Quantitative Sensory Testing Data Research Articles

Continuum of somatosensory profiles in breast cancer survivors with and without pain, compared to healthy controls and patients with fibromyalgia.

The prevalence of persistent pain among breast cancer survivors (BCS) is high, and it is unclear what distinguishes those with persistent pain from those without. Research suggests that differences in somatosensory function evaluated by quantitative sensory testing (QST) may be responsible. This study aimed to describe somatosensory profiles in terms of hyper- and hypoesthesia in BCS with and without persistent pain using reference data from healthy controls. Second, QST parameters of BCS with and without pain were compared with those of healthy controls (i.e., a negative control group) and patients with fibromyalgia (i.e., a positive control group). Participants (n = 128) were divided into four equal groups: healthy controls, BCS with persistent pain, BCS without persistent pain, and patients with fibromyalgia. Nine QST parameters were evaluated at the trunk and at a remote location. Somatosensory profiles were determined by Z-score transformation of QST data using normative data from healthy controls. At the trunk, compared to healthy controls, BCS with persistent pain exhibited sensory aberrations across five out of seven QST parameters: pressure pain threshold, mechanical detection, and thermal thresholds. Pain-free BCS showed similar sensory aberrations across the four QST parameters compared to healthy controls: mechanical detection and thermal thresholds. Temporal summation and conditioned pain modulation were not significantly different between groups. BCS with persistent pain exert aberrations in peripheral processing of nociceptive signals, heightened facilitation of nociceptive signals, and higher psychosocial burden when compared to pain-free BCS, healthy controls, and patients with fibromyalgia. This study investigates the somatosensory function of breast cancer survivors with and without persistent pain using quantitative sensory testing and two control group (i.e., patients with fibromyalgia and healthy controls). Our results indicate somatosensory aberrations within the peripheral, but not central pathways in breast cancer survivors with persistent pain. Our findings contribute to a better understanding of the somatosensory mechanisms underlying persistent pain, which may inform future interventions to prevent the development of persistent pain, and improve treatment modalities.

Unraveling the Left-Right Judgment Task in Chronic Low Back Pain: Insights Through Behavioral, Electrophysiological, Motor Imagery, and Bodily Disruption Perspectives

Bodily disruptions have been consistently demonstrated in individuals with chronic low back pain. The performance on the left-right judgment task has been purposed as an indirect measure of the cortical proprioceptive representation of the body. It has been suggested to be dependent on implicit motor imagery, although the available evidence is conflicting. Hence, the aim of this case-control observational study was to examine the performance (accuracy and reaction times) and event-related potentials while performing the left-right judgment task for back and hand images in individuals with chronic low back pain versus healthy controls, along with its relationship with self-reported measurements and quantitative sensory testing. While self-reported data suggested bodily disruptions in the chronic low back pain sample, this was not supported by quantitative sensory testing. Although both groups displayed the same performance, our results suggested an increased attentional load on participants with chronic low back pain to achieve equal performance, measured by a higher N1 peak amplitude in occipital electrodes, especially when the effect of contextual images arises. The absence of differences in the reaction times for the left-right judgment task between both groups, along with inconsistencies in self-reported and quantitative sensory testing data, could question the involvement of implicit motor imagery in solving the task. In conclusion, our results suggest disrupted attentional processing in participants with chronic low back pain to solve the left-right judgment task. PerspectiveAlthough there are no differences in the performance of the left-right judgment task (hits, reaction times) between chronic low back pain patients and controls, the analysis of event-related potentials revealed that patients require a higher cognitive load, measured by N1 peak amplitude.

