Pressure Pain Threshold Testing Research Articles

Effects of high frequency strengthening on pain sensitivity and function in female runners with chronic patellofemoral pain

ObjectiveTo investigate the effects of a high frequency strengthening program on function, pain, and pain sensitization in female runners with chronic patellofemoral pain (PFP). DesignCross-sectional study. SettingUniversity laboratory. ParticipantsThirty female runners (mean age 32 ± 8.1 years) with chronic PFP completed an 8-week home strengthening program. Main outcome measuresVariables assessed at baseline, 8-weeks, and 12 weeks included single leg step down test (SLSD), pain, Anterior Knee Pain Scale (AKPS), University of Wisconsin Running Injury and Recovery Index (UWRI), and quantitative sensory testing. ResultsThere was large and statistically significant improvement at 8 and 12 weeks for average knee pain (ηp2 = 0.334, p < 0.001), worst knee pain (ηp2 = 0.351, p < 0.001), SLSD (ηp2 = 0.161, p = 0.001), AKPS (ηp2 = 0.463, p < 0.001), and UWRI (ηp2 = 0.366, p < 0.001). A medium to large effect and statistically significant improvement in pressure pain threshold testing was found for all local and remote structures (ηp2 range, 0.110 to 0.293, range p < 0.001 to p = 0.009) at 8 and 12 weeks. ConclusionsThere was a significant decrease in local and remote hyperalgesia via mechanical and thermal pain sensitivity testing in female runners with chronic PFP. There was a large effect and significant improvement in self-reported pain and function.

Interhemispheric Inhibition Between Primary Motor Cortices is Not Altered in Individuals With Chronic Lateral Epicondylalgia

Lateral epicondylalgia (LE), commonly referred to as tennis elbow, is a musculoskeletal condition characterized by pain and sensorimotor dysfunction. In some individuals with chronic unilateral LE, sensorimotor symptoms develop on the unaffected side despite no evidence of tissue damage. Altered interhemispheric inhibition (IHI) is one mechanism that could underpin this phenomenon. The aim of this cross-sectional study was to examine IHI between the primary motor cortices (M1) in individuals with chronic LE and healthy controls. In 20 individuals with chronic LE and 20 healthy participants, transcranial magnetic stimulation was used to assess 1) short and long-latency IHI from the affected (corresponding to the injured side) to the unaffected M1 and 2) corticomotor excitability of the affected and unaffected M1. Sensorimotor function was evaluated bilaterally at the extensor carpi radialis brevis muscle using pressure pain threshold, grip strength, 2-point discrimination, and temporal summation tests. Short- and long-latency IHI from the affected to the unaffected M1 and corticomotor excitability of the affected and unaffected M1 were not altered in individuals with LE compared with healthy participants. No differences in sensorimotor function were observed for the affected or unaffected extensor carpi radialis brevis muscles when individuals with LE were compared with healthy participants. IHI is not altered in individuals with chronic LE. Further studies are required to determine the mechanisms that underpin the development of bilateral sensorimotor symptoms in unilateral LE. PerspectiveIHI is unaltered from the affected M1 (corresponding to the painful muscle) to unaffected M1 in individuals with LE compared to healthy controls. The absence of bilateral sensorimotor dysfunction and low pain severity in this cohort of individuals with LE may explain this finding.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

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.

Signs of Nervous System Sensitization in Female Runners with Chronic Patellofemoral Pain.

