Reliability Of Pressure Pain Threshold Research Articles

Pressure pain mapping of equine distal joints: feasibility and reliability.

Osteoarthritis is a prevalent degenerative joint disease initiating chronic pain and lameness in horses. While several objective gait analysis systems have been developed and validated to quantify lameness severity in horses, methods to evaluate whether peripheral sensitization contributes to the pain experienced are missing. To evaluate whether periarticular pressure pain mapping could be proposed as an auxiliary assessment tool in horses. Specific aims were to evaluate the feasibility and intra- and inter-rater reliability of pressure pain thresholds (PPT) determination at sites overlying the distal thoracic limb joints of clinically healthy horses. Prospective, randomized validation study. For feasibility assessment, PPT were measured with a hand-held digital algometer at six periarticular landmarks (2 sites per joint, 3 joints) bilaterally on the distal thoracic limb of 40 healthy horses (20 warmblood and 20 Freiberger). The joints tested were the metacarpophalangeal, on the latero-palmar and dorsal aspects (L-MCP and D-MCP), the proximal interphalangeal, on the dorsal and palmar aspect (D-PIP and P-PIP) and the distal interphalangeal, on the dorsal and lateral aspect (D-DIP and L-DIP). A feasibility score, ranging from 0 to 5, was attributed to each testing session. For intra- and inter-rater reliability assessment, L-MCP and D-MCP were selected to be tested again at 2 weeks intervals in 20 out of the 40 horses. Data were analyzed using a mixed-effect linear model to test differences in threshold per site and limb. Intra- and inter-rater correlation was calculated. Bland-Altman plots were performed to evaluate the variability of the measures. The procedure was considered feasible (score <2) in 95% of horses (95% CI 88%-100%). Overall, median [interquartile range (IQR)] PPT was 9.4 (7.5-11.3) N. No significant side differences were found. P-PIP and D-DIP recorded significantly lower PPT (p < 0.001 and p = 0.002, respectively) than L-MCP. Median (IQR) were 9.9 (7.3-12.4) N, 8.4 (6.1-10.5) N and 9.0 (7.4-10.6) N for L-MCP, P-PIP and D-DIP, respectively. The intra-rater agreement was 0.68 (95% CI 0.35-0.86) for L-MCP, and 0.50 (95% CI 0.08-0.76) for D-MCP. Inter-rater agreement was 0.85 (95% CI 0.66-0.94) for L-MCP and 0.81 (0.57, 0.92) for D-MCP. Evaluation of feasibility was performed only for distal thoracic limbs joints; no data are provided for hind limbs or proximal joints. Only warmblood and Freiberger horses were included. Intra- and inter-rater reliability assessments were performed exclusively on data collected at the MCP joint. Pressure pain mapping of distal thoracic limb joints was feasible in horses. Local sensitivity differed among sites and no side differences were noticed. Data collected from the MCP joint suggest highly variable, subject dependent intra-rater reliability, ranging from poor to good, and good to excellent inter-rater reliability. Further studies evaluating pathologic vs. healthy joints are needed before recommendations can be made about clinical usability and diagnostic validity.

The reliability of pressure pain threshold in individuals with low back or neck pain: a systematic review.

Low-back and neck pain affect a great number of individuals worldwide. The pressure pain threshold has the potential to be a useful quantitative measure of mechanical pain in a clinical setting, if it proves to be reliable in this population. The objectives of this systematic review are to: (1) analyze the literature evaluating the reliability of pressure pain threshold (PPT) measurements in the assessment of neck and low-back pain, (2) summarize the evidence from these studies, and (3) characterize the limitations of PPT measurement. Relevant literature from PubMed and the Web of Science electronic databases were screened in a 3-step process according to inclusion/exclusion criteria. Relevant studies were assessed for risk of bias using the Quality Appraisal of Reliability Studies (QAREL) tool, and results of all studies were summarized and tabulated. Of 922 citations identified, 11 studies were deemed relevant for critical appraisal, and 8 studies were deemed to have low risk-of bias. Intra-rater reliability, reported in all studies (n = 637) and inter-rater reliability, reported in 2 studies (n = 200) were consistently reported to be good to excellent (ICC 0.75-0.99 and ICC 0.81-0.90, respectively). Studies were also found to have significant variation in PPT measurement procedures. Though intra- and inter-rater reliability was found to be high in all studies, the variation in PPT measurement protocols could affect validity and absolute reliability. As such, it is recommended that standard guidelines be developed for clinical use.

