Evidence of impaired pain modulation in adolescents with idiopathic scoliosis and chronic back pain

Pelvic rotation correction combined with Schroth exercises for pelvic and spinal deformities in mild adolescent idiopathic scoliosis: A randomized controlled trial

INTRODUCTION

Individualized treatment of spinal deformity is needed for adolescent idiopathic scoliosis (AIS), and the integration of pelvic rotation correction based on proprioceptive neuromuscular facilitation (PNF) into regular physiotherapy may be a promising approach. However, few high-quality studies have investigated its effects. This study aimed to evaluate the efficacy of pelvic rotation correction combined with Schroth exercises in the treatment of mild AIS.

METHODS

This was a randomized controlled trial. Forty-two AIS patients were randomly divided into experimental and control groups. Both groups underwent 20 therapeutic sessions over 24 weeks. All patients (n = 42) performed Schroth exercises at each session. In addition, the experimental group (n = 21) also participated in a pelvic rotation correction program based on PNF at each session. The primary outcome was the concave/convex ratio of hipbone widths, and the secondary outcomes included the Cobb angle, trunk rotation angle, self-perception, apical vertebral translation, and apical vertebral rotation. Patients were evaluated before and after 24 weeks of intervention.

RESULTS

There was a significant between-group difference in the change from baseline between the experimental and control groups for the following parameters: concave/convex ratio 2.89% (95% confidence interval [CI], 1.58 to 4.20, P<0.001), trunk rotation angle -1.26° (95% CI, -2.20 to -0.32; P = 0.01), and apical vertebral rotation improved by at least one class from baseline in 3 patients (14.3%) in the control group and 9 patients (42.9%) in the experimental group (P = 0.04). While Cobb angle -1.60° (95% CI, -7.75 to 0.54; P = 0.14), self-image 0.149 (95% CI, 0.001 to 0.297; P = 0.049), apical vertebral translation -0.58 mm (95% CI, -3.83 to 2.67; P = 0.72), and pelvic obliquity 0.10° (95% CI, -0.21 to 0.41; P = 0.52) did not differ significantly.

CONCLUSIONS

Pelvic rotation correction combined with Schroth exercises more effectively improved pelvic axial rotation and other spinal deformities, including trunk rotation and apical vertebral rotation, than Schroth exercises alone in the treatment of mild AIS.

Incidence and risk factors of distal adjacent disc degeneration in adolescent idiopathic scoliosis patients undergoing fusion surgery: a systematic review and meta-analysis

PURPOSE

The objective of this meta-analysis was to determine the incidence of disc degeneration in patients with surgically treated adolescent idiopathic scoliosis (AIS) and identify the associated risk factors.

METHODS

PubMed, EMBASE, Scopus, and Cochrane Collaboration Library databases were searched. The outcomes of interest were the incidence of disc degeneration, SRS-22, and radiological risk factors. The lower instrumented vertebra (LIV) was also evaluated. Fixed effects were used if there was no evidence of heterogeneity. Statistical analysis was performed using Review Manager.

RESULTS

A meta-analysis was conducted including nine studies with a total of 565 patients. The analysis revealed that the global incidence of intervertebral disc degeneration in patients with surgically treated AIS patients was 24.78% (95% CI 16.59-32.98%) 10 years after surgery, which significantly increased to 32.32% (95% CI 21.16-43.47% at an average of 13.8 years after surgery. Among patients with significant degenerative disc changes, the SRS-22 functional, self-image, and satisfaction domains showed significantly worse results (MD - 0.25, 95% CI - 0.44 to - 0.05; MD - 0.50, 95% CI - 0.75 to - 0.25; and MD - 0.34, 95% CI - 0.66 to - 0.03, respectively). Furthermore, instrumentation at or above the L3 level was associated with a lower incidence of intervertebral disc degeneration compared to instrumentation below the L3 level (OR 0.25, 95% CI 0.10-0.64). It was also found that the preoperative and final follow-up lumbar curve magnitudes (MD 8.11, 95% CI 3.82-12.41) as well as preoperative and final follow-up lumbar lordosis (MD 0.42, 95% CI - 3.81 to 4.65) were associated with adjacent disc degeneration.

CONCLUSIONS

This meta-analysis demonstrated that the incidence of intervertebral disc degeneration significantly increased with long-term follow-up using fusion techniques, reaching up to 32% when patients were 28 years of age. Incomplete correction of deformity and fusion of levels below L3, were identified as negative prognostic factors. Furthermore, patients with disc degeneration showed worse functional outcomes.

Subgrouping of facilitatory or inhibitory conditioned pain modulation responses in patients with chronic knee pain. Explorative analysis from a multicentre trial

BACKGROUND

Facilitatory and inhibitory conditioned pain modulation (CPM) responses are observed in healthy volunteers and chronic pain patients, but the clinical implications for phenotyping are unknown. This study aimed to subgroup and compare chronic knee pain patients according to their CPM responses.

METHODS

This explorative, cross-sectional study included 127 patients with chronic knee pain (osteoarthritis or following total knee arthroplasty). Individual CPM responses were categorized as facilitatory (test stimuli pain intensity increased when conditioning stimuli were applied), as inhibitory (test stimuli pain intensity decreased) or as no change (defined as less than 5.3% change in pain intensity). Outcomes were clinical pain intensities, temporal summation, widespread pain, self-reported physical function, PainDETECT questionnaire and Pain Quality Assessment Scale. Data were analysed as comparisons between the inhibitory and the facilitatory groups and using multivariate linear regression models.

RESULTS

Fifty-four patients had facilitatory CPM responses, 49 had inhibitory CPM responses, and 24 showed no change in CPM response. A between-group difference was observed for self-reported physical function, with the facilitatory CPM group reporting better function (54.4 vs. 46.0, p = 0.028) and the facilitatory CPM group reported more deep pain sensations (3.2 vs. 2.0, p = 0.021). The remaining outcomes showed no between-group differences. Higher clinical pain intensity and facilitated temporal summation were associated in the facilitated CPM group but not in the inhibitory CPM group.

CONCLUSION

These explorative findings indicated that quantitative clinical and experimental differences exist between facilitatory or inhibitory CPM responses in a chronic knee pain patient population. Differences in patients' CPM responses should be further investigated to unravel possible clinical importance.

SIGNIFICANCE

Our findings confirm that conditioned pain modulation consist of inhibitory and facilitatory responders among a patient population with chronic knee pain. This explorative study indicates that patients with either facilitatory or inhibitory conditioned pain modulation could exhibit differences in pain outcomes. Subgrouping of chronic pain patients depending on individual conditioned pain modulation responses could be considered in phenotyping patients prior to inclusion in clinical trials or used for personalizing the management regime.