Patellofemoral pain (PFP) is a common overuse injury among runners, affecting females at a higher rate than males. PFP can often become chronic, with evidence suggesting it may be linked to both peripheral and central sensitization of the nervous system. Sensitization of the nervous system can be identified through quantitative sensory testing (QST). The primary objective of this pilot study was to quantify and compare pain sensitivity as identified through QST measures, in active female runners with and without PFP. Cohort Study. Twenty healthy female runners and 17 female runners with chronic PFP symptoms were enrolled. Subjects completed the Knee injury and Osteoarthritis Outcome Score for Patellofemoral Pain (KOOS-PF), University of Wisconsin Running Injury and Recovery Index (UWRI), and the Brief Pain Inventory (BPI). QST consisted of pressure pain threshold testing to three local and three distant sites to the knee, heat temporal summation, heat pain threshold, and conditioned pain modulation. Data was analyzed utilizing independent t-tests for comparison of between-group data, effect sizes for QST measures (Pearson's r), and Pearson's correlation coefficient between pressure pain threshold values at the knee and functional testing. The PFP group exhibited significantly lower scores on the KOOS-PF (p<0.001), BPI Pain Severity and Interference Scores (p<0.001), and UWRI (p<0.001). Primary hyperalgesia, identified through decreased pressure pain threshold at the knee, was detected in the PFP group at the central patella (p<0.001), lateral patellar retinaculum (p=0.003), and patellar tendon (p=0.006). Secondary hyperalgesia, a sign of central sensitization, was observed via differences in pressure pain threshold testing for the PFP group at the uninvolved knee (p=0.012 to p=0.042), involved extremity remote sites (p=0.001 to p=0.006), and uninvolved extremity remote sites (p=0.013 to p=0.021). Compared to healthy controls, female runners with chronic PFP symptoms exhibit signs of both peripheral sensitization. Despite actively participating in running, nervous system sensitization may contribute to continued pain in these individuals. For female runners with chronic PFP, physical therapy management may need to include interventions which address signs of central and peripheral sensitization. Level 3.

Effect of single end-range and not end-range Maitland mobilization on pressure pain threshold and functional measures in knee osteoarthritis: randomised, controlled clinical trial.

Hyperalgesia is attributed to peripheral and central sensitization in knee osteoarthritis (OA). Pressure pain threshold (PPT) is a relevant method for evaluating pain sensitivity in knee OA. The effect of end-range and not end-range Maitland mobilization for certain time-period on pain sensitivity has not been investigated in knee OA. The aim of this study was to investigate the effect of end-range and not end-range Maitland mobilization compared to sham manual therapy technique on PPT and functional measures. Randomised, controlled clinical trial. Outpatient setting. Sixty-six patients with mild-to-severe knee OA. Twenty-one patients (N.=21) received end-range Maitland mobilization (EMGr), twenty patients (N.=20) received not end-range Maitland mobilization (nEMGr) and twenty-two patients (N.=22) received sham manual therapy technique (CG). All interventions were performed once. Evaluation was conducted pre-, postintervention and on the following consecutive second days within a 6-day period. Outcomes were local and distant PPT, Timed Up and Go Test (TUG) and strength of passive resistance of knee at onset of pain. Local and distant PPT increased, TUG time and strength of passive resistance decreased immediately, local and distant PPT remained decreased in 6-day and 4-day period, TUG time remained decreased in 6-day period in EMGr (all changes P≤0.017). Local PPT increased immediately compared to baseline in nEMGr. In between group comparison, increase of local, distant PPT and strength of passive resistance endures on 2nd day, 4th day and postintervention, respectively, in EMGr compared to CG. EMGr compared to nEMGr presented significant difference on 6th day and 4th day in local and distant PPT, respectively (all changes P≤0.021). NEMGr presented no significant difference compared to CG on either follow-up. Single end-range Maitland mobilization is effective immediately and in 4-day period on pain sensitization and immediately on physical function compared to not end-range Maitland mobilization and sham manual therapy technique in knee OA. Based on the present results, applying end-range Maitland mobilization is suggested on every second day to maintain alleviation of pain sensitization and increasing passive knee joint mobility effectively in knee OA.

Is low intensity exercise sufficient to induce exercise-induced pain threshold modulation in people with persistent pain?