Within-Session Test-Retest Reliability of Pressure Pain Threshold and Mechanical Temporal Summation in Chronic Low Back Pain.

To determine the absolute and relative within-session test-retest reliability of pressure pain threshold (PPT) and temporal summation of pain (TSP) at the low back and the forearm in individuals with chronic low back pain (CLBP) and to test the impact of different sequences of measurements on reliability metrics. Twenty-eight adults with CLBP were recruited. Relative (intraclass correlation coefficient [ICC] and coefficient of variation) and absolute reliability (standard error of measurement and minimal detectable changes) were quantified at 4 sites (back: sacrum and lumbar erector spinae; wrist: hand dorsum and wrist flexors) for PPT and 2 sites (hand and low back) for TSP, for various sequences of measurements. Systematic differences were found between within test and retest for most PPT sequences at the lumbar erector spinae site and 1 TSP sequence (1-2-3) at back and hand sites, precluding reliability analyses for these data. Within-session PPT relative reliability was excellent at low back (ICC = 0.83 to 0.94) and wrist (ICC = 0.88 to 0.97) sites, whereas TSP showed good to excellent reliability at hand (ICC = 0.80 to 0.90) and low back (ICC = 0.73 to 0.89). In general, 2 and 3 measurements optimized absolute and relative reliability for TSP and PPT, respectively. Within-session reliability was generally excellent for PPT and TSP at the low back and hand sites among individuals with CLBP. We recommend using 3 measurements for PPT and 2 for TSP to optimize reliability. Caution is recommended when testing PPT of the painful lower back area since a systematic difference was present between the test and retest.

Intra-rater reliability of pressure pain threshold using a digital algometer

BackgroundPressure Pain Thresholds (PPT) has been the main sensory modality studied in headache disorders. It is usually repetitive, leading to potential variability between measurements. Since threshold estimation relies on the observer, patient, body site, and the device used, it is important to assess measurement reliability in the specific clinical and methodological scenario to be studied in order to minimize error. ObjectiveThe aim of this study is to confirm intra-rater reliability of PPT in the head of adults using a digital algometer device. MethodsPPT was measured with a digital algometer in 3 consecutive assessments conducted 10 min apart. Eight sites were measured in each time at the occipital, temporal and masseter regions bilaterally, frontal and vertex at midline. The reliability using intra-class variability (ICC) and covariance were calculated between times 1, 2, 3, and all times versus the mean. Scores above 0,75 were considered as having excellent reliability. ResultsTen healthy volunteers aged (21-55) were studied. The sum of all sites measured in the head was 2182 (+-672) KPa for the first measure, 2085 (+- 626) KPa for the second, 2185 (+-685) for the third, and 2150 (+-685) KPa for the mean. All ICC coefficients calculated were 0,975 or higher in all areas. ConclusionsWe concluded that one PPT measure in the head with a digital algometer is as reliable as 3 repetitive measures The intra-rater reliability for PPT is considered excellent. Future studies assessing pain vulnerability or predicting headache occurrence can be performed without a significant risk of bias. Keywords: Pressure PainThreshold, Algometry, Reliability, Intra-class.

Within- and between-session test-retest reliability of pressure pain threshold in individuals with lateral elbow tendinopathy

Introduction: Pressure pain threshold (PPT), defined as the minimum pressure required to elicit pain, can be used to measure mechanical hyperalgesia in musculoskeletal conditions. This study investigated the between- and within-session test-retest reliability and minimal detectable change (MDC) of PPT, in individuals with lateral elbow tendinopathy.