DIFFERENTIAL PAIN SENSATION AND GUT MICROBIOME BETWEEN YOUNG AND OLDER ADULTS

Abstract This study aimed to investigate the differences in pain sensation and gut microbiota between young and older adults. Twenty-one healthy young adults (YAs) and sixteen healthy older adults (OAs) were recruited. Quantitative sensory testing data, and stool samples were collected. The 16S rRNA V4 gene region of stool samples were sequenced and processed by using the Mothur 1.42.3 pipeline. The mean ages of YAs and OAs were 20.14 (SD = 1.39) and 63.19 (SD = 8.00), respectively. Eleven of the YAs and 12 of the OAs were female, and 8 of the YAs and 3 of the OAs reported pain. OAs had significantly higher heat pain threshold (HPT), higher pressure pain threshold (PPT), lower cold detection threshold (CDT), and lower cold pain threshold (CPT) than YAs (all p < 0.05). OAs had significantly different a-diversity indices including higher species of observed (Sobs), Chao index and Shannon index, and lower coverage, and significantly different beta diversity indices (Bray-Curtis, Jaccard, and Theta YC) than YAs. The significantly abundant taxa in YAs included Bacteroidaceae, Veillonellaceae, and Alcaligenaceae. Coriobacteriaceae, Streptococcaceae, Lachnospiraceae, Erysipelotrichaceae, and Verrucomicrobiaceae were significantly enriched in OAs. The Spearman correlation analysis showed that the CDT, CPT, and HPT were significantly associated with gut microbiota Sobs, Chao index, Shannon index, and coverage (all p < 0.05). But the directions and coefficients of correlations varied. OAs had distinguished peripheral sensation and gut microbiota profiles than YAs. The changed peripheral sensation and gut microbiota profiles among OAs may be biomarkers of aging-related pain processing.

Quantitative somatosensory testing of the abdomen: establishing initial reference values across developmental age and biological sex.

Abdominal pain is a common symptom of several debilitating conditions (eg, inflammatory bowel disease, irritable bowel syndrome, and endometriosis) and affects individuals throughout their lifespan. Quantitative sensory testing (QST) reference values exist for many body sites but not the abdomen. Using a QST battery adapted from the German Research Network on Neuropathic Pain, we collected QST data on the upper and lower abdomen in 181 pain-free participants, ages 12 to 50 years, to establish reference values by age and biological sex. The normative values are presented as medians for each QST measure by sex (male, n = 63; female, n = 118) and across 3 age categories (adolescents: 12-19 years, n = 48; young adults: 20-30 years, n = 87; and adults: 31-50 years, n = 46). Evaluating the sensory functioning of the abdomen and characterizing ranges of QST measures is an essential first step in understanding and monitoring the clinical course of sensory abnormalities in patients with underlying diseases affecting the abdomen and pelvis. The impact of age and development on sensory functioning is necessary, given age-related changes in pain perception and modulation.

PD34-03 PRE-OPERATIVE CENTRAL SENSITIZATION AND HYPERSENSITIVITY TO PAIN IS ASSOCIATED WITH URETERAL STENT PAIN: FINDINGS FROM THE URINARY STONE DISEASE RESEARCH NETWORK (USDRN)