ObjectivesWe investigated whether a 12-min walk test (12MWT) yielded exercise-induced pain threshold modulation (EIPM) within people with persistent pain and whether baseline self-report and pain sensitivity measures differed according to these responses. DesignCross-sectional study. MethodsTwo cohorts (tertiary/community) (n = 88) with persistent pain underwent pressure pain threshold (PPT) testing before and after a 12MWT to determine exercise-induced pain threshold modulation responses. Baseline self-report (pain severity, pain distribution, psychological distress, sleep) and baseline widespread pain sensitivity (WPS) (high/low) were recorded. Within and between-group differences were analysed using paired t-tests and repeated measure analyses of covariance. Individual EIPM responses were categorised as hyperalgesic, no change and hypoalgesic responses. Differences in baseline self-report and pain sensitivity measures between EIPM categories were investigated. ResultsNo significant within- or between-group differences in PPT following the 12MWT were detected (p > 0.05). Individual responses showed that up to 30% of the community and 44% of the tertiary cohort demonstrated >20% change in PPT (in either direction). Significant differences were shown in pain distribution (p = 0.002) and baseline WPS (p = 0.001) between people with hyperalgesic, no change, hypoalgesic responses. People with 4–5 pain regions were more likely hyperalgesic (χ2 = 9.0, p = 0.003); people with low baseline WPS were more likely to demonstrate no change (p = 0.002). ConclusionLow or self-selected intensity exercise was insufficient to induce exercise-induced pain modulation at group level. Individual responses were variable with pain distribution and baseline WPS differing between responses. Future research could evaluate responses and associated factors in larger samples with high baseline pain sensitivity specifically.

Susceptibility to movement-evoked pain following resistance exercise.

ObjectiveTo investigate the: (1) role of basic muscle pain sensitivity and psychological factors in the prediction of movement-evoked pain (MEP) following delayed onset muscle soreness (DOMS), and (2) association of MEP with changes in systemic muscle pain sensitivity following DOMS induction.MethodsFifty-one participants were assigned to either eccentric resistance exercise or control groups. They completed questionnaires evaluating psychological distress and underwent muscle pain sensitivity evaluation by the pressure pain threshold (PPT) test at the exercised and remote muscles, before and 24 hours following the intervention. MEP intensity was determined in response to lifting a 3kg canister using a visual analogue scale (VAS).ResultsThe exercise group demonstrated MEP intensity of 5/10 on VAS and reduced PPTs at the main exercised muscle (p<0.001). A regression tree analyses revealed that the level of anxiety trait predicted a higher MEP intensity. A secondary analysis showed that 53% participants who were DOMS responders (MEP > mild intensity; ≥ 3/10 VAS) exhibited decreased PPTs in the exercised (p<0.001) and remote (p = 0.027) muscles following eccentric exercise. Characterization of DOMS responders revealed that, at baseline, they had lower PPTs in the exercised (p = 0.004) and remote (p = 0.001) muscles and reported higher psychological distress i.e., anxiety trait and depression symptoms (p<0.05), compared to non-responders. A regression analysis revealed that lower PPT or high levels of anxiety trait increased the probability to become a responder (p = 0.001).ConclusionsSusceptibility to MEP following DOMS is determined by muscle pain hypersensitivity and high levels of anxiety trait. MEP at the early stage of DOMS is linked with an increase in systemic muscle pain sensitivity suggestive of central mechanisms. This knowledge is valuable in translating science into clinical musculoskeletal pain management.

The associations of psychological symptoms and cognitive patterns with pain and pain sensitization in people with hand osteoarthritis

ObjectiveTo examine whether psychological symptoms and cognitive patterns are associated with self-reported pain and pain sensitization in people with hand osteoarthritis (OA). DesignIn the Nor-Hand study (n ​= ​300), people with hand OA self-reported psychological symptoms (Hospital Anxiety and Depression Scale), cognitive patterns (Pain catastrophizing Scale and Arthritis Self-Efficacy Scale) as well as their pain severity in hands, overall pain and multi-joint pain. Central pain sensitization was measured clinically by temporal summation and pressure pain threshold tests. We examined whether psychological symptoms and cognitive patterns were cross-sectionally associated with pain using linear regression. Beta coefficients (β) per one standard deviation of the independent variable were presented. Stratified analyses were performed in cases of significant interactions (p ​< ​0.10). ResultsHigher levels of anxiety, depressive symptoms and pain catastrophizing and low levels of self-efficacy were statistically significantly associated with higher levels of hand pain by Numeric Rating Scale (β ​= ​0.43, 0.48 and −0.57, respectively). Similar associations were found for overall pain, but not for measures of central pain sensitization. In stratified analyses, anxiety and depressive symptoms were more strongly related with pain in subgroups with younger age and higher comorbidity burden. Pain catastrophizing was more strongly related with pain in subgroups with younger age, overweight/obesity, higher comorbidity burden and poor sleep. ConclusionPsychological symptoms and cognitive patterns were associated with self-reported OA pain, especially in people with younger age, overweight/obesity, higher comorbidity burden and poor sleep. No associations were found for psychological symptoms and cognitive patterns with pain sensitization.