Test-retest reliability of pressure pain threshold and heat pain threshold as test stimuli for evaluation of conditioned pain modulation

ObjectivesThere is growing interest in conditioned pain modulation (CPM) protocols for evaluating the function of the descending pain-modulatory system in clinical settings. The aim of this study was to evaluate test-retest reliability of a CPM protocol with contact heat as a conditioning stimulus (CS) and two test stimuli (pressure pain threshold (PPT) and heat pain threshold (HPT)), all applied within one session. In addition, gender and age differences were evaluated. MethodsThe study included 87 healthy subjects (average age 37.95 ± 12.02 years, 57.5% females). The magnitude of the results of the CPM test was calculated as the difference between subject-reported pain thresholds before and after application of the CS. To assess the reliability of the protocol, a subgroup of 66 subjects underwent re-test after 14±1 days. In order to investigate the influence of age on the CPM magnitude, subjects were divided into subgroups (20–29, 30–39, 40–49, 50–59 years). ResultsThe pain thresholds for both test stimuli (TS) were significantly higher following the application of the CS (p < 0.001). Values of the interclass correlation coefficient (ICC) for the CPM with PPT as the TS indicated good reliability (ICC=0.631, 95% CI:0.365–0.782), while those for the HPT indicated poor reliability (ICC=0.328, 95% CI:-0.067–0.582). Significant differences in CPM between genders were found for both TS. Significant CPM differences were not detected among the four age subgroups for either TS. ConclusionsCPM effects can be successfully induced with both PPT and HPT as a TS, but PPT showed significantly higher reliability.

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

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. 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. 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. 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.

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

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. 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). The MDC for the group (MDCgr) for PPT ranged from 28.71 to 50.56 kPa across the sites tested, whereas MDCgr 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. 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.

Reliability of pressure pain threshold to discriminate individuals with neck and low back pain.

Pressure pain threshold (PPT) is decreased in several musculoskeletal disorders, giving indirect evidence regarding pain status. Despite the fact that PPT has been already proven to be reliable in patients with acute conditions, there is great variability of methods and results observed within studies, and only a few evidences confirming its reliability in chronic conditions. The objective of this study was to determine the test-retest reliability of PPT in the neck and low back regions to discriminate individuals with neck or low back pain from healthy individuals. Additionally, one secondary aim was to establish the minimum detectable change (MDC) and the standard error of measurement for future clinical studies and interventions. In this reliability study, 74 individuals (15 individuals from the neck pain and 17 from the neck control group; 21 individuals from the low back pain and 21 from the low back control group). PPT was measured in the neck region (suboccipital, trapezius and supraspinal muscles) and in the lower back region (paraspinal muscles in the levels of L1, L3 and L5). Intrarater reliability was assessed using intraclass correlation coeficient and Bland-Altman. Excellent intra-rater reliability was observed for both (ICC of 0.874 for the neck pain versus ICC of 0.895 in neck control group; ICC of 0.932 for the low back pain group versus ICC of 0.839 for the control group). A small bias was observed for all groups (-0.08 for the neck pain group versus 0.10 in the control group; and 0.32 in low back pain group versus 0.44 in the control group). Minimum detectable change of 0.63kgf of neck pain and 1.21kgf of low back pain was calculated. It was found difference in PPT between pain and control groups (p< 0.05). It may be suggested that the protocol with PPT is reliable and able to discriminate individuals with and without neck and low back pain with a minor measurement error. Therefore, this method may be used to detect possible progress after interventions in patients with neck or low back pain.

Intra-session absolute and relative reliability of pressure pain thresholds in the low back region of vine-workers: ffect of the number of trials.