You have accessJournal of UrologyCME1 Apr 2023PD34-03 PRE-OPERATIVE CENTRAL SENSITIZATION AND HYPERSENSITIVITY TO PAIN IS ASSOCIATED WITH URETERAL STENT PAIN: FINDINGS FROM THE URINARY STONE DISEASE RESEARCH NETWORK (USDRN) Henry Lai, Hongqiu Yang, Jonathan Harper, Alana Desai, Gregory Tasian, Rebecca McCune, Ziya Kirkali, Hussein Al-Khalidi, Charles Scales, and Michele Curatolo Henry LaiHenry Lai More articles by this author , Hongqiu YangHongqiu Yang More articles by this author , Jonathan HarperJonathan Harper More articles by this author , Alana DesaiAlana Desai More articles by this author , Gregory TasianGregory Tasian More articles by this author , Rebecca McCuneRebecca McCune More articles by this author , Ziya KirkaliZiya Kirkali More articles by this author , Hussein Al-KhalidiHussein Al-Khalidi More articles by this author , Charles ScalesCharles Scales More articles by this author , and Michele CuratoloMichele Curatolo More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003327.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To examine the relationship between pre-operative central sensitization and hypersensitivity to pain, and post-operative stent pain after ureteroscopy (URS) for stones. METHODS: Adult participants enrolled in the USDRN STudy to Enhance uNderstanding of sTent-associated Symptoms (STENTS) underwent quantitative sensory testing (QST) prior to URS and stent placement. Hypersensitivity to mechanical pain was assessed with pressure algometer. Participants rated their pain intensity (0-100) to 2 kg and 4 kg pressure applied to the flank and lower abdominal quadrant on the side of planned stent, and the contralateral forearm (control). Pressure pain thresholds (PPT) were also assessed. Central sensitization was assessed by applying a pinprick stimulator and calculating temporal summation (TS). Post-operative stent pain was assessed using PROMIS questionnaires for pain intensity and pain interference. Data were analyzed using repeated-measures mixed-effects models. RESULTS: Among the 412 participants with QST data, median age was 54 years, 46% were female. Higher pre-operative pain ratings to mechanical pressure to the ipsilateral flank and abdominal areas were associated with higher stent pain intensity on post-operative days 1, 3, 5, 7-9, and 30 days post-stent removal (p<0.05). Lower pre-operative PPT (i.e. higher mechanical hypersensitivity) was associated with higher post-operative pain intensity (p<0.05). Greater degree of central sensitization pre-operatively (higher TS) was associated with higher post-operative pain intensity (p<0.05). Significant correlations existed between pre-operative QST measures at the ipsilateral flank area and post-operative stent pain intensity (Table). Similar correlations were observed for ipsilateral abdominal area but not consistently for the forearm control site (data not shown). CONCLUSIONS: We have identified a physiological risk factor associated with stent pain. Preoperative central sensitization and hypersensitivity to pain were associated with post-operative stent pain. QST is a potential tool to identify patients likely to experience post-URS stent pain, which may facilitate early identification for mitigation, counseling, and management options. Source of Funding: NIH/NIDDK © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e920 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Henry Lai More articles by this author Hongqiu Yang More articles by this author Jonathan Harper More articles by this author Alana Desai More articles by this author Gregory Tasian More articles by this author Rebecca McCune More articles by this author Ziya Kirkali More articles by this author Hussein Al-Khalidi More articles by this author Charles Scales More articles by this author Michele Curatolo More articles by this author Expand All Advertisement PDF downloadLoading ...

Lessons learned- Moving on from QST sensory profiles.

Quantitative sensory testing (QST) has been optimized to diagnose in particular small fiber neuropathy and has been successfully used for decades. "Sensory phenotypes" have been derived from the QST data in an attempt to stratify patients with chronic pain and to gain mechanistic insights. However, studies consistently show that there is no difference in sensory phenotypes between neuropathy patients with and without pain and no successful stratification has been shown using the current version of "sensory phenotypes". Thus, after falsification of the initial hypothesis it is time to focus on more promising approaches.

Assessment of Sensory Thresholds in Dogs using Mechanical and Hot Thermal Quantitative Sensory Testing.

Quantitative sensory testing (QST) is used to evaluate the function of the somatosensory system in dogs by assessing the response to applied mechanical and thermal stimuli. QST is used to determine normal dogs' sensory thresholds and evaluate alterations in peripheral and central sensory pathways caused by various disease states, including osteoarthritis, spinal cord injury, and cranial cruciate ligament rupture. Mechanical sensory thresholds are measured by electronic von Frey anesthesiometers and pressure algometers. They are determined as the force at which the dog exhibits a response indicating conscious stimulus perception. Hot thermal sensory thresholds are the latency to respond to a fixed or ramped temperature stimulus applied by a contact thermode. Following a consistent protocol for performing QST and paying attention to details of the testing environment, procedure, and individual study subjects are critical for obtaining accurate QST results for dogs. Protocols for the standardized collection of QST data in dogs have not been described in detail. QST should be performed in a quiet, distraction-free environment that is comfortable for the dog, the QST operator, and the handler. Ensuring that the dog is calm, relaxed, and properly positioned for each measurement helps produce reliable, consistent responses to the stimuli and makes the testing process more manageable. The QST operator and handler should be familiar and comfortable with handling dogs and interpreting dogs' behavioral responses to potentially painful stimuli to determine the endpoint of testing, reduce stress, and maintain safety during the testing process.

Quantitative sensory testing in patients with the muscle pain subtype of temporomandibular disorder: a systemic review and meta-analysis.

