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Key summary points: Aim: This study investigates differences in self-reported signs of central sensitization and pressure pain threshold in individuals with knee osteoarthritis and sarcopenia. Findings: Patients with knee osteoarthritis had significantly increased central sensitization inventory-9 scores compared with those with sarcopenia, but there was no significant difference in pressure pain threshold between patients with knee osteoarthritis and patients with sarcopenia. In addition, comparing sarcopenia and non-sarcopenia in community-based older-age participants, pressure pain threshold was significantly lower in those with sarcopenia, but there was no significant difference in central sensitization inventory-9. Message: The interpretation of the Central Sensitization Inventory-9 (CSI-9) and Pressure Pain Threshold (PPT) may differ in the context of knee osteoarthritis and sarcopenia, potentially affecting the assessment of central sensitization and Central Sensitization Syndrome (CSS), with the responsiveness of these measures varying according to the specific disease condition. Purpose: Neuroinflammation, which occurs in knee osteoarthritis and sarcopenia, has attracted attention as a mechanism of central sensitization, but the relationship between central sensitization and these conditions has not been widely studied. This study investigates differences in self-reported signs of central sensitization and pressure pain threshold in individuals with knee osteoarthritis and sarcopenia. Methods: We examined 340 patients (mean age ± standard deviation: 76 ± 5.9, women were 86.9%) with knee osteoarthritis scheduled to undergo total knee arthroplasty. For comparison, 129 community-dwelling older people (mean age ± standard deviation: 76 ± 5.5, women were 68.9%) individuals without a history of knee osteoarthritis or any other diagnosed illnesses were matched for age and sex. We assessed central sensitization inventory-9, pressure pain threshold, pain-related factors, skeletal muscle mass index, and hand grip strength. ANCOVA using 2 (patients with knee osteoarthritis and community older people without knee osteoarthritis) × 2 (sarcopenia and robust) was performed to assess outcome measurements. Results: The prevalence of sarcopenia among patients with knee osteoarthritis was 50.3%. ANCOVA revealed an interaction effect for the central sensitization inventory-9. For the main effect of knee osteoarthritis, there was a significant difference in central sensitization inventory-9, and for the main effect of sarcopenia, there was a significant difference in pressure pain threshold. Conclusions: Discrepancies in the evaluation of central sensitization were identified between knee osteoarthritis and sarcopenia. Individuals with knee osteoarthritis had elevated score of self-reported indications of central sensitization, whereas sarcopenic patients had reduced pressure pain thresholds. [ABSTRACT FROM AUTHOR]

Background: Central and peripheral sensitization are characterized by widespread hyperalgesia that is manifested by larger pain extent area and reduction in pressure pain threshold (PPT). PPT decreases in patients with migraine not only over the trigeminal cervical complex but also throughout the body. Methods: A cross-sectional study was adopted to assess the local and widespread hyperalgesia in chronic and episodic migraine patients respect to healthy controls. The guidelines of Andersen's were used to evaluate the PPT bilaterally over 3 muscles in the trigemino-cervical complex (temporalis, sub-occipitalis, trapezius) and over 1 muscle far from this area (tensor fasciae latae). Results: Thirty subjects with episodic migraine (35.8 ± 2.82 years), 30 with chronic migraine (53.03 ± 19.79 years), and 30 healthy controls (29.06 ± 14.03 years) were enrolled. The interaction effect was present for the trapezius muscle with a significant difference between the right and the left side in episodic group (p = 0.003). A group effect was highlighted in all four muscles analyzed such as suboccipital (p < 0.001), temporalis (p > 0.001), trapezius (p < 0.001), and TFL (p < 0.001). PPT was usually higher in the control group than in the episodic group which in turn was characterized by higher PPT values than the chronic group. Conclusions: People with chronic and episodic migraine presented lower PPT than healthy controls both in the trigeminal and in the extra-trigeminal area. People with chronic migraine presented lower PPT than episodic migraine only in the trigeminal area. Temporalis and sub-occipitalis are the most sensitive muscles in people with chronic and episodic migraine. