Quantitative Sensory Testing Outcomes Research Articles

A randomised controlled trial of the effect of intra-articular lidocaine on pain scores in inflammatory arthritis.

Chronic pain in inflammatory arthritis (IA) reflects a complex interplay between active disease in a peripheral joint and central pronociceptive mechanisms. Because intra-articular lidocaine may be used to abolish joint-specific peripheral input to the central nervous system, we aimed to validate its use as a clinical tool to identify those patients with IA whose pain likely incorporates centrally mediated mechanisms. We began by investigating whether there was a placebo response of intra-articular injection in patients with IA 1:1 randomised to receive intra-articular lidocaine or control (0.9% saline). After, in a larger patient cohort not randomized to placebo vs lidocaine groups, we tested whether patients with IA could be stratified into 2 cohorts based on their response to intra-articular lidocaine according to markers of centrally mediated pain. To this end, we evaluated postlidocaine pain numerical rating scale (NRS) scores alongside baseline painDETECT, fibromyalgia criteria fulfillment, and quantitative sensory testing outcomes. Numerical rating scale scores were collected at baseline and 3-, 5-, and 10-minutes postinjection. Firstly, the placebo effect of intra-articular injection was low: compared to baseline, the mean pain NRS score 5-minutes postinjection was reduced by 3.5 points in the lidocaine group vs 1.2 points in the control group. Secondly, postlidocaine NRS scores were significantly higher in those with a high (>18) baseline painDETECT score, fibromyalgia, and low-pressure pain threshold at the trapezius (P = 0.002, P = 0.001, P = 0.005, respectively). Persistent high pain after intra-articular lidocaine injection could be used as an indicator of pronociceptive mechanisms that are centrally mediated, informing centrally targeted analgesic strategies.

Impact of different CRPS phenotypes and diagnostic criteria on quantitative sensory testing outcomes: systematic review and meta-analysis.

This review and meta-analysis evaluated the impact of diagnostic criteria and clinical phenotypes on quantitative sensory testing (QST) outcomes in patients with complex regional pain syndrome (CRPS). Eight databases were searched based on a previously published protocol. Forty studies comparing QST outcomes between CRPS-I vs II, warm vs cold CRPS, upper vs lower limb CRPS, males vs females, or using Budapest vs older IASP criteria were included. Studies investigating QST differences between CRPS-I vs II (n = 4), between males vs females (n = 2), and between upper and lower limb CRPS (n = 2) showed no significant differences. Four studies compared QST outcomes in warm vs cold CRPS, showing heat hyperalgesia in warm CRPS, with thermal and mechanical sensory loss in cold CRPS. Although CRPS diagnosed using the Budapest criteria (24 studies) vs 1994 IASP criteria (13 studies) showed similar sensory profiles, there was significant heterogeneity and low quality of evidence in the latter. Based on the findings of this review, classifying CRPS according to presence or absence of nerve lesion into CRPS-I and II, location (upper or lower limb) or according to sex might not be clinically relevant as all appear to have comparable sensory profiles that might suggest similar underlying mechanisms. In contrast, warm vs cold phenotypes exhibited clear differences in their associated QST sensory profiles. To the extent that differences in underlying mechanisms might lead to differential treatment responsiveness, it appears unlikely that CRPS-I vs II, CRPS location, or patient sex would prove useful in guiding clinical management.

Quantitative Sensory Testing to Characterize Sensory Changes in Hidradenitis Suppurativa Skin Lesions

