Gender differences in pressure pain threshold in a repeated measures assessment

Cervical sensitivity, range of motion and strength in individuals with shoulder pain: A cross-sectional case control study

OBJECTIVES

To assess whether cervical sensitivity, range of motion (ROM) and strength are impaired in individuals with shoulder pain and how they interact with sociodemographic and clinical data.

METHODS

Forty-eight individuals with shoulder pain and 48 asymptomatic matched ones were included. Pressure pain thresholds (PPTs) in cervical region and tibialis anterior muscles, ROM of cervical flexion, extension, lateral flexions and rotations and cervical muscle strength of flexion, extension and lateral flexions were assessed. Between-groups comparisons and a logistic multiple regression model were performed.

RESULTS

The symptomatic group showed lower and not meaningful PPTs in trapezius of the unaffected/unmatched side, both sternocleidomastoid muscles, and tibialis anterior and reduced ROM in cervical extension (MD = -9.00°) when compared to the asymptomatic group. No differences were identified in muscle strength. Reduced PPT of the trapezius and reduced cervical extension ROM together accounted for 40.2% of the variance of the chance of presenting shoulder pain.

CONCLUSION

Individuals with shoulder pain have more, but not clinically relevant, cervical sensitivity and lower cervical extension than asymptomatic individuals. The lower the PPT of the upper trapezius and the cervical extension ROM, the higher was the chance to present shoulder pain. Regional interdependence between cervical spine and shoulder may explain cervical physical function alterations in shoulder pain.

The Effects of an Acute Maximal Seated Lumbar Spine Flexion Exposure on Low Back Mechanical Pain Sensitivity

Viscoelastic creep generated in the lumbar spine following sustained spine flexion may affect the relationship between tissue damage and perceived pain. Two processes supporting this altered relationship include altered neural feedback and inflammatory processes. Our purpose was to determine how low back mechanical pain sensitivity changes following seated lumbar spine flexion using pressure algometry in a repeated-measures, cross-sectional laboratory design. Thirty-eight participants underwent a 10-minute sustained seated maximal flexion exposure with a 40-minute standing recovery period. Pressure algometry assessed pressure pain thresholds and the perceived intensity and unpleasantness of fixed pressures. Accelerometers measured spine flexion angles, and electromyography measured muscular activity during flexion. The flexion exposure produced 4.4° (2.7°) of creep that persisted throughout the entire recovery period. The perception of low back stimulus unpleasantness was elevated immediately following the exposure, 20 minutes before a delayed increase in lumbar erector spinae muscle activity. Women reported the fixed pressures to be more intense than men. Sustained flexion had immediate consequences to the quality of mechanical stimulus perceived but did not alter pressure pain thresholds. Neural feedback and inflammation seemed unlikely mechanisms for this given the time and direction of pain sensitivity changes, leaving a postulated cortical influence.

Are people good prognosticators of their own pain? An exploration of the relationship between sex-specific pain beliefs and clinical pain evaluation

BACKGROUND

Under-explored to date are the interacting influences of patient sex on multi-modal evaluation techniques that tap different domains of the pain experience.

OBJECTIVES

The primary aim of Study 1 was to explore the accuracy of sex-specific personal pain beliefs in relation to quantitative pain indicators within sexes, and the secondary objective was to compare the accuracy of sex-specific personal pain beliefs in relation to quantitative pain indicators between sexes. The primary objective of Study 2 was to explore the accuracy of sex-specific personal pain beliefs and self-rated pain severity within sexes, and the secondary objective was to compare sex-specific personal pain beliefs and pain severity ratings between sexes.

METHODS

A cross-sectional analysis on two datasets was performed (Study 1, n = 50; Study 2, n = 111). For both studies, independent samples t-tests were used to identify differences in clinical pain evaluations based on sex-specific pain beliefs. Receiver Operating Characteristic (ROC) curves were used to compare the predictive accuracy of males and females clinical pain evaluations based on their ability to handle pain.

RESULTS

There were no statistically significant differences in clinical pain evaluations based on self-rated pain beliefs in either study. In Study 2, males were descriptively more accurate predictors of their clinical pain evaluations than were females, though none of the between sex comparisons were statistically significant.

CONCLUSION

This work highlights the importance of considering all available clinical pain evaluations as one technique is unlikely to represent the patients pain experience.