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between sensitization and postoperative function in patients undergoing arthroscopic rotator cuff repair (ARCR). The purpose of this study was to evaluate the effect of pre-and postoperative reductions in the pressure pain threshold (PPT) on postoperative clinical outcomes in patients with ARCR and investigate changes in PPT and clinical outcomes resulting from postoperative administration of weak opioids activating the central inhibitory system. Methods: This retrospective study included patients who underwent primary ARCR, categorized into Group A (excellent/good Constant scores) and B (fair/poor Constant scores). In a complementary study, patients were randomized to the Control or Tramadol groups. Both studies evaluated the PPT, visual analog scale, active range of motion (ROM), Constant score, and retear rates pre-and postoperatively. Results: In the primary study with 158 patients, those with poor clinical outcomes exhibited significantly lower PPT at the affected shoulder preoperatively at 3 months postoperatively compared to those with good outcomes. The PPT of the affected side was lower than that of the uninvolved side not only at 1 and 3 months but also preoperatively and at 6 months in the poor outcome group. In the secondary study involving 96 patients, weak opioid administration was associated with increased PPT for 3 months, improved ROM at 3 months postoperatively, and reduced postoperative pain 1 year postoperatively. Conclusion: Patients experiencing poor postoperative clinical outcomes exhibited prolonged lowered PPT. Lowered PPT due to sensitization may adversely affect functional recovery and pain perception. Elevating PPT using weak opioids improved clinical outcomes during the acute perioperative period after ARCR. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Prayer is considered to be the most common therapy used in alternative medicine. This study aimed to explore the effect of prayers on endogenous pain modulation, pain intensity, and sensitivity in healthy religious participants. A total of 208 healthy religious participants were enrolled in this study and randomly distributed into two groups, a prayer group (n = 156) and a poem reading or control group (n = 52). Participants from the prayer group were then selectively allocated using the prayer function scale to either an active prayer group (n = 94) receiving an active type of praying or to a passive prayer group (n = 62) receiving a passive type of praying. Pain assessments were performed before and following the interventions and included pressure pain threshold assessment (PPT), conditioned pain modulation (CPM), and a numerical pain rating scale. A significant group-by-time interaction for PPT (p = 0.014) indicated post-intervention increases in PPT in the prayer group but not in the poem reading control group. Participants experienced a decrease in CPM efficacy (p = 0.030) and a reduction in their NPRS (p < 0.001) following the interventions, independent of their group allocation. The results showed that prayer, irrespective of the type, can positively affect pain sensitivity and intensity, but does not influence endogenous pain inhibition during hot water immersion. Future research should focus on understanding the mechanism behind "prayer-induced analgesia." [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were to investigate if/how the presence of lymphedema affects the sensation of the upper limb and to assess whether complex decongestive physiotherapy (CDP) has a favorable impact on sensory testing. Methods: A total of 27 patients with unilateral stage 2 breast cancer–related lymphedema (BCRL) were included in the study. Bilateral circumferential measurements were taken with a tape measure at different levels. Based on these measurements, limb volumes were determined by summing segment volumes derived from the truncated cone formula. Circumferential measurements and ultrasonographic evaluations (epidermis, dermis, and subcutaneous fat thicknesses) were performed at 10 cm distal to the elbow crease. The Semmes–Weinstein monofilament (SWM), static and moving two-point discrimination, pressure pain threshold (PPT), and tactile localization tests were also applied at the same site. After an initial evaluation, all patients underwent CDP phase 1 program. All the evaluations were repeated at the end of the treatment period. Results: Before CDP, affected sides had significantly higher values than the unaffected sides in terms of SWM (p < 0.001), static (p = 0.002) and moving (p = 0.011) two-point discrimination, PPT (p = 0.001), and tactile localization (p < 0.001) values. After CDP, SWM (p = 0.002), static (p = 0.009) and moving (p = 0.024) two-point discrimination, PPT (p = 0.014), and tactile localization (p < 0.001) values decreased significantly on the affected sides. Conclusion: BCRL seems to reduce light touch, static and moving two-point discrimination, PPT, and tactile localization sensations, whereas CDP seems to improve these sensory perceptions in women with BCRL. Ultrasonographic measurements also appear to be promising for prompt and convenient follow-up in the management of BCRL. Trial registration: Clinical Trial Registration Number: NCT04296929 (date of registration: March 5, 2020) [ABSTRACT FROM AUTHOR]