Pain is the most impactful symptom in patients with hidradenitis suppurativa (HS). Characterization of sensory profiles may improve understanding of pain mechanisms in HS and facilitate identification of effective pain management strategies. To characterize somatosensory profiles in patients with HS at clinically affected and nonaffected sites compared with pain-free reference data. This cross-sectional study was conducted at the Emory University Dermatology Clinic. It was hypothesized (1) that patients with HS would demonstrate hypersensitivity to pain in HS lesions and (2) that some patients would have sensory profiles consistent with complex pain mechanisms. Therefore, adults with dermatologist-diagnosed HS and at least 1 painful HS lesion at the time of testing were enrolled between September 10, 2020, and March 21, 2022. Patients with other diagnoses contributing to pain or neuropathy were excluded. Data analysis was conducted between March and April 2022. Quantitative sensory testing was performed on HS lesions and control skin according to a standardized protocol. Quantitative sensory testing outcomes included innocuous thermal and mechanical sensitivity (cold, warmth, and light touch detection thresholds), noxious thermal and mechanical sensitivity (cold, heat, pinprick, and deep pressure pain thresholds and suprathreshold pinprick sensitivity), temporal summation of pinprick, paradoxical thermal sensations, and dynamic mechanical allodynia (pain upon light stroking of the skin). Sensitivity in HS lesions was compared with sensitivity in a control location (the hand) and in pain-free controls using t tests. This study included 20 participants with a median age of 35.5 (IQR, 30.0-46.5) years, the majority of whom were women (15 [75%]). In terms of race and ethnicity, 2 participants (10%) self-identified as Asian, 11 (55%) as Black, 6 (30%) as White, and 1 (5%) as more than 1 race or ethnicity. Compared with site-specific reference values from healthy, pain-free control participants, HS lesions were insensitive to innocuous cold and warmth, noxious heat, and light touch (t = -5.69, -10.20, -3.84, and 4.46, respectively; all P < .001). In contrast, HS lesions also demonstrated significant hypersensitivity to deep pressure pain (t = 8.36; P < .001) and cutaneous pinprick (t = 2.07; P = .046). Hypersensitivity to deep pressure pain was also observed in the control site (t = 5.85; P < .001). A subset of patients with HS displayed changes in pain processing that are often seen in neuropathic and nociplastic pain conditions, including hypersensitivity to repetitive pinprick (5 [26%]), paradoxical thermal sensations (3 [15%]), and pain upon light stroking of the skin (10 [50%]). The findings of this cross-sectional study suggest that HS involves local changes in the skin or its free nerve endings, possibly leading to peripheral neuropathy and alterations in the transduction of innocuous and noxious thermal and mechanical stimuli. For some patients, central nervous system changes in somatosensory processing may also occur, but confirmatory evidence is needed. Better understanding of neuropathic and nociplastic mechanisms in HS pain could lead to individually tailored treatments.

No effect of social interaction on experimental pain sensitivity: a randomized experimental study.

Quantitative sensory testing (QST) is a commonly applied paradigm to investigate pain, which is a subjective experience influenced by a myriad of social and contextual factors. Therefore, it is important to consider the potential sensitivity of QST to the test setting and the social interaction that naturally is a part of it. This may particularly be the case in clinical settings where patients have something at stake. Therefore, we investigated differences in pain responses using QST in different test setups with varying degrees of human interaction. In a parallel three-armed randomized experimental study, we included 92 participants with low back pain and 87 healthy volunteers allocated to 1 of the 3 QST setups: 1 setup with manual tests performed by a human tester, 1 setup with automated tests performed by a robot and orally guided by a human tester, and 1 setup with automated tests performed solely by a robot without social interaction with a human tester. All 3 setups consisted of the same pain tests in the same order, including pressure pain threshold and cold pressor tests. We found no statistically significant differences between setups on the primary outcome of conditioned pain modulation nor any secondary QST outcomes. While this study is not without limitations, the results indicate that QST procedures are robust enough not to be influenced by social interaction to an appreciable degree.

Outcomes of a QST Protocol in Healthy Subjects and Chronic Pain Patients: A Controlled Clinical Trial.

