Reliability of pressure pain threshold testing in healthy pain free young adults

The Association Between Respiratory Functions, Pain Tolerance and Body Awareness in Obstructive Lung Diseases

PURPOSE

There are only a limited number of studies in the literature evaluating body awareness, pain perception, and the relationship between clinical parameters and respiratory functions in patients with obstructive lung disease (OLD) and compared with healthy individuals. Therefore, this study aimed to evaluate respiratory functions, pain tolerance, and body awareness in patients with OLD and compare these findings with those of healthy individuals.

METHODS

The study included 33 patients and 30 healthy individuals. The respiratory function (spirometer), respiratory muscle strength (mouth pressure device), endurance (threshold loading device), pain level and tolerance (short-form McGill Pain Questionnaire and algometer), posture, and body awareness (Body Awareness Questionnaire-BAQ) were evaluated.

RESULTS

The pain threshold and tolerance of the biceps, triceps, trapezius, and quadriceps muscles were significantly lower and BAQ scores were higher in patients with OLD compared with healthy individuals (p < .05). There was a significant relationship between FEV1 (%) and pain tolerance of the triceps (r = 0.371, p = .047) and gastrocnemius muscles (r = 0.419, p = .024); FVC (%) and pain threshold of the gastrocnemius (r = 0.413, p = .023), triceps muscles (r = 0.394, p = .034), and pain tolerance of the gastrocnemius muscle (r = 0.549, p = .002).

CONCLUSIONS

Patients with OLD have a marked increase in pain perception and body awareness levels and a decrease in pain threshold and tolerance compared with healthy controls. Future studies should assess the effectiveness of pain management interventions as a part of pulmonary rehabilitation for patients with chronic respiratory diseases.

CLINICAL IMPLICATIONS

Pain management is important for planning pulmonary rehabilitation programmes.

Pain sensitivity mediates the relationship between empathy for pain and psychopathic traits

Psychopathic traits and antisocial behavior show a well-documented relationship with decreased empathic processing. It has been proposed that a reduced own experience of pain leads to perceiving others' pain as less severe, which potentially facilitates exploitative, aggressive behavior towards others. We evaluated the link between psychopathic traits, experimental pain sensitivity and empathy for pain in a community sample (n = 74). Participants rated images depicting painful situations through either a self-centered or other-oriented perspective. Psychopathic traits (Interpersonal, Affective, Lifestyle and Antisocial) were assessed with the Self-Report Psychopathy Scale, and pain threshold (cold, electrical, pressure) and tolerance (cold, electrical) were measured. A Bayesian Structural Equation Modelling approach indicated that self-centered pain estimates and sensitivity to electrical pain predicted judgments of others' pain ('pain empathy'). The superordinate psychopathy factor, encompassing the overlap in underlying features of the construct, was shown to indirectly affect pain empathy through the mediating role of electrical pain sensitivity. These results provide support for the notion that a reduced sensitivity to own pain underlies diminished pain empathy, and may hold important implications for understanding the mechanisms of antisocial behavior in psychopathy.

Words matter: Effects of instructional cues on pressure pain threshold values in healthy people

BACKGROUND

Pressure pain threshold (PPT) measurements require standardised verbal instructional cues to ensure that the increasing pressure is stopped at the correct time consistently. This study aimed to compare how PPT values and their test-retest reliability were affected by different instructional cues.

METHODS

At two separate sessions, two PPT measurements were taken at the anterior knee for each of four different instructional cues: the cue of the German Neuropathic Research Network instructions ('DFNS'), the point where pressure first feels uncomfortable ('Uncomfortable'), 3/10 on the numerical pain rating scale ('3NPRS'), and where pain relates to an image from the pictorial-enhanced NPRS scale ('Pictorial'). Linear mixed modeling was used to quantify differences between pairs of instructional cues. Test-retest reliability was estimated using intraclass correlation coefficients (ICC[2,1] and ICC[2,k]).

RESULTS

Twenty participants were recruited. The cue resulting in greatest PPT value was DFNS (394.32 kPa, 95%CI [286.32 to 543.06]), followed by Pictorial (342.49 kPa, 95%CI [248.68 to 471.68]), then Uncomfortable (311.85 kPa, 95%CI [226.43 to 429.48]), and lastly 3NPRS (289.78 kPa, 95%CI [210.41 to 399.09]). Five of six pairwise contrasts were statistically significant. Regardless of the cues, the point estimates of ICC (2,1) ranged from 0.80 to 0.86, and the ICC (2,k) values ranged from 0.89 to 0.93. No statistically significant differences were found between any pairwise contrasts of reliability indices.

CONCLUSION

Words matter when instructing people when to stop testing in pressure algometry. Clinicians should use the same instructional cue when assessing pain thresholds to ensure reliability.

The effect of six-week regular stretching exercises on regional and distant pain sensitivity: an experimental longitudinal study on healthy adults

BACKGROUND

Stretching exercises are widely used for pain relief and show positive effects on musculoskeletal, nociplastic and neuropathic pain; the magnitude of altered pain sensitivity responses following regular stretching is currently unknown. This study aimed to investigate the effect of six weeks of regular stretching exercise on regional and widespread pain sensitivity and range of motion and the effect of stretching cessation on regional and widespread pain sensitivity and range of motion.

METHODS

An experimental single-blind longitudinal repeated measures study. Twenty-six healthy adults were recruited. Regional and distant pressure pain thresholds and passive knee extension range of motion were measured at three points: before (baseline) and after six weeks (post-stretch) of daily bilateral hamstring stretching exercises and following four weeks of cessation (post-cessation) from stretching exercises.

RESULTS

Participants had a mean ± standard deviation (range) age of 23.8 ± 2.1 (21-30) years. There was a 36.7% increase in regional (p = 0.003), an 18.7% increase in distant pressure pain thresholds (p = 0.042) and a 3.6% increase in range of motion (p = 0.002) between baseline and post-stretch measures. No statistically significant differences were found for regional (p = 1.000) or distant pressure pain thresholds (p = 1.000), or range of motion (p = 1.000) between post-stretch and post-cessation. A 41.2% increase in distant pressure pain thresholds (p = 0.001), a 15.4% increase in regional pressure pain thresholds from baseline to post-cessation (p = 0.127) and a 3.6% increase in passive knee extension range of motion (p = 0.005) were found from baseline to post-cessation.

CONCLUSIONS

Six weeks of regular stretching exercises significantly decreased regional and widespread pain sensitivity. Moreover, the results showed that the hypoalgesic effect of stretching on regional and widespread pain sensitivity persisted following four weeks of cessation. The results further support the rationale of adding stretching exercises to rehabilitation efforts for patients experiencing nociceptive, nociplastic, and neuropathic pain. However, further research is needed to investigate how the long-term effects of stretching exercises compare with no treatment in clinical populations.

TRIAL REGISTRATION

The trial was registered June 1st, 2021 at ClinicalTrials.gov (Trial registration number NCT04919681).

One spinal manipulation session reduces local pain sensitivity but does not affect postural stability in individuals with chronic low back pain: a randomised, placebo-controlled trial

BACKGROUND

Clinical practice guidelines recommend spinal manipulation for patients with low back pain. However, the effects of spinal manipulation have contradictory findings compared to placebo intervention. Therefore, this study investigated the immediate effects of lumbar spinal manipulation on pressure pain threshold (PPT) and postural stability in people with chronic low back pain (cLBP). Second, we investigated the immediate effect of lumbar spinal manipulation on pain intensity and the interference of the participant beliefs about which treatment was received in the PPT, postural stability, and pain intensity.

METHODS

A two-arm, randomised, placebo-controlled, double-blind trial was performed. Eighty participants with nonspecific cLPB and a minimum score of 3 on the Numeric Pain Rating Scale received one session of lumbar spinal manipulation (n = 40) or simulated lumbar spinal manipulation (n = 40). Primary outcomes were local and remote PPTs and postural stability. Secondary outcomes were pain intensity and participant's perceived treatment allocation. Between-group mean differences and their 95% confidence intervals (CIs) estimated the treatment effect. One-way analysis of covariance (ANCOVA) was performed to assess whether beliefs about which treatment was received influenced the outcomes.

RESULTS

Participants had a mean (SD) age of 34.9 (10.5) years, and 50 (62.5%) were women. Right L5 [between-group mean difference = 0.55 (95%CI 0.19 to 0.90)], left L5 [between-group mean difference = 0.45 (95%CI 0.13 to 0.76)], right L1 [between-group mean difference = 0.41 (95%CI 0.05 to 0.78)], left L1 [between-group mean difference = 0.57 (95%CI 0.15 to 0.99)], left DT [between-group mean difference = 0.35 (95%CI 0.04 to 0.65)], and right LE [between-group mean difference = 0.34 (95%CI 0.08 to 0.60)] showed superior treatment effect in the spinal manipulation group than sham. Neither intervention altered postural stability. Self-reported pain intensity showed clinically significant decreases in both groups after the intervention. A higher proportion of participants in the spinal manipulation group achieved more than two points of pain relief (spinal manipulation = 90%; sham = 60%). The participants' perceived treatment allocation did not affect the outcomes.