Purpose: Pain is considered a stressful experience, related to real or possible tissue damage with emotional, sensory, social and cognitive components. The aim of the study was to evaluate and compare, using a digital algometer, the pressure pain threshold of temporal and masseter muscles of children and adolescents with and without intellectual disability. Methods: A cross-sectional study was conducted. Data regarding gender and age were collected from the caregiver of children and adolescents with and without intellectual disability. The evaluations followed this sequence: pressure pain threshold of the masseter and temporal muscles, evaluation of pain on touch using the visual analog scale and signs and symptoms of Temporomandibular disorder. The χ2 test, the Kolgomorov–Smirnov test, Student t test and Mann–Whitney test were performed. The significance level was set at 5%. Results: Two homogeneous groups by gender (P = 0.258) and age (P = 0.727) were evaluated, of which 25 children and adolescents presented intellectual disability and another 25 did not have intellectual disability. No significant difference was observed between groups on the pressure pain threshold of the masseter and temporal muscles, nor pressure average or exam time (P > 0.05). Regarding Temporomandibular dysfunction, no difference in signs or symptoms frequency was found (P > 0.05). However, the range of maximum mouth opening was smaller in the intellectual disability group (P = 0.006). Conclusion: Children and adolescents with intellectual disability and preserved basic functionalities do not present alterations in pain perception when evaluated with computerized pressure algometer and visual analog scale. They present similar threshold of pain to pressure as those reported by normative children and adolescents. These results emphasize the importance to treat these children and adolescents with intellectual disability with respect to their pain threshold. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to determine if oral dryness is associated with oral pain sensitivity in removable denture wearers. Materials and methods: The pressure pain threshold (PPT) in the mucosa at the midline between the central incisors in the maxilla and mandible was evaluated in 333 removable denture wearers (mean age 71.2 years, male 33.3%). The frequency of oral dryness and severity of anxiety were evaluated using self-reported questionnaires. Multilevel analyses considering the correlated data structure (jaws nested within individual) adjusted for age, sex, number of missing teeth, anxiety level, smoking status, and systemic diseases were performed to examine the association between PPT and oral dryness. Further subgroup analysis stratified by number of missing teeth was performed. Results: Oral dryness was present in 122 (21.6%) of 566 jaws in 73 (21.9%) of the 333 subjects. The mean (standard deviation) of the log PPT was 2.00 (0.26) in the subjects who perceived oral dryness and 2.04 (0.22) in those who did not. Oral dryness was associated with a lower log PPT, but the relationship was not significant (coefficient − 0.017; 95% confidence interval − 0.071, 0.038). Subjects with oral dryness and edentulous oral mucosa had a significantly lower PPT (coefficient − 0.145; 95% confidence interval − 0.283, − 0.006) than their partially dentate counterparts. Conclusion: There was a significant association of oral dryness with increased pressure pain sensitivity in the oral mucosa only in jaws with complete dentures. Clinical relevance: The approach to oral dryness could contribute to reduction of oral pain sensitivity. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the mechanical and thermal sensory thresholds of the gingiva in patients with plaque-induced gingivitis compared with a control group to help characterize effects of an inflammatory condition in the oral mucosa on somatosensory function. Materials and methods: Quantitative sensory testing (QST) was used in 22 patients (men 10, women 12, age 20–30 years) with plaque-induced gingivitis at the lower lateral incisors and in 22 age- and gender-matched healthy volunteers as a control group. One lower lateral incisor (32 or 42) was randomly identified for each included subject. Cold detection threshold (CDT), warm detection threshold (WDT), cold pain threshold (CPT), and heat pain threshold (HPT) of the attached gingiva at the identified lower lateral incisors were assessed in both groups. Pressure pain threshold (PPT) at the teeth was also tested from vertical and lateral