Chronic pain is an important cause of disability with a high burden to society. Quantitative sensory testing (QST) is a noninvasive multimodal method used to discriminate the function of nerve fibers. The aim of this study is to propose a new, reproducible, and less time-consuming thermal QST protocol to help characterize and monitor pain. Additionally, this study also compared QST outcomes between healthy and chronic pain subjects. Forty healthy young/adult medical students and fifty adult/elderly chronic pain patients were evaluated in individual sessions including pain history, followed by QST assessments divided into three proposed tests: pain threshold, suprathreshold, and tonic pain. In the chronic pain group, a significantly higher pain threshold (hypoesthesia) and a higher pain sensibility (hyperalgesia) were demonstrated at threshold temperature when compared to healthy participants. The sensitivity to the suprathreshold and tonic stimulus did not prove to be significantly different between both groups. The main results demonstrated that the heat threshold QST tests can be helpful in evaluating hypoesthesia and that the sensitivity threshold temperature test can demonstrate hyperalgesia in individuals with chronic pain. In conclusion, this study demonstrates the importance of using tools such as QST as a complement to detect changes in several pain dimensions.

Assessing central sensitization with quantitative sensory testing in inflammatory rheumatic diseases: A systematic review.

The major therapeutic challenge in inflammatory rheumatic diseases is the persistence of pain despite good responses to specific therapies. Central sensitization, which can be assessed clinically by psychophysical measurements, including quantitative sensory testing (QST), is a widely proposed mechanism for chronic pain. In this systematic review, we explored the scientific literature addressing quantitative sensory testing in inflammatory rheumatic diseases. We searched Pubmed and Embase for publications up to December 2021 concerning studies on quantitative sensory testing focusing on pain thresholds, temporal summation (TS) and conditioned pain modulation (CPM), in adult patients with chronic inflammatory rheumatism (e.g. rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, juvenile idiopathic arthritis). The exclusion criteria were reviews, inclusion of children and no reported pain threshold. Data quality was assessed with the National Institutes of Health (NIH) Quality Assessment tools. We identified 27 studies (18 controlled, 9 uncontrolled) including 1875 patients with inflammatory rheumatic diseases and 795 controls. A decrease in pressure pain threshold, in favor of allodynia, was found in 12 of 14 controlled studies on patients with rheumatoid arthritis and spondyloarthritis. The results of other psychophysical tests, including TS and CPM, were inconsistent due to population heterogeneity and a lack of standardization of the patients' disease duration, activity and treatment. Our review shows that pain in chronic inflammatory rheumatism is associated with pressure allodynia. However, given the heterogeneous quality and discrepant results of studies of other QST outcome measures, the hypothesis of central sensitization involvement in pain processing in these patients cannot be confirmed.

Differences in Quantitative Sensory Testing Outcomes Between Patients With Low Back Pain in Primary Care and Pain-free Controls.

Quantitative Sensory Testing (QST) is used to test somatosensory functioning in on people with chronic LBP in secondary/tertiary health care facilities. Studies using QST-testing on LBP populations in primary care are scarce. Central Sensitization Inventory (CSI) measures central sensitization (CS)-related symptoms and studies investigating the differences between QST-testing and participants with LBP with a positive and negative score on the CSI questionnaire are also rare. This case-control study investigates differences of an extensive QST-measurement between patients with acute, chronic LBP, and pain-free controls (PFCs) in primary care. Secondary aim is to investigate differences of an extensive QST-measurement between "CS" and "no-CS" group. Participants with LBP were recruited from November 2016 to October 2019. Demographic and clinical information was collected and a standardized QST protocol was taken. Data analysis involved determining differences between groups. Data of 100 participants with LBP and 50 PFCs were analyzed. Heat pain thresholds, pressure pain threshold, and conditioned pain modulation local and remote were significantly moderately to relatively strongly affected by acute, chronic LBP and PFCs (P<0.001 to 0.001). Lumbar temporal summation was significantly moderately affected by acute, chronic LBP, and PFCs (P=0.001). Only pressure pain threshold showed significant difference between "CS" and "no-CS" group (P=0.001 to 0.002). Signs of enhanced nociceptive processing and disturbed top-down nociceptive modulation are apparent in people with acute and chronic LBP in primary care. Results indicate existence of central mechanisms in LBP in primary care.

