Changes In Pressure Pain Threshold Research Articles

(179) Repeated Exposure to Conditioned Pain Modulation Reduces Situational Pain Catastrophizing to the Conditioning Stimulus

The Situational Pain Catastrophizing Scale (S-PCS) measures an individual's negative mental set in reference to an ongoing or recent painful experience. It is not known whether the relation of S-PCS to conditioned pain modulation (CPM) changes with repeated exposure. The aim of this study was to examine changes in S-PCS relative to the conditioning stimulus and its relation to the magnitude of CPM both within and between study sessions. Twenty subjects (19.9±1.3 years; 10 females) participated in three experimental sessions. CPM was measured once in the first and third sessions, and twice in the second session (separated by 45 minutes of quiet rest). CPM was measured as the relative change in pressure pain thresholds at the right quadriceps and deltoid muscles (test stimuli) before and during ice water immersion (conditioning stimulus; 6±0.5°C; 2-minute duration) of the left foot. Pain ratings of the left foot were reported using a numerical pain rating scale at 20 seconds and the end of the conditioning stimulus. S-PCS was completed following each CPM protocol in reference to the conditioning stimulus. Relative CPM magnitude was similar across sessions and between sites (p>0.05). Pain intensity during the ice water immersion at 20 seconds (4.08±1.9/10) and at the end (5.4±2.1/10) was similar across all CPM protocols (p>0.05). S-PCS decreased significantly across all three sessions (8.30, 6.65, 5.10/24; p 0.05). No correlation was found between subjects’ S-PCS scores and magnitude of CPM in all the trials (p>0.05); however, there was a correlation between S-PCS and reported foot pain at the end (r=0.48; p

(158) Responders and Non-Responders of Conditioned Pain Modulation May Depend On Testing Site and Repeated Measurement

Conditioned pain modulation (CPM) measures the efficiency of endogenous pain inhibition and is regarded as a systemic effect. It is unknown, whether individuals respond to CPM similarly between test sites and the effect of repeated measurements. The aim of this study was to investigate within individuals 1) whether CPM magnitude is consistent between test sites within the same CPM trial, 2) whether CPM responders and non-responders are similar between test sites, and 3) if these relations change with repeated measurement (within and between sessions). Twenty subjects (19.9±1.3 years; 10 females) participated in three experimental sessions separated by approximately one week. CPM was measured 4 times; once in the first and third sessions and twice in the second session (separated by 45-minutes of quiet rest). CPM was measured as the percent change in pressure pain thresholds at the right quadriceps and deltoid muscles (test stimuli) before and during ice-water immersion (conditioning stimulus; 6±0.5°C; 2-minute duration) of the left foot. Intraclass correlations (ICCs(2,k)) were computed between assessment sites in each CPM trial. CPM responders at each assessment site were determined based on a change greater than the standard error of measurement of each assessment site. Cohen's Kappa was computed to determine the level of agreement between the sites in each CPM trial. In the first and third sessions, there was good agreement in CPM magnitude between assessment sites (ICC first session=0.611 [0.008-0.847]; ICC third session=0.535 [-0.093-0.810]) but poor agreement in responders vs. non-responders (κ first session=-0.053; κ third session=-0.098). During the second session, agreement in both CPM trials improved between the sites in terms of magnitude (ICC first trial=0.878 [0.694-0.952]; ICC second trial=0.867 [0.669-0.947]) and responders/non-responders (κ first trial=-0.762; κ second trial=-0.375). The site of the test stimulus may produce opposite outcomes and influence how endogenous pain inhibition is interpreted.

(147) Relation of Fibromyalgia Severity and the Exercise-Induced Pain Response, Prognostic or Inconsequential?

This study investigated the relation of fibromyalgia severity on the acute pain response following isometric and dynamic muscle contractions. Thirty-four participants with fibromyalgia (52.5±11.9yr.; BMI:31.1±6.1; 32 women) completed a quiet rest and two randomized exercise sessions (isometric or dynamic) of the elbow flexors matched for intensity, duration, and duty-cycle. The quiet rest session included assessment of fibromyalgia severity (Fibromyalgia Symptom Scale [FS]), conditioned pain modulation (CPM), and mechanical temporal summation (TS). CPM was assessed by measuring the change in pressure pain thresholds (PPT) at the biceps and quadriceps muscles prior to and during immersion of the foot in noxious ice water. TS was measured as the change in pain ratings during application of a constant mechanical stimulus to the index finger for two-minutes. Exercise sessions included assessment of PPT at the biceps and quadriceps muscles, TS, and self-report whole-body pain (0-10 VAS) before and immediately after exercise. FS correlated with baseline TS (r=0.343, p=0.047) but not with CPM (p>0.05) or the change in PPT following both exercise types (p>0.05). Only isometric contractions lead to a significant decrease in TS (p=0.042) and FS correlated with this change (r=-0.465, p=0.006). Whole-body pain increased following isometric (p=0.049) and dynamic (p

Ulnar nerve instability in the cubital tunnel of asymptomatic volunteers.