directions and analyzed. One-way ANOVA was used to compare the mean values of the identified lower lateral incisors between the two groups. Results: The results showed that the CDT (P = 0.027), WDT (P = 0.021), and HPT (P = 0.005) at the gingiva and PPT (P < 0.001) at the identified lower lateral incisors from the vertical direction were significantly less sensitive, whereas the PPT (P = 0.016) at the gingiva of the identified lateral incisors were significantly more sensitive in the gingivitis group compared to the control group. Plaque-induced gingivitis and the inflammatory response appear to be associated with significant changes in somatosensory sensitivity at the gingiva and periodontal tissue in a bidirectional mode, i.e., both increased and decreased sensitivity to different types of stimuli. Conclusions: Inflammatory reactions in the gingiva seem to be associated with demonstrable changes in somatosensory function including both hypo- and hyperesthesia. Clinical relevance: These findings may have significance for general oral health and well-being in patients with even plaque-induced gingivitis. [ABSTRACT FROM AUTHOR]

Purpose: Anterior knee pain is a frequent symptom in the osteoarthritic knee. Its intensity has been classically evaluated by the visual analogic score (VAS). The main objective of the study was to assess whether pressure algometry (PA) can be used as a reliable tool to quantify anterior pain in the osteoarthritic knee. Methods: A prospective study was designed, including 160 patients scheduled for unilateral total knee arthroplasty. Patellar pain and function were evaluated according to a specific patellofemoral pain questionnaire and the Knee Society Score. Patients were asked about their pain at rest, while walking and in the stairs with the VAS score. PA by an algometer was used in the anterior part of the patella to determine the pressure pain threshold (PPT): the minimal pressure when the patient feels a painful sensation. Results: The mean values of PPT were 385.1 kPa in the knees going to be operated and 403.4 kPa in the contralateral knees (p < 0.05). The anterior knee pain in the patellar score averaged 6.9, and the total patellar score averaged 15.2. PPT values were correlated with the anterior pain in the patellar score (ρ = 0.31, p < 0.001) and also with the total patellar score (ρ = 0.33; p < 0.001). Conclusions: PA demonstrated to be suitable to measure anterior knee pain in the osteoarthritic knee. PA can specifically assess the anterior knee pain better than other methods as VAS score. PA could be used as the main measurement when comparing different treatments for the anterior knee pain caused by osteoarthritis. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated changes in electrical pain threshold (EPT) after repeated eccentric exercise bouts to test the hypothesis that fascia would become more sensitive than muscle when greater delayed onset muscle soreness (DOMS) is induced. Methods: Ten young men performed two eccentric exercise bouts (ECC1, ECC2) consisting of ten sets of six maximal isokinetic eccentric contractions of the elbow flexors with the same arm separated by 4 weeks. Maximal voluntary isometric contraction torque, range of motion, muscle soreness assessed by a visual analogue scale (VAS) and pressure pain threshold (PPT) were measured before, immediately after and 1-5 days after exercise. EPT was assessed in the biceps brachii fascia (BBF), biceps brachii muscle, and brachialis fascia (BF) 1 day before, immediately after, and 1, 2 and 4 days after exercise. Results: All measures showed smaller changes ( P < 0.05) after ECC2 than ECC1. EPT decreased after both bouts and the largest decreases were evident at 2 days post-exercise ( P < 0.05). The decreases in EPT after ECC1 were greater ( P < 0.05) for both BBF (Baseline: 1.45 ± 0.23 mA, 2 days post-exercise: 0.13 ± 0.11 mA) and BF (1.64 ± 0.29 mA, 0.26 ± 0.2 mA) than muscle (1.56 ± 0.29 mA, 0.69 ± 0.33 mA). Changes in EPT were correlated with the changes in PPT ( r = 0.63-0.87, P ≤ 0.05) but not with VAS ( r = −0.01 to 0.50). Conclusion: These results show that fascia becomes more sensitive than muscle to electrical stimulation after the initial eccentric exercise, suggesting that damage inflammation to fascia than muscle fibres is more associated with DOMS. [ABSTRACT FROM AUTHOR]

