nociceptive gain processing in people with CTS.

METHODS

The trial was conducted at a local regional Hospital in Madrid, Spain from August 2014 to February 2015. In this randomized parallel-group, blinded, clinical trial, 100 women with CTS were randomly allocated to either manual therapy (n = 50), who received three sessions (once/week) of manual therapies including desensitization manoeuvres of the central nervous system, or surgical intervention (n = 50) group. Outcomes including pressure pain thresholds (PPT), thermal pain thresholds (HPT or CPT), and pain intensity which were assessed at baseline, and 3, 6, 9 and 12 months after the intervention by an assessor unaware of group assignment. Analysis was by intention to treat with mixed ANCOVAs adjusted for baseline scores.

RESULTS

At 12 months, 95 women completed the follow-up. Patients receiving manual therapy exhibited higher increases in PPT over the carpal tunnel at 3, 6 and 9 months (all, p < 0.01) and higher decrease of pain intensity at 3 month follow-up (p < 0.001) than those receiving surgery. No significant differences were observed between groups for the remaining outcomes.

CONCLUSIONS

Manual therapy and surgery have similar effects on decreasing widespread pressure pain sensitivity and pain intensity in women with CTS. Neither manual therapy nor surgery resulted in changes in thermal pain sensitivity.

SIGNIFICANCE

The current study found that manual therapy and surgery exhibited similar effects on decreasing widespread pressure pain sensitivity and pain intensity in women with carpal tunnel syndrome at medium- and long-term follow-ups investigating changes in nociceptive gain processing after treatment in carpal tunnel syndrome.

Association between pain sensitivity in the hand and outcomes after surgery in patients with lumbar disc herniation or spinal stenosis

PURPOSE

To investigate the association between pain sensitivity in the hand pre-surgery, and patient-reported outcomes (PROs) in function, pain and health pre- and post-surgery in patients with disc herniation or spinal stenosis.

METHODS

This is a prospective cohort study with 82 patients. Associations between pressure-, cold- and heat pain threshold (PPT, CPT, HPT) in the hand pre-surgery and Oswestry, VAS pain, EQ-5D, HADS, and Self-Efficacy Scale, pre- and three months post-surgery; were investigated with linear regression.

RESULTS

Patients with disc herniation more sensitive to pressure pain pre-surgery showed lower function and self-efficacy, and higher anxiety and depression pre-surgery, and lower function, and self-efficacy, and higher pain post-surgery. Results for cold pain were similar. In patients with spinal stenosis few associations with PROs were found and none for HPT and PROs.

CONCLUSIONS

Altered pain response in pressure- and cold pain in the hand, as a sign of widespread pain pre-surgery had associations with higher pain, lower function and self-efficacy post-surgery in patients with disc herniation.

Effect of lumbar spinal manipulation on local and remote pressure pain threshold and pinprick sensitivity in asymptomatic individuals: a randomised trial

BACKGROUND

The mechanisms of clinical pain relief associated with spinal manipulative therapy (SMT) are poorly understood. Our objective was to determine whether lumbar high-velocity low-amplitude SMT altered pressure pain threshold (PPT) and pinprick sensitivity (PPS) locally and remotely, how long any change lasted (up to 30 min), and whether changes related to the side of SMT.

METHODS

Thirty-four asymptomatic participants (mean age 22.6 years ±4.0) received a right- or left-sided lumbar SMT. PPT and PPS were measured bilaterally at the calf, lumbar spine, scapula, and forehead before and immediately, 10, 20, and 30 min after intervention. Data were collected between October 2014 and June 2015.

RESULTS

Bilateral calf and lumbar spine PPT increased significantly after 10 - 20 min and was maintained at 30 min (7.2-11.8 % increase). PPS decreased significantly in all locations at various times (9.8 - 22.5 % decrease). At the calf and lumbar spine, PPT increased slightly more ipsilateral to the SMT than contralateral.