This meta-analysis aimed to evaluate quantitative sensory testing (QST) evidence for pain processing in patients with the muscle pain subtype of temporomandibular disorders (mTMD). A comprehensive systematic electronic search strategy was performed in online literature databases. All full-text observational studies published up to July 2021 with the aim of investigating pain sensitization in humans with mTMD using QST measures were eligible for inclusion. Meta-analysis of QST data was performed using a random effects model, which included results comparing patients with mTMD to healthy controls, and standard mean difference (SMD) results were analyzed. Twelve studies with 732 participants (371 patients with mTMD and 361 healthy controls) were analyzed following screening and quality appraisal. Compared with healthy controls, patients with mTMD had significantly lower pressure pain threshold (SMD - 1.10, 95% confidence interval [CI] - 1.52 to - 0.68) with high heterogeneity (Tau2 = 0.61, I2 = 86%), and significantly lower mechanical pain threshold (SMD - 0.64, 95% CI - 0.95 to - 0.32) with no heterogeneity (Tau2 = 0.00, I2 = 0%). No difference was observed in the cold pain threshold (SMD 0.16, 95% CI - 0.13 to 0.45), heat pain threshold (SMD - 0.13, 95% CI - 0.40 to 0.15), and wind-up ratio (SMD 0.63, 95% CI - 0.11 to 1.38) between patients with mTMD and healthy controls. Other QST parameters were also discussed. The study results suggest that the pain processing of deep tissues is likely sensitized in mTMD and calls for more QST studies with standard procedures to reduce inter-study heterogeneity. The major findings of this meta-analysis support using PPT to examine the pain processing in patients with mTMD in clinical scenario.

Anti-nociceptive effects of oxytocin receptor modulation in healthy volunteers-A randomized, double-blinded, placebo-controlled study.

There is increasing evidence for oxytocin as a neurotransmitter in spinal nociceptive processes. Hypothalamic oxytocinergic neurons project to the spinal dorsal horn, where they activate GABA-ergic inhibitory interneurons. The present study tested whether the long-acting oxytocin-analogue carbetocin has anti-nociceptive effects in multi-modal experimental pain in humans. Twenty-five male volunteers received carbetocin 100 mcg and placebo (0.9% NaCl) on two different sessions in a randomized, double-blinded, cross-over design. Multi-modal quantitative sensory testing (QST) including a model of capsaicin-induced hyperalgesia and allodynia were performed at baseline and at 10, 60 and 120min after drug administration. QST data were analysed using mixed linear and logistic regression models. Carbetocin plasma concentrations and oxytocin receptor genotypes were quantified and assessed in an exploratory fashion. An anti-nociceptive effect of carbetocin was observed on intramuscular electrical temporal summation (estimated difference: 1.26mA, 95% CI 1.01 to 1.56mA, p=.04) and single-stimulus electrical pain thresholds (estimated difference: 1.21mA, 95% CI 1.0 to 1.47mA, p=.05). Furthermore, the area of capsaicin-induced allodynia was reduced after carbetocin compared to placebo (estimated difference: -6.5 cm2 , 95% CI -9.8 to -3.2 cm2 , p<.001). This study provides evidence of an anti-nociceptive effect of carbetocin on experimental pain in humans. This study provides evidence of the anti-nociceptive effect of intravenous administration of the oxytocin agonist carbetocin in healthy male volunteers.

A single bout of coordination training does not lead to EIH in young healthy men – a RCT

Physical activity can lead to hypoalgesic effects and is often recommended as part of multidisciplinary pain management. Based on the idea, that in future specific and more differentiated sports therapeutic interventions could be used for a multidisciplinary pain management, various type of sports and their effects on pain sensitivity should be analysed. Whereas endurance as well as strengthening exercises are associated with a decrease in pain sensitivity in healthy people as well as people with chronic pain states, the effects of a specific coordination training (CT) on pain sensitivity have not yet been sufficiently investigated. Therefore, aim of the present study was to examine if a single bout of CT leads to exercised-induced hypoalgesia in young healthy men. Thirty five healthy men (mean age 27±3 years) were examined in a randomised crossover design before and after a single bout of 45-min CT and a 45-min resting session as control condition by means of Quantitative Sensory Testing (QST). The QST is a validated instrument to assess the function of the somatosensory system, by applying thermal and mechanical stimuli. By doing so, various detection and pain thresholds were determined at the dorsum of one foot. Exercises of CT were chosen to generate high proprioceptive input for the ankle joints. Analysis of the QST data in respect of the factors group (CT/control condition), time (pre/post) and stimuli (parameter of QST) revealed no statistically significant main effects of a single bout of CT on somatosensory system, neither for the factors group*time (p=0.51), nor the factors group*time*stimuli (p=0.32). All stimuli remained constant in the course of both conditions (e.g. mean±sd of heat pain threshold pre/post in °C: coordination: 44.7±3.1/44.8±2.9; rest: 45.5±3.0/44.9±3.0). In this setting, a single bout of CT had no effect on the somatosensory system in young healthy men. Therefore, this specific CT did not lead to an exercised-induced hypoalgesia in healthy people. Intensity of sensory input during training intervention might be too low to generate analgesic effects in a non-pathological altered somatosensory system of young healthy men. Further research is needed to clarify if a CT can induce exercised-induced hypoalgesia in people with pathological alterations of the somatosensory system. In addition, it has to examined if analgesic effects can be induced by changing the intensity of CT in healthy people. Detailed knowledge regarding the effects of different training interventions on pain modulation is needed to completely understand the mechanism of exercised-induced hypoalgesia.