Observing Altered Nociceptive Detection Thresholds in Patients With Persistent Spinal Pain Syndrome Type 2 With a Dorsal Root Ganglion Stimulator

ObjectivesThere is a lack of clinically relevant measures for quantification of maladaptive mechanisms of the nociceptive system leading to chronic pain. Recently, we developed a method that tracks nociceptive detection thresholds (NDTs) using intraepidermal electrical stimulation. In this study, we explored the feasibility of using this NDT method in patients with persistent spinal pain syndrome type 2 (PSPS-T2) and its potential to enable observation of altered nociceptive processing induced by dorsal root ganglion (DRG) stimulation. In addition, we compared NDTs with quantitative sensory testing (QST) measurements and numeric rating scale (NRS). Materials and MethodsA total of 12 patients with PSPS-T2 (seven men; 60.4 ± 12.3 years) experiencing chronic unilateral lower limb pain treated with DRG stimulation were included in the study. Both the NDT method and electrical and pressure QST methods were performed twice in the L5 dermatome on both the affected and the unaffected foot, once with the DRG stimulator turned off and, subsequently, once with the DRG stimulator turned on. ResultsThe NDT method can be applied to patients with PSPS-T2. With the DRG stimulator turned off, NDTs on the affected side were significantly higher than on the unaffected side. This difference was no longer present once the DRG stimulator was turned on. Furthermore, DRG stimulation affected QST (electrical and pressure) values and NRS scores. Finally, NDTs showed larger contrasts between the sides than QST measures. ConclusionsThe NDT method permitted observation of altered nociceptive function. The effect of DRG stimulation also was reflected in QST outcomes and NRS scores. The larger contrast between the sides for NDTs suggests that the NDT method might be valuable for future quantification of nociceptive dysfunction in chronic pain.

Pain mechanisms in carpal tunnel syndrome: a systematic review and meta-analysis of quantitative sensory testing outcomes.

Carpal tunnel syndrome (CTS) is the most common nerve compression in the arm. A mix of peripheral and central contributions on quantitative sensory testing (QST) has been reported in the literature. Thus, this systematic review or meta-analysis aimed to identify the dominant sensory phenotype and draw conclusive evidence about the presence of central sensitization (CS) in CTS. Based on an a priori published protocol and using PRISMA guidelines, 7 databases were searched (Embase, Web of Science, Scopus, PubMed, SAGE, EBSCOhost, and ProQuest). Eligible studies compared the QST findings of individuals with subacute and chronic CTS with those of healthy controls through thermal, mechanical, and vibration detection thresholds; thermal, pressure, and mechanical pain thresholds; mechanical pain sensitivity; presence of allodynia; wind-up ratio; and conditioned pain modulation. Thirty-seven studies were included in the qualitative analysis. Results showed a significant loss of all detection thresholds of hand median nerve territories and hand extramedian areas (little finger and hand dorsum) in CTS ( P < 0.05) but no significant difference ( P > 0.05) in wind-up ratio, cold, heat, or mechanical pain thresholds of the median nerve territories. Furthermore, there was a significant increase in mechanical pain sensitivity in median nerve territories and remotely in the forearm ( P < 0.05) and a significant gain in pressure and heat pain thresholds in the carpal area ( P < 0.05). Conditioned pain modulation was impaired in CTS. Hypoesthesia and increased thermal and mechanical pain ratings are the dominant sensory phenotype with inconclusive evidence about CS in CTS due to the heterogenous results of thermal and mechanical pain thresholds.

Experimental Pain and Auditory Sensitivity in Overactive Bladder Syndrome: A Symptoms of the Lower Urinary Tract Dysfunction Research Network (LURN) Study.