Intra-rater and inter-rater reliability of pressure pain threshold assessment in stroke patients.

As pain is a common symptom following a stroke, pressure pain threshold (PPT) assessment can be used to evaluate pain status or pain sensitivity of patients. However, the reliability of PPT test in stroke patients is still unknown. To examine the intra- and inter-rater reliability of PPT measurements in poststroke survivors and explore their factors. An observational study. The setting of the study is a rehabilitation hospital. The population of the study was represented by a total of 54 patients after stroke. The study included 16 measured points on the affected and unaffected sides. PPT was assessed by two raters in turn. Intra- and inter-rater reliability was evaluated by intraclass correlation coefficients (ICC). All intra-rater (ICC=0.84-0.97) and inter-rater (ICC=0.83-0.95) reliability for PPT assessment were good or excellent in stroke patients. Of the 16 points, 12 showed higher intra-rater ICC values than inter-rater, whereas no evident difference was observed between the affected and unaffected sides. Furthermore, patients who were male, ischemic, or with higher motor function generally performed higher ICC values than those who were female (24 out of 32 results), hemorrhagic (28 out of 32 results), or mobility dysfunction (26 out of 32 results), respectively. PPT assessment with good or excellent reliability can be used in stroke patients. Neither of the two sides (affected or unaffected) affects PPT reliability, and intra-rater reliability is better than inter-rater reliability. In addition, gender, stroke type, and motor function can affect the reliability of measuring mechanical pain threshold in poststroke survivors. The pressure algometer can be used as a reliable and portable tool to assess the mechanical pain tolerance and sensory function in stroke patients in clinics.

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. PerspectiveThis 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.

Genicular artery embolization as a novel treatment for mild to moderate knee osteoarthritis: protocol design of a randomized sham-controlled clinical trial

IntroductionKnee osteoarthritis is a common disease with pain as the most prevalent symptom. Previous cohort studies have shown genicular artery embolization to reduce pain symptoms in patients with mild to moderate knee osteoarthritis. Patients resistant to conservative therapy but not eligible yet for surgical treatment due to young age or comorbidities may profit from an effective and sustained pain reduction treatment. This study is a randomized sham-controlled trial to evaluate the efficacy of genicular artery embolization in patients with knee osteoarthritis.Methods and analysisFifty-eight patients with mild-to-moderate knee osteoarthritis will be recruited and randomly allocated to the treatment or control group in a 1:1 ratio. Participants in the treatment group will undergo genicular artery embolization. Patients in the control group will undergo sham treatment. Outcome measurements will be assessed at baseline and after 1, 4, 8, and 12 months with questionnaires, pressure pain threshold testing, and MR imaging. The MR imaging protocol is designed to (semi)quantitatively assess osteoarthritis in the knee joint. The primary outcome is the change from baseline of the Knee injury and Osteoarthritis Outcome Score (KOOS) pain subscale after 4 months. Secondary outcomes include change in osteoarthritis-related questionnaires, pressure pain threshold, and OA-related MRI features, particularly synovitis and bone marrow lesions.Ethics and disseminationThis trial will determine the efficacy of genicular artery embolization compared to a sham treatment. This is of importance to assess before proceeding to larger-scale efficiency studies and, ultimately, implementing this treatment into day to day clinical practice.Trial registrationClinicalTrials.gov NCT03884049. Registered on 21 March 2019

Heritability of musculoskeletal pain and pain sensitivity phenotypes: 2 generations of the Raine Study.