Pain Experience, Physical Function, Pain Coping, and Catastrophizing in Children With Sickle Cell Disease Who Had Normal and Abnormal Sensory Patterns

ContextSickle cell disease (SCD) is associated with recurrent pain that could lead to abnormal sensory patterns (ASPs). ObjectivesThe purpose of this study is to compare children with SCD who had normal sensory patterns (NSPs) and ASPs in pain experience, physical function, pain coping, and pain catastrophizing. MethodsChildren with quantitative sensory testing data were selected from a larger study that examined pain and symptoms in children with SCD. Comparisons were made between children with NSP (n = 35; 13.9 ± 1.9 years) and ASP (n = 13; 12.8 ± 1.9 years). Children completed the Adolescent Pediatric Pain Tool, Functional Disability Inventory, Pain Coping Questionnaire, and Pain Catastrophizing Scale. ResultsNo significant differences were found in pain intensity (2.9 ± 3.0 vs. 2.6 ± 2.8 on 0–10 Visual Analogue Scale) between the NSP and ASP, respectively. The most common marked pain sites for both groups were lower extremities (22.9%), head and neck (20.8%), and upper extremities (20.8%). Functional Disability Inventory scores were significantly worse in ASP (38.5%) compared with NSP (11.4%). The ASP group had significantly worse scores in emotion-focused pain coping subscales. ConclusionChildren with SCD with ASP had worse functional disability, were expressing more affective pain quality, and had emotion-focused pain coping compared with NSP. Future studies are needed to examine the effectiveness of physical activities on the physical function as well as psychosocial interventions such as peer support and creative arts expression to minimize development of ASP in children with SCD.

Pain thresholds and intensities of CRPS type I and neuropathic pain in respect to sex.

Healthy women have generally been found to have increased experimental pain perception and chronic pain has a higher prevalence in female as compared to male patients. However, no study has investigated whether pain intensity and pain perception thresholds are distinct or similar between sexes within various chronic pain entities. We investigated whether average pain intensities and pain thresholds assessed using quantitative sensory testing (QST) differed between women and men suffering from three distinct chronic pain conditions: Complex Regional Pain Syndrome (CRPS type I), peripheral nerve injury (PNI) or polyneuropathy (PNP), as compared to paired healthy volunteers. QST data of 1,252 patients (669 female, 583 male) with PNI (n=342), PNP (n=571) or CRPS (n=339), and average pain intensity reports from previously published studies were included. Absolute and z-values (adjusted for age and body region) of cold, heat, pressure (PPT) and pinprick pain thresholds were compared in generalized linear models with aetiology, duration of underlying pain disease and average pain intensity as fixed effects. Average pain intensity during the past four weeks did not differ between women and men, in both mean and range. In women absolute pain thresholds for cold, heat and pinprick were lower than in males across all diagnoses (p<.05). However, after z-transformation these differences disappeared except for PPT in CRPS (p=.001). Pain thresholds in patients show only minor sex differences. However, these differences mimic those observed in healthy subjects and do not seem to be linked to specific pathophysiological processes. Female healthy participants and female patients with neuropathic pain conditions or CRPS I report lower pain thresholds compared to males, but pain intensity is similar and there is no sex difference in the extent to which the thresholds are altered in neuropathic pain or CRPS. Thus, the sex differences observed in various chronic pain conditions mimic those obtained in healthy participants, indicating that these differences are not linked to specific pathophysiological processes and are of minor clinical relevance.