Ulnar nerve instability (UNI) in the cubital tunnel is defined as ulnar nerve subluxation or dislocation. It is a common disorder that may be noted in patients with neuropathy or in the asymptomatic. Our prospective, single-site study utilized high-resolution ultrasonography (US) to evaluate the ulnar nerve for cross-sectional area (CSA) and measures of shear-wave elastography (SWE). Mechanical algometry was obtained from the ulnar nerve in the cubital tunnel to assess pressure pain threshold (PPT). Forty-two asymptomatic subjects (n = 84 elbows) (25 males, 17 females) aged 22-40 were evaluated. Two chiropractic radiologists, both with 4years of ultrasound experience performed the evaluation. Ulnar nerves in the cubital tunnel were sampled bilaterally in three different elbow positions utilizing US, SWE, and algometry. Descriptive statistics, two-way ANOVA, and rater reliability were utilized for data analysis with p ≤ 0.05. Fifty-six percent of our subjects demonstrated UNI. There was a significant increase in CSA in subjects with UNI (subluxation: 0.066mm2 ± 0.024, p = 0.027; dislocation: 0.067mm2 ± 0.024, p = 0.003) compared to controls (0.057mm2 ± 0.017) in all three elbow positions. There were no significant group differences in SWE or algometry. Inter- and intra-observer agreements for CSA of the ulnar nerves within the cubital tunnel were assessed using intraclass correlation coefficient (ICC) and demonstrated moderate (ICC 0.54) and excellent (ICC 0.94) reliability. Most of the asymptomatic volunteers demonstrated UNI. There was a significant increase in CSA associated with UNI implicating it as a risk factor for ulnar neuropathy in the cubital tunnel. There were no significant changes in ulnar nerve SWE and PPT. Intra-rater agreement was excellent for the CSA assessment of the ulnar nerve in the cubital tunnel. High-resolution US could be utilized to assess UNI and monitor for progression to ulnar neuropathy.

Effects of eccentric exercise in pressure pain threshold in subjects with functional ankle equinus condition

Stretching exercises are widely used by the population before sporting activities. One of the most common technique is eccentric exercise. Here, we made a clinical examination of 98 subjects with equinus condition before activity and after 30 min of running (49 participants with previous eccentric exercise and 49 with no previously eccentric exercise). The clinical assessment of the Achilles tendon was based on the pressure pain threshold (PPT). We identified significant PPT changes between the previous eccentric stretching and the non-previous eccentric stretching group in the Achilles tendon evaluations. Based on our findings, we propose that subjects with equinus condition could use eccentric stretching in order to improve the Achilles tendon status.

Differential modulation of pressure pain threshold in response to transcutaneous spinal direct current stimulation with physical activity level

This study investigated the interaction between physical activity level and responses to transcutaneous spinal direct current stimulation (tsDCS) as reflected in changes in pressure pain threshold (PPT) in the lower extremity. Participants (n = 35, 15 males) consisted of physically active young adults. PPTs were determined at three sites (thigh, leg and foot) on the dominant leg before and after 20-min of anodal tsDCS applied at mid-thoracic level. Based on a questionnaire, participants were assigned to either a low-moderately active (n = 21) or highly active group (n = 14). At baseline, participants in the two activity groups exhibited comparable PPTs. After the intervention, PPTs were significantly elevated at all sites at 5-min and 30-min post-tsDCS. An interaction was found between activity groups and tsDCS-induced changes at the thigh site owing to a larger elevation in PPTs in the highly active group. These results corroborate previous findings regarding antalgic effects of tsDCS and point to the role of physical activity level as a potential factor susceptible to modulate responses to tsDCS interventions.