There is a need to better understand biological factors that increase the risk of persistent musculoskeletal (MSK) pain and heightened pain sensitivity. Knowing the heritability (how genes account for differences in people's traits) can enhance the understanding of genetic vs environmental influences of pain and pain sensitivity. However, there are gaps in current knowledge, including the need for intergenerational studies to broaden our understanding of the genetic basis of pain. Data from Gen1 and Gen2 of the Raine Study were used to investigate the heritability of MSK pain and pressure and cold pain sensitivity. Participants included parents (Gen1, n = 1092) and their offspring (Gen2, n = 688) who underwent a battery of testing and questionnaires including pressure and cold pain threshold testing and assessments of physical activity, sleep, MSK pain, mental health, and adiposity. Heritability estimates were derived using the Sequential Oligogenic Linkage Analysis Routines software. Heritability estimates for MSK pain and pressure pain sensitivity were significant, accounting for between 0.190 and 0.289 of the variation in the phenotype. By contrast, heritability of cold pain sensitivity was not significant. This is the largest intergenerational study to date to comprehensively investigate the heritability of both MSK pain and pain sensitivity, using robust statistical analysis. This study provides support for the heritability of MSK pain and pain sensitivity to pressure, suggesting the need for further convergence of genetic and environmental factors in models for the development or maintenance of these pain disorders.

The effects of dry needling to the thoracolumbar junction multifidi on measures of regional and remote flexibility and pain sensitivity: A randomized controlled trial

BackgroundDry needling (DN) has been consistently shown to decrease pain sensitivity and increase flexibility local to the site of treatment, however it is unclear whether these effects are limited to the region of treatment or can be observed remote to the area of treatment. ObjectiveTo determine the immediate, short-term effects of DN to the thoracolumbar junction on regional and remote flexibility, and to observe if changes in pain sensitivity can occur remote to site of treatment. DesignDouble-blind randomized clinical trial. MethodsFifty-four subjects with low back pain and decreased length in at least one hamstring were randomized to receive either DN or sham DN to the T12 and L1 multifidi. Participants underwent regional (fingertip-to-floor) and remote flexibility (passive knee extension, passive straight leg raise) and pressure pain threshold (PPT) testing of the upper and lower extremity before, immediately after and 1 day after treatment. ANCOVAs were used to analyze flexibility data, with the covariate of pre-treatment values. Paired t-tests were used for difference in remote pain sensitivity. ResultsStatistically larger improvements in regional flexibility, but not remote flexibility, were observed immediately post-treatment in those who received DN than in those receiving sham DN (p = .0495; adjusted difference 1.2, 95% CI 0.002–2.3). Differences between upper and lower extremity PPT were not significant. ConclusionDN can potentially have immediate changes in regional flexibility, but effects are not sustained at 24-h follow-up. DN may not affect remote flexibility or segmental pain sensitivity.

Elevated tau and β-amyloid in the serum of fibromyalgia patients.

Fibromyalgia (FM) is a chronic widespread pain syndrome. Although its mechanism remains relatively unknown, accelerated neurodegeneration in the brain has been reported in patients with FM. Sleep disturbance can increase the risk of neurocognitive disorders, which are associated with tau and beta-amyloid (Aβ) protein accumulation. We hypothesize neurodegeneration in patients with FM may be associated with sleep disturbance. In this case-control study, we analyzed serum tau and Aβ levels and their association with symptom profiles for patients with FM, by recruiting 22 patients with FM and 22 age-matched healthy participants. The visual analog scale, Fibromyalgia Impact Questionnaire, pressure pain threshold test, Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory-II, Beck Anxiety Inventory, and serum tau and beta-amyloid-42 (Aβ-42) levels were recorded. The Mann-Whitney test was conducted to compare questionnaire and protein level results between the groups. Pearson correlation test was conducted to investigate the correlation of questionnaire scores with tau and Aβ-42 levels in patients with FM. The significance level was set at P<.05. Serum tau and Aβ-42 levels were significantly higher in patients with FM than in controls. A positive correlation between serum tau levels and PSQI scores was observed in patients with FM (r=0.476, P=.025). We found that only sleep disturbance in patients with FM was significantly associated with higher serum tau levels among all symptom scores. We suggest sleep disturbance may play a vital role in the pathomechanism of accelerated neurodegeneration in FM.