The objective of this study was to investigate the presence of nonbladder sensory abnormalities in participants with overactive bladder syndrome (OAB). Symptoms of Lower Urinary Tract Dysfunction Research Network (LURN) study participants with OAB symptoms and controls were recruited from 6 U.S. tertiary referral centers. Quantitative sensory testing (QST) was performed to determine pressure pain sensitivity at the thumbnail bed and auditory sensitivity. Fixed and mixed effect multivariable linear regressions and Weibull models were used to compare QST responses between groups. Pearson correlations were used to assess the relationship between QST measures. Associations between QST and self-reported symptoms were explored with linear regression. A total of 297 participants were analyzed (191 OAB, 106 controls; 76% white, 51% male). OAB cases were older than controls (57.4 vs 52.2 years, p=0.015). No significant differences in experimental thumbnail (nonbladder) pain or auditory sensitivity were detected between OAB cases and controls. Correlations between pressure and auditory derived metrics were weak to moderate overall for both groups, with some significantly stronger correlations for cases. Exploratory analyses indicated increased pressure pain and auditory sensitivity were modestly associated with greater self-reported bladder pain and pain interference with physical function. As a group, no significant differences between OAB cases and controls were observed in experimental nonbladder pain or auditory sensitivity during QST. Associations between QST outcomes and clinical pain raise the possibility of centrally mediated sensory amplification in some individuals with OAB.

Methadone maintenance patients lack analgesic response to a cumulative intravenous dose of 32 mg of hydromorphone

ObjectivesAcute pain management in patients with opioid use disorder who are maintained on methadone presents unique challenges due to high levels of opioid tolerance in this population. This randomized controlled study assessed the analgesic and abuse liability effects of escalating doses of acute intravenous (IV) hydromorphone versus placebo utilizing a validated experimental pain paradigm, quantitative sensory testing (QST). MethodsIndividuals (N = 8) without chronic pain were maintained on 80−100 mg/day of oral methadone. Participants received four IV, escalating/incremental doses of hydromorphone over 270 min (32 mg total) or four placebo doses within a session test day. Test sessions were scheduled at least one week apart. QST and abuse liability measures were administered at baseline and after each injection. ResultsNo significant differences between the hydromorphone and placebo control conditions on analgesic indices for any QST outcomes were detected. Similarly, no differences on safety or abuse liability indices were detected despite the high doses of hydromorphone utilized. Few adverse events were detected, and those reported were mild in severity. ConclusionsThe findings demonstrate that methadone-maintained individuals are highly insensitive to the analgesic effects of high-dose IV hydromorphone and may require very high doses of opioids, more efficacious opioids, or combined non-opioid analgesic strategies to achieve adequate analgesia.

Drop homotopic effects of masseter-muscle pain on somatosensory sensitivity in healthy participants

Current pain classifications use 1.0-kg palpation of the masseter muscle to distinguish between “pain patients” and “healthy controls” but a thorough understanding of the normal physiological responses to various somatosensory stimuli is lacking. The aim of this study was to investigate somatosensory function of the skin over the masseter muscle in healthy participants that were divided into a masseter pain prone group (MPP) (n = 22) and non-MPP group (n = 22), according to the response to a 1.0-kg palpation. Quantitative sensory testing (QST) was performed at the skin above the right masseter muscle (homotopic). In an additional experiment, 13 individuals each from MPP and non-MPP received application of 60% topical lidocaine tape to the skin over the masseter muscle for 30 min. Immediately after, mechanical pain sensitivity (MPS), dynamic mechanical allodynia, and pressure pain threshold were tested. Homotopic MPS was significantly higher and PPTs significantly lower in MPP than in N-MPP (P < 0.05). Strikingly, no other differences in QST outcomes were observed between the groups (P > 0.05). After lidocaine application, no significant differences in homotopic MPS were observed between groups. The presence or absence of acute provoked pain in masseter muscle is exclusively associated with differences in homotopic MPS which is decreased following topical anesthesia.

Noninvasive motor cortex stimulation effects on quantitative sensory testing in healthy and chronic pain subjects: a systematic review and meta-analysis.