Sensitivity and Specificity of a Neuropathic Screening Tool (Self-Report Leeds Assessment of Neuropathic Symptoms and Signs, S-LANSS) in Adolescents With Moderate-Severe Chronic Pain

Neuropathic screening tools improve recognition of neuropathic pain in adults. Although utilized in pediatric populations, the sensitivity, specificity and methodology of screening tool delivery have not been compared in children. We evaluated the Self-Report Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) in adolescents (10-18 years) referred to a tertiary pediatric pain clinic. History and examination by specialist clinicians and multidisciplinary assessment informed classification of the primary pain type. In a prospective cohort, scores were obtained at interview (S-LANSS interview; n = 161, 70% female), and following substitution of self-reported signs with examination findings in the primary pain region (Leeds Assessment of Neuropathic Symptoms and Signs, LANSS examination). Secondly, we retrospectively retrieved questionnaires self-completed by adolescents at their initial clinic appointment (S-LANSS self-completed; n = 456, 73% female). Thirdly, we explored relationships between patient-reported outcomes and S-LANSS scores. S-LANSS interview scores varied with pain classification, and S-LANSS self-completed scores were similarly highest with neuropathic pain (median [interquartile range]: 18 [11, 21]) and complex regional pain syndrome (21 [14, 24]), variable with musculoskeletal pain (13 [7, 19]) and lowest with visceral pain (6.5 [2, 11.5]) and headache (8.5 [4, 14]). As in adults, the cutpoint score of 12/24 was optimal. Sensitivity was highest with inclusion of examination findings and lowest with self-completion (LANSS examination vs S-LANSS interview vs S-LANSS self-completed: 86.3% vs 80.8% vs 74.7%), but specificity was relatively low (37.8% vs 36.7% vs 48%). High S-LANSS scores in non-neuropathic groups were associated with female sex and high pain catastrophizing. The S-LANSS is a sensitive screening tool for pain with neuropathic features in adolescents, but needs to be interpreted in the context of clinical evaluation (clinicaltrials.gov NCT03312881). PERSPECTIVE: This article reports high sensitivity of the S-LANSS screening tool for identifying pain with neuropathic features in adolescents with moderate-severe chronic pain. However, as sensitivity is lower than in adult populations, further interdisciplinary evaluation is necessary to inform diagnosis and management.

Pain during the first year after scoliosis surgery in adolescents, an exploratory, prospective cohort study

Objective

Approximately 50% of adolescents who have undergone scoliosis surgery still experience severe pain one year postoperatively. We explored the postoperative pain trajectory and the potential value of preoperative Thermal Quantitative Sensory Testing (T-QST) as predictor of chronic postsurgical pain after scoliosis surgery.

Design

Single-center prospective cohort study in adolescents undergoing scoliosis surgery.

Outcomes

Prevalence of chronic postsurgical pain (CPSP) one year after scoliosis surgery and postsurgical pain course during this year. The need for rescue medication and the relationship between pre-operative T-QST, acute pain and CPSP.

Results

Thirty-nine patients (mean age 13.9 years; SD 1.9 years) completed the study. One year postoperatively, ten patients (26%) self-reported pain [numeric rating scale (NRS) score ≥ 4]) when moving and two (5%) when in rest. Four of these patients (10.3%) experienced neuropathic pain. The pre-operative cold pain threshold was lower (p = 0.002) in patients with CPSP at 12 months. Preoperative cold and heat pain thresholds were correlated with the number of moderate or severe pain reports (NRS ≥ 4) in the first week postoperatively (r -.426; p = 0.009 and r.392; p = 0.016, respectively).

Conclusions

One year after scoliosis surgery, a significant part of patients (26%) still reported pain, some with neuropathic characteristics. Better diagnosis and treatment is needed; our study suggests that T-QST could be further explored to better understand and treat children with this negative outcome.

Pain history and experimental pressure pain responses in adolescents: Results from a population-based birth cohort

BACKGROUND

Sensitized pain mechanisms are often reported in musculoskeletal pain conditions, but population-based paediatric studies are lacking. We assessed whether adolescents with musculoskeletal pain history had evidence of increased responsiveness to experimental pressure stimuli.

METHODS

Data were from 1496 adolescents of the Generation XXI birth cohort. Pain history was collected using the Luebeck Pain Questionnaire (self-reported at 13, parent-reported at 7 and 10 years). Two case definitions for musculoskeletal pain were considered: (1) cross-sectional-musculoskeletal pain lasting more than 3 months at age 13 and (2) longitudinal-musculoskeletal pain at age 13 with musculoskeletal pain reports at ages 7 and/or 10. Lower limb cuff pressure algometry was used to assess pain detection and tolerance thresholds, conditioned pain modulation effects (CPM, changes in thresholds in the presence on painful conditioning) and temporal summation of pain effects (TSP, changes in pain intensity to 10 phasic painful cuff stimulations).

RESULTS

Adolescents with musculoskeletal pain at age 13 plus a history of pain in previous evaluations (longitudinal definition) had lower pain tolerance thresholds compared to the remaining sample (40.2 v. 49.0 kPa, p = 0.02), but showed no differences in pain detection threshold, CPM effect and TSP effect. Pain sensitivity, CPM effects and TSP effects were not significantly different when the current pain only case definition (cross-sectional) was used.

CONCLUSIONS

Adolescents with current musculoskeletal pain who had a history of pain since childhood had lower tolerance to cuff stimulation. This may suggest long-standing musculoskeletal pain since childhood may contribute to sensitisation, rather than the presence of current pain only.

SIGNIFICANCE

Repeated musculoskeletal pain up to age 13 years may contribute to higher pain sensitivity (particularly lowered pressure pain tolerance) in the general adolescent population. This does not seem to be the case when reported pain experiences are recent or when the outcomes are temporal pain summation or CPM. In this community-based paediatric sample, the vast majority showed no sign of altered pain processing, but a small fraction may reveal some pain sensitization at 13 years of age.

Pain Experience and Sensory Changes in Astronauts During and After Short-Lasting Commercial Spaceflight: A Proof-of-Concept Study

Space travel has been associated with musculoskeletal pain, yet little is known about the nociceptive changes and pain experience during spaceflight. This preliminary study aims to investigate the pain experience and sensory alterations in astronauts following a 17-day mission to the International Space Station (ISS) on Axiom Space's AX-1 commercial space flight. Two participants were enrolled, and data were collected pre-flight, in-flight, post-flight, and three-month post-flight. Validated pain questionnaires assessed anxiety, catastrophizing, impact on physical and mental health, disability, and overall pain experience. Qualitative interviews were conducted post-landing and conditioned pain modulation (CPM) and quantitative sensory testing (QST) were performed. Both astronauts reported musculoskeletal pain during and after the flight, which was managed with anti-inflammatories and stretching techniques. Pain levels returned to baseline after three months. Pain questionnaires revealed heightened pain experiences in-flight and immediately post-flight, although their adequacy in assessing pain in space is uncertain. Qualitative interviews allowed astronauts to describe their pain experiences during the flight. Sensory changes included increased mechanical touch detection thresholds, temporal pain summation, heat pain thresholds, and differences in conditioned pain modulation post-flight. This preliminary study suggested that spaceflight may affect various aspects of sensory perception and regulation in astronauts, albeit in a variable manner. More data are needed to gain insight of on gain and loss of sensory functions during space missions. Further investigation into the multifactorial stressors affecting the somatosensory system during space travel could contribute to advancements in space and pain medicine.