Quantitative sensory testing of periauricular skin in healthy adults

The aim of this study was to investigate the test-retest reliability of quantitative sensory testing (QST) and mechanical sensitivity mapping of the periauricular skin. Twenty volunteers (10 men, 10 women) participated in two sessions at intervals of one week. Cold and warm detection threshold (CDT&WDT), cold and heat pain threshold (CPT&HPT), mechanical detection and pain threshold (MDT&MPT), pressure pain threshold (PPT) and two-point discrimination (2PD) were measured at five sites: bilateral subauricular and postauricular sites (LA, RA, LB, RB) and the dorsum of left hand (control). Pressure stimulation was applied at each of the four periauricular test sites. The test-retest reliability of the QST data implied fair to excellent agreement as evaluated by the intra-class correlation coefficients (ICC; all >0.4) for different days. There was no difference between each side in the QST parameters and mechanical sensitivity mapping (P ≥ 0.057). Significant differences between subauricular and postauricular sites were shown for WDT and PPT (P ≤ 0.028). NRS scores of mechanical sensitivity mapping showed significant effects of gender, site and point (P ≤ 0.040). QST and mechanical sensitivity mapping can be considered to be a reliable technique to assess somatosensory function of the periauricular skin.

Quantitative sensory testing predicts histological small fiber neuropathy in postural tachycardia syndrome.

Retrospective investigation of the somatosensory profile and prediction of histologic small fiber neuropathy (SFN) in postural orthostatic tachycardia syndrome (POTS) was performed using quantitative sensory testing (QST) as a standardized noninvasive test. In this investigation, full data sets from 30 patients (age: 34.03 ± 10.82 years, n = 6 males), including results of autonomic function testing, norepinephrine values, skin biopsy, and QST, were retrospectively analyzed. The QST data were compared with healthy controls (HCs) (age: 34.20 ± 10.5 years, n = 6 males, t test: 0.95). The evaluation of all QST parameters in POTS compared with HCs yielded differences in all thermal parameters (cold detection threshold: p < 0.05, warm detection threshold: p < 0.001, thermal sensory limen: p < 0.001, cold pain threshold: p < 0.05, and heat pain threshold: p < 0.001) and in paradoxical heat sensations (p < 0.05). Differences in nonpainful stimuli (mechanical detection threshold: p < 0.05 and vibration detection threshold: p < 0.001) were also detected. All patients who had clinical signs of SFN in combination with impairment of small fibers in QST also had SFN on skin biopsy. These results suggest that a non-region-specific SFN in POTS compared with controls can be detected by noninvasive QST that predicts histologic small fiber pathology.

(112) Childhood Adversity Linked to Heightened Pain Sensitivity in Adults

Childhood experiences of adverse social conditions have demonstrated lifelong downstream health-related consequences. Since more exposure to adverse childhood events (ACEs) are associated with poorer outcomes, their exposure can be considered a social determinant of health and wellness. The mechanism of ACEs contributing to adverse health consequences may lie in chronic activation of the stress pathway, leading to dysregulation of the neuroendocrine, immune, and autonomic systems. Chronic stress, experienced in childhood, appears to change the physiologic response to subsequent stress, perhaps though HPA and immune axes. A link appears to exist between retrospective reports of ACEs and adult pain-related medical conditions like arthritis, neck and back pain and headaches. The “sensitization” hypothesis posits that prior exposure to distress sensitizes individuals to respond more robustly to subsequent stressors. Those with more ACEs generally experience more chronic inflammation and heightened pro-inflammatory mediators may be a common pathway of increased risk for facilitating pain. The current study sought to evaluate pain facilitation, hyper-responsiveness of nociceptive pathways. Pain facilitation can be measured in healthy participants using quantitative sensory testing (QST). We conducted secondary data analyses of QST data from 130 healthy participants to examine the effect of childhood adversity on psychosocial factors and pain facilitation. Participants completed several questionnaires and underwent a QST battery with multiple pain facilitatory indices, including thermal and mechanical temporal summation, and assessment of aftersensations (Z-scored and combined into one composite score). Correlations revealed significant associations between ACEs and psychosocial factors, including the traumatic life events, catastrophizing, fear of pain, depression, insomnia and sleep quality, aches and pains (r's=0.2-0.5; p's

Do We Measure What Patients Feel?: An Analysis of Correspondence Between Somatosensory Modalities Upon Quantitative Sensory Testing and Self-reported Pain Experience.