Personal influencing factors for pressure pain threshold in healthy people: A systematic review and meta-analysis

All studies that investigated personal factors influencing pressure pain threshold (PPT) in healthy people were synthesized. Data was summarized, and risk of bias (RoB) and level of evidence were determined. Results were pooled per influencing factor, grouped by body region and included in meta-analyses. Fifty-four studies were eligible. Five had low, nine moderate, and 40 high RoB. Following meta-analyses, a strong conclusion was found for the influence of scapular position, a moderate for the influence of gender, and a weak for the influence of age (shoulder/arm region) and blood pressure on PPT. In addition, body mass index, gender (leg region), alcohol consumption and pain vigilance may not influence PPT. Based on qualitative summary, depression and menopause may not influence PPT. For other variables there was only preliminary or conflicting evidence. However, caution is advised, since the majority of included studies showed a high RoB and several were not eligible to include in meta-analyses. Heterogeneity was high in the performed meta-analyses, and most conclusions were weak. More standardized research is necessary.

Profiling and Association over Time between Disability and Pain Features in Patients with Chronic Nonspecific Neck Pain: A Longitudinal Study

OBJECTIVES

To longitudinally investigate the relationships between neck/arm disability and pain profile measures in individuals with chronic nonspecific neck pain (NSNP) at baseline, one month, and six months after a standardized physiotherapy intervention. A secondary aim was to compare pain sensitivity of individuals with chronic NSNP at baseline to healthy controls.

METHODS

A total of sixty-eight individuals with chronic NSNP and healthy controls were recruited. Neck disability index (NDI), the 11-item disabilities of the arm, shoulder, and hand questionnaire (QuickDASH), temporal summation (TS), pressure pain thresholds (PPTs), pain intensity and pain extent were assessed in individuals with chronic NSNP. For the cross-sectional assessment, TS and PPTs were compared to healthy controls.

RESULTS

After following a standardized physiotherapy intervention, local and distal PPTs to the neck region decreased at one and six month follow-ups, respectively. Pain extent decreased at one and six months. Furthermore, a positive correlation between neck/arm disability and pain intensity was found at baseline, whereas moderate positive correlations (e.g., between NDI and pain extent) at baseline, one and six month follow-ups and negative correlations at six months (e.g., between arm disability and PPTs) were found.

DISCUSSION

Overall, these findings indicate that pain sensitivity can worsen following treatment despite reduced pain extent and unchanged neck disability and pain intensity scores over a six-month period in individuals with chronic NSNP.

Randomized cross-over evaluation of investigator gender on pain thresholds in healthy volunteers

Background and aims: This randomized cross-over study in healthy volunteers was designed primarily to evaluate the potential impact of investigator gender on electrical pain threshold (EPT) and corresponding pain intensity levels, and secondly to evaluate potential differences in those interventions between female and male study participants. Methods: Forty adult volunteers (22 females) were included. An electrical stimulation device was used to determine EPT levels (in pain magnitude scores) in series of three in each study participant - once by a female, and once by a male investigator - according to a predefined cross-over design schedule. Corresponding levels of pain intensity were scored on a visual analog scale (VAS) slide ruler. Results: Study data was obtained and analysed in all participants. Significantly higher EPT levels were determined by the female investigator compared with the male investigator (median 22 (IQR 12-31) vs. 8 (6-10) pain magnitude scores; p<0.0001), despite similar levels of reported pain intensity (1.9 (1.2-3.0) vs. 2.0 (1.1-3.4) VAS units; p>0.300). There were no differences in EPT levels between female and male subjects evaluated by female (p>0.300) and male (p=0.125) investigators, or between the first and second series of stimulation (p>0.300). Conclusions: Our finding of significantly higher EPT levels when study participants of both genders - despite no difference in reported pain intensity - were evaluated by a female than by a male investigator, indicates a potential impact of investigator gender on the individual perception of pain. Implications: By contributing to a better understanding of how individual pain threshold levels are potentially influenced by investigator gender, this study might facilitate future evaluation of pain conditions in both preclinical and clinical settings.

The influence of sex and level of physical activity on maximum tolerance to mechanical pain

Background

A difference in maximum tolerance to mechanical pain (MTMP) between the sexes is widely studied but there is still no consensus on whether the level of physical activity (PA) influences pain.