Pain thresholds are widely used in behavioral research, but unlike other pain modalities, a standardized assessment of pressure pain remains a challenge. In this research, we describe the application of an automatic pressure algometer with a linear increase in force. Ergonomically designed fixation devices were developed to increase the accuracy and to shorten the time of each measurement. Ten healthy volunteers were included in a pilot study to test the algometry method. Pressure pain thresholds (PPTs) were investigated over 2 experimental days in three nonconsecutive runs at 29 measurement sites. During the experiment, subjects reported their subjective sleepiness, level of state-anxiety, psychological status and the perceived pain intensity of each measurement. Pain intensity ratings indicate that instructions were followed. State-anxiety and subjective sleepiness levels were low throughout the experiment. The method has proven to be suitable for standardized PPT measurements across the body in an ergonomic, safe, and user-friendly fashion. [ABSTRACT FROM AUTHOR]

This study investigated the effect of low-level laser therapy (LLLT) on the masticatory performance (MP), pressure pain threshold (PPT), and pain intensity in patients with myofascial pain. Twenty-one subjects, with myofascial pain according to Research Diagnostic Criteria/temporomandibular dysfunction, were divided into laser group ( n = 12) and placebo group ( n = 9) to receive laser therapy (active or placebo) two times per week for 4 weeks. The measured variables were: (1) MP by analysis of the geometric mean diameter (GMD) of the chewed particles using Optocal test material, (2) PPT by a pressure algometer, and (3) pain intensity by the visual analog scale (VAS). Measurements of MP and PPT were obtained at three time points: baseline, at the end of treatment with low-level laser and 30 days after (follow-up). VAS was measured at the same times as above and weekly throughout the laser therapy. The Friedman test was used at a significance level of 5 % for data analysis. The study was approved by the Ethics Committee of the Federal University of Sergipe (CAAE: 0025.0.107.000-10). A reduction in the GMD of crushed particles ( p < 0.01) and an increase in PPT ( p < 0.05) were seen only in the laser group when comparing the baseline and end-of-treatment values. Both groups showed a decrease in pain intensity at the end of treatment. LLLT promoted an improvement in MP and PPT of the masticatory muscles. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the effect of repeated bouts of eccentric exercise on the nociceptive withdrawal reflex (NWR) threshold, a measure of sensitivity in the spinal nociceptive system. Methods: Sixteen healthy students (age 25.7 ± 0.6 years, BMI 24.8 ± 1 kg m) participated in this randomized, controlled, crossover study. Two identical bouts of high-intensity eccentric exercises were performed on the tibialis anterior muscle 7 days apart. Control sessions involving no exercise were performed 4 weeks apart the exercise sessions. Pressure pain thresholds (PPT) and the NWR threshold were recorded before, immediately after, and 1 day after both bouts of exercise. Results: Pressure pain thresholds decreased significantly at two of the muscle belly sites on the day after initial bout compared with baseline. NWR threshold decreased by 25 ± 4 % immediately after initial bout and by 30 ± 5 % the next day ( p < 0.05) as an indication of generalized pain hypersensitivity. On the contrary, no changes were found in both pain thresholds after second bout of eccentric exercise indicating that both localized and generalized pain sensitivity were normalized. Conclusion: In conclusion, this study for the first time documented that an initial bout of unaccustomed high-intensity eccentric exercise, which results in muscle soreness can induce central sensitization. A repeated bout of exercise, however, facilitates inherent protective spinal mechanisms against the development of muscle soreness. [ABSTRACT FROM AUTHOR]

Quantitative sensory testing (QST) can provide useful information about the underlying mechanisms involved in chronic pain. However, currently available devices typically employed suffer from operator-dependent effects, or are too cumbersome for routine clinical care. This paper presents the design and initial validation of a novel automated pressure-pain type QST platform, termed the multi-modal automated sensory testing (MAST) system. The MAST configuration presented consists of wireless, hand-held thumbnail pressure stimulators (with circular 10 mm rubber tips) and graphical touch screen interface devices to manage the QST process and obtain patient feedback. Validation testing of the custom-designed force sensor showed a 1 % error for low forces increasing to 2 % error for larger loads up to 100 N (full-scale). Validation of the controller using three ramp rates (64, 248, and 496 kPa/s) and six pressures (32, 62, 124, 273, 620, and 1116 kPa) showed an overall mean error of 1.7 % for applied stimuli. Clinical evaluation revealed decreased pressure pain thresholds in chronic pain patients (98.07 ± SE 16.34 kPa) compared to pain free, healthy control subjects (259.88 ± SE 33.54 kPa, p = 0.001). The MAST system is portable and produces accurate, repeatable stimulation profiles indicating potential for point-of-care applications. [ABSTRACT FROM AUTHOR]