CONCLUSION

One spinal manipulation session reduces lumbar pain sensitivity but does not affect postural stability compared to a sham session in individuals with cLPB. Self-reported pain intensity lowered in both groups and a higher proportion of participants in the spinal manipulation group reached clinically significant pain relief. The participant's belief in receiving the manipulation did not appear to have influenced the outcomes since the adjusted model revealed similar findings.

Reliability of quantitative sensory testing in the assessment of somatosensory function after high-frequency stimulation-induced sensitisation of central nociceptive pathways

ABSTRACT

The high frequency stimulation (HFS) model can be used alongside quantitative sensory testing (QST) to assess the sensitisation of central nociceptive pathways. However, the validity and between-session reliability of using QST z -score profiles to measure changes in mechanical and thermal afferent pathways in the HFS model are poorly understood. In this study, 32 healthy participants underwent QST before and after HFS (5× 100 Hz trains; 10× electrical detection threshold) in the same heterotopic skin area across 2 repeated sessions. The only mechanical QST z -score profiles that demonstrated a consistent gain of function across repeated test sessions were mechanical pain threshold (MPT) and mechanical pain sensitivity (MPS), which were associated with moderate and good reliability, respectively. There was no relationship between HFS intensity and MPT and MPS z -score profiles. There was no change in low intensity, but a consistent facilitation of high-intensity pin prick stimuli in the mechanical stimulus response function across repeated test sessions. There was no change in cold pain threshold (CPT) and heat pain threshold (HPT) z -score profiles across session 1 and 2, which were associated with moderate and good reliability, respectively. There were inconsistent changes in the sensitivity to innocuous thermal QST parameters, with cool detection threshold (CDT), warm detection threshold (WDT), and thermal sensory limen (TSL) all producing poor reliability. These data suggest that HFS-induced changes in MPS z -score profiles is a reliable way to assess experimentally induced central sensitisation and associated secondary mechanical hyperalgesia in healthy participants.

Neural and Psychosocial Mechanisms Underlying Alcohol Use and Pain Interactions: Overview of Current Evidence and Future Directions

Purpose of Review

A growing body of research indicates bidirectional associations between alcohol use and pain. In this review, we highlight common neural and psychosocial mechanisms underlying pain and alcohol use and identify current gaps in the literature regarding alcohol/pain interactions. We also suggest future directions for the field moving forward, including more nuanced conceptualization of alcohol's negative reinforcing effects in the context of pain, broader use of clinically-relevant experimental pain induction modalities, and characterization of age, biological sex, gender, race, and ethnicity as moderators of pain/alcohol interactions.

Recent Findings

Acute alcohol intake has analgesic and negative-reinforcing effects in the context of pain, and chronic heavy alcohol use appears to increase risk for development of chronic pain. At the same time, pain, both acute and chronic, acts as a proximal antecedent for alcohol use and is associated with relapse risk for individuals in recovery from alcohol use disorder.

Summary

Although the links between alcohol use and pain are increasingly appreciated, significant gaps in understanding remain and systematic study of alcohol/pain interactions at all levels, including basic, preclinical, translational, and interventional, is needed.

The Association Between the Patient Self-Report Survey for the Assessment of Fibromyalgia with Pain Sensitivity and Psychological Factors in Individuals with Musculoskeletal Pain

Purpose

The Patient Self-Report Survey for the Assessment of Fibromyalgia may potentially be a method for subgrouping patients with musculoskeletal pain who have a nociplastic pain presentation. Limited research has explored the convergent validity of this questionnaire against psychophysical measures of pain sensitivity and psychological factors in individuals with musculoskeletal pain. Therefore, the purpose of this study is to examine the strength of the association between total scores on the Patient Self-Report Survey for the Assessment of Fibromyalgia with clinical, pain sensitivity, and psychological factors.

Patients and Methods

As a secondary analysis of a cross-sectional study, participants with shoulder (n = 20) or low back pain (n = 20) completed Quantitative Sensory Testing (QST), pain-related psychological questionnaires, and the Patient Self-Report Survey for the Assessment of Fibromyalgia. A Spearman correlation determined the association between total scores on the Patient Self Report Survey for the Assessment of Fibromyalgia with psychological factors and pain sensitivity behaviorally assessed with QST.

Results

Negative psychological factors demonstrate moderate to strong positive associations with the Patient Self-Report Survey for the Assessment of Fibromyalgia (rho range = 0.36-0.80), suggesting greater negative psychological factors were observed in patients with higher severity of fibromyalgia symptoms. Pain sensitivity factors demonstrated weak to moderate negative associations with The Patient Self-Report Survey for the Assessment of Fibromyalgia (PPT rho range=-0.36- -0.41), suggesting that elevated pain sensitivity was observed in individuals with higher severity of nociplastic pain symptoms.

Conclusion

Collectively, this supports the convergent validity of the Patient Self-Report Survey for the Assessment of Fibromyalgia with psychological and pain sensitivity factors in patients with musculoskeletal pain.

Effect of high-intensity laser therapy in patients with non-specific chronic neck pain: study protocol for a randomized controlled trial

BACKGROUND

Chronic non-specific neck pain (CNNP) is a prevalent musculoskeletal disorder known for its significant disability and economic burden, ranking second only to low back pain in musculoskeletal conditions. Physical therapy offers effective interventions for CNNP, including low-level laser therapy (LLLT). High-intensity laser therapy (HILT) is a recent treatment for musculoskeletal pain, but studies that support its use in CNNP are limited. The objective of this study is to assess the effect of high-intensity laser therapy on pain intensity in patients with CNNP, given the existing evidence on LLLT for this condition.

METHODS

This is a 2-arm, randomized, placebo-controlled trial with blinded evaluators. The research will be carried out in the laboratory of physical agents at the Andrés Bello University, Campus Casona de las Condes. Eligible participants include the entire internal and external community associated with Andrés Bello University suffering from chronic non-specific NP. Participants will be stratified by sex (4 subgroups) and randomized into 2 study groups: group 1 (HILT and stretching exercises) and group 2 (sham HILT and stretching exercises). Treatments will be performed twice a week for 4 weeks with 3 assessments: before treatment (T0), at the end of treatment (T1), and 12 weeks after treatment (follow-up) (T2). The main outcomes will be pain intensity at rest, pain intensity at movement (active cervical movements: flexion, extension, right and left side bending, and right and left rotation), and pain pressure threshold (average obtained for six evaluation points). Secondary outcome measures will include neck range of motion in the sagittal, coronal, and transverse planes and neck disability.

DISCUSSION

In this study, HILT's effects on patients with non-specific NP will be compared to those of a sham laser intervention. This RCT will offer new evidence regarding the potential benefits of HILT in terms of pain intensity, range of movement, and disability in people suffering with non-specific NP.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05689788. January 19, 2023.

Prolonged slumped sitting causes neck pain and increased axioscapular muscle activity during a computer task in healthy participants - A randomized crossover study

INTRODUCTION

Sitting posture may contribute to spinal pain. Effects of postures on pain, sensitivity and muscle activity during computer tasks were investigated.

METHODS

Twenty-five healthy participants, seated at a workstation without backrest, completed four, 15-min typing tasks: A)Upright with forearm-support; B)Upright without forearm-support; C)Slumped with forearm-support; D)Slumped without forearm-support. Participants rated pain every minute on a numerical rating scale (NRS). RMS-EMG was recorded from upper/lower trapezius (UT, LT), serratus anterior and anterior/middle deltoid. At baseline and after tasks, pressure pain thresholds (PPTs) were recorded bilaterally over the head, UT, and leg.

RESULTS

All tasks caused clinically relevant increased NRS (≥2/10) compared to baseline (P < 0.001). NRS was higher in Task-D (P < 0.003) and lower in Task-B (P < 0.005) than others. PPTs did not change from baseline. Task-D caused higher UT and LT RMS-EMG (P < 0.02) than other tasks.

CONCLUSION

A 15-min task caused pain irrespective of posture with some causing larger changes than others.

The Interaction Between Psychosocial Factors and Exercise-Induced Hypoalgesia in Pain-Free Nurses

Purpose

This cross-sectional study aimed to investigate whether psychosocial factors were predictive for exercise-induced hypoalgesia (EIH) in pain-free adults.

Methods

A sample of 38 pain-free nurses with a mean (SD) age of 26 (6) years were included in this study. Participants completed psychosocial questionnaires prior to physical tests. Pressure pain threshold (PPT) was assessed bilaterally at the calves (local), lower back (semi-local) and forearm (remote) before and immediately after a maximal graded cycling exercise test. Separate linear mixed effects models were used to determine change in PPT before and after cycling exercise (EIH). Multiple linear regression for all psychosocial variables and best subset regression was used to identify predictors of EIH at all locations.

Results

The relative mean increase in PPT at the forearm, lumbar, calf, and globally (all sites pooled) was 6.0% (p<0.001), 10.1% (p<0.001), 13.9% (p<0.001), and 10.2% (p=0.013), respectively. Separate best subset multiple linear regression models at the forearm (predictors; Multidimensional Scale of Perceived Social Support (MSPSS) total), lumbar (predictors; MSPSS total, Pain Catastrophizing Scale (PCS) total, Depression Anxiety Stress Scale (DASS) depression), calf (predictors; MSPSS friends, PCS total), and global (predictors; MSPSS friends, PCS total) accounted for 7.5% (p=0.053), 13% (p=0.052), 24% (p=0.003), and 17% (p=0.015) of the variance, respectively.