BackgroundPressure pain thresholds (PPT) are commonly used to quantify mechanical pain sensitivity of deep structures. Excellent PPT reliability has been previously reported among the low back of healthy subjects. However, there is a lack of studies assessing PPT over the low back of workers exposed to biomechanical risk factors of low back pain. Thus, the purpose of this study was threefold: (1) to evaluate the intra-session absolute and relative reliability as well as minimal detectable change (MDC) values of PPT within 14 locations covering the low back region of vine-workers and (2) to determine the number of trial required to ensure reliable PPT assessments and (3) to assess the effect of modifier factors such as gender, age, body mass index (BMI) and pain intensity on PPT reliability.MethodsTwenty-nine vine-workers voluntarily participated in this study. Twenty-two reported low intensity of low-back pain while seven were pain-free. PPTs were assessed among 14 anatomical locations in the lower back region. Three trials were performed on each location with an interval time of at least one minute. Reliability was assessed computing intraclass correlation coefficients (ICC), standard error of measurement (SEM) for all possible combinations between trials. Bland-Altman plots were also generated to assess potential bias in the dataset. Finally, a repeated measure analysis of variance (RM-ANOVA) with the number of trials used as within subject factor was performed on (1) PPT, (2) ICC and (3) SEM values.ResultsICC ranged from 0.86 to 0.99 for all anatomical locations and for all possible combinations between trials. SEM for comparison between trial 1–2, 2–3, 1–3 and, 1-2-3 ranged from respectively, 36.7–77.5, 27.8–77.7, 50–95.2 and, 39.3–80.8 kPa. ICC and SEM remained similar to the ones obtained for the entire population when taking modifier factors in consideration. The visual analysis of Bland-Altman plots suggested small measurement errors for all anatomical locations and for all possible combinations between trials.ConclusionsThe assessment of PPTs of the lower back among vine-workers was found to have excellent relative and absolute reliability. Moreover, reliable measurements can be equally achieved when using the mean of three PPT measurement or with the first one.

Cross friction algometry (CFA): Comparison of pressure pain thresholds between patients with chronic non-specific low back pain and healthy subjects

Palpation is widely used to assess muscular sensitivity in clinical settings but still remains a subjective evaluation. This cross-sectional study assessed a newly developed cross-friction algometry making palpation measurable. The objective was to investigate the reliability of pressure pain thresholds obtained using Cross-Friction Algometry (CFA-PPTs) measured at the level of Erector spinae and Gluteus maximus central muscle parts, and to compare the CFA-PPTs between patients with chronic nonspecific low back pain (nCLBP) and matching healthy subjects. Patients presenting nCLBP to GP's and send into a Pain Center and healthy subjects recruited via university ad valvas & flyers distribution. 30 patients with nCLBP were measured for cross-friction algometry. Other evaluations consisted of the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI). The inter- and intra-reliability were tested and found to be sufficient. The mean CFA-PPT values of the Erector spinae at levels T8, T10, L1 & L3 and the Gluteus maximus of the nCLBP group were significantly lower (p≤0.001) when compared to the CFA-PPT values of the healthy group. The greatest difference (-58%) was found at L1 Erector spinae level and at the superior part of the Gluteus maximus measuring point (-59%). Within the group of patients with nCLBP it was surprising to notice that there was no significant correlation between all the reference points measured using CFA-PPTs and the outcomes of the VAS and ODI scores. With the aid of CFA, the importance of local muscular disorder in the lumbar part of the Erector spinae and Gluteus maximus in patients with nCLBP is obviously demonstrated, but also reveals the very large inter-individual differences in muscular fibrosis sensitivity and/or pain behavior in daily life. This possibly re-opens the debate on which influences can be put forward as the most important: the central or the peripheral sensitization system.

Day-to-day reliability of pressure pain threshold and pain ratings in college-aged men.

The purpose of this study was to examine the reliability of pressure pain threshold (PPT) and pain tolerance assessment in the finger over three testing days. PPT was assessed in the middle finger at the mid-point between the proximal and distal interphalangel joints in 49 college-aged men on three occasions (day 1, day 2, day 3) each separated by 48 h. The pressure evoking PPT was subsequently applied for up to 120 s to assess pain tolerance, whereas pain intensity was rated every 15 s. PPTs were reduced from day 1 to day 2 (P<0.001; intraclass correlation coefficient=0.63), but demonstrated excellent reliability from day 2 to day 3 (P=0.62; intraclass correlation coefficient=0.89). No differences were observed in pain tolerance. Ratings of pressure pain intensity rose over time during the 120 s test (P≤0.002) and were reduced on testing day 3 compared with day 1 (P=0.029). Our results suggest the use of least one familiarization session would lead to significantly improved day-to-day reliability of PPT assessment in the finger. In addition, the application of the force eliciting PPT was a poor discriminator of pain tolerance because of the fact the majority of participants (146 out of 147 sessions) could tolerate the stimulus for the entire 120 s.