Study of the mechanisms of action of the hypoalgesic effect of pressure under shock waves application: A randomised controlled trial

ObjectiveTo determine if the perceived pain intensity during the application of shock waves (SWs) is a determinant mechanism in producing hypoalgesic changes in pressure pain thresholds (PPTs) in asymptomatic individuals. DesignA randomised, single-blind controlled trial [NCT03455933]. SettingUniversity. ParticipantsSixty-three asymptomatic individuals. InterventionsParticipants were randomised into three groups: 1-SWs causing mild pain (SW-DP); 2-SWs generating moderate pain (SW-MP); and 3-cold pressor test (CPT). Main outcome measurementsBefore and after the intervention, the PPT was evaluated bilaterally at the following points: lateral epicondyle, median nerve in the flexure of the elbow, and tibia. ResultsThe results showed differences between various groups over time for all PPTs assessments, due to the existence of statistically significant differences in the interaction group x times (dominant arm lateral epicondyle [P < 0.001; η2p = 0.255]; dominant arm median nerve [P = 0.001; η2p = 0.212]; nondominant arm lateral epicondyle [P < 0.001; η2p = 0.275]; nondominant arm median nerve [P < 0.001; η2p = 0.268]; tibia [P = 0.012, η2p = 0.138]). The SW-MP group obtained a significant increase in all the PPT evaluations compared with the SW-DP group (d > 0.80). The CPT group only showed significantly higher results, and of high magnitude (d > 0.80), regarding the SW-DP group for the PPT evaluation in the dominant member. The SW-MP group showed differences compared with the CPT only for the PPT obtained in the nondominant arm. ConclusionsThe findings show that SW treatment generates a hypoalgesic effect on the application point, with moderate pain. Further studies are necessary in order to link these hypoalgesic changes to the activation of the descending inhibitory systems.

Physical Activity Levels Predict Exercise-induced Hypoalgesia in Older Adults

This study examined potential psychological and physical activity predictors of the magnitude of EIH after submaximal isometric exercise in healthy older adult men and women. Fifty-two healthy older adults completed a test of EIH, the Pain Catastrophizing Scale, the Tampa Scale of Kinesiophobia, and wore an accelerometer on the hip for 1 wk to assess physical activity levels. For the test of EIH, participants complete a 3-min isometric handgrip at 25% of maximum voluntary contraction. Pressure pain thresholds (PPT) and a 30-s continuous heat pain test were completed before and immediately after the exercise. Mixed-model ANOVA revealed that older adults demonstrated significantly decreased PPT after isometric exercise (P = 0.030), and no changes on the heat pain trials from pretest to posttest (P > 0.05). A multiple regression revealed that accumulated moderate to vigorous physical activity (MVPA) per week significantly predicted the change in PPT after exercise (β = 0.35, P = 0.012). Participants who averaged greater MVPA experienced a greater increase in PPT after exercise. No relationships were found with EIH and the psychological variables. Older adults did not exhibit EIH after submaximal isometric exercise. However, those who did more MVPA per week experienced a greater magnitude of pain inhibition after acute exercise.

Changes in Cervicocephalic Kinesthetic Sensibility, Widespread Pressure Pain Sensitivity, and Neck Pain After Cervical Thrust Manipulation in Patients With Chronic Mechanical Neck Pain: A Randomized Clinical Trial

ObjectiveThe purpose of the current randomized clinical trial was to examine the effects of cervical thrust manipulation or sham manipulation on cervicocephalic kinaesthetic sense, pain, pain-related disability, and pressure pain sensitivity in patients with mechanical neck pain. MethodsFifty-four individuals with neck pain were randomly assigned to receive either a cervical manipulation (right or left) or a sham manipulation. Immediate outcomes included cervical kinesthetic sense as assessed by joint position sense error (JPSE) and pressure pain thresholds (PPTs). At 1 week, neck pain intensity (numerical pain rate scale) and neck pain-related disability (Neck Disability Index [NDI]) outcomes were also collected. ResultsThe mixed-model analysis of covariance revealed a significant group × time interaction in favor of the cervical thrust manipulation group for the JPSE on rotation and extension. There was also a significant interaction for changes in PPTs at C5 to C6 and tibialis anterior. At the 1-week follow-up, a significant interaction existed for neck-related disability but not for neck pain at rest, worst pain, or lowest pain experienced the preceding week. ConclusionsOur results suggest that cervical spine thrust manipulation improves JPSE, PPT and NDI in participants with chronic mechanical neck pain. Furthermore, changes in JPSE and NDI were large and surpass published minimal detectable changes for these outcome measures. In addition, the effect sizes of PPTs were medium; however, only C5 to C6 zygapophyseal joint exceeded the minimal detectable change. In contrast, cervical thrust manipulation did not improve neck pain intensity at 1 week after the intervention.