CONCLUSIONS

Lumbar SMT reduced deep pressure sensitivity locally and in the lower limbs for at least 30 min, whereas sensitivity to pinprick was reduced systemically. These findings suggest that SMT specifically inhibits deep pressure sensitivity distally. These findings are novel compared to other lumbar SMT studies, and may reflect a local spinal or complex supraspinal analgesic mechanism.

TRIAL REGISTRATION

Registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000682640).

Pressure and cold pain threshold reference values in a large, young adult, pain-free population

Background and aims

Currently there is a lack of large population studies that have investigated pain sensitivity distributions in healthy pain free people. The aims of this study were: (1) to provide sex-specific reference values of pressure and cold pain thresholds in young pain-free adults; (2) to examine the association of potential correlates of pain sensitivity with pain threshold values.

Methods

This study investigated sex specific pressure and cold pain threshold estimates for young pain free adults aged 21–24 years. A cross-sectional design was utilised using participants (n =617) from the Western Australian Pregnancy Cohort (Raine) Study at the 22-year follow-up. The association of site, sex, height, weight, smoking, health related quality oflife, psychological measures and activity with pain threshold values was examined. Pressure pain threshold (lumbar spine, tibialis anterior, neck and dorsal wrist) and cold pain threshold (dorsal wrist) were assessed using standardised quantitative sensory testing protocols.

Results

Reference values for pressure pain threshold (four body sites) stratified by sex and site, and cold pain threshold (dorsal wrist) stratified by sex are provided. Statistically significant, independent correlates of increased pressure pain sensitivity measures were site (neck, dorsal wrist), sex (female), higher waist-hip ratio and poorer mental health. Statistically significant, independent correlates of increased cold pain sensitivity measures were, sex (female), poorer mental health and smoking.

Conclusions

These data provide the most comprehensive and robust sex specific reference values for pressure pain threshold specific to four body sites and cold pain threshold at the dorsal wrist for young adults aged 21–24 years. Establishing normative values in this young age group is important given that the transition from adolescence to adulthood is a critical temporal period during which trajectories for persistent pain can be established.

Implications

These data will provide an important research resource to enable more accurate profiling and interpretation of pain sensitivity in clinical pain disorders in young adults. The robust and comprehensive data can assist interpretation of future clinical pain studies and provide further insight into the complex associations of pain sensitivity that can be used in future research.

Psychophysical and Patient Factors as Determinants of Pain, Function and Health Status in Shoulder Disorders

Objective:

To estimate the extent to which psychophysical quantitative sensory test (QST) and patient factors (gender, age and comorbidity) predict pain, function and health status in people with shoulder disorders. To determine if there are gender differences for QST measures in current perception threshold (CPT), vibration threshold (VT) and pressure pain (PP) threshold and tolerance.

Design:

A cross-sectional study design.

Setting:

MacHAND Clinical Research Lab at McMaster University.

Subjects:

34 surgical and 10 nonsurgical participants with shoulder pain were recruited.

Method:

Participants completed the following patient reported outcomes: pain (Numeric Pain Rating, Pain Catastrophizing Scale, Shoulder Pain and Disability Index) and health status (Short Form-12). Participants completed QST at 4 standardized locations and then an upper extremity performance-based endurance test (FIT-HaNSA). Pearson r’s were computed to determine the relationships between QST variables and patient factors with either pain, function or health status. Eight regression models were built to analysis QST’s and patient factors separately as predictors of either pain, function or health status. An independent sample t-test was done to evaluate the gender effect on QST.

Results:

Greater PP threshold and PP tolerance was significantly correlated with higher shoulder functional performance on the FIT-HANSA (r =0.31-0.44) and lower self-reported shoulder disability (r = -0.32 to -0.36). Higher comorbidity was consistently correlated (r =0.31-0.46) with more pain, and less function and health status. Older age was correlated to more pain intensity and less function (r =0.31-0.57). In multivariate models, patient factors contributed significantly to pain, function or health status models (r² =0.19-0.36); whereas QST did not. QST was significantly different between males and females [in PP threshold (3.9 vs. 6.2, p < .001) and PP tolerance (7.6 vs. 2.6, p < .001) and CPT (1.6 vs. 2.3, p =.02)].