Conclusion

These findings confirm that cycling exercise produced EIH in young nurses and provided preliminary evidence to support the interaction between perceived social support, pain catastrophizing and EIH. Further investigation is required to better understand psychological and social factors that mediate EIH on a larger sample of adults at high risk of developing chronic musculoskeletal pain.

Assessing safety and treatment efficacy of running on intervertebral discs (ASTEROID) in adults with chronic low back pain: protocol for a randomised controlled trial

Poor intervertebral disc (IVD) health is associated with low back pain (LBP). This 12-week parallel randomised controlled trial will evaluate the efficacy of a progressive interval running programme on IVD health and other clinical outcomes in adults with chronic LBP. Participants will be randomised to either a digitally delivered progressive interval running programme or waitlist control. Participants randomised to the running programme will receive three individually tailored 30 min community-based sessions per week over 12 weeks. The waitlist control will undergo no formal intervention. All participants will be assessed at baseline, 6 and 12 weeks. Primary outcomes are IVD health (lumbar IVD T2 via MRI), average LBP intensity over the prior week (100-point visual analogue scale) and disability (Oswestry Disability Index). Secondary outcomes include a range of clinical measures. All outcomes will be analysed using linear mixed models. This study has received ethical approval from the Deakin University Human Research Ethics Committee (ID: 2022-162). All participants will provide informed written consent before participation. Regardless of the results, the findings of this study will be disseminated, and anonymised data will be shared via an online repository. This will be the first study to evaluate whether a progressive interval running programme can improve IVD health in adults with chronic LBP. Identifying conservative options to improve IVD health in this susceptible population group has the potential to markedly reduce the burden of disease. This study was registered via the Australian New Zealand Clinical Trials Registry on 29 September 2022 (ACTRN12622001276741).

The effect of theta burst stimulation over the primary motor cortex on experimental hamstring pain: A randomised, controlled study

Theta burst stimulation (TBS) over the primary motor cortex (M1) is an emerging technique that may have utility in the treatment of musculoskeletal pain. However, previous work exploring the analgesic effects of noninvasive brain stimulation has been limited largely to the arm or hand, despite 80% of acute musculoskeletal injuries occurring in the lower limb. This is a pertinent point, given the functional and neurophysiological differences between upper and lower limb musculature, as well as evidence suggesting that reorganization of corticomotor pathways is region-specific. This study investigated the effect of excitatory TBS on pain, function, and corticomotor organization during experimentally induced lower limb pain. Twenty-eight healthy participants attended 2 experimental sessions. On Day 0, participants completed 10 sets of 10 maximal eccentric contractions of the right hamstring muscles to induce delayed onset muscle soreness. Four consecutive blocks of either active or sham TBS were delivered on Day 2. Measures of mechanical sensitivity, pain (muscle soreness, pain intensity, pain area) function (single-leg hop distance, maximum voluntary isometric contraction, lower extremity functional scale), and corticomotor organization were recorded before and after TBS on Day 2. Pain and function were also assessed daily from Days 2 to 10. Active TBS reduced mechanical sensitivity compared to sham stimulation (P = .01). Corticomotor organization did not differ between groups, suggesting that improvements in mechanical sensitivity were not mediated by changes in M1. Subjective reports of pain intensity and function did not change following active TBS, contrasting previous reports in studies of the upper limb. PERSPECTIVE: M1 TBS reduces mechanical sensitivity associated with experimentally induced hamstring pain. Though further work is needed, these findings may hold important implications for those seeking to expedite recovery or reduce muscle sensitivity following hamstring injury.

Abdominal examination using pressure pain threshold algometer reflecting clinical characteristics of complementary and alternative medicine in Korea: A systematic review and a brief proposal

BACKGROUND

A review was conducted to determine a pressure algometry measurement during abdominal examination that reflects clinical settings of traditional Korean medicine.

METHODS

After reviewing the previous studies, we have proposed a reference index, common posture and method for performing pressure algometry during abdominal examination. Keyword search using eight databases was performed. To identify the characteristics of pressure algometry during abdominal examination, keywords (e.g., abdomen, abdominal examination) were searched in national Korean databases, including Korean studies Information System (KISS), Research Information Sharing Service (RISS), and Oriental Medicine Advanced Searching Integrated System (OASIS). To examine the methods of measuring pressure pain threshold (PPT) with validity and reliability, combination keywords (e.g., PPT, pressure algometry, pressure pain, validity, reliability) were searched in Pubmed, Cochrane library, Google scholar, Ovid Embase, and China Knowledge Resource Integrated Database (CNKI).

RESULTS

A total of 652 articles were identified, and 22 relevant articles were included. The following main indices are proposed as a standardized pressure algometry method during abdominal examination: unit of measurements, measuring tools, target locations, pressure area, pressure rate, posture of patients, and evaluators. Based on the results of the review combined with clinical practice, useful indices for pressure algometer during abdominal examination were derived (target location: CV 12, unit of measurement: MPa, pressure area: 4 cm2, pressure rate: 0.098 MPa/s, posture of patient: supine position, number, and intervals of measurement: three consecutive measurements at intervals of 30 seconds, 5 minutes rest prior to commencement). Postures and method sequence of pressure algometry during abdominal examination are also proposed.

CONCLUSIONS

Using standardized indices, postures and method for abdominal examination in clinical settings will help make objective assessments.

Autonomic Nervous System Function and Central Pain Processing in People With Frozen Shoulder: A Case-control Study

OBJECTIVES

The pathophysiology of a frozen shoulder (FS) is thought to be related to chronic inflammation. Chronic inflammation may disturb the immune system and consequently the nervous system as part of an overarching system. The aim of this study was to determine the presence of disturbed autonomic nervous system function and altered central pain processing (CPP) in patients with FS. Secondarily, the presence of psychological variables (catastrophizing and hypervigilance) and self-reported associated symptoms of altered CPP in patients with FS were investigated.

METHODS

Patients with FS and healthy controls completed the Composite Autonomic Symptom Score (autonomic function) and underwent quantitative sensory testing to assess tactile sensitivity (ie, allodynia), pressure pain thresholds (PPTs, ie, hyperalgesia), temporal summation of pain, and Conditioned Pain Modulation (CPM). Psychological issues were explored with the Pain Catastrophizing Scale and the Pain Vigilance and Awareness Questionnaire, and self-reported symptoms associated with altered CPP were determined with the Central Sensitization Inventory.

RESULTS

Thirty-two patients with FS and 35 healthy controls were analyzed in the study. Patients with FS showed more self-reported autonomic symptoms and symptoms of altered CPP, higher levels of pain catastrophizing and hypervigilance, and are more sensitive to tactile touches and mechanical pressure compared with controls.

DISCUSSION

On the basis of the effect sizes, between-group differences in allodynia, hyperalgesia, catastrophizing, and hypervigilance were clinically relevant, but only local allodynia, hyperalgesia, catastrophizing, and hypervigilance were statistically different. Therefore, obvious altered CPP was not present at the group level in patients with FS compared with controls.

Detection of altered pain facilitatory and inhibitory mechanisms in patients with knee osteoarthritis by using a simple bedside tool kit (QuantiPain)

Supplemental Digital Content is Available in the Text.

A simple bedside quantitative sensory testing tool kit demonstrated acceptable reliability and assessment validity for detecting altered pain facilitatory and inhibitory mechanisms in patients with painful osteoarthritis.

Purpose:

Altered pain facilitatory and inhibitory mechanisms have been recognized as an important manifestation in patients with chronic pain, and quantitative sensory testing (QST) can act as a proxy for this process. We have recently developed a simple bedside QST tool kit (QuantiPain) for more clinical use. The purpose of this study was to investigate its test–retest reliability and to evaluate its validity compared with the laboratory-based QST protocols in patients with knee osteoarthritis (OA).

Methods:

QuantiPain consists of 3 items: “pressure algometer” (for pressure pain thresholds [PPTs]), “pinprick” (for temporal summation of pain [TSP]), and “conditioning clamp” (for conditioned pain modulation [CPM]). In experiment-A, intrarater and interrater test–retest reliabilities were investigated in 21 young healthy subjects by using interclass correlation coefficient (ICC). In experiment-B, 40 unilateral painful patients with OA and 40 age-matched, healthy control subjects were included to compare the bedside tool kit against the computerized pressure algometry.

Results:

In experiment-A, excellent to moderate intrarater and interrater reliabilities were achieved in PPT and TSP (ICC: 0.60–0.92) while the agreements of CPM were good to poor (ICC: 0.37–0.80). In experiment-B, localized and widespread decrease of PPT, facilitated TSP, and impaired CPM was found by using the bedside tool kit in patients with OA compared with controls (P < 0.05). The data were significantly correlated with the established laboratory-based tools (R = 0.281–0.848, P < 0.05).

Conclusion:

QuantiPain demonstrated acceptable test–retest reliability and assessment validity with the sensitivity to separate patients with painful OA from controls, which has a potential to create more practical approach for quantifying altered pain mechanisms in clinical settings.

Pain threshold in selected trigger points of superficial muscles of the back in young adults

BACKGROUND

Monitoring of pain threshold is the basis for verification of the effectiveness of therapy or assessment of the patient's condition. This study aimed to determine the pain threshold of selected superficial muscles of the back taking into account trigger point activity in young and healthy males and females, with the evaluation of intrarater reliability of algometric measurements.

