The Clinical Journal of Pain

Investigating the Causal Mechanisms of Symptom Recovery in Chronic Whiplash-associated Disorders Using Bayesian Networks Objectives: The present study's objective was to understand the causal mechanisms underpinning the recovery of individuals with whiplash-associated disorders (WAD). We applied Bayesian Networks (BN) to answer 2 study aims: (1) to identify the causal mechanism(s) of recovery underpinning neck-specific exercise (NSE), and (2) quantify if the cyclical pathway of the fear-avoidance model (FAM) is supported by the present data. Materials and Methods: We analyzed a prospective cohort data set of 216 individuals with chronic WAD. Fifteen variables were used to build a BN model: treatment group (NSE with or without a behavioral approach, or general physical activity), muscle endurance, range of motion, hand strength, neck proprioception, pain catastrophizing, fear, anxiety, depression, self-efficacy, perceived work ability, disability, pain intensity, sex, and follow-up time. Results: The BN model showed that neck pain reduction rate was greater after NSE compared with physical activity prescription (β=0.59 points per month [P<0.001]) only in the presence of 2 mediators: global neck muscle endurance and perceived work ability. We also found the following pathway of variables that constituted the FAM: anxiety, followed by depressive symptoms, fear, catastrophizing, self-efficacy, and consequently pain. Conclusions: We uncovered 2 mediators that explained the mechanisms of effect behind NSE, and proposed an alternative FAM pathway. The present study is the first to apply BN modelling to understand the causal mechanisms of recovery in WAD. In doing so, it is anticipated that such analytical methods could increase the precision of treatment of individuals with chronic WAD.

Comparing Novel and Existing Measures of Sensitivity to Physical Activity Among People With Chronic Musculoskeletal Pain: The Importance of Tailoring Activity to Pain Objectives: Increasing pain during physical activity is an important, but often poorly assessed, barrier to engaging in activity-based rehabilitation among people with chronic musculoskeletal pain. Preliminary work has addressed this problem by developing new clinical measures of sensitivity to physical activity (SPA). Indices of SPA are generated by evaluating how pain changes in relation to brief physical tasks. Three strategies have been identified for structuring SPA-related physical tasks (self-paced, standardized, and tailored). This cross-sectional study aimed to comparatively estimate the extent of the 3 SPA tasks' evoked pain responses, predictive value of pain severity and pain interference, and their underlying psychological and sensory constructs, among 116 adults with chronic musculoskeletal pain. Materials and Methods: Testing included questionnaires, quantitative sensory testing, and the 3 SPA measures (self-paced, standardized, and tailored). The primary analysis estimated the predictive value of each SPA measure for pain severity and pain interference. Correlational analyses were first conducted between all variables of interest to determine what variables will be included in the hierarchical regression analysis, which in turn was conducted for each outcome. Results: Analyses revealed that the tailored SPA index was most effective at evoking activity-related pain, was uniquely associated with temporal summation of pain, and was a unique predictor of pain and pain-related interference, even when controlling for established psychological and sensory risk factors. Discussion: This study further emphasizes SPA as an important and unique attribute of the pain experience and reveals the added value of using a tailored approach to assess SPA.

Deficient Inhibitory Endogenous Pain Modulation Correlates With Periaqueductal Gray Matter Metabolites During Chronic Whiplash Injury Objectives: This study examined predictive correlations between periaqueductal gray (PAG) and anterior cingulate cortex (ACC) metabolite levels with deficient inhibitory endogenous pain modulation (EPM), including sensory and affective measures of pain during chronic whiplash injury (WHI). Materials and Methods: Healthy patients, and participants with chronic WHI, without (WHI-noP) or with pain (WHI-P), were screened with the Douleur Neuropathique 4 tool (DN4). EPM was assessed with C6 tonic heat pain stimuli with a Conditioned Pain Modulation (CPM) protocol. Magnetic resonance spectroscopy quantified ACC and PAG metabolite levels. Results: WHI-P participants were characterized with high pain intensity and interference, and lower quality of life scores, compared with WHI-noP. Inhibitory CPM at 30 seconds was identified in the healthy noninjured (−45±16%; P<0.001) and WHI-noP groups (−36±8%; P<0.001). However, inhibitory EPM was not detected in the WHI-P group (−25±15%; P=0.06). Best fit and stepwise multiple regression revealed that the PAG glutamate/myoinositol metabolite ratio (P=0.01) and total creatine levels (P=0.02) predicted loss of EPM in the WHI-P group (r2=0.71, α=0.97). Although myoinositol predicted loss of EPM in the ACC (P=0.04), this was below statistical power (r2=0.31; α=0.56). The ACC N-acetyl-aspartate/myoinositol ratio (P=0.006) predicted chronic pain (DN4, r2=0.53; α=0.87). Discussion: The results of this study demonstrate deficient EPM at 30 seconds during tonic heat pain stimulation in WHI-P participants, compared with noninjured healthy volunteers or individuals with WHI-noP. In addition, quantification of PAG and ACC metabolites related to glutamate and glia predicted central chronic pain mechanisms related to loss of inhibitory EPM, while ACC metabolites characterized chronic pain described by descriptors and sensory changes.