Conclusion:

Psychophysical dimensions and patient factors (gender, age and comorbidity) affect self-reported and performance-based outcome measures in people with shoulder disorders.

Improvement of sensory function after sequestrectomy for lumbar disc herniation: a prospective clinical study using quantitative sensory testing

BACKGROUND

Previous studies have investigated sensory recovery in patients with lumbar disc herniation using rather subjective methods. There have been no reports on changes of sensory function in patients suffering from a preoperative sensory deficit using quantitative sensory testing (QST). The aims of this prospective study were (1) to assess the recovery of preoperative sensory dysfunction after lumbar sequestrectomy and (2) to quantify the strength of relationship between a sensory deficit and the patient's quality of life.

METHODS

We applied the QST protocol of the German Research Network on Neuropathic Pain (DFNS) in fifty-two patients with a single lumbar disc herniation confirmed on MRI treated by lumbar sequestrectomy. Further evaluation included a detailed medical history, a physical examination, numeric rating scale for leg, EQ-5D questionnaire, and thermometer.

RESULTS

Disc surgery resulted in a significant reduction of leg pain and a significant gain of quality of life. Thermal, mechanical, and vibration perception thresholds showed an obvious side-to-side difference preoperatively (p < 0.005). An early recovery of mechanical and vibration perception thresholds was detected, whereas cold perception needed more than 6 months to recover (p < 0.05). Quality of life was independent from perception thresholds, but correlated significantly with pain reduction.

CONCLUSION

Our data clearly show that there is a subjective and quantifiable improvement in sensory dysfunction postoperatively. The current data suggest that a sensory dysfunction does not influence a patient's quality of life.

Prognostic value of quantitative sensory testing in low back pain: a systematic review of the literature

Quantitative sensory testing (QST) measures have recently been shown to predict outcomes in various musculoskeletal and pain conditions. The aim of this systematic review was to summarize the emerging body of evidence investigating the prognostic value of QST measures in people with low back pain (LBP). The protocol for this review was prospectively registered on the International Prospective Register of Systematic Reviews. An electronic search of six databases was conducted from inception to October 2015. Experts in the field were contacted to retrieve additional unpublished data. Studies were included if they were prospective longitudinal in design, assessed at least one QST measure in people with LBP, assessed LBP status at follow-up, and reported the association of QST data with LBP status at follow-up. Statistical pooling of results was not possible due to heterogeneity between studies. Of 6,408 references screened after duplicates removed, three studies were finally included. None of them reported a significant association between the QST measures assessed and the LBP outcome. Three areas at high risk of bias were identified which potentially compromise the validity of these results. Due to the paucity of available studies and the methodological shortcomings identified, it remains unknown whether QST measures are predictive of outcome in LBP.

Clinical Ratings of Pain Sensitivity Correlate With Quantitative Measures in People With Chronic Neck Pain and Healthy Controls: Cross-Sectional Study

BACKGROUND

Correlations between clinical and quantitative measures of pain sensitivity are poor, making it difficult for clinicians to detect people with pain sensitivity. Clinical detection of pain sensitivity is important because these people have a different prognosis and may require different treatment.

OBJECTIVE

The purpose of this study was to investigate the relationship between clinical and quantitative measures of pain sensitivity across individuals with and without neck pain.

METHODS

This cross-sectional study included 40 participants with chronic neck pain and 40 age- and sex-matched controls. Participants underwent quantitative sensory testing of cold pain thresholds (CPTs) and pressure pain thresholds (PPTs). Clinical tests for pain sensitivity were the ice pain test and the pressure pain test. All tests were undertaken at standardized local (neck and upper trapezius muscles) and remote (wrist and tibialis anterior muscles) sites. Median and interquartile range (IQR) were calculated for neck pain and control groups, and parametric and nonparametric tests were used to compare groups. Correlation coefficients were calculated between quantitative and clinical measures.