MATERIAL AND METHODS

The study examined 30 young adult participants (15 males and 15 females) aged 26.23 ± 3.21, and BMI of 23.80 ± 3.43. The Pain Test FPX Algometer (Wagner) was used for the study. Trigger points on the levator scapulae and trapezius muscles (superior and inferior portion) on both sides were examined. It was also verified whether the trigger points studied are active or inactive. Furthermore, an author's survey questionnaire was used.

RESULTS

Within the trigger points of the right (p = 0.04) and left (p = 0.02) superior trapezius muscle and the left (p = 0.04) levator scapulae muscle, the pain threshold values were higher in the male group. There was a statistically significantly higher number of active trigger points in the female group compared to that in the male group (2.49 ± 1.51 vs. 1.07 ± 1.16, respectively), p = 0.01. For all muscles tested, mean pain threshold values were significantly higher for inactive trigger points. A greater number of active trigger points is associated with lower pain thresholds at these points (left: the superior trapezius, r = -0.597, the inferior trapezius, r = -0.609; the levator scapulae, r = -0.746; right: the superior trapezius, r = -0.610, the inferior trapezius, r = -0.604; the levator scapulae, r = -0.747). The evaluation of the intrarater reliability showed excellent agreement between the first and second measurements, ICC > 0.987 for all examined trigger points.

CONCLUSIONS

(1) Women who reported pain more than once a week in the studied muscles showed a greater number of active trigger points. (2) A greater number of active trigger points in female is related to a lower pain threshold (which is associated with greater pain sensitivity) in female than in male. (3) A sample size of 30 people seems sufficient to detect variations in the pain threshold at active and inactive trigger points of selected back muscles, especially when the frequency of occurrence of both types of points is comparable.

Relationships between alexisomia and the presence of latent trigger points in the upper trapezius of healthy volunteers

BACKGROUND

Alexisomia is characterized by difficulties in the awareness and expression of somatic feelings. Trigger points are classified into two types, active and latent, according to the presence or absence of identifying spontaneous pain.

OBJECTIVE

We aimed to examine the association between alexisomia and the presence of latent trigger points (LTrPs) in the upper trapezius of healthy volunteers.

METHODS

This study was designed as a cross-sectional survey. A correlation analysis between the Shitsu-Taikan-Sho Scale (STSS) and LTrPs was performed on 154 healthy volunteers. The LTrP odds ratio for healthy volunteers with alexisomia was selected as the primary endpoint.

RESULTS

LTrPs were seen in the upper trapezius of 82 healthy volunteers (53.2%). There was no significant difference between the LTrP and non-LTrP groups in STSS total score (p= 0.11). However, there was a significant difference between them in STSS difficulty of identifying bodily feelings (DIB) score (p= 0.03). In the alexisomic versus non-alexisomic groups, the LTrP odds ratio for STSS total score was 2.30 (95% confidence interval [CI] 1.03-5.10) and for STSS DIB score, 2.08 (95% CI 1.05-4.11).

CONCLUSIONS

In STSS DIB in particular, alexisomia was associated with the presence of LTrP in the upper trapezius of healthy volunteers.

Effect of White Willow Bark on Delayed Onset Muscle Soreness Following Resistance Training: A Pilot Study

OBJECTIVES Delayed onset muscle soreness (DOMS) is discomfort that occurs within 8-24hrs following an unaccustomed bout of physical activity that peaks within 24-27hrs and slowly resolves on its own. White willow bark (WWB) is a nutritional supplement that is believed to have anti-inflammatory and analgesic properties like aspirin but without the risk of GI adverse effects. The purpose of this investigation is to determine the effectiveness of WWB on alleviating the symptoms of DOMS following exercise.METHODS Twenty-five individuals volunteered to participate and were randomly assigned to take WWB (798mg salicin) or placebo for 5 days following a lower body resistance training session which consisted of 5X10 lunges at 40% body weight (BW) and 3X fatigue leg press at 75%BW. Test procedures included visual analog scale (VAS), mid-thigh circumference and pressure pain threshold. VAS was measured pre, all five days of the supplementation period and day 6 (post-supplementation). All other variables were measured at pre, immediate, day 3(72hrs), and day 6 (post-supplementation).RESULTS No condition X time interaction was observed (p > 0.05) for any variable. However, VAS scores were lower in the WWB compared to the placebo for all time frames. There was a significant main effect of time for VAS scores indicating muscle soreness for hamstrings (p < 0.001), gluteal (p < 0.001), gastrocnemius (p < 0.001) and quadriceps (p < 0.001). In addition, there was a significant main effect of time for right midthigh pressure pain threshold (p = 0.02), mid-right (p < 0.001) and mid-left (p < 0.001) thigh circumference.CONCLUSIONS WWB may reduce subjective feelings of muscle soreness and appears to have analgesic properties.

The Main Role of Diaphragm Muscle as a Mechanism of Hypopressive Abdominal Gymnastics to Improve Non-Specific Chronic Low Back Pain: A Randomized Controlled Trial

BACKGROUND

Chronic low back pain (LBP) has been stated as one of the main health concerns in the XXI century due to its high incidence.

OBJECTIVE

The objective of this study was to determine the effects of an 8-week program of hypopressive abdominal gymnastics (HAG) on inspiratory muscle strength, diaphragm thickness, disability and pain in patients suffering from non-specific chronic LBP.

METHODS

A total of 40 patients with chronic LBP were randomly divided into two groups. The experimental group carried out an 8-week supervised program of HAG (two sessions/week), whereas the control group did not receive any treatment. Outcomes were measured before and after the intervention, comprising diaphragm thickness during relaxed respiratory activity, maximal inspiratory pressure (PImax), pain intensity (NRS), pressure pain threshold and responses to four questionnaires: Physical Activity Questionnaire (PAQ), Roland-Morris Disability Questionnaire (RMQ), Central Sensitization Inventory (CSI) and Tampa Scale of Kinesiophobia-11 Items (TSK-11).

RESULTS

Statistically significant differences (p < 0.05) were observed for greater thickness of the left and right hemi-diaphragms at inspiration, as well as higher PImax and decreased NRS, CSI and RMQ scores in the intervention group. After treatment, the increases in the thickness of the left and right hemi-diaphragms at inspiration and PImax, as well as the decrease in the NRS and RMQ scores, were only predicted by the proposed intervention (R2 = 0.118-0.552).

CONCLUSIONS

An 8-week HAG intervention seemed to show beneficial effects and predicted an increase in diaphragm thickness and strength during inspiration, as well as a reduction in pain intensity, central sensitization and disability, in patients suffering from chronic non-specific LBP with respect to non-intervention.

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

ABSTRACT

There is a need to better understand biological factors that increase the risk of persistent musculoskeletal pain and heightened pain sensitivity. Knowing the heritability (how genes account for differences in people's traits) can enhance the understanding of genetic versus 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 musculoskeletal pain, and pressure and cold pain sensitivity. Participants included parents (Gen 1, n=1092) and their offspring (Gen 2, n=688) who underwent a battery of testing and questionnaires including pressure and cold pain threshold testing and assessments of physical activity, sleep, musculoskeletal pain, mental health and adiposity. Heritability estimates were derived using the Sequential Oliogenic Linkage Analysis Routines (SOLAR) software. Heritability estimates for musculoskeletal pain and pressure pain sensitivity were significant, accounting for between 0.190 and 0.289 of the variation in the phenotype. In contrast, heritability of cold pain sensitivity was not significant. This is the largest intergenerational study to date to comprehensively investigate the heritability of both musculoskeletal pain and pain sensitivity, using robust statistical analysis. This study provides support for the heritability of musculoskeletal pain and pain sensitivity to pressure, suggesting the need for further convergence of genetic and environmental factors in models for the development and/or maintenance of these pain disorders.

Reliability of pressure pain threshold on myofascial trigger points in the trapezius muscle of women with chronic neck pain

OBJECTIVE

The aim of this study was to evaluate the intra- and inter-rater reliability of pressure pain threshold measurement on myofascial trigger points in the trapezius muscle in women with chronic neck pain.

METHODS

This reliability study involved 30 volunteers with neck pain for more than 90 days. The assessment procedures were performed by blinded researchers. Two examiners, who were previously trained in the use of algometry, independently performed two assessments of the pressure pain threshold at two time intervals, one week apart.

RESULTS

The study sample consisted of 30 young adult women. Excellent intra- and inter-rater reliability were found for the pressure pain threshold on myofascial trigger points, with intraclass correlation coefficient values ranging between 0.752 and 0.874, standard error of measurement ranging between 0.18 and 0.22 kg/cm2, and minimum detectable change ranging between 0.45 and 0.62 kg/cm2.

CONCLUSION

The present study showed that the assessment of pressure pain threshold through algometry presents satisfactory intraclass correlation coefficient values, considering different time and examiners, contributing to the spread of the use of this tool as a quantitative method of pain evaluation in myofascial trigger points.

Has the Phase of the Menstrual Cycle Been Considered in Studies Investigating Pressure Pain Sensitivity in Migraine and Tension-Type Headache: A Scoping Review

OBJECTIVE

The aim of this scoping review was to identify if the phase of the menstrual cycle was considered in observational studies comparing pressure pain sensitivity between women with migraine or tension-type headache (TTH) and headache-free women.