Background and aims: Aging implies a physiological decline in skeletal muscle mass and strength, pain perception, transmission and processing, causing pain thresholds to increase (presbyalgesia). This study compares the pressure pain thresholds (PPTs) of 18 head and neck muscles in groups of young and elderly subjects. Methods: A cross-sectional study was conducted on 40 subjects, selected from a group of 97, referred for dental consultation. The inclusion criterion was subjects' age (from 20 to 30, and over 65 years). Exclusion criteria were all conditions which may alter PPTs. In two groups, A (young subjects; 10 men, 10 women) and B (elderly subjects; 11 men, 9 women) PPTs were evaluated by one calibrated examiner with a Fischer algometer. Data are described with mean values ± standard error and the 95% confidence interval The Mann-Whitney test was used to compare PPT values between the two groups (a=0.05). Results: There was a significant difference between the PPTs of group A and B, which were higher in the elderly group in all muscles except five. Conclusions: These preliminary data demonstrate that PPTs increase with aging in the muscles examined. Other confirmatory studies with a larger sample size are necessary. (Aging Clin Exp Res 2012; 24: 239-244) [ABSTRACT FROM AUTHOR]

Chronic pain is often associated with hyperalgesia in cross-sectional studies. In the present study, a random cohort of 40-year-old individuals ( n = 264) from the general population was assessed for low back pain (LBP) status and pressure pain threshold (PPT), with follow-up assessment 4 and 8 years later. Low PPT at baseline as a potential risk factor for the development of LBP was investigated longitudinally and the association between LBP and hyperalgesia was studied cross-sectionally at baseline and 8-year follow-up. Generalized ( p < 0.03) and localized pressure hyperalgesia ( p < 0.02) was found in participants with long-lasting LBP, but not with recent LBP ( p > 0.08). Of the participants without recent or long-lasting LBP, those with a low PPT at baseline (lower 10% percentile) had no increased risk of developing LBP ( p > 0.05). The findings indicate that PPT decreases as a consequence of long-lasting pain, whereas a low PPT seems not to constitute a separate risk factor for the development of LBP. [ABSTRACT FROM AUTHOR]

Myofascial pain syndromes (MPSs) from trigger points (TrPs) and fibromyalgia syndrome (FMS) are common musculoskeletal pain conditions that frequently coexist in the same patients. In recent decades, it has become evident that these entities greatly influence each other's clinical expression. FMS is mainly rooted in the central nervous system, while TrPs have a peripheral origin. However, the nociceptive impulses from TrPs may have significant impact on symptoms of FMS, probably by enhancing the level of central sensitization typical of this condition. Several attempts have been made to assess the effects of treatment of co-occurring TrPs in FMS. We report the outcomes of these studies showing that local extinction of TrPs in patients with fibromyalgia produces significant relief of FMS pain. Though further studies are needed, these findings suggest that assessment and treatment of concurrent TrPs in FMS should be systematically performed before any specific fibromyalgia therapy is undertaken. [ABSTRACT FROM AUTHOR]

This study compared the first and second exercise bouts consisting of electrically evoked isometric contractions for muscle damage profile. Nine healthy men (31 +/- 4 years) had two electrical muscle stimulation (EMS) bouts separated by 2 weeks. The knee extensors of one leg were stimulated by biphasic rectangular pulses (75 Hz, 400 mus, on-off ratio 5-15 s) at the knee joint angle of 100 degrees (0 degrees , full extension) to induce 40 isometric contractions, while the current amplitude was increased to maintain maximal force generation. Maximal voluntary isometric contraction (MVC) torque of the knee extensors at 100 degrees , muscle soreness, pressure pain threshold and plasma creatine kinase (CK) activity were used as indirect markers of muscle damage, and measured before and 1, 24, 48, 72 and 96 h after EMS bout, and the changes over time were compared between bouts. The torque produced during exercise was approximately 30% of MVC, and no significant difference between bouts was evident for the changes in peak and average torque over 40 contractions. MVC decreased significantly (P < 0.05) by 26% immediately and 1 h after both bouts, but the recovery was significantly (P < 0.05) faster after the second bout (100% at 96 h) compared with the first bout (81% at 96 h). Development of muscle soreness and tenderness, and increases in plasma CK activity were significantly (P < 0.05) smaller after the second than the first bout. These results show that changes in muscle damage markers were attenuated in the second EMS bout compared with the initial EMS bout. [ABSTRACT FROM AUTHOR]