RESULTS

There were significant differences for clinical and quantitative measures of cold and pressure sensitivity between the neck pain and control groups (eg, CPT neck pain group: median=22.31°C, IQR=18.58°C; control group: median=5.0°C, IQR=0.74°C). Moderate-to-good correlations were found between the clinical ice pain test and CPT at all sites (.46 to .68) except at the wrist (.29 to .40). Fair correlations were found for the clinical pressure pain test and PPT (-.26 to -.45). Psychological variables contributing to quantitative measures of pain sensitivity included catastrophization, sleep quality, and female sex.

LIMITATIONS

Clinical pressure pain tests were not quantitatively standardized in this study.

CONCLUSIONS

The ice pain test may be useful as a clinical correlate of CPT at all sites except the wrist, whereas the pressure pain test is less convincing as a clinical correlate of PPT.

Quantitative sensory testing in pain management

Quantitative sensory testing (QST), a set of noninvasive methods used to assess sensory and pain perception, has been used for three decades. The precision of the instruments and the uninvasiveness encouraged many QST-based trials. The developments made have benefited multiple disciplines. QST relies on analysis of an individual's response to external stimuli, reflecting the integrity of the PNS and the sensory pathway. The sensory pathway cannot be assessed in isolation from the affective and cognitive characteristics of patients or testers. Many variables potentially affect the reliability and reproducibility of QST, which after all, is designed for the testing of individuals by other individuals. Several decades of QST research have yielded exciting contributions, but the future of QST cannot be fully known.

Cross friction algometry (CFA): Comparison of pressure pain thresholds between patients with chronic non-specific low back pain and healthy subjects

Palpation is widely used to assess muscular sensitivity in clinical settings but still remains a subjective evaluation. This cross-sectional study assessed a newly developed cross-friction algometry making palpation measurable. The objective was to investigate the reliability of pressure pain thresholds obtained using Cross-Friction Algometry (CFA-PPTs) measured at the level of Erector spinae and Gluteus maximus central muscle parts, and to compare the CFA-PPTs between patients with chronic nonspecific low back pain (nCLBP) and matching healthy subjects.

PARTICIPANTS

Patients presenting nCLBP to GP's and send into a Pain Center and healthy subjects recruited via university ad valvas & flyers distribution.

OUTCOME MEASURES

30 patients with nCLBP were measured for cross-friction algometry. Other evaluations consisted of the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI).

RESULTS

The inter- and intra-reliability were tested and found to be sufficient. The mean CFA-PPT values of the Erector spinae at levels T8, T10, L1 & L3 and the Gluteus maximus of the nCLBP group were significantly lower (p ≤ 0.001) when compared to the CFA-PPT values of the healthy group. The greatest difference (-58%) was found at L1 Erector spinae level and at the superior part of the Gluteus maximus measuring point (-59%). Within the group of patients with nCLBP it was surprising to notice that there was no significant correlation between all the reference points measured using CFA-PPTs and the outcomes of the VAS and ODI scores.

CONCLUSIONS

With the aid of CFA, the importance of local muscular disorder in the lumbar part of the Erector spinae and Gluteus maximus in patients with nCLBP is obviously demonstrated, but also reveals the very large inter-individual differences in muscular fibrosis sensitivity and/or pain behavior in daily life. This possibly re-opens the debate on which influences can be put forward as the most important: the central or the peripheral sensitization system.

Pain sensitization in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis examined the evidence for pain sensitization in people with knee OA and the relationship between pain sensitization and symptom severity.

METHODS

A search of electronic databases and reference lists was carried out. All full text observational studies published between 2000 and 2014 with the aim of investigating pain sensitization in humans with knee OA using quantitative sensory testing (QST) measures of hyperalgesia and central hyperexcitability were eligible for inclusion. Meta-analysis of data was carried out using a random effects model, which included results comparing knee OA participants to controls, and results comparing high symptom severity to low symptom severity.

RESULTS

Fifteen studies were identified following screening and quality appraisal. For the meta-analysis, pressure pain threshold (PPT) and heat pain threshold (HPT) means and standard deviations were pooled using random effects models. The point estimate was large for differences in PPTs between knee OA participants and controls [-0.85; confidence interval (CI): -1.1 to -0.6], and moderate for PPT differences between knee OA participants with high symptom severity vs those with low symptom severity (0.51; CI: -0.73 to -0.30). A small point estimate was found for differences in HPTs between knee OA participants and controls (-0.42; CI: -0.87 to 0.02).