Objectives

To compare the MTMP between men and women with different levels of PA.

Methods

Sixty five individuals were divided in female (n = 35) and male group (n = 30). The main outcome measures were PA level and MTMP by pressure algometry. Pressure was applied three times on both sides at the following points: cervical (5^th and 7^th) and lumbar (3^th and 5^th) vertebrae; trapezius, rhomboid, gluteus, gastrocnemius, pectoralis major, tibialis anterior, and deltoid muscles, elbow, hand, knee, and ankle.

Results

It was observed that the PA level has little influence on the MTMP at all the assessed points and that men have greater MTMP than women.

Conclusion

Sex, not the PA level, influences the MTMP.

Sex Differences in the Blood Oxygen Level-Dependent Signal to Placebo Analgesia and Nocebo Hyperalgesia in Experimental Pain: A Functional MRI Study

Objective

Placebo as well as nocebo responses are widely found in scientific research and clinical practice. Growing evidence suggests sex differences in placebo as well as nocebo responses. However, data concerning this question are still insufficient. This study examined whether the BOLD signals of two responses, as measured with functional MRI (fMRI), differ by sex under conditions of equivalent experimental pain perception.

Method

Thirty-one healthy volunteers (14 female) underwent two fMRI scans, once during a placebo intervention and once during a nocebo intervention, pseudorandomly ordered, in an acute lower back pain (ALBP) model. We collected visual analog scale (VAS) data after each scanning. fMRI data from different sex groups were subjected to functional connectivity (FC) analysis and behavioral correlation analysis (BCA).

Results

The results showed statistical differences in VAS scores between male and female participants, in both placebo and nocebo responses. Both groups also showed reduced FC in the pain-associated network of the placebo response and elevated FC in the pain-related network of the nocebo response. However, in the placebo condition, male participants displayed increased FC in the ventromedial prefrontal cortex, parahippocampal gyrus (PHP), and posterior cingulate cortex (PCC), while female participants showed increased FC in the dorsolateral prefrontal cortex, hippocampal gyrus (HP), and insular cortex (IC). In the nocebo condition, male participants showed decreased FC in the PCC and HP, while female participants displayed decreased FC in the mid-cingulate cortex, thalamus (THS), and HP. The BCA results of the two groups were also different.

Conclusion

We found that the endogenous opioid system and reward circuit play a key role in sex differences of placebo response and that anxiety and its secondary reactions may cause the sex differences of nocebo response.

"Big girls don't cry": the effect of the experimenter's sex and pain catastrophising on pain

OBJECTIVES

The expression of pain in males and females involves complex socio-psychological mechanisms. Males may report lower pain to a female experimenter to appear strong, whereas females may report higher pain to a male experimenter to appear weak and to seek protection. However, evidence to support these stereotypes is inconclusive. Individuals who catastrophise about pain rate higher pain than those who do not. How pain catastrophising interacts with the effect of the experimenter's sex on pain reports is yet to be explored. Thus, the aim of this study was to determine whether pain catastrophising moderated the effect of the experimenter's sex on pain reports in healthy males and females.

METHODS

Participants (n=60, 30 males) were assigned to one of four experimental conditions: males tested by male experimenters, males tested by female experimenters, females tested by male experimenters, and females tested by female experimenters. Participants completed the Pain Catastrophising Scale, and then sensitivity to heat and to blunt (pressure-pain threshold) and sharp stimuli was assessed on both forearms, and to high frequency electrical stimulation (HFS) administered to one forearm.

RESULTS

Females reported lower pressure-pain thresholds than males irrespective of the experimenters' sex. Females reported lower sharpness ratings to male than female experimenters only when the test stimuli were moderately or intensely sharp. Higher pain catastrophising scores were associated with higher sharpness ratings in females but not males. Additionally, higher pain catastrophising scores were associated with greater temporal summation of pain to HFS, and with lower pressure-pain thresholds in females who were tested by male experimenters.

CONCLUSIONS

These findings indicate that the experimenters' sex and the participant's pain catastrophising score influence pain reports, particularly in females. Awareness of these psychosocial factors is important in order to interpret pain responses in a meaningful way, especially when females are tested by male experimenters. A greater awareness of sex/gender role biases and their potential interaction with pain catastrophising may help researchers and clinicians to interpret pain reports in meaningful ways. In turn, this may help to improve delivery of treatments for patients with chronic pain.