Tender point count (TPC) is central to fibromyalgia syndrome (FMS), and with total myalgic score (TMS) is often used to monitor the patient’s condition. This study aimed to determine the stability of TPC and TMS over time, and to examine how well these measures reflected patients’ perceptions of their condition. Twenty-four patients with FMS completed the Fibromyalgia Impact Questionnaire (FIQ) and a visual analogue scale (VAS) measuring well-being, at entrance into the study, and 7 and 28 days later. There was no significant change in TPC ( P = 0.074), FIQ score ( P = 0.291) or VAS ( P = 0.079) of well-being with time. However, mean TMS score did change over time ( P = 0.021). There was no correlation between total FIQ score and the other measures (all P-values > 0.05). The significant change in TMS over time may reflect the natural fluctuation in the clinical presentation of FMS. [ABSTRACT FROM AUTHOR]

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Recurrent low back pain (LBP) is a common pain condition in elderly workers in a variety of occupations, but little is known about its origin and the mechanisms leading to an often disabling sensation of pain that may be persistent or intermittent. In the present study we evaluated the pressure pain thresholds (PPTs) in subjects suffering from recurrent LBP, as well as in healthy controls, to investigate if recurrent LBP is associated with an increased sensitivity of the muscular and ligamentous structures located on the lower back. One hundred and six female workers, aged between 45 and 62 years and working either in administrative or nursing professions were examined. The subjects were classified into LBP cases and controls based on the Nordic questionnaire. Subjects indicating 8–30 or more days with LBP during the past 12 months were graded as cases. PPTs were measured on 12 points (six on each side of the body) expected to be relevant for LBP (paravertebral muscles, musculus quadratus lumborum, os ilium, iliolumbar ligament, musculus piriformis and greater trochanter), as well as on a reference point (middle of the forehead) using a digital dolorimeter. The PPTs on all points on the lower back highly correlated with each other and a high internal consistency was found with a Cronbach alpha coefficient > 0.95. There was a moderate and significant correlation of the PPT on the forehead with the PPT on the lower back with correlation coefficients ranging from 0.36 to 0.49. In LBP cases from administrative professions, the PPT on the forehead was significantly decreased ( P < 0.05). The PPT on the lower back did not significantly differ between the four groups studied, namely nurses and administrative workers with and without recurrent LBP. These results give evidence that recurrent LBP is not associated with an altered sensitivity of the muscular and myofascial tissues in the lumbar region. Furthermore, they raise questions about the value of reference point measurements in recurrent LBP. [ABSTRACT FROM AUTHOR]

Delayed onset muscle soreness (DOMS) involves central and peripheral pain mechanisms. Referred pain patterns following stimulation of DOMS affected tissue have not been fully described. Referred pain may provide information on how central mechanisms are involved in DOMS, as referred pain is a central mechanism. Further, tendon tissue involvement in DOMS is not clear. This study assessed pressure pain threshold (PPT) sensitivity at the tendon, tendon–bone junction (TBJ) and muscle belly sites of tibialis anterior pre- and during DOMS in 45 subjects (34 males, 11 females). Furthermore, pain and referred pain areas at these three sites in response to hypertonic saline injection ( n = 15 per injection site) were investigated pre- and during DOMS. DOMS was induced using controlled plantarflexion from a platform (bodyweight as resistance) causing eccentric contraction of the tibialis anterior muscle. DOMS induced PPT decrease was found at the TBJ and muscle belly sites only ( P < 0.001). No mechanical effect was found in the unexercised limb. Maximal pain intensity induced by hypertonic saline given pre-DOMS was significantly higher for the tendon and TBJ injections compared to intramuscular injections ( P < 0.05). Significantly higher referred pain frequency and enlarged pain areas were found at the muscle belly and TBJ sites following injection during DOMS compared to pre-DOMS. The results indicate that muscle belly and TBJ sites are sensitised while tendon tissue per se is unaffected by DOMS. Central sensitivity changes caused by DOMS may explain the increase in referred pain frequency and enlarged pain areas. