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

An observational cross-sectional study on the characteristics of children and adolescents with non-specific spinal pain stratified by pain severity

BACKGROUND

Distinguishing self-limiting ('trivial') from potentially consequential spinal pain in childhood and adolescence is crucial to prevent over- or under-medicalization. The aim of this study was to stratify participants for severity of spinal pain and to investigate associations of pain severity with potential consequences of pain and some psychophysical and clinical factors.

METHODS

In 2020 and 2021, children and adolescents took part in a voluntary population-based spine screening event across Switzerland organized by the Swiss Chiropractors Association. The screening consisted of a questionnaire (14 questions) based on the Young Spine Questionnaire and a clinical examination by a chiropractor. Three subgroups of pain severity [no pain (including mild, occasional pain), one-sited moderate pain, one-sited severe or moderate/severe pain at multiple sites of the spine] were formed by combining the self-reported measures for pain intensity and pain frequency for two recall periods (lifetime, last week) according to literature. Multivariable logistic regression analyses were conducted to determine the associations between pain severity and potential pain consequences (impact of spinal pain on health and seeking medical advice because of spinal pain), as well as between pain severity and some psychophysical factors (head and/or belly pain, sleep problems, daytime tiredness) and clinical measures [trunk symmetry (rib hump), trunk muscle endurance (plank position)].

RESULTS

Of all participants (N = 457; 6-16 years; mean age = 10.9 ± 3.0 years; 220 boys), those with most severe spinal pain and with one-sited moderate pain in the last week had higher odds for reporting an impact of spinal pain on their health (OR = 13.5, 95%CI = 4.9-36.8; OR = 4.7, 95%CI = 1.5-14.4) and for searching medical advice because of spinal pain (OR = 11.6, 95%CI = 4.5-30.1; OR = 3.9, 95%CI = 1.6-9.2). Headache and/or belly pain (OR = 2.6, 95%CI = 1.2-5.5) and daytime tiredness (OR = 3.2, 95%CI = 1.3-7.9) increased the odds for having most severe pain compared to having no pain. The clinical measures were not associated with pain severity.

CONCLUSION

Stratification by pain severity, particularly when asked for pain in the last week, might help to minimize over- and under-medicalization of spinal pain in childhood and adolescence. Prospective studies are needed to clarify the relevance of the investigated clinical tests in the context of adolescent spinal pain.

A Systematic Review and Meta-Analysis of Conditioned Pain Modulation in Children and Young People with Chronic Pain

BACKGROUND/OBJECTIVES

Conditioned pain modulation (CPM) is a psychophysical experimental measure of the endogenous pain inhibitory pathway in humans, wherein one pain stimulus (the conditioning stimulus) is used to inhibit an individual's perception of a second painful (test) stimulus. Research provides evidence of impaired endogenous inhibitory pain responses in adults with chronic pain. CPM is now increasingly applied in paediatric research and clinical practice. The primary aim of this systematic review was to examine the efficacy of CPM in paediatric chronic pain populations (6-24-year-olds) compared to pain-free children and young people (CYP).

METHODS

The protocol was registered on PROSPERO (CRD42020221927). A systematic search of seven databases was conducted from database inception to 20th June 2024. Study inclusion criteria were as follows: (i) recruited a sample of CYP aged 6 to 24 (inclusive) with chronic pain or who were pain-free; and (ii) applied a CPM paradigm comprising both a painful test and conditioning stimuli that were sufficiently detailed to allow for replication,(iii) adhered to a study design of randomised control trial, case control or cohort study, including cross-sectional or longitudinal; (iv) available in the English language. Study exclusion criteria were: (i) The CPM paradigm used a non-painful test or conditioning stimulus only; and (ii) was only available as an abstract, letter, poster, editorial, case report, or review with or without meta-analyses. Risk of bias was assessed using the Appraisal Tool for Cross Sectional Studies (AXIS). Meta-analyses were conducted in Comprehensive Meta Analysis 3.0 using random effects models to compare the overall CPM responses in CYP with chronic pain conditions to healthy control CYP.

RESULTS

Thirty-two studies were eligible for inclusion, six of which were included in one or more meta-analysis (n = 407 chronic pain, n = 205 control). Meta-analysis revealed significantly weaker CPM responses in CYP with a variety of chronic pain conditions compared to healthy controls (standardized mean difference (SMD) = 0.352), and significantly weaker CPM responses in CYP with abdominal pain conditions compared to healthy controls (SMD = 0.685). No significant difference in CPM response was found between CYP with migraine and healthy controls (SMD = -0.201).

CONCLUSIONS

Variable results were found across individual studies, and the meta-analysis of the small number of eligible studies provides tentative evidence for impaired CPM in CYP with chronic pain compared to healthy controls. Further research is clearly needed. In particular, studies should present CPM results separately for different age groups, ethnic groups, and sexes, as these variables shape clinical pain responses.

Sensory phenotypes in complex regional pain syndrome and chronic low back pain-indication of common underlying pathomechanisms

Introduction

First-line pain treatment is unsatisfactory in more than 50% of chronic pain patients, likely because of the heterogeneity of mechanisms underlying pain chronification.

Objectives

This cross-sectional study aimed to better understand pathomechanisms across different chronic pain cohorts, regardless of their diagnoses, by identifying distinct sensory phenotypes through a cluster analysis.

Methods

We recruited 81 chronic pain patients and 63 age-matched and sex-matched healthy controls (HC). Two distinct chronic pain cohorts were recruited, ie, complex regional pain syndrome (N = 20) and low back pain (N = 61). Quantitative sensory testing (QST) was performed in the most painful body area to investigate somatosensory changes related to clinical pain. Furthermore, QST was conducted in a pain-free area to identify remote sensory alterations, indicating more widespread changes in somatosensory processing.

Results

Two clusters were identified based on the QST measures in the painful area, which did not represent the 2 distinct pain diagnoses but contained patients from both cohorts. Cluster 1 showed increased pain sensitivities in the painful and control area, indicating central sensitization as a potential pathomechanism. Cluster 2 showed a similar sensory profile as HC in both tested areas. Hence, either QST was not sensitive enough and more objective measures are needed to detect sensitization within the nociceptive neuraxis or cluster 2 may not have pain primarily because of sensitization, but other factors such as psychosocial ones are involved.

Conclusion

These findings support the notion of shared pathomechanisms irrespective of the pain diagnosis. Conversely, different mechanisms might contribute to the pain of patients with the same diagnosis.

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.