Intensity-dependent effects of aerobic training on pressure pain threshold in overweight men: A randomized trial.

To investigate the chronic and acute effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on pressure pain thresholds (PPT) in overweight men. Twenty-eight participants performed stationary cycling exercise three times per week for 6weeks. Participants were randomly allocated to HIIT (10×1-min intervals at 90% peak heart rate) or MICT (30min at 65-75% peak heart rate). PPTs were assessed over the rectus femoris, tibialis anterior and upper trapezius before and after the 6-week training programme (chronic effect) as well as before and after the first, middle and final exercise sessions (acute effect). For chronic exercise, PPTs increased more after MICT compared to HIIT over the rectus femoris (p=0.009, effect size r=0.54) and tibialis anterior (p=0.012, r=0.54), but not the trapezius (p=0.399, r=0.29). The effect of acute exercise on PPT was more varied and ranged from moderate hypoalgesia to moderate hyperalgesia. Overall, however, there was no consistent change in PPT after acute exercise for HIIT or MICT (p≥0.231, r≥-0.31 and ≤0.31). Six weeks of MICT cycling (chronic exercise) increased PPT for the lower body, but not upper body, in overweight men, whereas HIIT did not provide any hypoalgesic effect for chronic exercise. The acute effect of exercise on PPT was highly variable and negligible overall. This study shows that aerobic training increases pressure pain threshold in pain-free adults. This effect was observed only for MICT over-exercised muscles, implying intensity- and site-specific effects of exercise training on pain threshold.

An investigation of contextual factors in the application of multisensory illusions for analgesia in hand osteoarthritis.

ObjectiveEmerging evidence suggests that multisensory illusions can modulate pain and can lead to changes in body perception. The aim of this study was to investigate whether contextual factors could explain the analgesic effects of multisensory body illusions on pain and body perception in people with hand OA (HOA).MethodsIn a crossover study, 28 individuals with painful HOA viewed their most affected hand in and outside of a real-time mediated reality system, with illusory stretching of the hand and changes in sensory input. The outcome measures were pain ratings, pressure pain thresholds, hand function and the subjective experience of the illusion.ResultsStretching the hand both inside and outside the virtual environment led to a reduction in subjective pain ratings (all P < 0.05). Virtual stretching led to changes in body perception (P < 0.05) with no changes in pressure pain threshold (all P > 0.05). Higher pain at baseline predicted susceptibility to the stretch illusion and mean susceptibility ratings were greatest after the stretch illusion.ConclusionThe current study highlights the importance of the context in which pain occurs and in which potential treatments may be applied. In this case, virtual and physical stretching modulated pain, but not viewing the hand alone. The research opens important implications for future research, including the use of contextual control conditions and the development of visual feedback interventions for a range of similarly visible chronic conditions for which pain, body image disturbances and body dissatisfaction may be apparent.

Effect of Sacroiliac Joint Mobilization on the Level of Soft Tissue Pain Threshold in Asymptomatic Women

ObjectiveThis study aimed to evaluate the effect of sacroiliac joint (SIJ) mobilization and/or self-mobilization on the level of soft tissue pain threshold in 21- to 23-year-old asymptomatic women (n = 20). MethodsThe FPIX Wagner Algometer was applied to compute the pressure pain threshold (PPT) over the right and left side of the iliolumbar ligament and lumbar erector spinae (L3). Measurements were taken of the right SIJ before and after a randomized protocol of oscillating mobilization, self-mobilization, and placebo treatment. ResultsA main effect of intervention (mobilization, self-mobilization, placebo) was confirmed by analysis of variance, with increases in PPT over the iliolumbar ligament (F = 13.04, P < .05) and erector spinae (F = 12.28, P < .05) on the mobilized side. The Wilcoxon test indicated that SIJ mobilization increased PPT over the iliolumbar ligament (P < .05) and erector spinae (P < .05) on both sides. Self-mobilization increased erector spinae PPT on the exercised side (P < .05), whereas the placebo did not cause any changes in PPT (P > .05). ConclusionThe study provides evidence of local and global pain modulation resulting from oscillatory mobilization of the SIJ in women without pain symptoms. Self-mobilization of the SIJ has limited analgesic application.