Trajectories of Pain Intensity Over 1 Year in Adults With Disabling Subacute or Chronic Neck Pain Objectives: The objectives of this study were to describe the 1-year trajectories of disabling subacute or persistent neck pain and to investigate whether baseline age, sex, pain characteristics, and depressive symptoms are associated with such trajectories. Study Design and Setting: Participants (n=617) included in a randomized controlled trial provided weekly pain intensity ratings by responding to text messages over 1 year. We used latent class mixed model analyses to identify clusters of individual trajectories. Thereafter, we used logistic regression to determine the association between baseline age, sex, pain characteristics, depressive symptoms and treatment, and trajectories of neck pain. Results: Six different clusters of trajectories were identified. Most participants (73%) followed a trajectory of decreasing pain throughout follow-up. The remaining experienced unfavorable trajectories: persistent pain of high intensity (22%) and slightly (3%) or highly (2%) fluctuating levels of pain reaching high levels of pain intensity. Pain intensity at baseline: odds ratio (OR): 3.76 (95% confidence interval [CI]: 2.49-5.68), depressive symptoms: OR: 3.46 (95% CI: 2.01-5.95), younger age: OR: 2.29 (95% CI: 1.48-3.54), female sex: OR: 1.51 (95% CI: 1.01-2.26), and sudden onset of pain: OR: 1.74 (95% CI: 1.13-2.69) were associated with unfavorable trajectories. Conclusions: Most individuals with disabling subacute or chronic neck pain show improvement in pain intensity over a year. However, a quarter present unfavorable trajectories. High pain intensity at baseline, depressive symptoms, younger age, female sex, and sudden onset of pain are factors associated with unfavorable trajectories.

Patient-controlled Analgesia For Vaso-Occlusive Crisis: A Cohort Study Background: Sickle cell disease (SCD) accounts for over 68,000 hospital admissions each year in the United States, with long inpatient length of stays (LOS) and frequent readmission common. Patient-controlled analgesia (PCA) has been used to treat patients admitted with vaso-occlusive crisis (VOC), but it is unknown if PCA is associated with shorter LOS and reduced risk of readmission. Methods: We examined all admissions for acute VOC treated with parenteral opioids to an urban, academic health system over 3 years. We compared LOS, 30-day readmission, and discharges against medical advice between admissions treated with PCA versus standard therapy in unadjusted and adjusted analyses using generalized estimating equations to adjust for demographic and clinical characteristics. Results: Of 823 admissions included, 536 (65.1%) were treated with PCA and 287 (34.9%) were treated with standard nurse-administered opioid therapy. Treatment with PCA was associated with significantly shorter LOS in the unadjusted analyses (7.46 vs. 9.42 d, P=0.001), but the difference was not significant after adjustment (adjusted difference: 1.47 d, P=0.06). Treatment with PCA was also associated with significantly decreased risk of 30-day readmission in unadjusted analysis (odds ratio [OR]unadj: 0.69; 95% confidence interval [CI]: 0.54-0.89, P=0.004), but after adjustment the association was no longer significant (ORadj: 0.76; 95% CI: 0.54-1.06, P=0.11). Finally, treatment with PCA was not associated with increased risk of discharge against medical advice in Generalized Estimating Equation modeled unadjusted (ORunadj: 1.10; 95% CI: 0.69-1.76, P=0.68), or adjusted analysis (ORadj: 1.19; 95% CI: 0.73-1.94, P=0.49). Conclusions: Treatment with PCA may be associated with shorter LOS and may be considered as the primary modality for opioid-based pain control for patients with SCD who are admitted with painful VOC.

Remifentanil for Procedural Sedation and Analgesia in Central Venous Catheter Insertion: A Randomized, Controlled Trial Objective: Central venous catheter (CVC) insertion is a common practice for anesthetists, but this invasive procedure generates anxiety and pain in patients that are often underestimated. We compared target-controlled infusion of remifentanil and local lidocaine infiltration with placebo and local lidocaine infiltration to decrease pain scores during CVC placement. Materials and Methods: We included conscious, adult patients without contraindication to remifentanil or lidocaine. We excluded pregnant women, emergency situations, and opioid abuse. Patients requiring CVC were randomly assigned, using computer-generated allocation numbers stored in sealed envelopes, to receive target-controlled infusion of remifentanil or placebo—all patients received local anesthesia with lidocaine. All patients were hospitalized in a recovery room or intensive care unit, monitored, and received 4 L/min of oxygen. The primary outcome was global pain (Verbal Numeric Rating Pain Scale) during the procedure. Secondary outcomes were pain perceived at every stage of the procedure, anxiety, patient satisfaction, operational ease, and side effects. Results: In this double-blind study, we included 90 patients (split into 2 groups of 45 patients). Global pain was significantly reduced in the remifentanil group: 20 of 100 (95% confidence interval, 16-40) versus 50 of 100 (95% confidence interval, 40-60) in the placebo group; P=0.0009. No major adverse events were observed during this study, and there were no significant differences between both groups regarding side effects. Discussion: Target-controlled infusion of remifentanil is an effective drug to reduce pain during CVC insertion in association with lidocaine-based local anesthesia, in conscious patients.