Effect of Age, Sex and Gender on Pain Sensitivity: A Narrative Review

Introduction:

An increasing body of literature on sex and gender differences in pain sensitivity has been accumulated in recent years. There is also evidence from epidemiological research that painful conditions are more prevalent in older people. The aim of this narrative review is to critically appraise the relevant literature investigating the presence of age and sex differences in clinical and experimental pain conditions.

Methods:

A scoping search of the literature identifying relevant peer reviewed articles was conducted on May 2016. Information and evidence from the key articles were narratively described and data was quantitatively synthesised to identify gaps of knowledge in the research literature concerning age and sex differences in pain responses.

Results:

This critical appraisal of the literature suggests that the results of the experimental and clinical studies regarding age and sex differences in pain contain some contradictions as far as age differences in pain are concerned. While data from the clinical studies are more consistent and seem to point towards the fact that chronic pain prevalence increases in the elderly findings from the experimental studies on the other hand were inconsistent, with pain threshold increasing with age in some studies and decreasing with age in others.

Conclusion:

There is a need for further research using the latest advanced quantitative sensory testing protocols to measure the function of small nerve fibres that are involved in nociception and pain sensitivity across the human life span.

Implications:

Findings from these studies should feed into and inform evidence emerging from other types of studies (e.g. brain imaging technique and psychometrics) suggesting that pain in the older humans may have unique characteristics that affect how old patients respond to intervention.

A systematic review of sex differences in the placebo and the nocebo effect

Objectives

The present review investigated whether there are systematic sex differences in the placebo and the nocebo effect.

Methods

A literature search was conducted in multiple electronic databases. Studies were included if the study compared a group or condition where a placebo was administered to a natural history group or similar cohort.

Results

Eighteen studies were identified – 12 on placebo effects and 6 on nocebo effects. Chi-square tests revealed that 1) males responded more strongly to placebo treatment, and females responded more strongly to nocebo treatment, and 2) males responded with larger placebo effects induced by verbal information, and females responded with larger nocebo effects induced by conditioning procedures.

Conclusion

This review indicates that there are sex differences in the placebo and nocebo effects, probably caused by sex differences in stress, anxiety, and the endogenous opioid system.

Tensiomyography, sonoelastography, and mechanosensitivity differences between active, latent, and control low back myofascial trigger points: A cross-sectional study

The myofascial pain syndrome (MPS) is considered the most common musculoskeletal condition. The lumbopelvic pain (LPP) is established as one of the most prevalent musculoskeletal disorders. Nevertheless, previous research has not yet studied the contractibility changes by tensiomyography between myofascial trigger point (MTrP) types and normal tissue. Therefore, the aim of this study was to determine the tensiomyography, sonoelastography, and pressure pain threshold (PPT) differences between the palpation area of active and latent MTrPs with regards to control points in the lumbar erector spinae muscles of subjects with LPP. A cross-sectional descriptive study was performed. A convenience sample of 60 points (20 active MTrPs, 20 latent MTrPs, and 20 control points) was registered bilaterally in the lumbar erector spinae muscles from subjects with nonspecific LPP. The palpation order of active MTrPs, latent MTrPs, or control points was randomized for each side. The outcome assessors were blinded to the order or point type. The outcome measurements order for each point was sonoelastography manual strain index, tensiomyography, and PPT, separated by 15 minutes. Five contractile objective parameters were: maximal radial displacement (Dm), contraction time (Tc), sustain time (Ts), delay time (Td), and half-relaxation time (Tr). Tensiomyography parameters did not show any statistically significant difference (P > 0.05) between active MTrPs, latent MTrPs, and control points. Nevertheless, PPT and sonoelastography showed statistically significant differences (P < 0.05) between all point types, except for active and latent MTrPs PPT comparison (P = 0.091). Regarding the active MTrPs, a moderate positive correlation was observed between PPT and Dm (P = 0.047; τB = 0.450). Considering the control points, a moderate positive correlation was shown between sonoelastography and Td (P = 0.044; τB = 0.328). The tensiomyography contractile properties did not seem to show differences, while the sonoelastography and mechanosensitivity presented a higher stiffness and a lower PPT, respectively, between the palpation area of active and latent MTrPs with regards to control points in the lumbar erector spinae muscles of subjects with LPP. Considering the correlations, further research is needed regarding the muscle contractile properties modifications under MPS treatments, especially Dm in active MTrPs and Td in normal sites.