One of the potential mechanisms of motor cortex stimulation by noninvasive brain stimulation (NIBS) effects on pain is through the restoration of the defective endogenous inhibitory pain pathways. However, there are still limited data on quantitative sensory testing (QST), including conditioned pain modulation (CPM), supporting this mechanism. This systematic review and meta-analysis aimed to evaluate the effects of noninvasive motor cortex stimulation on pain perception as indexed by changes in QST outcomes. Database searches were conducted until July 2019 to include randomized controlled trials that performed sham-controlled NIBS on the motor cortex in either the healthy and/or pain population and assessed the QST and CPM. Quality of studies was assessed through the Cochrane tool. We calculated the Hedge's effect sizes of QST and CPM outcomes and their 95% confidence intervals (95% CIs) and performed random-effects meta-analyses. Thirty-eight studies were included (1178 participants). We found significant increases of pain threshold in healthy subjects (ES = 0.16, 95% CI = 0.02-0.31, I2 = 22.2%) and pain populations (ES = 0.48, 95% CI = 0.15-0.80, I2 = 68.8%), and homogeneous higher CPM effect (pain ratings reduction) in healthy subjects (ES = -0.39, 95% CI = -0.64 to -0.14, I2 = 17%) and pain populations (ES = -0.35, 95% CI = -0.60 to -0.11, I2 = 0%) in the active NIBS group compared with sham. These results support the idea of top-down modulation of endogenous pain pathways by motor cortex stimulation as one of the main mechanisms of pain reduction assessed by QST, which could be a useful predictive and prognostic biomarker for chronic pain personalized treatment with NIBS.

Characterization of chemotherapy-induced peripheral neuropathy (CIPN) using patient-reported outcomes (PRO) and quantitative sensory testing (QST).

e24078 Background: CIPN is a common, potentially debilitating, and dose-limiting side effect experienced by cancer survivors. CIPN encompasses symptoms such as pain, numbness, and tingling, which can be measured subjectively by PRO, or semi-objectively by QST; however, little is known about how QST measures differ among patients with and without CIPN, or if QST outcomes correlate with symptom profiles measured by PRO. Methods: CIPN is a common, potentially debilitating, and dose-limiting side effect experienced by cancer survivors. CIPN encompasses symptoms such as pain, numbness, and tingling, which can be measured subjectively by PRO, or semi-objectively by QST; however, little is known about how QST measures differ among patients with and without CIPN, or if QST outcomes correlate with symptom profiles measured by PRO. Results: 116 patients with CIPN and 10 control patients without CIPN were analyzed. NRS and FACT/GOG-Ntx scores were significantly worse in the CIPN group compared to controls (all p&lt; 0.001). The mean (Standard Deviation) TT for CIPN and control patients was 3.61 (0.43) and 3.38 (0.32), respectively (p = 0.059), in hands; and 3.86 (0.70) and 3.38 (0.56), respectively (p = 0.043), in feet. The mean VT was 6.06 (3.45) and 3.87 (1.01), respectively (p=0.032), in hands; and 19.14 (11.09) and 8.43 (3.22), respectively (p&lt;0.001), in feet. There was no significant difference in THT between groups. The correlation coefficients between PRO with QST measures in all patients are listed in the table below. Conclusions: Our study suggested that patients with CIPN have significantly worse symptoms and tactile and vibratory threshold measured by QST when compared with controls. Mild to moderate correlations were observed between PROs and QST, suggesting that CIPN symptoms severity correspond to sensory sensitivity. As CIPN presents a diverse range of symptoms, improved quantification of subjective and objective measures for CIPN can help the incorporation of these tools into future clinical trials. Clinical trial information: NCT03183037 and NCT03292328 . [Table: see text]

Cannabinoid effects on responses to quantitative sensory testing among individuals with and without clinical pain: a systematic review.

There has been an explosion of interest in the utility of cannabinoids as potential analgesics. This systematic review critically synthesizes the evidence for cannabinoid analgesic effects on quantitative sensory testing outcomes in both healthy adults and patients with chronic noncancer pain. Our systematic review protocol is preregistered on PROSPERO (CRD42018117367). An electronic search was made in PsycINFO, Cochrane, Google Scholar, Embase, and Pubmed of all literature published until August 2018. Of the 1217 studies found from the search, a total 39 placebo-controlled studies that met the eligibility criteria were synthesized for this study. Because of substantial heterogeneity of study designs, populations, cannabinoid compounds, and quantitative sensory testing outcomes, meta-analysis was not conducted. More consistent evidence of cannabinoid analgesia was observed for inhaled cannabis than synthetic cannabinoids. Analgesic effects were most commonly observed in tests of cold pain sensitivity, and hyperalgesic effects were most commonly observed in tests of electrical stimulation. Patterns of findings from studies with healthy subjects did not substantively differ from those with chronic noncancer pain. However, these observations are qualified by the high degree of inconsistency across studies and methodological heterogeneity. We offer recommendations for future studies to improve study rigor and reproducibility.