Parental Report of Self and Child Worry During Acute Pain: A Critical Factor in Determining Parental Pain Judgment Objective: The objective of this study was to determine which variables predict parental postvaccination pain ratings. It was hypothesized that after child behavior, parental sensitivity, and parental reports of worry would be the strongest predictors. Methods: Data for 215 parent-child dyads were analyzed from a longitudinal cohort at the preschool (4 to 5 y of age) vaccination. Preschoolers' pain behaviors 15 seconds, 1 minute 15 seconds, and 2 minutes 15 seconds after the painful immunization were observed and rated. Parental sensitivity, as well as parental own worry and their assessment of their child's worry, were assessed before and after the needle. Three regression models were used to determine the impact of these variables on parental pain assessment. Results: Preschoolers' pain behaviors moderately accounted for variance in parental pain judgment (R2=0.23 to 0.28). Parental sensitivity was not a significant unique predictor of parental pain rating at the preschool age. Parental assessment of their own worry and worry about their preschoolers after the needle were critical contributors to parental pain judgment. Post hoc analyses suggest that parents who report low child worry, are more congruent with their child during regulatory phases postvaccination. However, both parents with high and low self-worry had more congruent pain ratings with child pain behavior scores during the reactivity phase. Discussion: The study suggests that the majority of variance in parent pain ratings was not predominantly based on preschoolers' pain behaviors. Parental worry levels and their assessment of their child's worry were also significant predictors. Clinical implications are discussed.

The Impact of Psychological Interventions on Posttraumatic Stress Disorder and Pain Symptoms: A Systematic Review and Meta-Analysis Objectives: Posttraumatic stress disorder (PTSD) and pain often co-occur, introducing clinical challenges and economic burden. Psychological treatments are considered effective for each condition, yet it is not known which therapies have the potential to concurrently address PTSD and pain-related symptoms. Materials and Methods: To conduct a systematic review and meta-analysis, databases were searched for articles published between January 2007 and December 2017 describing results from clinical trials of interventions addressing PTSD and pain-related symptoms in adults. Two independent reviewers finalized data extraction and risk of bias assessments. A random-effects model was used for meta-analysis and to calculate pooled and subgroup effect sizes (ESs) of psychological-only (single modality) and multimodal interventions. Results: Eighteen trials (7 uncontrolled, 11 randomized controlled trials, RCTs), totaling 1583 participants, were included in the systematic review. RCT intervention types included exposure-based, cognitive-behavioral, and mindfulness-based therapies. Data from 10 RCTs (N=1, 35) were available for meta-analysis, which demonstrated moderate effect for reduced PTSD severity (ES=−0.55, confidence interval [CI]: −0.83, −0.26) and nonsignificant effect for pain intensity (ES=−0.14, CI: −0.43, 0.15) and pain interference (ES=−0.07, CI: −0.35, 0.20) outcomes. Findings from uncontrolled trials supported meta-analytic results from RCTs. Using GRADE assessment, the quality of evidence was deemed as moderate for RCTs and low for non-RCTs. Discussion: Findings indicated that the majority of the interventions appeared to have a greater impact on reducing PTSD rather than pain-related symptoms. There remains a need to further develop interventions that consistently impact PTSD and pain-related outcomes when these 2 conditions co-occur.

The Validity of Skin Conductance For Assessing Acute Pain in Infants: A Scoping Review Objectives: Measuring pain in infants is important but challenging, as there is no "gold standard." The measurement of skin conductance (SC) is considered to be a measure of stress and as a surrogate indicator of pain. The objectives of this study were to identify the extent of research conducted and to synthesize the validity evidence of SC for assessing acute pain in infants. Methods: The Arksey and O'Malley framework for scoping reviews was followed, and 9 electronic databases were searched. Data were analyzed thematically and presented descriptively including the following main categories: study information/details, sampling information, characteristics of participants and settings, SC outcome measures, and validity evidence. Results: Twenty-eight studies with 1061 infants were included, including 23 cross-sectional observation studies and 5 interventional studies. The most studied infants were those with mild severity of illness (n=13) or healthy infants (n=12). The validity evidence of SC was tested in relation to referent pain measures (13 variables), stimuli (13 variables), age (2 variables), and other contextual variables (11 variables). SC was not significantly correlated with vital signs, except for heart rate in 2 of the 8 studies. SC was significantly correlated with the unidimensional behavioral pain assessment scales and crying time rather than with multidimensional measurements. Fourteen of 15 studies (93.3%) showed that SC increased significantly during painful procedures. Conclusions: Inconsistent findings on validity of SC exist. Future research should aim to identify the diagnostic test accuracy of SC compared with well-accepted referent pain measures in infants, study the validity evidence of SC in critically ill infants, and utilize rigorous research design and transparent reporting.

Presurgical Comorbidities as Risk Factors For Chronic Postsurgical Pain Following Total Knee Replacement: More Details, More Significance No abstract available

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com