Reliability of Pressure Pain Thresholds in Healthy Young Adults

AbstractObjectives: The aim of this study was to investigate the inter-rater and intra-rater reliability of pressure pain threshold [PPT] measurements in the supraspinatus muscle tendon, anterior talofibuler ligament, and the extensor digitorum communis muscle belly in healthy young subjects.Methods: A total of 100 healthy undergraduates participated in this study. Two examiners had three trials of measuring the supraspinatus muscle tendon, anterior talofibuler ligament, and extensor digitorum communis muscle belly on the dominant side, which were marked by the first examiner [E1]. Three consecutive measurements were taken with a 60-s interval between trials. The average of three measurements was calculated for each region. After a 60-min interval, the same procedure was repeated by the second examiner [E2] on the same day.Results: Our results indicated that E1 and E2 showed high intra-rater reliability. Significant difference was found between E1 and E2 in anterior talofibular ligament and extensor digit...

Reliability of four experimental mechanical pain tests in children

PurposeIn order to study pain in children, it is necessary to determine whether pain measurement tools used in adults are reliable measurements in children. The aim of this study was to explore the intrasession reliability of pressure pain thresholds (PPT) in healthy children. Furthermore, the aim was also to study the intersession reliability of the following four tests: (1) Total Tenderness Score; (2) PPT; (3) Visual Analog Scale score at suprapressure pain threshold; and (4) area under the curve (stimulus–response functions for pressure versus pain).Participants and methodsTwenty-five healthy school children, 8–14 years of age, participated. Test 2, PPT, was repeated three times at 2 minute intervals on the same day to estimate PPT intrasession reliability using Cronbach’s alpha. Tests 1–4 were repeated after median 21 (interquartile range 10.5–22) days, and Pearson’s correlation coefficient was used to describe the intersession reliability.ResultsThe PPT test was precise and reliable (Cronbach’s alpha ≥ 0.92). All tests showed a good to excellent correlation between days (intersessions r = 0.66–0.81). There were no indications of significant systematic differences found in any of the four tests between days.ConclusionAll tests seemed to be reliable measurements in pain evaluation in healthy children aged 8–14 years. Given the small sample size, this conclusion needs to be confirmed in future studies.

Comparison between the reliability levels of manual palpation and pressure pain threshold in children who reported orofacial pain

The aim of this study was to compare the intra- and inter-rater reliability of pressure pain threshold (PPT) and manual palpation (MP) of orofacial structures in symptomatic and symptom-free children for temporomandibular disorders (TMD). Fourteen children reporting pain in masticatory muscles or the temporomandibular joint and 16 symptom-free children were randomly assessed on three different occasions: by rater-1 in the first and third session and by rater-2 in the second session. The trained raters applied algometry and MP as recommended by the Research Diagnostic Criteria for TMD. Intraclass correlation coefficients and the Kappa statistic were used to assess the levels of reliability of PPT and MP, respectively. Excellent intra- and inter-rater reliability levels were observed for PPT values at most of the examined sites for symptom-free children and excellent and moderate reliability levels for children reporting pain. For MP, moderate and poor intra-rater and inter-rater reliability levels were observed for most sites in both groups. Algometry showed higher reliability levels for both groups of children and is recommended for pain assessment in children in association with MP.