Idiopathic musculoskeletal pain in Indian children-Prevalence and impact on daily routine

OBJECTIVES

To study the prevalence of idiopathic musculoskeletal pain (IMSP) in school going children and its impact on daily life.

METHODS

One thousand eighteen apparently healthy school children aged 5-16 years were assessed and analysed for IMSP and its associated problems. Standard tests for significance were applied.

RESULTS

One hundred and sixty-five (16.2%) children mostly males (55.2%) reported IMSP. Lower limbs (52.1%) were the most common location of pain. More than 1 year of pain history was present in 15%. Thirty-seven percent children complained of discomfort during walking, 30.9%, had pain during physical exercise, 29.2% had difficulty attending lessons and 4.2% had interference in pursuing hobbies. The children were also further sub grouped into preadolescents and adolescents. There was significant difference in pain duration and duration of each pain episode in the two groups (p=0.01). A significant number of children (21.2%) with IMSP reported school absenteeism (p<0.001). A significant number of adolescents had history positive for contact sports (p=0.001). Sleep disturbances were also reported to be higher in children with IMSP (29% vs. 5.7%, p=0.001). Other associated problems in children with IMSP found were day time tiredness (51.1%), headache (47.3%) and abdominal pain (24.8%).

CONCLUSIONS

Prevalence of IMSP in school children aged 5-16 yrs was found to be 16.2% and a significant percentage of these children experience interference with daily activities including school absenteeism.

Protocol: Testing the Relevance of Acupuncture Theory in the Treatment of Myofascial Pain in the Upper Trapezius Muscle

A protocol for a prospective single-blind parallel four-arm randomized placebo-controlled trial with repeated measures was designed to test the effects of various acupuncture methods compared with sham. Eighty self-selected participants with myofascial pain in the upper trapezius muscle were randomized into four groups. Group 1 received acupuncture to a myofascial trigger point (MTrP) in the upper trapezius. Group 2 received acupuncture to the MTrP in addition to relevant distal points. Group 3 received acupuncture to the relevant distal points only. Group 4 received a sham treatment to both the MTrP and distal points using a deactivated acupuncture laser device. Treatment was applied four times within 2 weeks with outcomes measured throughout the trial and at 2 weeks and 4 weeks posttreatment. Outcome measurements were a 100-mm visual analog pain scale, SF-36, pressure pain threshold, Neck Disability Index, the Upper Extremity Functional Index, lateral flexion in the neck, McGill Pain Questionnaire, Massachusetts General Hospital Acupuncture Sensation Scale, Working Alliance Inventory (short form), and the Credibility Expectance Questionnaire. Two-way analysis of variance (ANOVA) with repeated measures were used to assess the differences between groups.

Presence of Latent Myofascial Trigger Points and Determination of Pressure Pain Thresholds of the Shoulder Girdle in Healthy Children and Young Adults: A Cross-sectional Study

OBJECTIVE

The primary objective of this study was to compare the number of myofascial trigger points (MTPs) and the pressure pain thresholds (PPTs) in the shoulder girdle, on the dominant and nondominant sides, between healthy children and adults. The secondary aim was to assess the correlations between the number of MTPs and the PPTs in these populations.

METHODS

A cross-sectional study was performed. Thirty-five children (aged 9.1 ± 1.7 years) and 35 adults (aged 23.4 ± 3.4 years) with no history of shoulder or cervical pathology were included. All participants were examined for MTPs in the shoulder muscles and assessed for PPTs in the neck, shoulder, and tibialis anterior. Parametric and nonparametric tests, effect sizes, and odds ratios were used to determine the differences between groups and sides. Spearman's σ test was used to assess correlations between latent MTPs (LTPs) and PPTs in each group.

RESULTS

Children had fewer LTPs than adults did (P = .03). The upper trapezius was the muscle with the largest number of LTPs, affecting 13 adults on the dominant side. Children had lower PPTs compared with adults (P < .05). Correlations between the number of LTPs (on both sides and in total) and PPTs were observed only in adults.