Hyperalgesia and allodynia are typical signs of neuropathic pain. Quantitative sensory testing (QST) is a validated tool to clinically assess these phenomena. However, whether QST reveals findings that are reported by the patients is unclear. The aim of this study was therefore to investigate the association between self-reported symptoms assessed with the painDETECT questionnaire (PDQ) with results of validated QST. PDQ and QST data of 96 patients with chronic neuropathic pain were analyzed. Questions upon presence of painful light touch, painful cold or heat, light pressure triggering pain, and numbness upon PDQ were compared with findings of dynamic mechanical allodynia, increased sensitivity to heat, cold, or pressure pain as well as loss of detection upon QST, respectively. Self-reported pain symptoms upon PDQ showed only a small to moderate concordance with corresponding signs assessed upon QST, whereat the highest, but still only moderate association between self-reported symptoms and measured signs could be obtained for self-reported presence of painful light touch and dynamic mechanical allodynia upon QST. However, the positive and negative likelihood ratio to predict QST values with PDQ scores did not reach convincing values. Results demonstrate that self-reported PDQ symptoms cannot predict abnormal QST values. The poor predictive power of the PDQ may depend on several factors based on possibility of comparison between PDQ and QST and also on methodical issues. Both, symptoms (questionnaires) and signs address complementary aspects of the pain experience and should be considered for diagnosis and treatment of neuropathic pain.

Pain sensitization associated with nonresponse after physiotherapy in people with knee osteoarthritis.

In knee osteoarthritis (OA), pain sensitization has been linked to a more severe symptomatology, but the prognostic implications of pain sensitivity in people undergoing conservative treatment such as physiotherapy are not established. This study aimed to prospectively investigate the association between features of pain sensitization and clinical outcome (nonresponse) after guideline-based physiotherapy in people with knee OA. Participants (n = 156) with moderate/severe knee OA were recruited from secondary care. All participants completed self-administered questionnaires and underwent quantitative sensory testing at baseline, thereby establishing subjective and objective measures of pain sensitization. Participants (n = 134) were later classified after a physiotherapy intervention, using treatment responder criteria (responder/nonresponder). Quantitative sensory testing data were reduced to a core set of latent variables using principal component analysis. A hierarchical logistic regression model was constructed to investigate whether features related to pain sensitization predicted nonresponse after controlling for other known predictors of poor outcome in knee OA. Higher temporal summation (odds ratio 2.00, 95% confidence interval 1.23-3.27) and lower pressure pain thresholds (odds ratio 0.48, 95% confidence interval 0.29-0.81) emerged as robust predictors of nonresponse after physiotherapy, along with a higher comorbidity score. The model demonstrated high sensitivity (87.8%) but modest specificity (52.3%). The independent relationship between pain sensitization and nonresponse may indicate an underlying explanatory association between neuroplastic changes in nociceptive processing and the maintenance of ongoing pain and disability in knee OA pain. These preliminary results suggest that interventions targeting pain sensitization may warrant future investigation in this population.

(104) - Order of heat and pressure tests impacts pain responsivity ratings

Considering the volume and variety of trials that use quantitative sensory testing (QST), accounting for potential order effects is imperative when determining the study protocol as well as for accurate data analysis. The present secondary data analyses examined whether the order of two common testing methods (heat and pressure) affected subsequent subjective participant pain ratings. 106 participants (50 females, mean age 30) underwent both thermal pain threshold and tolerance testing and pressure pain threshold testing in randomized order. Thermal pain threshold and tolerance was administered to the right ventral forearm using the Medoc Pathway with a .5 sec/minute rate of rise. Participants indicated when they first felt pain (threshold) and when it became intolerable (tolerance) by pressing a mouse button, which turned the device off. The temperature for each was recorded. Pressure was applied to the left and right trapezius muscle and the left and right thumb joint using an SBMedic algometer. Participants were instructed to say “pain” when they first felt pain as a result of the pressure stimulus. Heat and pressure were measured twice for each area, and an average was calculated for each testing method. T-tests revealed a significant order effect for pressure ratings, such that thermal testing performed first resulted in higher pressure ratings for both the trapezius (P = .013) and thumb (P = .025). Testing order was also significant for heat pain threshold (P = .049) and marginally significant for heat pain tolerance (P = .067), such that performing thermal testing first resulted in higher heat pain temperatures. These data suggest that order of testing impacts overall levels of pain responsivity, particularly in relation to heat and pressure, and could have implications for the interaction of other types of sensory testing (e.g. cold pain tolerance) as well. The current findings speak to the importance of controlling for testing order in QST data.