METHODS

A systematic electronic literature search in PubMed, Medline, Web of Science, Scopus, and CINAHL databases was conducted. Observational studies including one or more groups with TTH and/or migraine comparing pressure pain thresholds (PPTs) were included. The methodological quality (risk of bias) was assessed with the Newcastle-Ottawa Scale. Authors, objectives, inclusion/exclusion criteria, size sample, female sample, tool to assess PPTs, mean age, and the use of any medication were extracted and analyzed independently by two authors.

RESULTS

From a total of 1404 and 1832 identified articles for TTH and migraine, 30 and 18 studies satisfied the criteria and were included. Nineteen (63.4%) studies assessing TTH patients and eleven (61.1%) assessing migraine patients showed a high risk of bias. The most common flaws were attributed to improper selection of control and control over other additional factors. Based on the systematic review, just one study including TTH and one including migraine patients considered the menstrual cycle.

CONCLUSION

The results of this scoping review identified that the phase of the menstrual cycle has been rarely considered in studies investigating sensitivity to pressure pain in primary headaches, such as TTH or migraine, although there is evidence showing the relevance of the phase of the menstrual cycle in pain perception.

Medial Prefrontal High-Definition Transcranial Direct Current Stimulation to Improve Pain Modulation in Chronic Low Back Pain: A Pilot Randomized Double-blinded Placebo-Controlled Crossover Trial

Chronic low back pain (CLBP) is highly disabling, but often without identifiable source. Focus has been on impaired anti-nociceptive mechanisms contributing to pain maintenance, though methods of targeting this impairment remain limited. This randomised-controlled cross-over pilot trial used active versus sham medial prefrontal cortex (mPFC) high-definition transcranial direct current stimulation (HD-tDCS) for 3-consecutive days to improve descending pain inhibitory function. Twelve CLBP patients were included with an average visual analogue scale (VAS) pain intensity of 3.0 ± 1.5 and pain duration of 5.3 ± 2.6 years. Pressure pain thresholds (PPTs), conditioned pain modulation (CPM), and temporal summation of pain (TSP) assessed by cuff algometry, as well as pain symptomatology (intensity, unpleasantness, quality, disability) and related psychological features (pain catastrophizing, anxiety, affect), were assessed on Day1 before 3 consecutive days of HD-tDCS sessions (each 20 minutes), at 24-hours (Day 4) and 2-weeks (Day 21) following final HD-tDCS. Blinding was successful. No significant differences in psychophysical (PPT, CPM, TSP), symptomatology or psychological outcomes were observed between active and sham HD-tDCS on Day4 and Day21. CPM-effects at Day 1 negatively correlated with change in CPM-effect at Day4 following active HD-tDCS (P = .002). Lack of efficacy was attributed to several factors, not least that patients did not display impaired CPM at baseline. TRIAL REGISTRATION: : ClinicalTrials.gov (NCT03864822). PERSPECTIVE: Medial prefrontal HD-tDCS did not alter pain, psychological nor psychophysical outcomes, though correlational analysis suggested response may depend on baseline pain inhibitory efficacy, with best potential effects in patients with severe impairments in descending pain inhibitory mechanisms. Future work should focus on appropriate patient selection and optimising stimulation targeting.

High concurrent validity between digital and analogue algometers to measure pressure pain thresholds in healthy participants and people with migraine: a cross-sectional study

Background

Pressure pain thresholds (PPTs) are commonly assessed to quantify mechanical sensitivity in various conditions, including migraine. Digital and analogue algometers are used, but the concurrent validity between these algometers is unknown. Therefore, we assessed the concurrent validity between a digital and analogue algometer to determine PPTs in healthy participants and people with migraine.

Methods

Twenty-six healthy participants and twenty-nine people with migraine participated in the study. PPTs were measured interictally and bilaterally at the cephalic region (temporal muscle, C1 paraspinal muscles, and trapezius muscle) and extra-cephalic region (extensor carpi radialis muscle and tibialis anterior muscle). PPTs were first determined with a digital algometer, followed by an analogue algometer. Intraclass correlation coefficients (ICC_3.1) and limits of agreement were calculated to quantify concurrent validity.

Results

The concurrent validity between algometers in both groups was moderate to excellent (ICC_3.1 ranged from 0.82 to 0.99, with 95%CI: 0.65 to 0.99). Although PPTs measured with the analogue algometer were higher at most locations in both groups (p < 0.05), the mean differences between both devices were less than 18.3 kPa. The variation in methods, such as a hand-held switch (digital algometer) versus verbal commands (analogue algometer) to indicate when the threshold was reached, may explain these differences in scores. The limits of agreement varied per location and between healthy participants and people with migraine.

Conclusion

The concurrent validity between the digital and analogue algometer is excellent in healthy participants and moderate in people with migraine. Both types of algometer are well-suited for research and clinical practice but are not exchangeable within a study or patient follow-up.

Influence of Cognitive Orientation and Attentional Focus on Pain Perception

Background. Recently, a growing interest has emerged in the role of attention and hypervigilance in the experience of pain. Shifting attention away from pain seems likely to reduce the perception of pain itself. Objectives. The present study has been designed to test the following overall hypotheses: (1) disposition to catastrophize, self-efficacy perceived in pain resistance (task self-efficacy), previous experiences concerning the tolerance of physical pain, and degree of impulsiveness are significant predictors of the decision to abandon a painful test such as the cold pressor test (CPT); (2) the manipulation of the attentive focus (internal or external) can influence the level of perceived pain. Methods. Effects of the manipulation of attentional focus (internal and external) on pain perception and response of trial abandonment were evaluated in a sample of university students (n = 246) subjected to the cold pressor test. Results. A significant effect (p < 0.05) was found through a test–retest comparison on the final level of perceived pain among subjects who had received instruction to externalize the focus of their attention (mixed factorial analysis of variance), but no significance was observed with respect to the decision to abandon the experiment. A general explanatory model of the abandonment behavior demonstrating overall good fit measurements was tested too. Conclusion. The abandonment of tests has been shown to be predicted mainly by catastrophic attitude. Attentive impulsiveness showed a further positive effect on catastrophic attitude. Perceived self-efficacy in the tolerance of pain limited learned helplessness, which in turn positively influenced catastrophizing.

Immediate Effects of Dry Needling on the Autonomic Nervous System and Mechanical Hyperalgesia: A Randomized Controlled Trial

BACKGROUND

Dry needling (DN) is often used for the treatment of muscle pain among physiotherapists. However, little is known about the mechanisms of action by which its effects are generated. The aim of this randomized controlled trial was to determine if the use of DN in healthy subjects activates the sympathetic nervous system, thus resulting in a decrease in pain caused by stress.

METHODS

Sixty-five healthy volunteer subjects were recruited from the University of Alcala, Madrid, Spain, with an age of 27.78 (SD = 8.41) years. The participants were randomly assigned to participate in a group with deep DN in the adductor pollicis muscle or a placebo needling group. The autonomic nervous system was evaluated, in addition to local and remote mechanical hyperalgesia.

RESULTS

In a comparison of the moment at which the needling intervention was carried out with the baseline, the heart rate of the dry needling group significantly increased by 20.60% (SE = 2.88), whereas that of the placebo group increased by 5.33% (SE = 2.32) (p = 0.001, d = 1.02). The pressure pain threshold showed significant differences between both groups, being significantly higher in the needling group (adductor muscle p = 0.001; d = 0.85; anterior tibialis muscle p = 0.022, d = 0.58).

CONCLUSIONS

This work appears to indicate that dry needling produces an immediate activation in the sympathetic nervous system, improving local and distant mechanical hyperalgesia.

The Effect of Conditioned Pain Modulation on Tonic Heat Pain Assessed Using Participant-Controlled Temperature

OBJECTIVE

Descending pain modulation can be experimentally assessed by way of testing conditioned pain modulation. The application of tonic heat as a test stimulus in such paradigms offers the possibility of observing dynamic pain responses, such as adaptation and temporal summation of pain. Here we investigated conditioned pain modulation effects on tonic heat employing participant-controlled temperature, an alternative tonic heat pain assessment. Changes in pain perception are thereby represented by temperature adjustments performed by the participant, uncoupling this approach from direct pain ratings. Participant-controlled temperature has emerged as a reliable and sex-independent measure of tonic heat.

METHODS

Thirty healthy subjects underwent a sequential conditioned pain modulation paradigm, in which a cold water bath was applied as the conditioning stimulus and tonic heat as a test stimulus. Subjects were instructed to change the temperature of the thermode in response to variations in perception to tonic heat in order to maintain their initial rating over a two-minute period. Two additional test stimuli (i.e., lower limb noxious withdrawal reflex and pressure pain threshold) were included as positive controls for conditioned pain modulation effects.

RESULTS

Participant-controlled temperature revealed conditioned pain modulation effects on temporal summation of pain (P = 0.01). Increased noxious withdrawal reflex thresholds (P = 0.004) and pressure pain thresholds (P < 0.001) in response to conditioning also confirmed inhibitory conditioned pain modulation effects.

CONCLUSIONS

The measured interaction between conditioned pain modulation and temporal summation of pain supports the participant-controlled temperature approach as a promising method to explore dynamic inhibitory and facilitatory pain processes previously undetected by rating-based approaches.