CONCLUSIONS

Healthy children have fewer LTPs and lower PPTs in the shoulder girdle than healthy adults. A relationship was observed between sensitivity to pressure and the presence of LTPs in adults, in whom lower PPT was associated with more LTPs. This relationship was not detected in children.

Increased deep pain sensitivity in persistent musculoskeletal pain but not in other musculoskeletal pain states

Background

Pressure pain thresholds (PPTs) in a non-painful body area are known to be affected in some chronic pain states. The aim of this study is to investigate PPTs in a pain-free body part in relation to pain persistence and intensity in patients with musculoskeletal pain.

Methods

Patients with musculoskeletal pain were divided into three different pain groups: acute pain (pain duration < 3 months, n = 38), regularly recurrent pain (regularly recurrent pain duration > 3 months, n = 56), persistent pain (persistent pain duration >3 months, n = 52) and a healthy control group (n = 51). PPT measures were conducted over the tibialis anterior muscle on the right leg in all groups.

Results

The persistent pain group showed significantly lower PPTs over the tibialis anterior muscle compared to controls. No significant differences were found between the acute and regularly recurrent pain groups compared to healthy controls. Significant correlations, albeit small, were found between pain intensity and PPTs.

Conclusions

Increased deep pain sensitivity was found in patients with persistent musculoskeletal pain, but not in regularly recurrent pain or in acute pain. Yet, a limitation of the study is that it did not have sufficient power to detect small levels of increased deep pain sensitivity among the latter groups when compared to healthy controls.

Implications

Knowledge about increased general hypersensitivity in persistent musculoskeletal pain could be important in clinical treatment.

The McGill University Health Centre Cancer Pain Clinic: A Retrospective Analysis of an Interdisciplinary Approach to Cancer Pain Management

Context. The McGill University Health Center (MUHC) Cancer Pain Clinic offers an interdisciplinary approach to cancer pain management for patients. The core team includes a nurse clinician specialist in oncology and palliative care, a palliativist, an anaesthetist, and a radiation oncologist. This tailored approach includes pharmacological and nonpharmacological therapies offered concurrently in an interdisciplinary fashion. Objectives. Description of the interdisciplinary MUHC cancer pain approach and analysis of treatments and outcomes. Methods. A retrospective analysis of new outpatients completing two subsequent visits (baseline and follow-ups: FU₁, FU₂) was conducted. Variables included (a) symptom severity measured by the Edmonton Symptom Assessment Scale, (b) pain and disability measured with the Brief Pain Inventory, and (c) analgesic plan implementation including pharmacological and nonpharmacological therapies. Results. 71 charts were reviewed. Significant pain relief was achieved consistently at FU₁ and FU₂. The average pain severity decreased by 2 points between initial assessment and FU₂. More than half (53%) of patients responded with a pain reduction greater than 30%. Severity of other symptoms (i.e., fatigue, nausea, depression, and anxiety) and disability also decreased significantly at FU₂. The total consumption of opioids remained stable; however, the consumption of short acting preparations decreased by 52% whereas the prescription of nonopioid agents increased. Beyond drug management, 60% of patients received other analgesic therapies, being the most common interventional pain procedures and psychosocial approaches. Conclusion. The MUHC interdisciplinary approach to cancer pain management provides meaningful relief of pain and other cancer-related symptoms and decreases patients' disability.

Repeated tender point injections of granisetron alleviate chronic myofascial pain--a randomized, controlled, double-blinded trial

Background

Serotonin (5-HT) mediates pain by peripheral 5-HT₃-receptors. Results from a few studies indicate that intramuscular injections of 5-HT₃-antagonists may reduce musculoskeletal pain. The aim of this study was to investigate if repeated intramuscular tender-point injections of the 5-HT₃-antagonist granisetron alleviate pain in patients with myofascial temporomandibular disorders (M-TMD).

Methods

This prospective, randomized, controlled, double blind, parallel-arm trial (RCT) was carried out during at two centers in Stockholm, Sweden. The randomization was performed by a researcher who did not participate in data collection with an internet-based application (www.randomization.com). 40 patients with a diagnose of M-TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were randomized to receive repeated injections, one week apart, with either granisetron (GRA; 3 mg) or isotonic saline as control (CTR).

Results

The median weekly pain intensities decreased significantly at all follow-ups (1-, 2-, 6-months) in the GRA-group (Friedman test; P < 0.05), but not in the CTR-group (Friedman-test; P > 0.075). The numbers needed to treat (NNT) were 4 at the 1- and 6-month follow-ups, and 3.3 at the 2-month follow-up in favor of granisetron.

