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

The Tampa Scale of Kinesiophobia: Structural Validation among Adolescents with Idiopathic Scoliosis Undergoing Spinal Fusion Surgery.

AIMS: Spinal fusion surgery is one of the most invasive orthopedic surgeries. Pain while moving or a fear of experiencing pain after surgery may delay return to function and cause prolonged disability. The purpose of the study was to examine the psychometric properties of the Tampa Scale of Kinesiophobia (TSK) in pediatric patients undergoing scoliosis surgery. METHODS: Fifty-five adolescents (10-18 years old) scheduled for spinal fusion surgery were enrolled. Participants completed the TSK questionnaire before surgery and six weeks after surgery. Reliability, exploratory and confirmatory factor analyses were performed on the two-factors TSK including activity avoidance (TSK-AA) and somatic focus (TSK-SF). RESULTS: Before and after surgery, all TSK-AA items conformed into the same factor component and revealed good internal reliability with Cronbach's alpha of .76 and .70 respectively. TSK-SF items were separated into different factor components and revealed poor reliability (.11 and .56). The TSK-AA also produced an adequate fit to the data, as reflected with several fit indices at both timepoints, respectively: χ2/df = 1.19 and 1.22; CFI=.96 and .94; and RMSEA=.06 and .06. CONCLUSIONS: The TSK-AA demonstrated good psychometric properties in patients undergoing scoliosis surgery, which provides empirical evidence for pediatrics. Its validation in distinct populations and settings is recommended prior to its use.

Perioperative Pain Assessment in a 14-Year-Old Boy with Lumbar Disc Herniation.

This case report illustrates the value of a comprehensive perioperative pain assessment composed of quantitative sensory testing and self-reported measures that highlight the impact of pain experienced by a 14-year-old boy suffering from chronic low back pain and sciatica. Before surgery, the pain assessment revealed inefficient endogenous inhibitory pain control with presence of temporal summation of pain. The severe pain was constant and lasted for 18 months. The patient was in a high-anxiety state, and reported significant functional disability and poor sleep quality. Six months after surgery, the patient was pain free. Quantitative sensory testing showed an improvement in his inhibitory pain control with the absence of temporal summation of pain. The patient was no longer anxious, was back to normal functional abilities, and reported good sleep quality. By including neurophysiology and other pain measures, the clinical application of a comprehensive pain assessment can provide objective measurements of treatment efficacy.