Somatosensory Profile Changes Evoked by Topical Application of Capsaicin to the Tongue in Healthy Individuals.

To assess the effect of topical application of capsaicin to the tongue as a surrogate model of burning mouth syndrome (BMS) on somatosensory sensitivity by using a standardized battery of quantitative sensory testing (QST) in healthy volunteers. This study comprised two experimental sessions (experimental [capsaicin] and control [Vaseline]) with QST in 16 healthy women. The examiner applied capsaicin or Vaseline to the tongue tip for 5 minutes. Each participant kept their tongue tip in contact with the capsaicin/Vaseline at the bottom of a disposable cup for 5 minutes, during which time the participant rated the perceived intensity of the tongue pain every 30 seconds on an electronic 0 to 10 visual analog scale (VAS). QST was performed on the tongue tip before and immediately after application in each session. The QST data were analyzed by two-way analysis of variance (ANOVA). Mean ± standard error of the mean (SEM) of VAS pain scores during the capsaicin and control sessions were 8.2 ± 0.5 and 1.9 ± 0.2, respectively. The peak of the perceived pain in the capsaicin session was significantly higher than in the control session (P < .001). In the capsaicin session, the postapplication heat pain threshold (HPT) was significantly higher than the preapplication HPT, and the postapplication cold detection threshold (CDT) and mechanical pain threshold (MPT) were significantly lower than before application (P < .001). The average z scores showed a significant somatosensory loss regarding CDT. In the control session, there were no differences between preapplication and postapplication values. Topical application of capsaicin to the tongue tip changed somatosensory sensitivity in healthy participants.

Effect of Experimental Periodontal Ligament Pain on Gingival Somatosensory Sensitivity.

To use a randomized, blinded, crossover design to evaluate the possible heterotopic effects of experimental periodontal ligament pain on adjacent gingival somatosensory sensitivity. A total of 12 healthy volunteers (8 female, 4 male; mean age ± standard error in means (SEM): 28 ± 1 years) participated in two randomized experimental quantitative sensory testing (QST) sessions, one in which capsaicin (experimental) was injected into the periodontal ligament and one in which isotonic saline (control) was injected. A total of 13 standardized QST measures were obtained on the buccal attached gingiva of a maxillary central incisor before, immediately after, and 30 minutes after injection of 30 μL of 5% capsaicin or isotonic saline into the periodontal ligament of the same incisor. The injection-evoked pain was evaluated on a 0-10 numeric rating scale (NRS). QST data were analyzed with two-way repeated measurement analysis of variance. Capsaicin injected into the periodontal ligament evoked moderate levels of pain (mean peak NRS ± SEM: capsaicin: 5.5 ± .7; control: 0.6 ± 0.5 [P < .001]). Capsaicin injected into the periodontal ligament significantly modulated gingival somatosensory sensitivity: increased sensitivity to warmth and painful heat stimuli occurred immediately and 30 minutes after the injection (P < .025), whereas decreased sensitivity to both tactile and painful mechanical stimuli (P < .011) occurred immediately after the injection and to painful mechanical stimuli only after 30 minutes (P = .016). No somatosensory changes were detected following the injection of isotonic saline (P > .050). Capsaicin injected into the periodontal ligament caused gain of heterotopic somatosensory sensitivity toward warmth and painful heat stimuli as well as reduction in mechanical sensitivity of the gingiva adjacent to the injected tooth. These findings may have implications for interpretation of somatosensory functions in patients with chronic intraoral pain, where gingival somatosensory profiles similar to those detected after capsaicin injection in the present study may be interpreted as signs of nerve damage.