Neuromuscular Mechanosensitivity in Subjects with Chronic Ankle Sprain: A Cross-Sectional Study

BACKGROUND

Ankle sprain is one of the most common musculoskeletal injuries in sports, at work, and at home. Subjects who suffer from this injury may develop ankle instability. Functional instability has been associated with a high rate of resprain and impaired neuromuscular control in patients with ankle instability.

OBJECTIVE

Measurement of neural and muscular mechanosensitivity after ankle sprain injury and establishment of the relationship between these variables.

METHODS

A cross-sectional case-control study was performed with a sample of 58 students from Alcalá de Henares University (21 males and 37 females, mean age ± SD = 21 ± 3.7 years). Subjects were divided into two groups: a case group (N = 29, subjects with unstable ankle) and a control group (N = 29, healthy subjects). The pressure pain threshold (PPT) of the tibialis anterior, peroneus longus, and peroneus brevis muscles and mechanosensitivity of the common peroneus and tibial nerves were evaluated in all subjects through a manual mechanical algometer.

RESULTS

Neuromuscular PPTs showed significant differences (P < 0.05) between both groups, such that, compared with the control group, the case group exhibited significantly lower PPT levels. In the case group, a strong positive correlation was observed between neural and muscular homolateral mechanosensitivity in both lower limbs.

CONCLUSIONS

Participants with chronic ankle instability showed higher neuromuscular mechanosensitivity in muscles and nerves surrounding the ankle joint than healthy subjects. These findings indicate that low PPT values may be associated with symptoms that characterize this disease.

A novel metric of reliability in pressure pain threshold measurement

The inter-session Intraclass Correlation Coefficient (ICC) is a commonly investigated and clinically important metric of reliability for pressure pain threshold (PPT) measurement. However, current investigations do not account for inter-repetition variability when calculating inter-session ICC, even though a PPT measurement taken at different sessions must also imply different repetitions. The primary aim was to evaluate and report a novel metric of reliability in PPT measurement: the inter-session-repetition ICC. One rater recorded ten repetitions of PPT measurement over the lumbar region bilaterally at two sessions in twenty healthy adults using a pressure algometer. Variance components were computed using linear mixed-models and used to construct ICCs; most notably inter-session ICC and inter-session-repetition ICC. At 70.1% of the total variance, the source of greatest variability was between subjects (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\sigma }_{subj}^{2}$$\end{document}σsubj2 = 222.28 N²), whereas the source of least variability (1.5% total variance) was between sessions (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\sigma }_{sess}^{2}$$\end{document}σsess2 = 4.83 N²). Derived inter-session and inter-session-repetition ICCs were 0.88 (95%CI: 0.77 to 0.94) and 0.73 (95%CI: 0.53 to 0.84) respectively. Inter-session-repetition ICC provides a more conservative estimate of reliability than inter-session ICC, with the magnitude of difference being clinically meaningful. Quantifying individual sources of variability enables ICC construction to be reflective of individual testing protocols.

Effect of pain neuroscience education and transcutaneous electrical nerve stimulation on trigeminal postherpetic neuralgia. A case report

Introduction: Postherpetic neuralgia (PHN) is a complex neuropathic painful condition in which pain is a direct consequence of the response to peripheral nerve damage experienced during herpes zoster attack. PHN is the most common chronic complication of herpes zoster and it causes considerable suffering, affecting the physical functioning and psychological well-being of patients. Objective: To describe the effect of a conservative treatment using pain neuroscience education (PNE) and transcutaneous electrical nerve stimulation (TENS) in a patient with trigeminal PHN. Case Description: A 67-year-old woman sought care for pain, dysfunction, and sensory loss in the left jaw. The assessment included: 1) pain, using the numerical pain rating scale (NPRS), pressure pain threshold (PPT), Douleur Neuropathique 4 (DN4), McGill Pain Questionnaire (MPQ), Graded Chronic Pain Scale (GCPS), and classic body charts of the cranial region; 2) somatosensory function, by means of mechanical detection threshold (MDT) and pressure pain threshold (PPT); 3) jaw function, using the Jaw Functional Limitation Scale-20 (JFLS-20); and 4) psychosocial features, by means of the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorders Questionnaire-7 (GAD-7). Treatment consisted of 12 sessions of PNE and TENS. Outcomes: After treatment, a clinically significant improvement in NPRS, DN4, MDT, GCPS, and PHQ-9 was observed. Conclusion: In this case report, a treatment based on the combination of PNE and TENS seemed to have contributed to improving pain, sensory abnormalities, and jaw function. Psychosocial factors also showed a trend to improve after the treatment.

The Effect of Stress on Repeated Painful Stimuli with and Without Painful Conditioning

OBJECTIVES

Stress and pain have been interrelated in clinical widespread pain conditions. Studies indicate that acute experimental stress in healthy volunteers has a negative effect on the descending inhibitory pain control system and thus the ability to inhibit one painful stimulus with another (conditioned pain modulation [CPM]) although without effect on general pain sensitivity. CPM effects can be assessed immediately after the stress induction, whereas some physiological stress responses (e.g., cortisol release) are delayed and longer lasting. It is unclear whether CPM may relate to stress-induced increases in cortisol.

DESIGN

Twenty-five healthy men had CPM effects measured over a period of 10 minutes. Pain detection thresholds (PDTs) were assessed by repeated test stimuli with cuff algometry on one leg, with and without painful cuff pressure conditioning on the contralateral leg. CPM effects, assessed as the increase in PDT during conditioning stimulation compared with without, were measured before and after experimental stress and a control condition (Montreal Imaging Stress Task [MIST]). Saliva cortisol levels and self-perceived stress were collected.

RESULTS

Participants reported the MIST to be more stressful compared with the MIST control, but cortisol levels did not change significantly from baseline. In all sessions, PDT increased during conditioning (P = 0.001), although the MIST compared with the MIST control had no significant effect on PDT or CPM effects. A negative correlation between changes in cortisol and conditioned PDT was found when applying the MIST (P < 0.03).

CONCLUSIONS

No significant effect of stress was found on CPM compared with a matched control condition. Individual changes in experimental stress and in conditioned pain sensitivity may be linked with cortisol.

Within-session test-retest reliability of pressure pain threshold and mechanical temporal summation in healthy subjects

Objective

To determine the absolute and relative intra-rater within-session test-retest reliability of pressure pain threshold (PPT) and mechanical temporal summation of pain (TSP) at the low back and the forearm in healthy participants and to test the influence of the number and sequence of measurements on reliability metrics.

Methods

In 24 participants, three PPT and TSP measures were assessed at four sites (2 at the low back, 2 at the forearm) in two blocks of measurements separated by 20 minutes. The standard error of measurement, the minimal detectable change (MDC) and the intraclass correlation coefficient (ICC) were investigated for five different sequences of measurements (e.g. measurement 1, 1–2, 1-2-3).

Results

The MDC for the group (MDC_gr) for PPT ranged from 28.71 to 50.56 kPa across the sites tested, whereas MDC_gr for TSP varied from 0.33 to 0.57 out of 10 (numeric scale). Almost all ICC showed an excellent relative reliability (between 0.80 and 0.97), except when only the first measurement was considered (moderate). Although minimal differences in absolute PPT reliability were present between the different sequences, in general, using only the first measurement increase measurement error. Three TSP measures reduced the measurement error.

Discussion

We established that two measurements of PPT and three of TSP reduced the measurement error and demonstrated an excellent relative reliability. Our results could be used in future pain research to confirm the presence of true hypo/hyperalgesia for paradigms such as conditioned pain modulation or exercise-induced hypoalgesia, indicated by a change exceeding the measurement variability.

Instrumental validity and intra/inter-rater reliability of a novel low-cost digital pressure algometer

Background

Pain assessment is a key measure that accompanies treatments in a wide range of clinical settings. A low-cost valid and reliable pressure algometer would allow objective assessment of pressure pain to assist a variety of health professionals. However, the pressure algometer is often expensive, which limits its daily use in both clinical and research settings.

Objectives

This study aimed to assess the instrumental validity, and the intra- and inter-rater reliability of an inexpensive digital adapted pressure algometer.

Methods

A single rater applied 60 random compressions on a force platform. The pressure pain thresholds of 20 volunteers were collected twice (3 days apart) by two raters. The main outcome measurements were as follows: the maximal peak force (in kPa) and the pressure pain threshold (adapted pressure algometer vs. force platform). Cronbach’s α test was used to assess internal consistency. The standard error of measurement provided estimates of measurement error, and the measurement bias was estimated with the Bland–Altman method, with lower and upper limits of agreement.

Results

No differences were observed when comparing the compression results (P = 0.51). The validity and internal intra-rater consistencies ranged from 0.84 to 0.99, and the standard error of measurement from 0.005 to 0.04 kPa. Very strong (r = 0.73–0.74) to near-perfect (r = 0.99) correlations were found, with a low risk of bias for all measurements. The results demonstrated the validity and intra-rater reliability of the digitally adapted pressure algometer. Inter-rater reliability results were moderate (r = 0.55–0.60; Cronbach’s α = 0.71–0.75).

Conclusion

The adapted pressure algometer provide valid and reliable measurements of pressure pain threshold. The results support more widespread use of the pressure pain threshold method among clinicians.