Pain Mechanisms in Low Back Pain: A Systematic Review With Meta-analysis of Mechanical Quantitative Sensory Testing Outcomes in People With Nonspecific Low Back Pain.

Mechanical quantitative sensory testing (QST) assesses sensory functioning and detects functional changes in (central) nociceptive processing. It has been hypothesized that these functional changes might be apparent in people with nonspecific low back pain (LBP), although the results are mixed. The aim of this systematic review was to examine whether sensory function, measured with QST, was altered in people with nonspecific LBP. This systematic review was conducted according to PRISMA guidelines. Six databases were searched for relevant literature. Studies comparing mechanical QST measures involving people with subacute and chronic LBP and healthy controls were included if (1) pressure pain thresholds (PPTs), (2) temporal summation, or (3) conditioned pain modulation were reported. Risk of bias was assessed using the Newcastle-Ottawa scale. When possible, the results from different studies were pooled. Twenty-four studies were included. Scores on the Newcastle-Ottawa scale varied between 1 and 6 points. People with nonspecific LBP, compared to healthy controls, had significantly lower PPTs at remote sites and increased temporal summation at the lower back. The PPTs measured at the scapula were significantly lower in patients with nonspecific LBP than in healthy controls (pooled mean difference, 119.2 kPa; 95% confidence interval: 91.8, 146.6 kPa; P<.001). The PPT measurements at remote body parts were significantly lower in people with nonspecific LBP compared with healthy controls. Temporal summation and conditioned pain modulation measurements had mixed outcomes. Therapy, level 3a. J Orthop Sports Phys Ther 2019;49(10):698-715. Epub 23 Aug 2019. doi:10.2519/jospt.2019.8876.

Sensory Function and Pain Experience in Arthritis, Complex Regional Pain Syndrome, Fibromyalgia Syndrome, and Pain-Free Volunteers: A Cross-Sectional Study.

This study aimed to identify relationships between sensory function and pain in 3 common pain conditions (arthritis, Complex Regional Pain Syndrome [CRPS] and fibromyalgia syndrome [FMS]) and pain-free participants. Sensory abnormalities are known to be concomitant with some types of chronic pain but comparison across pain conditions using existing research is difficult due to methodological differences. Pragmatic Quantitative Sensory Testing (QST) methods were used. Hot and cold sensitivity, light touch threshold (LTT), two-point discrimination and pain threshold were assessed in 143 participants (n=37 pain-free, n=34 arthritis, n=36 CRPS, n=36 FMS). Outcomes were assessed in the index ("affected" or right) and contralateral arm. Participants also completed the Brief Pain Inventory and the McGill Pain Questionnaire. There were statistically significant differences between groups for all QST outcomes except two-point discrimination. Relative to pain-free participants, FMS displayed heat hyperesthesia in both arms and cold hyperesthesia in the contralateral arm. CRPS demonstrated no changes in thermal sensitivity. Both CRPS and FMS exhibited bilateral pressure hyperalgesia. LTT hypoesthesia was observed bilaterally for CRPS but only in the contralateral arm for FMS. CRPS and FMS had pressure hyperalgesia in the index arm relative to arthritis patients. There were no differences between arthritis and pain-free participants for any QST outcome. In CRPS, there were significant correlations between LTT and pain outcomes bilaterally. People with FMS and CRPS demonstrate extensive sensory dysfunction. Arthritis patients had sensory profiles closer to pain-free participants. LTT may provide a clinically relevant and accessible assessment for CRPS.