Role of inflammatory and pain genes polymorphisms in temporomandibular disorder and pressure pain sensitivity

ObjectiveThe aim of this study was to assess the correlation of inflammatory and pain genes polymorphisms with the presence of temporomandibular disorder (TMD) patients and with pressure pain sensitivity. DesignData was collected from 268 consecutive subjects at Bauru School of Dentistry. Subjects aged younger than 20 years, with dental and neuropathic pain, sinusitis, cognitive and neurologic disorder were excluded. Included subjects were evaluated using the Research Diagnostic Criteria for Temporomandibular disorders and divided into two groups: TMD cases and healthy controls. Groups were submitted to pressure pain threshold (PPT) test for the temporomandibular joint, anterior temporalis and masseter muscles and genotyped for Val158Met, IL6−174, IL-1β-3954 and TNFA-308. Student’s t-test and Pearson chi-square test were used to comparisons between groups. A linear multiple regression was used to evaluate the influence of genetics variables on the PPT and a bivariate analysis was used to assesses the influence of genetics variables on pain sensitivity below the PPT cut off of the structures in TMD group. ResultsTMD group showed significantly lower PPT values for all structures when compared with control group (p < 0.001). SNP IL6−174 predicted higher pain sensitivity in the temporomandibular joint (p < 0.005) and in anterior temporalis muscle (p < 0.044) and SNP Val158Met in the masseter muscle (p < 0.038); when TMD group was divided according to PPT cut-off values the SNP Val158Met influenced increase pain sensibility in the masseter muscle. ConclusionTNFA-308 was associated with TMD and SNP IL6−174 and SNP Val158Met influenced pain sensitivity of patients with TMD.

Temporomandibular dysfunction in patients with a history of stroke.

Background: The temporomandibular joint (TMJ) is certainly one of the most complex joints in the human body. The American Academy of Orofacial Pain defines temporomandibular joint disorder (TMD) as a set of disorders involving the masticatory muscles, the TMJ, and associated structures. It is pointed as the main cause of non-dental pain in the orofacial region, including head, face and related structures. The most common TMD symptoms involve joint, chewing and face pain. There may also be crackling when opening and closing the mouth, earache, tinnitus, dizziness, dislocations, limitation of movement and painful tenderness to palpation. Stroke causes sequelae in subjects that include motor disorders, speech or language disorders, and swallowing disorders. Approximately 50% of patients with hemiparesis after stroke are known to have facial control deficiency, weakened orofacial and mandibular functions. Objective: To evaluate patients with a history of stroke, seeking a possible relationship with TMD, the pain associated with this change, and the limitations of range of motion related to the presence of hemibody spasticity in patients post stroke. Methods: The sample consisted of 19 patients of both genders, aged 55 to 70 years, who had suffered stroke. It was used the RDC/TMD for TMD diagnosis, Pressure Pain Threshold test, Ashworth scale, and Sanny Fleximeter for cervical ROM evaluation, being the statistical analysis performed by the software Bioestat version 5.3. Results: TMD was diagnosed in 81.8% of the sample, and of these, 45.4% had a diagnosis of disc displacement with reduction. Conclusion: There was an increase in the muscle tone and the pressure pain threshold, and a decrease in cervical spine ROM, related to the affected side and diagnosed with this disorder, observing that the muscle alterations caused by stroke may be predisposing factors to patients, to the development of muscle TMD or even joint TMD.

Application of pain pressure threshold test in lumbar intervertebral disc herniation study