The Association Between Conditioned Pain Modulation and Manipulation-induced Analgesia in People With Lateral Epicondylalgia

OBJECTIVES

Conditioned pain modulation (CPM) and manipulation-induced analgesia (MIA) may activate similar neurophysiological mechanisms to mediate their analgesic effects. This study assessed the association between CPM and MIA responses in people with lateral epicondylalgia.

MATERIALS AND METHODS

Seventy participants with lateral epicondylalgia were assessed for CPM followed by MIA. A single assessor measured pressure pain thresholds (PPT) before, during, and after cold water immersion (10°C) of the asymptomatic hand and contralateral lateral glide (CLG) mobilization of the neck. For analyses, linear mixed models evaluated differences in CPM and MIA responses. Pearson partial correlations and regression analyses evaluated the association between CPM and MIA PPT.

RESULTS

There was a significant increase (CPM and MIA, P<0.001) in PPT from baseline during the interventions (CPM mean: 195.84 kPa for elbow and 201.87 kPa for wrist, MIA mean: 123.01 kPa for elbow and 126.06 kPa for wrist) and after the interventions (CPM mean: 126.06 kPa for elbow, 114.24 kPa for wrist, MIA mean: 123.50 kPa for elbow and 122.16 kPa for wrist). There were also significant moderate and positive partial linear correlations (r: 0.40 to 0.54, P<0.001) between CPM and MIA measures, controlling for baseline measures. Regression analyses showed that CPM PPT was a significant predictor of MIA PPT (P<0.001) and the models explained between 73% and 85% of the variance in MIA PPT.

DISCUSSION

This study showed that CPM and MIA responses were significantly correlated and that the CPM response was a significant predictor of MIA response.

Pressure pain threshold and temporal summation in adults with episodic and persistent low back pain trajectories: a secondary analysis at baseline and after lumbar manipulation or sham

BACKGROUND

People with chronic low back pain (LBP) typically have increased pain sensitivity compared to healthy controls, however its unknown if pain sensitivity differs based on LBP trajectory at baseline or after manual therapy interventions. We aimed to compare baseline pressure pain threshold (PPT) and temporal summation (TS) between people without LBP, with episodic LBP, and with persistent LBP, and to compare changes over time in PPT and TS after a lumbar spinal manipulation or sham manipulation in those with LBP.

METHODS

Participants were aged 18-59, with or without LBP. Those with LBP were categorised as having either episodic or persistent LBP. PPT and TS were tested at baseline. LBP participants then received a lumbar spinal manipulation or sham, after which PPT and TS were re-tested three times over 30 min. Generalised linear mixed models were used to analyse data.

RESULTS

One hundred participants (49 female) were included and analysed. There were 20 non-LBP participants (mean age 31 yrs), 23 episodic LBP (mean age 35 yrs), and 57 persistent LBP (mean age 37 yrs). There were no significant differences in PPT or TS between groups at baseline. There was a non-significant pattern of lower PPT (higher sensitivity) from the non-LBP group to the persistent LBP group at baseline, and high variability. Changes in PPT and TS after the interventions did not differ between the two LBP groups.

DISCUSSION

We found no differences between people with no LBP, episodic LBP, or persistent LBP in baseline PPT or TS. Changes in PPT and TS following a lumbar manual therapy intervention do not appear to differ between LBP trajectories.

TRIAL REGISTRATION

The trial was prospectively registered with ANZCTR (ACTRN12617001094369).

Changes in pressure pain threshold and temporal summation in rapid responders and non-rapid responders after lumbar spinal manipulation and sham: A secondary analysis in adults with low back pain

BACKGROUND

People with LBP who experience rapid improvement in symptoms after spinal manipulative therapy (SMT) are more likely to experience better longer-term outcomes compared to those who don't improve rapidly. It is unknown if short-term hypoalgesia after SMT could be a relevant finding in rapid responders.

OBJECTIVES

We aimed to explore whether rapid responders had different short-term pressure pain threshold (PPT) and temporal summation (TS) outcomes after SMT and sham compared to non-rapid responders.

METHODS

This was a planned secondary analysis of a randomised controlled trial that recruited 80 adults with LBP (42 females, mean age 37 yrs). PPT at the calf, lumbar spine, and shoulder and TS at the hands and feet were measured before and three times over 30 min after a lumbar SMT or sham manipulation. Participants were classified as rapid responders or non-rapid responders based on self-reported change in LBP over the following 24 h.

RESULTS

Shoulder PPT transiently increased more in the rapid responders than non-rapid responders immediately post-intervention only (between-group difference in change from baseline = 0.29 kg/cm², 95% CI 0.02-0.56, p = .0497). There were no differences in calf PPT, lumbar PPT, hand TS, or foot TS based on responder status.

CONCLUSIONS

Hypoalgesia in shoulder PPT occurred transiently in the rapid responders compared to the non-rapid responders. This may or may not contribute to symptomatic improvement after SMT or sham in adults with LBP, and may be a spurious finding. Short-term changes in TS do not appear to be related to changes in LBP.

Lumbar interspinous pressure pain threshold values for healthy young men and women and the effect of prolonged fully flexed lumbar sitting posture: An observational study

BACKGROUND

Low back pain (LBP) is a common condition with large burden worldwide. Exposure to prolonged sitting with a flexed lumbar posture has been suggested in the literature to be a potential risk factor for self-reported LBP. No study has previously investigated whether exposure to prolonged flexed sitting posture provokes discomfort/pain and decreased interspinous pressure pain thresholds for healthy young men and women without back pain, despite this being a suggested risk factor for LBP.

AIM

To investigate whether sitting in a prolonged flexed lumbar posture provokes discomfort and lowers interspinous pressure pain thresholds in the lumbar spine for healthy young men and women without previous LBP.

METHODS

This is a an observational before and after study of 26 participants (13 men, 13 women) between 20-35 years old. Algometry was used to examine the pain threshold for pressure applied between spinous processes of the lumbar spine L1-L5. Pressure algometer measures were performed in prone before and after participants were instructed to sit in a fully flexed posture for a maximum of 15 min or until discomfort was experienced in the low back (Borg CR10 = 7/10). Wilcoxon signed-rank test was used for analyze values from the before and after test conditions. Mann-Whitney U test was used to investigate potential gender difference.

RESULTS

Fully flexed lumbar spine sitting posture up to 15 min provoked temporary discomfort but the proportion of participants experiencing discomfort 7/10 in the low back was 62%. For all pain pressure threshold locations tested, there was a significant difference for the study population with moderate-large decreased (r = -0.56) pressure pain threshold after exposure to prolonged flexed sitting posture (P < 0.01). Comparisons between gender did not show any significant difference.

CONCLUSION

The result showed that exposure to fully flexed lumbar sitting posture for up to 15 min produced temporary discomfort in the low back in young healthy adults with no previous history of LBP and significantly reduced lumbar interspinous pressure pain thresholds. No gender-based differences were observed.

The Influence of a Positive Empathetic Interaction on Conditioned Pain Modulation and Manipulation-induced Analgesia in People With Lateral Epicondylalgia

OBJECTIVE

Conditioned pain modulation (CPM) and manipulation-induced analgesia (MIA) are 2 forms of endogenous analgesia. Many forms of analgesia can be influenced by the nature of the patient-clinician interaction. The aim of this study was to evaluate the influence of an empathetic and supportive interaction on CPM and MIA in people with lateral epicondylalgia (LE).

MATERIAL AND METHODS

In a double-blind, randomized, controlled trial, 68 participants with LE were assigned to 2 groups: the empathetic and neutral interaction groups. The interactions were carried out by a trained, professional role-play actor, playing the part of a research assistant. The research assistant actor spent 15 minutes before CPM and MIA assessment interacting with the participants in an empathetic or neutral manner. Immediately after the interaction, a blinded assessor measured pressure pain threshold at the symptomatic elbow and ipsilateral wrist during CPM and MIA testing. Linear mixed models were used to evaluate differences in CPM and MIA responses between the interaction groups.

RESULTS

There was a significant difference in Consultation and Relational Empathy scores between the groups (P<0.001), indicating that the intervention group experienced a more empathic interaction. Both groups showed a significant increase in pressure pain threshold measures, indicative of a CPM and MIA analgesic response (P<0.001), however, the analgesic responses were greater in the group that had experienced a supportive, empathetic interaction (post CPM, wrist: P<0.001; elbow: P=0.001) (post MIA wrist: P<0.001; elbow: P=0.001).

DISCUSSION

A single session of empathetic interaction positively influenced both CPM and MIA responses in people with LE.

No difference in pressure pain threshold and temporal summation after lumbar spinal manipulation compared to sham: A randomised controlled trial in adults with low back pain

BACKGROUND

Changes in quantitative sensory tests have been observed after spinal manipulative therapy (SMT), particularly in pressure pain thresholds (PPT) and temporal summation (TS). However, a recent systematic review comparing SMT to sham found no significant difference in PPT in patients with musculoskeletal pain. The sham-controlled studies were generally low quality, and conclusions about other quantitative sensory tests could not be made.

OBJECTIVES

We aimed to perform a sham-controlled study with the specific objective of investigating changes in PPT and TS short-term after lumbar SMT compared to sham manipulation in people with low back pain.