Proprioception-related gene mutations in relation to the aetiopathogenesis of idiopathic scoliosis: A scoping review

Since idiopathic scoliosis is a multifactorial disorder, the proprioceptive defect is considered one of its etiological factors. Genetic studies have separately revealed this relationship, yet it remains indeterminate which specific genes that related to proprioception contributed to the initiation, progression, pathology, and treatment outcomes of the curvature. A systematic search was conducted on four online databases, including PubMed, Web of Science, Embase, and Academic search complete. Studies were included if they involved human or animal subjects with idiopathic scoliosis and evaluated with proprioceptive genes. The search period was the inception of the database to February 21, 2023. Four genes (i.e., Ladybird homeobox 1 [LBX1], Piezo type mechanosensitive ion channel component 2 [PIEZO2], Runx family transcription factor 3 [RUNX3], and neurotrophin 3 [NTF3]) investigated in 19 studies were included. LBX1 has confirmed the correlation with the development of idiopathic scoliosis in 10 ethnicities, whereas PIEZO2 has shown a connection with clinical proprioceptive tests in subjects with idiopathic scoliosis. However, curve severity was less likely to be related to the proprioceptive genes. The potential pathology took place at the proprioceptive neurons. Evidence of proprioception-related gene mutations in association with idiopathic scoliosis was established. Nevertheless, the causation between the initiation, progression, and treatment outcomes with proprioceptive defect requires further investigation.

Impact of mental health components on the development of back pain in young adults with adolescent idiopathic scoliosis

BACKGROUND

Back pain occurs commonly in adults and is multifactorial in nature. This study aimed to assess the prevalence and intensity of back pain during young adulthood in subjects with adolescent idiopathic scoliosis (AIS), as well as factors that may be associated with its prognosis.

METHODS

Subjects with AIS aged 20-39 treated conservatively were included in this study. Patient-reported outcome measures in adulthood involved episodes of back pain, and scales of self-image, depression, anxiety, and stress. Additionally, pain, self-image, and mental health scores were retrieved at the first clinic consultation. Occurrence of back pain was defined as a numeric pain rating scale ≥ 6.

RESULTS

101 participants were enrolled. The prevalence of back pain in the lifetime, past 12 months, past 6 months, past 1 month, past 7 days, and past 24 h were 37%, 35%, 31%, 27%, 23%, and 20%, respectively. Male, self-image, and depression were significant associated factors for the development of back pain at all time points. Furthermore, the analyses of the initial presentation of participants have shown that participants with back pain in adulthood were characterised by poor self-image and mental health during their adolescence.

CONCLUSION

The present study addressed the natural history of back pain in young adults with conservatively treated AIS. Psychological makeup has been shown to constitute the development of back pain and is strongly hinted as an early sign of having back pain in adulthood among subjects with AIS.

Novel Interdisciplinary Enhanced Recovery after Surgery Protocol Implementation in Paediatric Orthopaedics

The enhanced recovery after surgery (ERAS) protocol is not routine management in paediatric orthopaedics. Cultural differences or assumptions about the financing of medical care in different countries encourage creative adaptation of general assumptions in local communities. The aim of this study was to compare the quality of the perioperative period before and after the introduction of an interdisciplinary protocol adopted to organisational conditions. A group of 4098 children were included in the "before-after" observational study. The data of 1553 patients (BEFORE group) were analysed in terms of compliance with the enhanced recovery after surgery protocol guidelines and the time and cost of hospitalisation over a 20-month period. A novel interdisciplinary protocol was developed, including an education and training app called BackOnFeet (BOF®), standardised hospital management, and the introduction of methods novel to Poland (intraoperative nerve cryoanalgesia in children). A further 2545 patients (AFTER group) were reassessed over a period of 20 months. It was found that the groups differed in hospitalisation time (p < 0.001), type of procedures, and percentage ratio of costs incurred to revenue generated. The usefulness of the BOF® app as an effective educational tool was demonstrated. The optimisation of perioperative management in paediatric orthopaedics based on novel tools and the interdisciplinary ERAS protocol is possible and brings tangible benefits in psychological, organisational, and financial terms.

Feasibility and reliability of a quantitative sensory testing protocol in youth with acute musculoskeletal pain postsurgery or postinjury

ABSTRACT

Quantitative sensory testing (QST) is increasingly used in pediatric chronic pain; however, assessment in youth with acute musculoskeletal (MSK) pain is limited. This study evaluated the feasibility, reliability, and sources of variability of a brief QST protocol in 2 clinical samples of youth with acute MSK pain. Participants were 277 youth (M age = 14.5 years, SD = 2.0, range = 11-18 years, 59% female, 81% non-Hispanic) across 3 geographic study sites who completed a QST protocol assessing pressure and thermal pain sensitivity, temporal summation of pain, and conditioned pain modulation 8 weeks after MSK surgery (n = 100) or within 4 weeks after an acute MSK injury (n = 177). High feasibility was demonstrated by protocol completion rates ranging from 97.5% to 100% for each task, with 95.3% of youth completing all tasks. Reliability was high, with reliability coefficients of >0.97 for 7 out of 8 QST parameters and minimal influence of examiner or participating site effects. Younger youth had lower pressure and heat pain thresholds (11-12 vs 13-18 years, d = -0.80 to -0.56) and cold pain tolerance (d = -0.33). Hispanic youth had higher pressure and heat pain thresholds (d = 0.37-0.45) and pain ratings for cold pain tolerance (d = 0.54) compared with non-Hispanic youth. No significant differences were observed in QST values by sex or personal contextual factors at the time of assessment (momentary pain, menstrual period, use of pain medications). Overall findings demonstrate feasibility of a brief QST protocol with youth with diverse acute MSK pain and data provide initial support for the reliability of this QST protocol for multisite research studies.

Back pain in adolescent idiopathic scoliosis: A comprehensive review

Purpose

Adolescent idiopathic scoliosis (AIS) is a common spinal deformity that affects millions of children worldwide. A variety of treatment algorithms exist for patients based on radiographic parameters such as the Cobb angle and the Risser stage. However, there has been a growing focus on nonradiographic outcomes such as back pain, which can cause functional disability and reduced quality of life for patients. In spite of this, back pain in AIS is poorly characterized in the literature. We aimed to summarize various factors that may influence back pain in AIS and the impact of different treatment methods on pain reduction.

Methods

A comprehensive systematic review was undertaken using the PubMed and Cochrane database. Keywords that were utilized and combined with "Adolescent Idiopathic Scoliosis" included, "back pain," "treatment," "biomechanics," "biochemistry," "epidemiology," and "biopsychosocial." The literature was subsequently evaluated and deemed relevant or not relevant for inclusion.

Results

A total of 93 articles were ultimately included in this review. A variety of contradictory literature was present for all sections related to epidemiology, underlying biomechanics and biochemistry, biopsychosocial factors, and treatment methodologies.

Conclusion

Back pain in AIS is common but remains difficult to predict and treat. The literature pertaining to causative factors and treatment options is heterogeneous and inconclusive. Longer-term prospective studies combining biopsychosocial intervention in conjunction with existing curve correction techniques would be meaningful.

Axial rotation and pain are associated with facet joint osteoarthritis in Adolescent Idiopathic Scoliosis

OBJECTIVE

Facet joints are crucial for spinal stability and develop premature osteoarthritis in patients with adolescent idiopathic scoliosis (AIS). Here, we evaluated the association between facet joint cartilage and subchondral bone homeostasis, perceived back pain and 3-dimensional spinal deformity to understand better the role of facet joint degeneration in AIS progression and pain.

METHOD

Cartilage and bone osteoarthritic states of AIS facet joint surgical samples were characterized using histological OARSI scoring, visual morphological grading and μCT analysis, respectively. Back pain was self-reported using a numerical rating scale and expressed relative to the location on the patient's back. The scoliotic curves from our patient cohort were digitally reconstructed using biplanar radiographs and the eOS system (EOS imaging). The deformity was then reduced to 3 intervertebral angles (coronal, sagittal and axial) for each pair of bilateral facet joints. Statistical associations between the intervertebral angles, osteoarthritis parameters and pain intensity were performed using the Spearman method and Friedman test.