CONCLUSION

Evidence from this systematic review and meta-analysis suggests that pain sensitization is present in people with knee OA and may be associated with knee OA symptom severity.

The comparative effects of spinal and peripheral thrust manipulation and exercise on pain sensitivity and the relation to clinical outcome: a mechanistic trial using a shoulder pain model

STUDY DESIGN

Single-blind randomized trial.

OBJECTIVES

To compare the effects of cervical and shoulder thrust manipulation (TM) and exercise on pain sensitivity, and to explore associations with clinical outcomes in patients with shoulder pain.

BACKGROUND

Experimental studies indicate that spinal TM has an influence on central pain processes, supporting its application for treatment of extremity conditions. Direct comparison of spinal and peripheral TM on pain sensitivity has not been widely examined.

METHODS

Seventy-eight participants with shoulder pain (36 female; mean ± SD age, 39.0 ± 14.5 years) were randomized to receive 3 treatments of cervical TM (n = 26), shoulder TM (n = 27), or shoulder exercise (n = 25) over 2 weeks. Twenty-five healthy participants (13 female; mean ± SD age, 35.2 ± 11.1 years) were assessed to compare pain sensitivity with that in clinical participants at baseline. Primary outcomes were changes in local (eg, shoulder) and remote (eg, tibialis anterior) pressure pain threshold and heat pain threshold occurring over 2 weeks. Secondary outcomes were shoulder pain intensity and patient-rated function at 4, 8, and 12 weeks. Analysis-of-variance models and partial-correlation analyses were conducted to examine comparative effects and the relationship between measures.

RESULTS

At baseline, clinical participants demonstrated lower local (mean difference, - 1.63 kg; 95% confidence interval [CI]: -2.40, -0.86) and remote pressure pain threshold (mean difference, -1.96 kg; 95% CI: -3.09, -0.82) and heat pain threshold (mean difference, -1.15°C; 95% CI: -2.06, -0.24) compared to controls, suggesting enhanced pain sensitivity. Following intervention, there were no between-group differences in pain sensitivity or clinical outcome (P>.05). However, improvements were noted, regardless of intervention, for pressure pain threshold (range of mean differences, 0.22-0.32 kg; 95% CI: 0.03, 0.43), heat pain threshold (range of mean differences, 0.30-0.58; 95% CI: 0.06, 0.96), pain intensity (range of mean differences, -1.79 to -1.45; 95% CI: -2.34, -0.94), and function (range of mean differences, 3.15-3.82; 95% CI: 0.69, 6.20) at all time points. We did not find an association between pain sensitivity changes and clinical outcome (P>.05). Conclusion Clinical participants showed enhanced pain sensitivity, but did not respond differently to cervical or peripheral TM. In fact, in this sample, cervical TM, shoulder TM, and shoulder exercise had similar pain sensitivity and clinical effects. The lack of association between pain sensitivity and clinical pain and function outcomes suggests different (eg, nonspecific) pain pathways for clinical benefit following TM or exercise.

LEVEL OF EVIDENCE

Therapy, level 1b.

Investigating dynamic pain sensitivity in the context of the fear-avoidance model

BACKGROUND

Although nearly everyone at some point in their lives experiences back pain; the amount of interference with routine activity varies significantly. The fear-avoidance (FA) model of chronic pain explains how psychological variables, such as fear, act as mediating factors influencing the relationship between clinical pain intensity and the amount of interference with daily activities. What remains less clear is how other mediating factors fit within this model. The primary objective of this report was to examine the extent to which a dynamic measure of pain sensitivity provides additional information within the context of the FA model.

METHOD

To address our primary objective, classic mediation and moderated mediation analyses were conducted on baseline clinical, psychological and quantitative sensory measures obtained on 67 subjects with back pain (mean age, 31.4 ± 12.1 years; 70% female).