Test-Retest Reliability of Pressure Pain Threshold Measurements of the Upper Limb and Torso in Young Healthy Women

The goal of this study was to determine the intra- and interday reliability of pressure pain thresholds (PPT) in the upper extremity and torso of asymptomatic women. Nineteen healthy women (20-39 years) with no underlying musculoskeletal problems had 3 PPT trials performed on 8 different locations in the upper extremity and torso over 4 consecutive days. The test-retest reliability of PPT values was robust and highly consistent over the 4 days. The PPT intraclass correlations (ICC) were highly consistent and repeatable over the 4 days of testing (day 1: ICC = 0.94; day 2: ICC = 0.96; day 3: ICC = 0.97 and day 4: ICC = 0.96). When compared with baseline measurements obtained on day 1, the PPT values were significantly lower (P < .05) on days 2, 3, and 4 at all 8 locations. Although the PPT test-retest reliability is robust and consistent throughout the 4 days, there appears to be a similar overall decline in the magnitude of the absolute PPT response at each of the 8 locations. A specific explanation for this greater overall sensitivity in PPTs at all 8 locations is lacking; however, a centrally mediated alteration in pressure/pain sensation could contribute to the overall trend observed in this study. PPT measurements of the upper limb and torso will be significantly lower with repeated measures over a short period time. A standardized evaluation grid should be included in baseline so as to accurately evaluate the progression in shoulder rehabilitation in women with shoulder dysfunction.

Pressure pain thresholds, clinical assessment, and differential diagnosis: reliability and validity in patients with myogenic pain

Four studies are presented testing the validity and reliability of pressure pain thresholds (PPTs) and of examination parameters believed to be important in the clinical assessment of sites commonly used for such measures in patient samples. Forty-five patients with a myogenous temporomandibular disorder were examined clinically prior to PPT measures. Criteria for history and examination included functional aspects of the pain, tissue quality of the pain site, and the type of pain elicited from palpation. Control sites within the same muscle and in the contralateral muscle were also examined. PPTs were measured as an index of tenderness using a strain gauge algometer at these sites. The data from the 5 male subjects were excluded from subsequent analyses due to the higher PPT in the males and to their unequal distribution among the various factorial conditions. The first study demonstrated strong validity in PPT measures between patients (using pain sites replicating the patients' pain) and matched controls (n = 11). The PPT was not significantly different between the primary pain site (referred pain and non-referred pain collapsed) and the no-pain control site in the same muscle (n = 16). The PPT was significantly lower at the pain site compared to the no-pain control site in the contralateral muscle (n = 13). The second study indicated adequate reliability in patient samples of the PPT measures. In the third study, the PPT was significantly lower at sites producing referred pain on palpation compared to sites producing localized pain on palpation. The PPT findings from the control sites were inconsistent on this factor. The fourth study presented preliminary evidence that palpable bands and nodular areas in muscle were most commonly associated with muscle regions that produce pain; such muscle findings were not specific, however, for regions that produce pain. Further, the intraexaminer reliability in reassessing these pain sites qualitatively was only fair. Referred pain had a poor association with the pain pattern and physical findings, which may suggest a need to reevaluate part of the theory regarding referred muscle pain. The reliability of PPT measures was better overall than the reliability of the signs and site-specific symptoms, suggesting that pressure pain thresholds may be an important tool in clinical studies of pain. PPT measures demonstrate a high within-subject variability in pain patient subjects as well as non-pain subjects. Factors such as gender, type of pain, and relation of the palpation-pain to the pain of chief complaint appear to have important effects on PPT measures. The type of pain response on palpation may be an important determinant of the clinical examination procedure.

Pressure pain thresholds in normal muscles: reliability, measurement effects, and topographic differences

This project sought to determine measurement effects, topographic variability, and reliability of pressure pain thresholds (PPT) as an index of normal tenderness in the masseter and temporalis muscles of non-patient subjects. PPTs were measured using the ascending method of limits in 10 subjects. The PPT over 5 trials at each of 5 temporalis sites and 10 masseter sites was measured in 1 experiment. Interpretation of the data with repeated measures analysis of variance indicated that the PPT was significantly higher in the temporalis than in the masseter; additionally, the PPT at a tendon area was significantly higher than at the belly area. These differences should be considered in reducing unwanted variability in PPT measures, receptor distribution, and in inference based on patient examination. There were no differences in the PPT over 5 trials and, thus, no measurement effects. The mean of the first 2 trials at each site appeared to give a better estimate of the PPT than the data from either the first trial or second trial alone from that site. In a second experiment, the PPT was measured in 2 trials at each of 4 sites over 5 sessions. The between-session PPT across multiple sessions was reliable and without differences.