RESULTS

Facet joint cartilage degeneration was associated with decreased subchondral bone volume and quality. Most importantly, asymmetrical, and overall degeneration of facet joints was strongly correlated to intervertebral axial rotation. Additionally, kyphotic intervertebral segments in the sagittal plane were good predictors of increased facet joint degeneration and back pain.

CONCLUSION

Facet joint degeneration is associated with axial deformity, kyphotic intervertebral angle and back pain intensity in AIS. These results suggest that facet joints are important features to consider for rotational instability in AIS spines and related disease progression and perceived back pain.

Pilot Investigation of Somatosensory Functioning and Pain Catastrophizing in Pediatric Spinal Fusion Surgery

PURPOSE

Chronic post-surgical pain (CPSP) is a significant concern and contributes to the opioid epidemic; however, little is known about CPSP in young people.

DESIGN

This prospective study aimed to identify sensory, psychological, and demographic factors that may increase the risk of CPSP after spinal fusion surgery for children and adolescents with idiopathic scoliosis.

METHODS

32 children and adolescents from two children's hospitals completed quantitative sensory testing (QST) and the Pain Catastrophizing Scale Child (PCS-C) pre-and 4-6 months post spinal fusion surgery. Between-group differences were assessed using an independent samples t-test. Pearson's correlations and stepwise linear regression were used to assess the relationship between variables at both time points.

RESULTS

56% of patients endorsed pain post-surgery. They were more sensitive tomechanical detection on both a control non-pain site (r = -2.87, p = .004) and the back (r = -1.83, p = .04), as well as pressure pain (r=-2.37, p = .01) on the back. This group also reported worse pain scores pre-surgery. Pre-surgery helplessness positively correlated with preoperative pain (r = .67 p < .001), and age was negatively correlated with the post-surgical catastrophizing total score (r =-.39, p = .05), suggesting that younger patients endorsed more pain-related worry after surgery.

CONCLUSIONS

Patients who present with pain during their preoperative appointment may need to be monitored with increased vigilance throughout the perioperative period, possibly with bedside QST and psychological questionnaires, which nurses could administer. Biobehavioral interventions targeting pain intensity and feelings of helplessness and anxiety during the preoperative period may alleviate the transition to CPSP.

The complexities of the sleep-pain relationship in adolescents: A critical review

Chronic pain is a common and disabling condition in adolescents. Disturbed sleep is associated with many detrimental effects in adolescents with acute and chronic pain. While sleep and pain are known to share a reciprocal relationship, the sleep-pain relationship in adolescence warrants further contextualization within normally occurring maturation of several biopsychological processes. Since sleep and pain disorders begin to emerge in early adolescence and are often comorbid, there is a need for a comprehensive picture of their interrelation especially related to temporal relationships and mechanistic drivers. While existing reviews provide a solid foundation for the interaction between disturbed sleep and pain in youth, we will extend this review by highlighting current methodological challenges for both sleep and pain assessments, exploring the recent evidence for directionality in the sleep-pain relationship, reviewing potential mechanisms and factors underlying the relationship, and providing direction for future investigations. We will also highlight the potential role of digital technologies in advancing the understanding of the sleep and pain relationship. Ultimately, we anticipate this information will facilitate further research and inform the management of pain and poor sleep, which will ultimately improve the quality of life in adolescents and reduce the risk of pain persisting into adulthood.

Clusters of facilitatory and inhibitory conditioned pain modulation responses in a large sample of children, adolescents, and young adults with chronic pain

Supplemental Digital Content is Available in the Text.

Findings from the current study add to the literature by describing different clinical phenotypes of central pain mechanisms of youth with chronic pain.

Introduction:

When investigating the role of facilitatory and inhibitory pain mechanisms such as conditioned pain modulation (CPM) and temporal summation of pain (TSP), it is important to take both into consideration in a single experimental model to provide the most information on subgroups of patients. Therefore, the objective of this study was to identify subgroups in a large population of pediatric patients with chronic pain based on their facilitatory and inhibitory pain mechanisms and compare them with control subjects.

Methods:

Five hundred twenty-one female subjects and 147 male subjects between 8 and 21 years old underwent a CPM assessment using a 2-minute tonic noxious heat stimulation as the test stimulus and a 2-minute cold-pressor task (CPT) (12°C) as the conditioning stimulus.

Results:

The best partition of clusters of patients was 3 clusters accounting for 27.15% of the total variation in the data. Cluster 1 (n = 271) was best characterized by high pain intensity during the CPT, lack of TSP during the test stimuli, and efficient inhibitory CPM. Cluster 2 (n = 186) was best characterized by low pain intensity during the CPT, lack of TSP during the test stimuli, and efficient inhibitory CPM. Cluster 3 (n = 151) was best characterized by high pain intensity during the CPT, presence of TSP during the test stimuli, and inefficient inhibitory CPM.

Discussion:

A single thermal CPM experimental design can identify combinations of facilitatory and inhibitory pain modulation responses. Findings from the current study add to the literature by describing different clinical phenotypes of central pain mechanisms of youth with chronic pain.

Mechanism-Based Pharmacological Treatment for Chronic Non-cancer Pain in Adolescents: Current Approaches and Future Directions

Chronic non-cancer pain in pediatrics is a widespread phenomenon that affects about 20% of adolescents (10-19 years old). Although interdisciplinary pain treatment programs, which often include pharmacological treatment, have emerged as the standard of care in management of this patient population, evidence regarding an optimal treatment is lacking. The efficacy and safety profiles of pharmacological treatments used to help adolescents suffering from chronic non-cancer pain remain understudied. This lack of evidence may increase polypharmacy and the risk of drug interactions and adverse events. This review examines evidence for the use of pharmacological treatments prescribed to treat chronic pain in adolescents (10-19 years old), with a focus on mechanism-based pharmacology. The objectives of this review are to: (a) review the evidence for mechanism-based pharmacological treatments for chronic non-cancer pain in adolescents and (b) describe the pharmacological agents that are commonly prescribed to manage chronic pain in adolescents, including dosage information, mechanism, and potential adverse effects. Pharmacological treatments should be used carefully with adolescents, ideally within an interdisciplinary treatment program that will incorporate physical rehabilitation, integrative medicine/active mind-body techniques, psychology, and global efforts to normalize daily activities.

Accurate classification of pain experiences using wearable electroencephalography in adolescents with and without chronic musculoskeletal pain

Objective

We assessed the potential of using EEG to detect cold thermal pain in adolescents with and without chronic musculoskeletal pain.

Methods

Thirty-nine healthy controls (15.2 ± 2.1 years, 18 females) and 121 chronic pain participants (15.0 ± 2.0 years, 100 females, 85 experiencing pain ≥12-months) had 19-channel EEG recorded at rest and throughout a cold-pressor task (CPT). Permutation entropy, directed phase lag index, peak frequency, and binary graph theory features were calculated across 10-second EEG epochs (Healthy: 292 baseline / 273 CPT epochs; Pain: 1039 baseline / 755 CPT epochs). Support vector machine (SVM) and logistic regression models were trained to classify between baseline and CPT conditions separately for control and pain participants.