Test-Retest Reliabilty of Exercise-Induced Hypoalgesia After Aerobic Exercise.

Exercise increases pressure pain thresholds (PPTs) in exercising and nonexercising muscles, known as exercise-induced hypoalgesia (EIH). No studies have investigated the test-retest reliability of change in PPTs after aerobic exercise. Primary objectives were to compare the effect on PPTs after an incremental bicycling exercise compared with quiet rest and to investigate the relative and absolute test-retest reliability of the test stimulus (PPT) and the absolute and relative EIH response in exercising and nonexercising muscles. Laboratory. In two sessions, PPTs in the quadriceps and trapezius muscles were assessed before and after 15 minutes of quiet rest and 15 minutes of bicycling in 34 healthy subjects. Habitual physical activity was assessed by the International Physical Activity Questionnaire (IPAQ). Bicycling increased PPTs in exercising and nonexercising muscles in both sessions (P < 0.05). The magnitude of the EIH response in the exercising muscle was, however, larger in the second compared with the first session (P < 0.015). PPTs showed excellent (intraclass correlation [ICC] ≥ 0.84) within-session and between-session test-retest reliability. The EIH response in exercising and nonexercising muscles demonstrated fair (ICC = 0.45) between-session relative test-retest reliability, but agreement in EIH responders between sessions was not significant (quadriceps: κ = 0.24, P = 0.15; trapezius: κ = 0.01, P = 0.97). Positive correlations between the IPAQ score and PPTs were found (quadriceps: r = 0.44, P = 0.009; trapezius: r = 0.31, P = 0.07) before exercise. No significant association was found between IPAQ and EIH. Incremental bicycling exercise increased PPTs with fair relative and absolute reliability of the EIH response. These data might have an impact on future studies investigating EIH and for clinicians designing exercise programs for pain relief.

Being Adaptive to Pain Enhances Sham Acupuncture Analgesia: A Crossover Healthy Human Study

We have reported a model that distinguishes pain adaptive individuals (PA) from those who are pain non-adaptive (PNA). The present randomised, cross-over, participant-assessor blinded study aimed to determine the impact of pain adaptability on individuals’ response to real and sham acupuncture. Healthy volunteers (nine PA and 13 PNA) were randomly allocated to receive real and sham acupuncture on the left hand and forearm in two separate acupuncture sessions. Pressure pain thresholds (PPTs) were measured at bilateral forearms and right leg before, immediately after and 20 minutes after the end of acupuncture. Ratings to pinprick and suprathreshold PPT were also recorded. The two groups were comparable in their demographic and baseline data. Analgesia induced by real or sham acupuncture did not differ on any outcome measures. PA responded to acupuncture needling better than PNA, and to sham needling (20% increase in PPT) better than to real acupuncture (7.9%). Those differences were at 20 min after end of acupuncture in the areas distant to the needling sites. PNA reported little changes in PPT. Being adaptive to pain was associated with enhanced distant analgesia in response to sham acupuncture. Our finding might partly explain varied acupuncture analgesia in clinical practice and trials.

The immediate effects of manual stretching and cervicothoracic junction manipulation on cervical range of motion and upper trapezius pressure pain thresholds.

Myofascial pain is a common impairment treated with various manual interventions including spinal thrust manipulation and stretching; however, the comparative efficacy of each intervention is uncertain. Therefore, the purpose of this investigation was to evaluate thrust manipulation targeting the cervicothoracic junction compared to a manual stretch of the upper trapezius muscle on cervical range of motion and upper trapezius pressure pain thresholds (PPTs). Healthy participants with no significant history of neck pain were randomized into a thrust manipulation group, a stretching group, or a control group. Within group differences were evaluated via a dependent t-test, and group by time interactions were evaluated by a two-way repeated measures ANOVA. One hundred and two participants were recruited to participate. Baseline demographics revealed no significant differences between groups. Significant group by time interactions were found for changes in PPTs for both the right and left upper trapezius. Also, significant differences were found for changes in cervical extension, as well as right and left cervical side bending favoring the treatment groups. This study demonstrates the potential independent effectiveness of spinal thrust manipulation or stretching for reducing PPTs at the upper trapezius. Future research should further evaluate the limitation of PPTs as a measure of muscle sensitivity as well as factors that may contribute to variability in the measurements among individuals seeking care.