RESULTS

There was a moderately strong relationship (r = 0.52; p < 0.01) between clinical pain intensity and interference, explaining about 27% of the variance in the outcome. Mediation analyses confirmed fear partially mediated the total effect of clinical pain intensity on interference (Δβ = 0.27; p < 0.01), and accounted for an additional 16% of the variance. In our FA model, pain sensitivity did not demonstrate additional indirect effects; however, it did moderate the strength of indirect effects of fear.

CONCLUSION

This preliminary modelling suggests complex interactions exist between pain-related fear and pain sensitivity measures that further explain individual differences in behaviour.

Movement restriction does not modulate sensory and perceptual effects of exercise-induced arm pain

BACKGROUND

Movement restriction has been proposed as an important modulator of changes in sensory and perceptual function and motor imagery performance that are observed in musculoskeletal pain syndromes. There are no empirical data to support this view.

PURPOSE

The primary objective of this experiment was to determine the effects of movement restriction on local and widespread sensory, perceptual and motor imagery changes after exercise-induced muscular pain. Further objectives were to investigate whether changes in sensory perception are correlated with pain intensity and tactile acuity or motor imagery performance.

METHODS

In forty healthy volunteers, delayed onset muscle soreness (DOMS) of the non-dominant elbow flexors was induced using eccentric contractions until exhaustion. Participants were then randomised into two groups: a movement restriction group (wearing a sling) or a control group (not wearing a sling). Sensory and perceptual functions were measured using a range of sensory tests and a motor imagery performance task (left/right limb judgements).

RESULTS

Movement restriction did not modulate any of the measures. We found concurrent mechanical hypoesthesia (p < 0.01), reduced tactile acuity (p = 0.02) and pressure hyperalgesia (p < 0.01) at the painful side. We found evidence of widespread pressure hyperalgesia. Impaired tactile acuity was associated with a decrease in pain threshold to pressure (r = -0.34, p = 0.03). Motor imagery performance was unchanged (p > 0.35) by pain or movement restriction.

CONCLUSION

Short-term movement restriction did not influence local and widespread sensory changes induced by experimentally induced muscular pain.

The effect of pressure pain sensitivity and patient factors on self-reported pain-disability in patients with chronic neck pain

The study was conducted to estimate the extent to which pressure pain sensitivity (PPS) and patient factors predict pain-related disability in patients with neck pain (NP), and to determine if PPS differs by gender. Forty-four participants with a moderate level of chronic NP were recruited for this cross sectional study. All participants were asked to complete self-reported assessments of pain, disability and comorbidity and then underwent PPS testing at 4-selected body locations. Pearson`s r w was computed to explore relationships between the PPS measures and the self-reported assessments. Regression models were built to identify predictors of pain and disability. An independent sample t-test was done to identify gender-related differences in PPS, pain-disability and comorbidity. In this study, greater PPS (threshold and tolerance) was significantly correlated to lower pain-disability (r = -.30 to -.53, p≤0.05). Age was not correlated with pain or disability but comorbidity was (r= 0.42-.43, p≤0.01). PPS at the 4-selected body locations was able to explain neck disability (R²=25-28%). Comorbidity was the strongest predictor of neck disability (R² =30%) and pain (R²=25%). Significant mean differences for gender were found in PPS, disability and comorbidity, but not in pain intensity or rating. This study suggests that PPS may play a role in outcome measures of pain and disability but between-subject comparisons should consider gender and comorbidity issues.

Suprathreshold heat pain response predicts activity-related pain, but not rest-related pain, in an exercise-induced injury model