Results

SVM models significantly distinguished between baseline and CPT conditions in chronic pain (75.2% accuracy, 95% CI: 71.4%–77.1%; p < 0.0001) and control (74.8% accuracy, 95% CI: 66.3%–77.6%; p < 0.0001) participants. Logistic regression models performed similar to the SVM (Pain: 75.8% accuracy, 95% CI: 69.5%–76.6%, p < 0.0001; Controls: 72.0% accuracy, 95% CI: 64.5%–78.5%, p < 0.0001). Permutation entropy features in the theta frequency band were the largest contributor to model accuracy for both groups.

Conclusions

Our results demonstrate that subjective pain experiences can accurately be detected from electrophysiological data, and represent the first step towards the development of a point-of-care system to detect pain in the absence of self-report.

Association between the Use of Quantitative Sensory Testing and Conditioned Pain Modulation and the Prescription of Medication and Interventional Procedures in Children with Chronic Pain Conditions

The evidence supporting the use of pharmacological treatments in pediatric chronic pain is limited. Quantitative sensory testing (QST) and conditioned pain modulation evaluation (CPM) provide information on pain phenotype, which may help clinicians to tailor the treatment. This retrospective study aimed to evaluate the association between the use of QST/CPM phenotyping on the selection of the treatment for children with chronic pain conditions. We retrospectively analyzed the medical records of 208 female patients (mean age 15 ± 2 years) enrolled in an outpatient interdisciplinary pediatric complex pain center. Pain phenotype information (QST/CPM) of 106 patients was available to the prescribing physician. The records of 102 age- and sex-matched patients without QST/CPM were used as controls. The primary endpoint was the proportion of medications and interventions prescribed. The secondary endpoint was the duration of treatment. The QST/CPM group received less opioids (7% vs. 28%, respectively, p < 0.001), less anticonvulsants (6% vs. 25%, p < 0.001), and less interventional treatments (29% vs. 44%, p = 0.03) than controls. Patients with an optimal CPM result tended to be prescribed fewer antidepressants (2% vs. 18%, p = 0.01), and patients with signs of allodynia and/or temporal summation tended to be prescribed fewer NSAIDs (57% vs. 78%, p = 0.04). There was no difference in the duration of the treatments between the groups. QST/CPM testing appears to provide more targeted therapeutic options resulting in the overall drop in polypharmacy and reduced use of interventional treatments while remaining at least as effective as the standard of care.

Conditioned Pain Modulation in Children: The Effects of Painful and Nonpainful Conditioning Stimuli

Conditioned pain modulation (CPM), a psychophysical measure in which 1 pain stimulus (conditioning stimulus) is used to inhibit another pain stimulus (test stimulus), is an important indicator of endogenous pain inhibition in adults, but is understudied in children. Preliminary evidence suggests that CPM effects are present in healthy children and are more robust in adolescents. However, developmental differences in younger children are not well documented and few studies control for potential distraction effects of the conditioning stimulus (CS). Participants were 54 healthy children aged 6 to 12 years. After a baseline pressure pain threshold (PPT) test, participants underwent 2 conditioning trials in which PPT was assessed while they placed their left hand in a water bath maintained at either 12 °C (painful CS) or 22 °C (nonpainful sham CS) in counterbalanced order. Results revealed a significant CPM effect. PPT values were significantly higher relative to baseline during the painful CS trial; PPT during the nonpainful CS trial did not differ from baseline. There were no significant age differences in magnitude of CPM effect. The results indicate that children as young as 6 years of age demonstrate CPM, suggesting that descending inhibitory pathways may be better developed in young children than previously thought. PERSPECTIVE: This study was successful in producing inhibitory CPM effects in physically healthy children while controlling for sensory distraction. The findings provide strong evidence that the obtained CPM responses cannot be attributed to sensory distraction or other nonspecific effects. Future studies could utilize CPM paradigms to study various aspects of pediatric endogenous pain inhibition, in order to better predict pain responses and improve interventions.

Conditioned pain modulation is more efficient in patients with painful diabetic polyneuropathy than those with nonpainful diabetic polyneuropathy

ABSTRACT

Endogenous pain modulation, as tested by the conditioned pain modulation (CPM) protocol, is typically less efficient in patients with chronic pain compared with healthy controls. We aimed to assess whether CPM is less efficient in patients with painful diabetic polyneuropathy (DPN) compared with those with nonpainful DPN. Characterization of the differences in central pain processing between these 2 groups might provide a central nervous system explanation to the presence or absence of pain in diabetic neuropathy in addition to the peripheral one. Two hundred seventy-one patients with DPN underwent CPM testing and clinical assessment, including quantitative sensory testing. Two modalities of the test stimuli (heat and pressure) conditioned to cold noxious water were assessed and compared between patients with painful and nonpainful DPN. No significant difference was found between the groups for pressure pain CPM; however, patients with painful DPN demonstrated unexpectedly more efficient CPMHEAT (-7.4 ± 1.0 vs -2.3 ± 1.6; P = 0.008). Efficient CPMHEAT was associated with higher clinical pain experienced in the 24 hours before testing (r = -0.15; P = 0.029) and greater loss of mechanical sensation (r = -0.135; P = 0.042). Moreover, patients who had mechanical hypoesthesia demonstrated more efficient CPMHEAT (P = 0.005). More efficient CPM among patients with painful DPN might result from not only central changes in pain modulation but also from altered sensory messages coming from tested affected body sites. This calls for the use of intact sites for proper assessment of pain modulation in patients with neuropathy.

Clinical use of Electroencephalography in the Assessment of Acute Thermal Pain: A Narrative Review Based on Articles From 2009 to 2019

Nowadays, no practical system has successfully been able to decode and predict pain in clinical settings. The inability of some patients to verbally express their pain creates the need for a tool that could objectively assess pain in these individuals. Neuroimaging techniques combined with machine learning are seen as possible candidates for the identification of pain biomarkers. This review aimed to address the potential use of electroencephalographic features as predictors of acute experimental pain. Twenty-six studies using only thermal stimulations were identified using a PubMed and Scopus search. Combinations of the following terms were used: "EEG," "Electroencephalography," "Acute," "Pain," "Tonic," "Noxious," "Thermal," "Stimulation," "Brain," "Activity," "Cold," "Subjective," and "Perception." Results revealed that contact-heat-evoked potentials have been widely recorded over central areas during noxious heat stimulations. Furthermore, a decrease in alpha power over central regions was revealed, as well as increased theta and gamma powers over frontal areas. Gamma and theta rhythms were associated with connectivity between sensory and affective regions involved in pain processing. A machine learning analysis revealed that the gamma band is a predominant predictor of acute thermal pain. This review also addressed the need of supplementing current spectral features with techniques that allow the investigation of network dynamics.

Phenotyping Chronic Musculoskeletal Pain in Male and Female Adolescents: Psychosocial Profiles, Somatosensory Profiles and Pain Modulatory Profiles

Purpose

A major limitation in treatment outcomes for chronic pain is the heterogeneity of the population. Therefore, a personalized approach to the assessment and treatment of children and adolescents with chronic pain conditions is needed. The objective of the study was to subgroup pediatric patients with chronic MSK pain that will be phenotypically different from each other based on their psychosocial profile, somatosensory function, and pain modulation.

Patients and Methods

This observational cohort study recruited 302 adolescents (10–18 years) with chronic musculoskeletal pain and 80 age-matched controls. After validated self-report questionnaires on psychosocial factors were completed, quantitative sensory tests (QST) and conditioned pain modulation (CPM) were performed.