Conclusions

Repeated intramuscular tender-point injections with granisetron provide a new pharmacological treatment possibility for myofascial pain patients with repeated intramuscular tender-point injections with the serotonin type 3 antagonist granisetron. It showed a clinically relevant pain reducing effect in the temporomandibular region, both in a short- and long-term aspect.

Trial registration

European Clinical Trials Database 2005-006042-41 as well as at Clinical Trials NCT02230371.

[Idiopathic musculoskeletal pain in Indian Children-prevalence and impact on daily routine]

OBJECTIVES

To study the prevalence of idiopathic musculoskeletal pain (IMSP) in school going children and its impact on daily life.

METHODS

One thousand eighteen apparently healthy school children aged 5-16 years were assessed and analysed for IMSP and its associated problems. Standard tests for significance were applied.

RESULTS

One hundred and sixty five (16.2%) children mostly males (55.2%) reported IMSP. Lower limbs (52.1%) were the most common location of pain. More than 1 year of pain history was present in 15%. Thirty seven percent children complained of discomfort during walking, 30.9%, had pain during physical exercise, 29.2% had difficulty attending lessons and 4.2% had interference in pursuing hobbies. The children were also further sub grouped into preadolescents and adolescents. There was significant difference in pain duration and duration of each pain episode in the two groups (p=0.01). A significant number of children (21.2%) with IMSP reported school absenteeism (p<0.001). A significant number of adolescents had history positive for contact sports (p=0.001). Sleep disturbances were also reported to be higher in children with IMSP (29% vs. 5.7%, p=0.001). Other associated problems in children with IMSP found were day time tiredness (51.1%), headache (47.3%) and abdominal pain (24.8%).

CONCLUSIONS

Prevalence of IMSP in school children aged 5-16 yrs was found to be 16.2% and a significant percentage of these children experience interference with daily activities including school absenteeism.

Sex differences in opioid analgesia and addiction: interactions among opioid receptors and estrogen receptors

Opioids are widely used as the pain reliever and also notorious for being addictive drugs. Sex differences in the opioid analgesia and addiction have been reported and investigated in human subjects and animal models. Yet, the molecular mechanism underlying the differences between males and females is still unclear. Here, we reviewed the literature describing the sex differences in analgesic responses and addiction liabilities to clinically relevant opioids. The reported interactions among opioids, estrogens, opioid receptors, and estrogen receptors are also evaluated. We postulate that the sex differences partly originated from the crosstalk among the estrogen and opioid receptors when stimulated by the exogenous opioids, possibly through common secondary messengers and the downstream gene transcriptional regulators.

Effects of ethnicity and gender role expectations of pain on experimental pain: a cross-cultural study

BACKGROUND

Gender role expectations of pain (GREP) have been shown to mediate sex differences in experimental pain. Few studies have investigated the role of ethnicity in shaping GREP. The aim of this study was to examine interactions between ethnicity and GREP on experimentally induced pressure and ischaemic pain in Libyan and white British students in their respective countries.

METHODS

Libyan (n = 124) and white British (n = 51) students completed a GREP questionnaire and their response to experimental pain was measured. Blunt pressure pain threshold (PPT) was measured over the 1st interosseous muscle using algometry. Pain intensity and pain unpleasantness (100 mm visual analogue scale) were measured at 1-min intervals during a submaximal effort tourniquet test on the forearm.

RESULTS

Multivariate analysis of variance detected significant effects for Sex and Ethnicity on pain measurements. Men had higher PPTs than women (p < 0.001). Libyans had higher PPTs than white British participants (p < 0.001). There were significant effects for Sex and Ethnicity for pain intensity ratings (p < 0.01) but no significant differences between the sexes in pain unpleasantness (p > 0.05). Libyan participants had higher pain intensity (p < 0.01) and pain unpleasantness (p < 0.05) ratings compared with white British participants. There were effects for Sex and Ethnicity for all GREP dimensions. Libyan participants exhibited stronger stereotypical views in GREP than white British participants (p < 0.001).

CONCLUSIONS

GREP was the mediator of sex but not ethnic differences in pain report, suggesting that gender stereotypical attitudes to pain account for differences in pain expression between men and women.