(327) Exactly What You Think: Perceived Threat and Challenge Predict Quantitative Sensory Testing Outcomes in Temporomandibular Joint Disorder

While perceived threat (anticipated harm) and challenge (test of abilities) have been previously found to predict pain intensity ratings to thermal stimuli in healthy populations, few studies have assessed the relationship between threat and challenge and experimental pain outcomes in patients with chronic pain. This study examined associations of perceived threat and challenge on quantitative sensory testing (QST) outcomes in patients with temporomandibular joint disorder (TMJD) and healthy controls. In the present study, 40 adults with TMJD (n = 35 female, mean age = 30.4, SD = 6.19) and 22 healthy controls (n = 18 female, mean age = 27.8, SD = 7.07) provided separate ratings of threat and challenge immediately prior to completing painful heat, pressure, and punctate QST. Participants provided ratings of pain intensity following each stimulus. In both patients with TMJD and healthy controls, challenge ratings correlated with ratings of thermal pain intensity (r= .30, p = .02), while ratings of both challenge and threat correlated with ratings of pressure and punctate pain intensity (r’s = .36 - .50, p’s .05). These results replicate and extend prior research by demonstrating that perceived threat and challenge of a QST procedure can predict pain outcomes in patients with chronic pain. Future research should explore relationships between perceptions of threat and challenge with other QST modalities (i.e., delayed-onset muscle pain, electric pain), and explore how perception of QST parameters may influence pain chronicity. Supported by NIDCRR00DE022368-03.

Experimental pain tolerance is decreased and independent of clinical pain intensity in patients with endometriosis

To investigate alterations in tactile, pain thresholds and pain tolerance thresholds in patients with endometriosis using a multimodality approach. Cross-sectional study. Multidisciplinary referral center. Women with proven endometriosis (N = 35) and healthy controls (N = 38). Pain processing was tested using quantitative sensory testing (QST) to investigate sensation, pain, and pain tolerance thresholds for thermal, electrical, and pressure stimuli. Differences in QST measures in patients with endometriosis and in healthy controls on the endometriosis site and control sites, and the association between QST outcomes and patient characteristics. We observed a significantly decreased pain tolerance in patients with endometriosis, independent of clinical pain intensity or revised American Society for Reproductive Medicine stage, compared with healthy controls. Increasing knowledge concerning mechanisms underlying the pain of women with endometriosis creates opportunities to develop new treatment options. More attention should be paid not only to treat endometriosis in a surgical or pharmacologic way, but also to desensitize by pain education or cognitive therapy.

Evidence for Central Sensitization in Patients with Temporomandibular Disorders: A Systematic Review and Meta-analysis of Observational Studies.

Several authors have evaluated different pain measurements, including quantitative sensory testing (QST), temporal summation (TS), and conditioned pain modulation (CPM) in order to determine the presence of central sensitization (CS) and its influence on patients with temporomandibular disorders (TMD). Since there are no convincing studies about this topic, the purpose of this study was to conduct a review of the studies involving CS-related measures in TMD patients. A meta-analysis of case-control and cohort/cross sectional studies was conducted. Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated for relevant QST outcomes and pooled in a meta-analysis using the random effects model. Twenty-two studies (eleven case-control and eleven cross sectional studies) met the inclusion criteria; eight were included in the meta-analysis (five cross-sectional and three case-control). Patients with TMD had decreased pressure pain thresholds in both trigeminal (five studies; n = 1,985; SMD = -1.55, 95% CI -2.23 to -0.77; P < 0.01) and remote areas (five studies; n = 1,985; SMD = -1.92, 95% CI -2.95 to -0.89; P < 0.01). When analyzing for thermal hyperalgesia (hot and cold pain thresholds), differences were not found in trigeminal areas or remote areas in patients with TMD. The TS qualitative analysis showed strong evidence of spinal hyperexcitability for mechanically evoked pain. These meta-analyses support the existence of differences in widespread pressure pain sensitivity in patients with TMD when compared with asymptomatic subjects. Spinal and central hyperexcitability can be found in TMD patients as shown by an increase in mechanical TS.