Results

Three psychosocial subgroups were identified: adaptive pain (n=125), high pain dysfunctional (n=115), high somatic symptoms (n=62). Based on QST, four somatosensory profiles were observed: normal QST (n=155), thermal hyperalgesia (n=98), mechanical hyperalgesia (n=34) and sensory loss (n=15). Based on CPM and temporal summation of pain (TSP), four distinct groups were formed, dysfunctional central processing group (n=27) had suboptimal CPM and present TSP, dysfunctional inhibition group (n=136) had suboptimal CPM and absent TSP, facilitation group (n=18) had optimal CPM and present TSP, and functional central processing (n=112) had optimal CPM and absent TSP. A significant association between the psychosocial and somatosensory profiles. However, no association was observed between the psychosocial or somatosensory profiles and pain modulatory profiles.

Conclusion

Our results provide evidence that adolescents with chronic musculoskeletal pain are a heterogenous population comprising subgroups that may reflect distinct mechanisms and may benefit from different treatment approaches. The combination of screening self-reported questionnaires, QST, and CPM facilitate subgrouping of adolescents with chronic MSK pain in the clinical context and may ultimately contribute to personalized therapy.

Psychosocial and psychophysical assessment in pediatric patients and young adults with chronic back pain: a cluster analysis

Background

Identifying subgroups with different clinical profiles may inform tailored management and improve outcomes. The objective of this study was to identify psychosocial and psychophysical profiles of children and adolescents with chronic back pain.

Methods

One hundred and ninety‐eight patients with chronic back pain were recruited for the study. Pain assessment was mainly conducted in the form of an interview and with the use of validated pain‐related questionnaires assessing their psychosocial factors and disability. All patients underwent mechanical and thermal quantitative sensory tests assessing detection and pain thresholds, and conditioned pain modulation efficacy.

Results

Hierarchal clustering partitioned our patients into three clusters accounting for 34.73% of the total variation of the data. The adaptive cluster represented 45.5% of the patients and was characterized to display high thermal and pressure pain thresholds. The high somatic symptoms cluster, representing 19.2% of patients, was characterized to use more sensory, affective, evaluative and temporal descriptors of pain, more likely to report their pain as neuropathic of nature, report a more functional disability, report symptoms of anxiety and depression and report poor sleep quality. The pain‐sensitive cluster, representing 35.4% of the cohort, displayed deep tissue sensitivity and thermal hyperalgesia.

Conclusions

This study identified clinical profiles of children and adolescents experiencing chronic back pain based on specific psychophysical and psychosocial characteristics highlighting that chronic pain treatment should address underlying nociceptive and non‐nociceptive mechanisms.

Significance

To our current knowledge, this study is the first to conduct cluster analysis with youth experiencing chronic back pain and displays clinical profiles based on specific physical and psychosocial characteristics. This study highlights that in a clinical context, chronic pain assessment should include multiple elements contributing to pain which can be assessed in a clinical context and addressed when pathoanatomical symptoms are unidentifiable.

Developmental Mechanisms of CPSP: Clinical Observations and Translational Laboratory Evaluations

Understanding mechanisms that underly the transition from acute to chronic pain and identifying potential targets for preventing or minimizing this progression have specific relevance for chronic postsurgical pain (CPSP). Though it is clear that multiple psychosocial, family, and environmental factors may influence CPSP, this review will focus on parallels between clinical observations and translational laboratory studies investigating the acute and long-term effects of surgical injury on nociceptive pathways. This includes data related to alterations in sensitivity at different points along nociceptive pathways from the periphery to the brain; age- and sex-dependent mechanisms underlying the transition from acute to persistent pain; potential targets for preventive interventions; and the impact of prior surgical injury. Ongoing preclinical studies evaluating age- and sex-dependent mechanisms will also inform comparative efficacy and preclinical safety assessments of potential preventive pharmacological interventions aimed at reducing the risk of CPSP. In future clinical studies, more detailed and longitudinal peri-operative phenotyping with patient- and parent-reported chronic pain core outcomes, alongside more specialized evaluations of somatosensory function, modulation, and circuitry, may enhance understanding of individual variability in postsurgical pain trajectories and improve recognition and management of CPSP.

The Relationship of Kinesiophobia with Pain and Quality of Life in Idiopathic Scoliosis

STUDY DESIGN

Prospective, multi-centric, cross-sectional study.

OBJECTIVE

To analyze the construct validity of the Tampa Scale of Kinesiophobia (TSK) in a cohort of patients with adolescent idiopathic scoliosis (AIS).

SUMMARY OF THE BACKGROUND DATA

Back pain is not uncommon in AIS. The fear of movement (kinesiophobia) in response to pain is related to back pain. TSK psychometric properties in AIS patients have not been properly analyzed.

METHODS

Patients with AIS and no prior spine surgery were prospectively included. They fulfilled the Spanish version of the TSK-11 questionnaire, a pain intensity numerical rating scale (NRS), refined SRS-22 (SRS-22r), the Hospital Anxiety and Depression Scale (HADS), and item 7 of the Core Outcome Measurement Index (COMI). The sample was split into two groups for the statistical analysis: adolescents and young adults. Cronbach alpha was used to assess internal consistency. Discriminant and concurrent validity were obtained by computing Pearson correlation coefficients between the TSK score and several criterion measures.

RESULTS

A total of 275 patients were included-198 adolescents (mean age of 14.6 yrs) and 77 young adults (mean age of 26.9 yrs). The Cobb of largest curve means were 44.9° and 48.9°, respectively. In the adolescent group, the TSK mean (±SD) was 21.5 (±5.93), with a floor effect of 2.5%. In the adult group, the TSK mean was 24.2 (±6.63), with a floor effect of 3.9%. The ceiling effect was 0% in both groups. Cronbach alphas for the adolescent and adult groups were 0.76 and 0.79, respectively. No correlation was found in any group between the TSK score and the curve magnitude or pattern (Lenke classification). The TSK was significantly correlated with HAD depression and SRS-22r in both groups. However, these correlations were weaker in adolescents. In adults, the TSK also significantly correlates with NRS and work/school absenteeism.

CONCLUSION

The Spanish version of TSK-11 is a reliable and valid instrument to analyze kinesiophobia in AIS. However, the weak correlation between kinesiophobia and pain intensity, disability, and emotional condition in adolescents requires further study.Level of Evidence: 4.

Assessment of pain associated with chronic pancreatitis: An international consensus guideline

Pain is the most common symptom in chronic pancreatitis (CP) with a major impact on quality of life. Few validated questionnaires to assess pain in CP exist, and the lack of consensus negatively impacts clinical management, research and meta-analysis. This guideline aims to review generic pain questionnaires for their usability in CP, to outline how pain assessment can be modified by confounding factors and pain types, to assess the value of additional measures such as quality of life, mental health and quantitative sensory testing, and finally to review pain assessment questionnaires used specifically in CP. A systematic review was done to answer 27 questions that followed the PICO (Population; Intervention; Comparator; Outcome) template. Quality of evidence of the statements was judged by Grades of Recommendation, Assessment, Development and Evaluation (GRADE) criteria. The manuscript was sent for review to 36 experts from various disciplines and continents in a multi-stage Delphi process, and finally reviewed by patient representatives. Main findings were that generic pain instruments are valid in most settings, but aspects of pain are specific for CP (including in children), and instruments have to account for the wide phenotypic variability and development of sensitization of the central nervous system. Side effects to treatment and placebo effects shall also be considered. Some multidimensional questionnaires are validated for CP and are recommended together with assessment of quality of life and psychiatric co-morbidities. This guideline will result in more homogeneous and comprehensive pain assessment to potentially improve management of painful CP.