To quantify pain pressure threshold(PPT) in the patients with lumbar intervertebral disc herniation before and after treatment, and to study the clinical effects of the PPT test in lumbar intervertebral disc herniation. From January to December 2017, 59 patients with lumbar intervertebral disc hernation were treated, and another 59 normal persons were recruited as the normal control group. Visual analogue scale (VAS) was used to measure the patient's subjective pain intensity at admission, and the pain threshold of lumbar posterior joints was measured by the tenderness gauge. The pain threshold was measured three times with an interval of 1 min at the most painful posterior joints and the contralateral posterior joints, and the average value was recorded as the T-value.All patients were treated with one course of conservative treatment (Fengshi spine fixed-point rotation reduction plus routine dehydration and anti-inflammation). VAS score and pain threshold of posterior lumbar joints were measured after the treatment. One lumbar posterior joint was randomly selected in the normal control group to measure the pain threshold. (1)The patient group and the normal control group were comparable. There was no significant difference in age, body height, body weight and BMI between the two groups(P>0.05). (2) The pressure pain threshold test was consistent:variance analysis on the T-value before treatment [(4.72±2.14) kg / cm2, (4.96±2.10) kg / cm2, (5.11±2.09) kg / cm2] of the affected posterior joint, the T-value after treatment [(7.38±2.36) kg / cm2, (7.62±2.51) kg / cm2, (7.58±2.47) kg / cm2], the T-value of before treatment [(7.18±2.80) kg / cm2, (7.19±2.68) kg / cm2, (7.20±2.69) kg / cm2] of the contralateral posterior joint, T value after treatment [(9.54±2.89) kg / cm2, (9.76±3.01) kg / cm2, (9.77±3.09) kg / cm2]; and normal joint T-value [(12.23±1.56) kg / cm2, (12.51±1.48) kg / cm2, (12.6±1.63) kg / cm2] showed that there were no significant differences in the three successive measurements of pain threshold (P>0.05). (3) After conservative treatment, the pain threshold of the affected side[(7.58±2.38) kg / cm2] and the contralateral lumbar posterior joints [(9.70±2.92) kg / cm2] increased significantly, but T-value of the affected side was still lower than that of the contralateral side, and T value of the both sides were lower than that of the normal group [(12.48±1.44) kg / cm2]. The T-value of the affected side and the contralateral side had significant difference between before and after treatment (P<0.05). After treatment, there was significant difference in T-value between the affected side and the contralateral side (P<0.05);there were significant differences in T-value among the affected side, contralateral side and the normal group(P<0.05). (4)Greater the subjective pain intensity of the patient was lower the posterior joint pain threshold of the affected side would be. As the subjective pain intensity decreased, the posterior joint pain threshold of the lumbar spine also increased. There was a significant difference in the VAS score before and after treatment (P<0.05). Multiple regression analysis showed that the correlation coefficient r between the VAS score before and after treatment and the corresponding T-value of the affected side were significantly different(P<0.05), and the corresponding T-value of the contralateral side were not significantly different(P>0.05). The pressure pain threshold test can accurately evaluate the pain intensity and its changing patterns in the lumbar posterior joint. The pain pressure threshold test is clinically significantin the lumbar disc herniation.

Evaluation of the doyle index as a measure of pain sensitization: exploratory analyses from the nor-hand study

Purpose: Quantitative sensory testing of pressure pain threshold (PPT) is a measure of pain sensitization, i.e., altered pain processing mechanisms in the peripheral and/or central nervous system that cause increased sensitivity to pain. PPT values are lower in people with osteoarthritis (OA) and contribute to the pain experience. PPT testing may be a useful tool in classifying pain phenotypes, which may require different management strategies. However, PPT testing requires special equipment, which are not routinely used in clinics.

Determining Real Change in Conditioned Pain Modulation: A Repeated Measures Study in Healthy Volunteers

Conditioned pain modulation (CPM) is a potentially useful biomarker in pain populations; however, a statistically robust interpretation of change scores is required. Currently, reporting of CPM does not consider measurement error. Hence, the magnitude of change representing a “true” CPM effect is unknown. This study determined the standard error of measurement (SEM) and proportion of healthy participants showing a “true” CPM effect with a standard CPM paradigm. Fifty healthy volunteers participated in an intersession reliability study using pressure pain threshold (PPT) test stimulus and contact heat, cold water, and sham conditioning stimuli. Baseline PPTs were used to calculate SEM and >±2 × SEM to determine CPM effect. SEM for PPT was .21 kg/cm2. An inhibitory CPM effect (>+2 SEM) was elicited in 59% of subjects in response to cold stimulus; in 44% to heat. Intrasession and intersession reliability of within-subject CPM response was poor (kappa coefficient <.36). Measurement error is important in determining CPM effect and change over time. Even when using reliable test stimuli, and incorporating measures to limit bias and error, CPM intersession reliability was fair and demonstrated a large degree of within-subject variation. Determining “true” change in CPM will underpin future interrogations of intraindividual differences in CPM. PerspectiveThis study used a distribution-based statistical approach to identify real change in CPM, based on the SEM for the test stimulus. Healthy volunteers demonstrate substantial within-subject variation; CPM effect was paradigm dependent at intrasession testing and unstable to the same paradigm at intersession testing.