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to determine whether glutamate-induced mechanical sensitization of the masseter muscle in human volunteers involves activation of peripheral N-methyl- d-aspartate (NMDA) receptors. Healthy male volunteers ( n=18) participated in this randomized, two-session study. During each session, the volunteers received two injections into the right masseter muscle. An initial injection of glutamate (1 M, 0.2 ml) alone was followed 30 min later by a second injection of glutamate alone or glutamate combined with ketamine (10 mM). Pressure pain threshold (PPT) was assessed over the right masseter muscle at and 2 cm above the injection site, as well as over the right temporalis muscle and left masseter muscle prior to the first injection. The PPT was reassessed at all four sites every 5 min from 10 to 30 min after the second injection and once again 60 min after the second injection. Glutamate-evoked muscle pain, pain area and the sensory pain response index of the McGill pain questionnaire were all significantly reduced by co-injection of ketamine. The mean PPT values were significantly decreased by ~10%, 10, 15 and 25 min after injection of glutamate, but only over the site of injection. Co-injection of ketamine with glutamate also completely blocked the glutamate-induced mechanical sensitization 15 min post-injection as compared with glutamate alone. The lack of spread of mechanical sensitization outside the area of glutamate injection is consistent with the view that glutamate-induced mechanical sensitization results from a peripheral mechanism. The attenuation of glutamate-induced mechanical sensitization by ketamine suggests that this effect is mediated, in part, through activation of peripheral NMDA receptors. [ABSTRACT FROM AUTHOR]

It is not known whether or not muscle spasm of the back muscles presented in patients with sciatic scoliosis caused by lumbar disc herniation produces muscle pain and/or tenderness. Pressure pain thresholds (PPTs) of the lower back and low-back pain were examined in 52 patients (13 of 52 presenting sciatic scoliosis) with lumbar disc herniation who complained of radicular pain and in 15 normal subjects. PPTs were measured at five points bilaterally using an electronic pressure algometer. Low-back pain was evaluated using visual analogue scale (VAS) ratings. All patients complained of radicular leg pain and were divided into the following three groups according to the presence of and the region of low-back pain: no low-back pain group, low-back pain with no laterality group, and low-back pain dominantly on the herniation side group; the VAS rating on the side ipsilateral to the herniation side was higher than that on the contralateral side. In the normal subjects, there were no statistically significant differences between sides in mean PPTs at all sites examined. PPTs were not lower in the spasmodic side (concave side) than the convex side in patients with sciatic scoliosis. PPTs on the herniation side were significantly lower than those on the contralateral side in patients with low-back pain dominantly on the herniation side. Furthermore, the areas of low PPTs were beyond the innervation area of dorsal ramus of L5 and S1 nerve root. It was considered that not only the peripheral mechanisms but also the hyper excitability of the central nervous system might contribute in lowering PPTs of the lower back on the herniation side. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the pressure pain threshold (PPT), tactile threshold (TT) and pain intensity as measured on a Visual Analogue Scale (VAS) in patients with pain in the orofacial region. Twenty-six patients with myogenous pain (7 ss), myogenous and capsular pain (11 ss) or neuropathic pain (8 ss) participated in the study. At baseline, the PPT was evaluated using an algometer and the TT using von Frey hairs. In addition, the pain intensity was rated on a VAS scale and the psychological profile made using the SCL-90 questionnaire. In some of the patients, the measurement procedure was conducted 1 week later, immediately before active treatment started. As active treatment, patients with myogenous or capsular pain received physical therapy in addition to conscious relaxation of the masticatory system, while patients with neuropathic pain were treated using tricyclic antidepressant medication. After 4 to 6 weeks, the measurements were repeated. Statistical evaluation using a linear mixed model revealed no significant changes in TT. In patients with myogenous and capsular pain, as well as in patients with neuropathic pain, the PPT increased after active treatment, while it decreased in the group with pure myogenous pain. The VAS score decreased in all groups. Regarding psychological profiles, a variety of characteristics were observed and the scale for sleeping problems was especially elevated in a majority of the patients. [ABSTRACT FROM AUTHOR]