Pain Catastrophizing Throughout the Perioperative Period in Adolescents With Idiopathic Scoliosis

OBJECTIVES

Pain catastrophizing in children and adolescents has been associated to unfavorable postsurgical outcomes. However, pain catastrophizing is rarely measured throughout the perioperative period. Using a prospective longitudinal approach, the present study aimed to identify how pain catastrophizing changes over the perioperative period in pediatric surgical patients with adolescent idiopathic scoliosis.

MATERIALS AND METHODS

Adolescent patients undergoing spinal fusion surgery completed the Pain Catastrophizing Scale for Children and additional questionnaires to assess pain intensity, state and trait anxiety, and kinesiophobia before surgery, and 1, 2, 5 days, 6 weeks, and 6 months after surgery.

RESULTS

Patients who had higher levels of pain catastrophizing before surgery were more likely to be anxious, avoid activity that may cause pain, report higher pain intensity before surgery and anticipate more pain after surgery. Low pain catastrophizers increased into a moderate level of pain catastrophizing before decreasing after discharge from the hospital. Meanwhile, moderate and high pain catastrophizers both decreased into lower and moderate levels of catastrophizing, respectively, after discharge from the hospital.

DISCUSSION

These findings demonstrate that pain catastrophizing in adolescents changes over the perioperative period. Observing changes in pain catastrophizing throughout the perioperative period may help in recognizing when patients are most vulnerable during this time. Decreasing pain catastrophizing before surgery or in the acute postoperative period through therapies that target pain catastrophizing may help reduce the patient's likelihood of experiencing unfavorable postoperative outcomes.

Phenotyping peripheral neuropathic pain in male and female adolescents: pain descriptors, somatosensory profiles, conditioned pain modulation, and child-parent reported disability

ABSTRACT

Neuropathic pain (NeuP) can be difficult to diagnose and manage in children. Data regarding prevalence and sex-dependent differences are limited, and more detailed phenotyping is needed. This observational cohort study recruited adolescents (10-17 years) with NeuP or complex regional pain syndrome (CRPS). After pain history and NeuP questionnaires, quantitative sensory testing was performed. Individual z-score plots were calculated with body-region control measures and matched to mechanism-related sensory profiles (sensory loss, thermal hyperalgesia, and mechanical hyperalgesia). Conditioned pain modulation was assessed with pressure pain threshold and a contralateral cold conditioning stimulus, and meaningful conditioned pain modulation defined as twice the standard error of measurement. Patients and parents completed validated questionnaires for child quality of life (QoL), pain catastrophizing, and self-reported anxiety/depression. Males (n = 23) and females (n = 43) with NeuP (n = 52) or CRPS (n = 14) reported moderate-severe pain with neuropathic sensory descriptors. Mixed patterns of sensory gain/loss at pain sites were not sex-dependent. Thermal hyperalgesia was common in both NeuP and CRPS, whereas sensory loss occurred only with NeuP and in a smaller proportion than adult cohorts. Conditioned pain modulation was inhibitory in 54%, facilitatory in 14%, and nonresponders had variable cold conditioning sensitivity. Males and females reported marked impairment of QoL, increased emotional distress, and pain catastrophising. Child-parent QoL scores correlated, but catastrophizing scores were discordant when parents or adolescents reported higher anxiety/depression. NeuP in adolescents is associated with significant pain, physical impairment, and psychosocial impairment. Quantifying alterations in somatosensory profiles, descending modulation, child and parent psychological function will inform individualized therapy and stratification for future clinical trials.

Methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system: a systematic review

ABSTRACT

Mechanism-based classification of pain has been advocated widely to aid tailoring of interventions for individuals experiencing persistent musculoskeletal pain. Three pain mechanism categories (PMCs) are defined by the International Association for the Study of Pain: nociceptive, neuropathic, and nociplastic pain. Discrimination between them remains challenging. This study aimed to build on a framework developed to converge the diverse literature of PMCs to systematically review methods purported to discriminate between them; synthesise and thematically analyse these methods to identify the convergence and divergence of opinion; and report validation, psychometric properties, and strengths/weaknesses of these methods. The search strategy identified articles discussing methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system. Studies that assessed the validity of methods to discriminate between categories were assessed for quality. Extraction and thematic analysis were undertaken on 184 articles. Data synthesis identified 200 methods in 5 themes: clinical examination, quantitative sensory testing, imaging, diagnostic and laboratory testing, and pain-type questionnaires. Few methods have been validated for discrimination between PMCs. There was general convergence but some disagreement regarding findings that discriminate between PMCs. A combination of features and methods, rather than a single method, was generally recommended to discriminate between PMCs. Two major limitations were identified: an overlap of findings of methods between categories due to mixed presentations and many methods considered discrimination between 2 PMCs but not others. The results of this review provide a foundation to refine methods to differentiate mechanisms for musculoskeletal pain.

Development and Validation of a Predictive Model of Pain Modulation Profile to Guide Chronic Pain Treatment: A Study Protocol

Introduction: Quantitative sensory testing is frequently used in research to assess endogenous pain modulation mechanisms, such as Temporal Summation (TS) and Conditioned Pain Modulation (CPM), reflecting excitatory and inhibitory mechanisms, respectively. Numerous studies found that a dysregulation of these mechanisms is associated with chronic pain conditions. In turn, such a patient's “profile” (increased TS and/or weakened CPM) could be used to recommend different pharmacological treatments. However, the procedure to evaluate these mechanisms is time-consuming and requires expensive equipment that is not available in the clinical setting. In this study, we aim to identify psychological, physiological and socio-demographic markers that could serve as proxies to allow healthcare professionals to identify these pain phenotypes in clinic, and consequently optimize pharmacological treatments.

Method: We aim to recruit a healthy participant cohort (n = 360) and a chronic pain patient cohort (n = 108). Independent variables will include psychological questionnaires, pain measurements, physiological measures and sociodemographic characteristics. Dependent variables will include TS and CPM, which will be measured using quantitative sensory testing in a single session. We will evaluate one prediction model and two validation models (for healthy and chronic pain participants) using multiple regression analysis between TS/CPM and our independent variables. The significance thresholds will be set at p = 0.05, respectively.

Perspectives: This study will allow us to develop a predictive model to compute the pain modulation profile of individual patients based on their biopsychosocial characteristics. The development of the predictive model is the first step toward the overarching goal of providing clinicians with a set of quick and cheap tests, easily applicable in clinical practice to orient pharmacological treatments.

Neuropathic pain in children: Steps towards improved recognition and management

Neuropathic pain in children can be severe and persistent, difficult to recognise and manage, and associated with significant pain-related disability. Recognition based on clinical history and sensory descriptors is challenging in young children, and screening tools require further validation at older ages. Confirmatory tests can identify the disease or lesion of the somatosensory nervous system resulting in neuropathic pain, but feasibility and interpretation may be influenced by age- and sex-dependent changes throughout development. Quantitative sensory testing identifies specific mechanism-related sensory profiles; brain imaging is a potential biomarker of alterations in central processing and modulation of both sensory and affective components of pain; and genetic analysis can reveal known and new causes of neuropathic pain. Alongside existing patient- and parent-reported outcome measures, somatosensory system research methodologies and validation of mechanism-based standardised end-points may inform individualised therapy and stratification for clinical trials that will improve evidence-based management of neuropathic pain in children.