METHODS

This was a double-blind randomised controlled trial comparing high-velocity low-amplitude lumbar SMT against sham manipulation in participants with low back pain. Primary outcome measures were PPT at the calf, lumbar spine and shoulder, and TS at the hands and feet. These were measured at baseline, then immediately, 15 min and 30 min post-intervention.

RESULTS

Eighty participants (42 females) were included in the analyses (mean age 37 years), with 40 participants allocated to each intervention group. Significant between-group differences were only observed for calf PPT, which could be explained by a decrease in PPT (increased sensitivity) after SMT and an increase after sham. Feet TS decreased significantly over time after both SMT and sham, and any other changes over time were inconsistent.

CONCLUSIONS

Our results suggest that lumbar SMT does not have a short-term hypoalgesic effect, as measured with PPT and TS, when compared to sham manipulation in people with low back pain.

Associations of physical activity or sedentary behaviour with pain sensitivity in young adults of the Raine Study

Background and aims

There is high level evidence for physical activity (PA) improving outcomes in persistent pain disorders and one of the mechanisms proposed is the effect of exercise on central nociceptive modulation. Although laboratory studies and small field intervention studies suggest associations between physical activity and pain sensitivity, the association of objectively measured, habitual PA and sedentary behaviour (SB) with pain sensitivity requires further investigation. Current evidence suggests PA typically lowers pain sensitivity in people without pain or with single-site pain, whereas PA is frequently associated with an increase in pain sensitivity for those with multisite pain. The aim of this study was to explore the relationships of PA and SB with pain sensitivity measured by pressure pain thresholds and cold pain thresholds, considering the presence of single-site and multisite pain and controlling for potential confounders.

Methods

Participants from the Western Australian Pregnancy Cohort (Raine) Study (n = 714) provided data at age 22-years. PA and SB were measured via accelerometry over a 7-day period. Pain sensitivity was measured using pressure pain threshold (4 sites) and cold pain threshold (wrist). Participants were grouped by number of pain areas into “No pain areas” (n = 438), “Single-site pain” (n = 113) and “Multisite pain” (n = 163) groups. The association of PA and SB variables with pain sensitivity was tested separately within each pain group by multivariable regression, adjusting for potential confounders.

Results

For those with “Single-site pain”, higher levels (>13 min/day) of moderate-vigorous PA in ≥10 min bouts was associated with more pressure pain sensitivity (p = 0.035). Those with “Multisite pain” displayed increased cold pain sensitivity with greater amounts of vigorous PA (p = 0.011). Those with “No pain areas” displayed increased cold pain sensitivity with decreasing breaks from sedentary time (p = 0.046).

Conclusions

This study was a comprehensive investigation of a community-based sample of young adults with “No pain areas”, “Single-site pain” and “Multisite pain” and suggests some associations of measures of PA and SB with pain sensitivity.

Implications

The findings suggest that the pattern of accumulation of PA and SB may be important to inform improved clinical management of musculoskeletal pain disorders. This study provides a baseline for follow-up studies using the Raine Study cohort. Future research should consider temporal influences of PA and SB on pain sensitivity, pain experience and consider using a broader range of pain sensitivity measures.

Relative and absolute test-retest reliabilities of pressure pain threshold in patients with knee osteoarthritis

BACKGROUND AND AIMS

Pressure pain threshold (PPT) and PPT maps are commonly used to quantify and visualize mechanical pain sensitivity. Although PPT's have frequently been reported from patients with knee osteoarthritis (KOA), the absolute and relative reliability of PPT assessments remain to be determined. Thus, the purpose of this study was to evaluate the test-retest relative and absolute reliability of PPT in KOA. For that purpose, intra- and interclass correlation coefficient (ICC) as well as the standard error of measurement (SEM) and the minimal detectable change (MDC) values within eight anatomical locations covering the most painful knee of KOA patients was measured.

METHODS

Twenty KOA patients participated in two sessions with a period of 2 weeks±3 days apart. PPT's were assessed over eight anatomical locations covering the knee and two remote locations over tibialis anterior and brachioradialis. The patients rated their maximum pain intensity during the past 24 h and prior to the recordings on a visual analog scale (VAS), and completed The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and PainDetect surveys. The ICC, SEM and MDC between the sessions were assessed. The ICC for the individual variability was expressed with coefficient of variance (CV). Bland-Altman plots were used to assess potential bias in the dataset.

RESULTS

The ICC ranged from 0.85 to 0.96 for all the anatomical locations which is considered "almost perfect". CV was lowest in session 1 and ranged from 44.2 to 57.6%. SEM for comparison ranged between 34 and 71 kPa and MDC ranged between 93 and 197 kPa with a mean PPT ranged from 273.5 to 367.7 kPa in session 1 and 268.1-331.3 kPa in session 2. The analysis of Bland-Altman plot showed no systematic bias. PPT maps showed that the patients had lower thresholds in session 2, but no significant difference was observed for the comparison between the sessions for PPT or VAS. No correlations were seen between PainDetect and PPT and PainDetect and WOMAC.

CONCLUSIONS

Almost perfect relative and absolute reliabilities were found for the assessment of PPT's for KOA patients.

IMPLICATIONS

The present investigation implicates that PPT's is reliable for assessing pain sensitivity and sensitization in KOA patients.

Manipulation-induced hypoalgesia in musculoskeletal pain populations: a systematic critical review and meta-analysis

Background

Manipulation-induced hypoalgesia (MIH) represents reduced pain sensitivity following joint manipulation, and has been documented in various populations. It is unknown, however, whether MIH following high-velocity low-amplitude spinal manipulative therapy is a specific and clinically relevant treatment effect.

Methods

This systematic critical review with meta-analysis investigated changes in quantitative sensory testing measures following high-velocity low-amplitude spinal manipulative therapy in musculoskeletal pain populations, in randomised controlled trials. Our objectives were to compare changes in quantitative sensory testing outcomes after spinal manipulative therapy vs. sham, control and active interventions, to estimate the magnitude of change over time, and to determine whether changes are systemic or not.

Results

Fifteen studies were included. Thirteen measured pressure pain threshold, and four of these were sham-controlled. Change in pressure pain threshold after spinal manipulative therapy compared to sham revealed no significant difference. Pressure pain threshold increased significantly over time after spinal manipulative therapy (0.32 kg/cm², CI 0.22–0.42), which occurred systemically. There were too few studies comparing to other interventions or for other types of quantitative sensory testing to make robust conclusions about these.

Conclusions

We found that systemic MIH (for pressure pain threshold) does occur in musculoskeletal pain populations, though there was low quality evidence of no significant difference compared to sham manipulation. Future research should focus on the clinical relevance of MIH, and different types of quantitative sensory tests.

Trial registration

Prospectively registered with PROSPERO (registration CRD42016041963).

An incremental dual-task paradigm to investigate pain attenuation by task difficulty, affective content and threat value

There is accumulating evidence that task demands and psychological states can affect perceived pain intensity. Different accounts have been proposed to explain this attenuation based either on how limited attentional resources are allocated to the pain stimulus or on how the threat value of the pain stimulus biases attention. However, the evidence for both proposals remains mixed. Here we introduce an incremental dual-task paradigm in which participants were asked to detect pain on their fingertip without any additional tasks during baseline phases or while concurrently detecting visual targets during task phases. The force applied to participants' fingertip in all phases increased incrementally until they detected moderate pain. In Experiment 1, we used coloured shapes and in Experiment 2 we used affective images as visual targets. We also manipulated the threat value of the pain stimulus in Experiment 2. For both experiments, we found that a concurrent task attenuated perceived pain intensity: mean force was significantly greater for the same moderate pain during task compared to baseline phases. Furthermore although task difficulty and affective content did not affect pain perception, the threat value of the pain stimulus moderated the magnitude of pain attenuation.

Alterations in Temporal Summation of Pain and Conditioned Pain Modulation Across an Episode of Experimental Exercise-Induced Low Back Pain

Persistent pain conditions, including low back pain (LBP), are often accompanied by alterations in pronociceptive and antinociceptive mechanisms, as quantified by temporal summation of pain (TSP) and conditioned pain modulation (CPM). It remains unclear whether altered pain sensitivity, CPM, and/or TSP are a consequence of pain presence or determine the degree of pain development. Pressure pain sensitivity, TSP, and CPM were assessed across an episode of exercise-induced LBP maintained for several days. Thirty healthy individuals participated in 3 experimental sessions: before (day 0), 2 days after fatiguing back muscle exercise with exercise-induced LBP present (day 2), and after pain resolution (day 7). Both handheld and cuff pressure-pain thresholds, along with TSP (10-cuff pain stimuli at .5 Hz) and CPM (cuff pain detection threshold prior versus during painful pressure conditioning) were assessed, alongside questionnaires pertaining to pain, disability, mood, sleep, menstruation, physical activity, and catastrophizing. The exercise-induced LBP model produced mild pain and disability, and reductions in pressure pain thresholds over both the lumbar and distant testing sites (p < .007). No pain-related changes were observed for TSP (p > .44) or CPM (p > .17). The baseline TSP was associated with the peak pain intensity of the exercise-induced LBP (p < .003). Perspective: Pressure-pain sensitivity was impacted by the presence of exercise-induced LBP, whereas TSP seemed to be more stable and was instead associated with the intensity of pain developed. No significant pain-related changes or associations were observed for CPM, suggesting this measure may have less usefulness in mild musculoskeletal pain conditions.