Exercise-induced injury models are advantageous for studying pain since the onset of pain is controlled and both pre-injury and post-injury factors can be utilized as explanatory variables or predictors. In these studies, rest-related pain is often considered the primary dependent variable or outcome, as opposed to a measure of activity-related pain. Additionally, few studies include pain sensitivity measures as predictors. In this study, we examined the influence of pre-injury and post-injury factors, including pain sensitivity, for induced rest and activity-related pain following exercise induced muscle injury. The overall goal of this investigation was to determine if there were convergent or divergent predictors of rest and activity-related pain. One hundred forty-three participants provided demographic, psychological, and pain sensitivity information and underwent a standard fatigue trial of resistance exercise to induce injury of the dominant shoulder. Pain at rest and during active and resisted shoulder motion were measured at 48- and 96-hours post-injury. Separate hierarchical models were generated for assessing the influence of pre-injury and post-injury factors on 48- and 96-hour rest-related and activity-related pain. Overall, we did not find a universal predictor of pain across all models. However, pre-injury and post-injury suprathreshold heat pain response (SHPR), a pain sensitivity measure, was a consistent predictor of activity-related pain, even after controlling for known psychological factors. These results suggest there is differential prediction of pain. A measure of pain sensitivity such as SHPR appears more influential for activity-related pain, but not rest-related pain, and may reflect different underlying processes involved during pain appraisal.

Pain sensitivity subgroups in individuals with spine pain: potential relevance to short-term clinical outcome

BACKGROUND

Cluster analysis can be used to identify individuals similar in profile based on response to multiple pain sensitivity measures. There are limited investigations into how empirically derived pain sensitivity subgroups influence clinical outcomes for individuals with spine pain.

OBJECTIVE

The purposes of this study were: (1) to investigate empirically derived subgroups based on pressure and thermal pain sensitivity in individuals with spine pain and (2) to examine subgroup influence on 2-week clinical pain intensity and disability outcomes.

DESIGN

A secondary analysis of data from 2 randomized trials was conducted.

METHODS

Baseline and 2-week outcome data from 157 participants with low back pain (n=110) and neck pain (n=47) were examined. Participants completed demographic, psychological, and clinical information and were assessed using pain sensitivity protocols, including pressure (suprathreshold pressure pain) and thermal pain sensitivity (thermal heat threshold and tolerance, suprathreshold heat pain, temporal summation). A hierarchical agglomerative cluster analysis was used to create subgroups based on pain sensitivity responses. Differences in data for baseline variables, clinical pain intensity, and disability were examined.

RESULTS

Three pain sensitivity cluster groups were derived: low pain sensitivity, high thermal static sensitivity, and high pressure and thermal dynamic sensitivity. There were differences in the proportion of individuals meeting a 30% change in pain intensity, where fewer individuals within the high pressure and thermal dynamic sensitivity group (adjusted odds ratio=0.3; 95% confidence interval=0.1, 0.8) achieved successful outcomes.

LIMITATIONS

Only 2-week outcomes are reported.

CONCLUSIONS

Distinct pain sensitivity cluster groups for individuals with spine pain were identified, with the high pressure and thermal dynamic sensitivity group showing worse clinical outcome for pain intensity. Future studies should aim to confirm these findings.

Can quantitative sensory testing move us closer to mechanism-based pain management?

OBJECTIVE

This review summarizes the scientific literature relating to the use of quantitative sensory testing (QST) for mechanism-based pain management.

DESIGN

A literature search was undertaken using PubMed and search terms including quantitative sensory testing, pain, chronic pain, response to treatment, outcome measure.

SETTINGS AND PATIENTS

Studies including QST in healthy individuals and those with painful disorders were reviewed.

MEASURES

Publications reported on QST methodological issues including associations among measures and reliability. We also included publications on the use of QST measures in case-control studies, their associations with biopsychosocial mechanisms, QST measures predicting clinical pain, as well as predicting and reflecting treatment responses.

RESULTS

Although evidence suggests that QST may be useful in a mechanism-based classification of pain, there are gaps in our current understanding that need to be addressed including making QST more applicable in clinical settings. There is a need for developing shorter QST protocols that are clinically predictive of various pain subtypes and treatment responses without requiring expensive equipment. Future studies are needed, examining the clinical predictive value of QST including sensitivity and specificity for pain classification or outcome prediction. These findings could enable third-party payers' reimbursement, which would facilitate clinical implementation of QST.

CONCLUSIONS

With some developments, QST could become a cost-effective and clinically useful component of pain assessment and diagnosis, which can further our progress toward the goal of mechanism-based personalized pain management.