Characterization of peripheral and central sensitization after dorsal root ganglion intervention in patients with unilateral lumbosacral radicular pain: a prospective pilot study

BackgroundQuantitative sensory testing (QST) has been used to predict the outcome of epidural steroid injections in lumbosacral radicular pain and has the potential to be an important tool in the selection of appropriate treatment (such as epidural steroid injections vs surgery) for patients with chronic radicular pain. In addition, QST assists in identification of the pain pathways of peripheral and central sensitization in selected groups of patients. MethodsTwenty-three patients were given dorsal root ganglion (DRG) infiltration with local anaesthesia and steroid (‘DRG block’), and those who demonstrated at least 50% pain relief were offered pulsed radiofrequency (PRF) to the DRG. Questionnaires and QST scores were measured before the DRG blocks and at 1 week and 3 months after their procedure. Those who received PRF also answered questionnaires and underwent QST measurements at 1 week and 3 months after their procedure. ResultsThere was a significant increase in pressure pain threshold scores after DRG blocks. A reduced conditioned pain modulation response was seen before DRG, which increased after the procedure. Ten out of 23 patients underwent PRF to the DRG, and an increase in pressure pain threshold scores after PRF was observed. The conditioned pain modulation response was maintained in this group and increased after PRF. ConclusionsThe study demonstrates that patients with unilateral radicular low back pain who receive dorsal root ganglion interventions show changes in pressure pain thresholds and conditioned pain modulation that are consistent with a ‘normalization’ of peripheral and central sensitization.

Quantitative sensory testing measures individual pain responses in emergency department patients.

BackgroundRefining and individualizing treatment of acute pain in the emergency department (ED) is a high priority, given that painful complaints are the most common reasons for ED visits. Few tools exist to objectively measure pain perception in the ED setting. We speculated that variation in perception of fixed painful stimuli would explain individual variation in reported pain and response to treatment among ED patients.Materials and methodsIn three studies, we 1) describe performance characteristics of brief quantitative sensory testing (QST) in 50 healthy volunteers, 2) test effects of 10 mg oxycodone versus placebo on QST measures in 18 healthy volunteers, and 3) measure interindividual differences in nociception and treatment responses in 198 ED patients with a painful complaint during ED treatment. QST measures adapted for use in the ED included pressure sensation threshold, pressure pain threshold (PPT), pressure pain response (PPR), and cold pain tolerance (CPT) tests.ResultsFirst, all QST measures had high inter-rater reliability and test–retest reproducibility. Second, 10 mg oxycodone reduced PPR, increased PPT, and prolonged CPT. Third, baseline PPT and PPR revealed hyperalgesia in 31 (16%) ED subjects relative to healthy volunteers. In 173 (88%) ED subjects who completed repeat testing 30 minutes after pain treatment, PPT increased and PPR decreased (Cohen’s dz 0.10–0.19). Verbal pain scores (0–10) for the ED complaint decreased by 2.2 (95% confidence intervals [CI]: 1.9, 2.6) (Cohen’s dz 0.97) but did not covary with the changes in PPT and PPR (r=0.05–0.13). Treatment effects were greatest in ED subjects with a history of treatment for anxiety or depression (Cohen’s dz 0.26–0.43) or with baseline hyperalgesia (Cohen’s dz 0.40–0.88).ConclusionQST reveals individual differences in perception of fixed painful stimuli in ED patients, including hyperalgesia. Subgroups of ED patients with hyperalgesia and psychiatric history report larger treatment effects on ED pain and QST measures.

The Effect of the Posture of the “Hermit Doing Body Contortion” on Relief of Shoulder and Scapular Pain Caused by Chronic Myofascial Pain Syndrome: A Randomized, Parallel Group, Controlled Trial

Objective: To explore the ability of the posture of the “Hermit Doing Body Contortion” (HDBC) to relieve shoulder and scapular pain in patients with chronic myofascial pain syndrome (MPS). Methods: One hundred and thirty-six out-patients with chronic MPS were randomly assigned to one of two groups. The experimental group was advised to perform a posture of the HDBC named “posture for relieving abdominal pain, pain of the scapular blade” (PRASP) every day for two months. Both groups received Thai traditional massage treatment and hot herbal compresses once a week for four weeks. Using a numeric rating scale and dolorimeter, outcomes were assessed prior to commencing the intervention (M 0 ), and one and two months after commencing the intervention (M 1 and M 2, ). Results: The mean change in pain intensity between M 1 and M 2 differed significantly between the groups (1.32±1.45 in the experimental group and 0.47±2.26 in the control group; p = 0.039). Similarly, the mean change in pressure pain threshold between M 0 and M 2 also differed significantly between the groups (1.39±1.76 in the experimental group and 0.53±1.90 in the control group; p-value =0.027). In both cases, the experimental group achieved greater pain relief. Conclusion: In patients with chronic MPS, the posture of the HDBC combined with standard Thai traditional medicine treatments provided better ongoing relief of shoulder and scapular pain than did standard Thai traditional medicine treatments alone. Clinical trial registration no.: TCTR20151230002