Biopsychosocial Aspects in Individuals with Acute and Chronic Rotator Cuff Related Shoulder Pain: Classification Based on a Decision Tree Analysis

Biopsychosocial aspects seem to influence the clinical condition of rotator cuff related shoulder pain (RCRSP). However, traditional bivariate and linear analyses may not be sufficiently robust to capture the complex relationships among these aspects. This study determined which biopsychosocial aspects would better classify individuals with acute and chronic RCRSP and described how these aspects interact to create biopsychosocial phenotypes in individuals with acute and chronic RCRSP. Individuals with acute (<six months of pain, n = 15) and chronic (≥six months of pain, n = 38) RCRSP were included. Sociodemographic data, biological data related to general clinical health status, to shoulder clinical condition and to sensory function, and psychosocial data were collected. Outcomes were compared between groups and a decision tree was used to classify the individuals with acute and chronic RCRSP into different phenotypes hierarchically organized in nodes. Only conditioned pain modulation was different between the groups. However, the tree combined six biopsychosocial aspects to identify seven distinct phenotypes in individuals with RCRSP: three phenotypes of individuals with acute, and four with chronic RCRSP. While the majority of the individuals with chronic RCRSP have no other previous painful complaint besides the shoulder pain and low efficiency of endogenous pain modulation with no signs of biomechanical related pain, individuals with acute RCRSP are more likely to have preserved endogenous pain modulation and unilateral pain with signs of kinesiophobia.

Adolescent idiopathic scoliosis: evaluating perioperative back pain through a simultaneous morphological and biomechanical approach

Background

Adolescent idiopathic scoliosis (AIS) has been associated with diminished postural stability and a greater prevalence of back pain. Currently, the literature is lacking information on the effect of spinal fusion on both postural stability and its association with back pain. Our objectives were to evaluate the postsurgical effect of spinal morphological changes on static standing balance and assess the influence of these alterations on reported pain throughout the perioperative period.

Methods

Twenty consecutive AIS patients schedule to undergo spinal fusion surgery were recruited and followed prospectively at the Shriners Hospitals for Children-Canada. Data was collected at the preoperative, 6 weeks and 6 months postoperative visits. Spinal morphology data was collected through 3D reconstructed simultaneous standing biplanar radiographs using the SterEOS software. Postural balance was assessed through Moticon© sensor insoles and analyzed through their software. The data was simultaneously collected as part of the Global Biomechanical and morphological Assessment. Pain was evaluated through self-reported questionnaires.

Results

Morphological curve parameters were significantly reduced after surgery. Balance parameters did not change significantly throughout the perioperative period with the exception of the Center of Pressure of the left foot medial/lateral transient shift (P = 0.017) at 6 weeks. Of note, preoperative balance parameters were associated with the degree of right thoracic Cobb angles (P = 0.029 R = 0.528). Pain scores significantly improved 6 weeks and 6 months after the surgery. Pain intensity diminished in the thoracic and lumbar spine but worsen in the neck region at the 6 weeks and 6 months postoperative time points (P = 0.044). Greater residual Cobb angle difference between Mid thoracic and Thoracolumbar/Lumbar curves was associated with greater pain severity at 6 weeks postop (P < 0.005). In addition, greater residual thoracic deformity was associated with significant pain severity 6 months after surgery (P < 0.05).

Conclusions

Improved spinal morphology of postsurgical AIS patients has no significant impact on their static standing balance. Suggesting that other factors apart from the spinal morphology may contribute to AIS patients’ balance during stance. Although balance did not influence pain severity, spinal morphology and its correction appear to have influenced the intensity and location of back pain.

Pain inhibition is not affected by exercise-induced pain

Introduction:

Offset analgesia (OA) and conditioned pain modulation (CPM) are frequently used paradigms to assess the descending pain modulation system. Recently, it was shown that both paradigms are reduced in chronic pain, but the influence of acute pain has not yet been adequately examined.

Objectives:

The aim of this study is to investigate OA and CPM after exercise-induced pain to evaluate whether these tests can be influenced by delayed-onset muscle soreness (DOMS) at a local or remote body site.

Methods:

Forty-two healthy adults were invited to 3 separate examination days: a baseline appointment, the consecutive day, and 7 days later. Participants were randomly divided into a rest (n = 21) and an exercise group (n = 21). The latter performed a single intensive exercise for the lower back. Before, immediately after, and on the following examination days, OA and CPM were measured at the forearm and the lower back by blinded assessor.

Results:

The exercise provoked a moderate pain perception and a mild delayed-onset muscle soreness on the following day. Repeated-measurements analysis of variance showed no statistically significant main effect for either OA or CPM at the forearm or lower back (P > 0.05).

Conclusion:

Delayed-onset muscle soreness was shown to have no effect on the inhibitory pain modulation system neither locally (at the painful body part), nor remotely. Thus, OA and CPM are robust test paradigms that probably require more intense, different, or prolonged pain to be modulated.

Quantitative sensory testing in children with sickle cell disease: additional insights and future possibilities

Quantitative sensory testing (QST) is used in a variety of pain disorders to characterize pain and predict prognosis and response to specific therapies. In this study, we aimed to confirm results in the literature documenting altered QST thresholds in sickle cell disease (SCD) and assess the test-retest reliability of results over time. Fifty-seven SCD and 60 control subjects aged 8-20 years underwent heat and cold detection and pain threshold testing using a Medoc TSAII. Participants were tested at baseline and 3 months; SCD subjects were additionally tested at 6 months. An important facet of our study was the development and use of a novel QST modelling approach, allowing us to model all data together across modalities. We have not demonstrated significant differences in thermal thresholds between subjects with SCD and controls. Thermal thresholds were consistent over a 3- to 6-month period. Subjects on whom hydroxycarbamide (HC) was initiated shortly before or after baseline testing (new HC users) exhibited progressive decreases in thermal sensitivity from baseline to 6 months, suggesting that thermal testing may be sensitive to effective therapy to prevent vasoocclusive pain. These findings inform the use of QST as an endpoint in the evaluation of preventative pain therapies.

The publication trend of neuropathic pain in the world and China: a 20-years bibliometric analysis

Background

There has been tremendous change on neuropathic pain research in the past 20 years in China and around the world. We analyzed the global trend of neuropathic pain research and compared China’s quantity and quality of neuropathic pain-related publications with other developed countries.

Methods

Using terms “neuropathic pain”, we retrieved related publications from the Web of Science (WOS) database and PubMed database. From different aspects, such as the number of papers, total citations, average citations per item, H-index, research types, orientation, institutions, journals and funding, global neuropathic pain publications were classified and analyzed.

Results

From 1998 to 2017, 21,733 articles regarding neuropathic pain research were published worldwide. Of these, 9.394% were contributed by authors from Chinese institutions, which followed USA and ranked second. However, the quality indicators of publications, including total citations, average citations per item and H-index, were relatively low in China. High contribution journals and the 10 most-cited articles on neuropathic pain in world and China were also listed, which also can reflect the quality of neuropathic pain. Based on National Natural Science Foundation of China (NSFC), basic research was the main articles type, accounting for 32.91% of China’s neuropathic pain research.

Conclusion

Global neuropathic pain research increased rapidly during the 1998 to 2017 period. The USA was still the leader of neuropathic research. Although China had made great achievements, there was a significant gap in the high-quality studies between China and other leading countries.