Treatment of Myofascial Triggerpoints: A Comparison of “Spray and Stretch” and “Postisometric Relaxation”

Purpose: Referred pain from myofascial trigger points (MTrP) frequently can be found as the underlying condition in patients presenting with back pain, joint pain, or headache. The purpose of this trial was to compare the pain reduction of postisometric relaxation therapy (PIR) and spray and stretch therapy (SAS). Materials and Methods: Outpatients (24 female and 3 male) with at least one active MTrP were randomised to either SAS or PIR therapy. In both groups, every participant received 3 treatment sessions. The pressure pain threshold (PPT) was measured. Additionally, the pain level was rated by the patient using a visual analogue scale (VAS). The primary outcome was the difference in PPT at follow up after 3–4 weeks (t4) and time of randomisation (t0). As an exploratory data analysis PPT values and VAS ratings before and after each treatment session and VAS ratings at t0 and t4 have been evaluated. Results: The mean change in PPT was +22.1 kPa (SD 70.3 kPa) in the SAS group and −25.6 kPa (SD 80.5 kPa) in the PIR group. There was no significant difference between these mean values (p=0.1146). Hence no difference between these treatment options could be found. Also, the exploratory data analysis of PPT and VAS values did not suggest a difference between SAS and PIR treatments. In both groups, some patients worsened and some improved. In some cases PPT measurements and VAS ratings were inconsistent. Discussion: No difference was found between SAS and PIR, but the number of patients evaluated may have been too small to show an existing difference between the 2 treatment options. We included patients with acute myofascial pain as well as patients with chronic myofascial pain. They may react differently to treatment and should probably be evaluated separately. There may be a bias due to the change of the examiner in our trial. We can not explain the majority of women presenting with myofascial pain but this is consistent with former studies. Conclusions: Further research is necessary to reveal if either PIR or SAS therapy is more appropriate in terms of pain reduction. Patients with chronic pain and those with acute pain should be evaluated separately.

The interaction between NGF-induced hyperalgesia and acid-provoked pain in the infrapatellar fat pad and tibialis anterior muscle of healthy volunteers.

Tissue pH is lowered in inflamed tissues, and the increased proton concentration activates acid-sensing ion channels (ASICs), contributing to pain and hyperalgesia. ASICs can be upregulated by nerve growth factor (NGF). The aim of this study was to investigate two new human experimental pain models combining NGF- and acid-induced pain in a randomized, controlled, double-blind study. In experiment 1, volunteers (N=16) received an injection of either NGF or isotonic saline in each infrapatellar fat pad (IFP). One day after 5mL of phosphate-buffered acidic saline was infused into each IFP at a rate of 20mL/h. In experiment 2, the tibialis anterior (TA) muscle of additional volunteers (N=16) was examined, following the same procedure except that the volume and infusion rate of acid were different (10mL, 30mL/h). Continuous pain ratings were recorded during and after acid infusions. In addition, soreness scores on a Likert scale and pressure pain thresholds (PPTs) were assessed. The PPT of the IFP was significantly decreased at the NGF injection site on day 1, but acid-provoked pain ratings and the change in PPT from pre- to postinfusion between the knees were similar. In the muscle pain model, local mechanical hyperalgesia developed 3h after the NGF injection and a significant additional decrease in PPT was found after acid infusion compared to preinfusion. NGF sensitization in the IFP was not facilitated by acid, whereas an acid-provoked enhancement of muscle hyperalgesia was found. NGF sensitization of adipose tissue responds differently to acid provocation compared to muscle tissue. Quantification of two novel pain models combining NGF and acid. Hyperalgesia developed after NGF injection in the infrapatellar fat pad, but it was not facilitated by acid provocation. Contrary, NGF-induced hyperalgesia in muscle tissue was enhanced by acid.