Sleep, stress, neurocognitive profile and health-related quality of life in adolescents with idiopathic musculoskeletal pain

OBJECTIVES

The aims of this study were to measure levels of sleep, stress, and depression, as well as health-related quality of life, and to assess the neurocognitive profiles in a sample of adolescents with idiopathic musculoskeletal pain.

METHODS

Nineteen adolescents with idiopathic musculoskeletal pain and 20 age-matched healthy control subjects were evaluated regarding their levels of sleep and stress, as well as quality of life, and underwent neurocognitive testing.

RESULTS

The sample groups consisted predominantly of females (84%), and the socioeconomic status did not differ between the two groups. In addition, the occurrence of depressive symptoms was similar between the two groups; specifically, 26% of the idiopathic musculoskeletal pain patients and 30% of the control subjects had scores indicative of depression. Teenagers in the group with idiopathic musculoskeletal pain reported poorer quality of life and sleep scores than those in the control group. Regarding stress, patients had worse scores than the control group; whereas 79% of the adolescents with idiopathic musculoskeletal pain met the criteria for a diagnosis of stress, only 35% of the adolescents in the control group met the criteria. In both groups, we observed scores that classified adolescents as being in the resistance phase (intermediate) and exhaustion phase (pathological) of distress. However, the idiopathic musculoskeletal pain group more frequently reported symptomatic complaints of physical and emotional distress. The neurocognitive assessment showed no significant impairments in either group.

CONCLUSION

Adolescents with idiopathic musculoskeletal pain did not exhibit cognitive impairments. However, adolescents with idiopathic musculoskeletal pain did experience intermediate to advanced psychological distress and lower health-related quality of life, which may increase their risk of cognitive dysfunction in the future.

Gender role affects experimental pain responses: a systematic review with meta-analysis

Gender role refers to the culturally and socially constructed meanings that describe how women and men should behave in certain situations according to feminine and masculine roles learned throughout life. The aim of this meta-analysis was to evaluate the relationship between gender role and experimental pain responses in healthy human participants. We searched computerized databases for studies published between January 1950 and May 2011 that had measured gender role in healthy human adults and pain response to noxious stimuli. Studies were entered into a meta-analysis if they calculated a correlation coefficient (r) for gender role and experimental pain. Searches yielded 4465 'hits' and 13 studies were eligible for review. Sample sizes were 67-235 participants and the proportion of female participants was 45-67%. Eight types of gender role instrument were used. Meta-analysis of six studies (406 men and 539 women) found a significant positive correlation between masculine and feminine personality traits and pain threshold and tolerance, with a small effect size (r = 0.17, p = 0.01). Meta-analysis of four studies (263 men and 297 women) found a significant negative correlation between gender stereotypes specific to pain and pain threshold and tolerance, with a moderate effect size (r = -0.41, p < 0.001). In conclusion, individuals who considered themselves more masculine and less sensitive to pain than the typical man showed higher pain thresholds and tolerances. Gender stereotypes specific to pain scales showed stronger associations with sex differences in pain sensitivity response than masculine and feminine personality trait scales.

A systematic literature review of 10 years of research on sex/gender and experimental pain perception - part 1: are there really differences between women and men?

The purpose of this systematic review was to summarize and critically appraise the results of 10 years of human laboratory research on pain and sex/gender. An electronic search strategy was designed by a medical librarian and conducted in multiple databases. A total of 172 articles published between 1998 and 2008 were retrieved, analyzed, and synthesized. The first set of results (122 articles), which is presented in this paper, examined sex difference in the perception of laboratory-induced thermal, pressure, ischemic, muscle, electrical, chemical, and visceral pain in healthy subjects. This review suggests that females (F) and males (M) have comparable thresholds for cold and ischemic pain, while pressure pain thresholds are lower in F than M. There is strong evidence that F tolerate less thermal (heat, cold) and pressure pain than M but it is not the case for tolerance to ischemic pain, which is comparable in both sexes. The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities. In summary, 10 years of laboratory research have not been successful in producing a clear and consistent pattern of sex differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain. Whether laboratory studies in healthy subjects are the best paradigm to investigate sex differences in pain perception is open to question and should be discussed with a view to enhancing the clinical relevance of these experiments and developing new research avenues.

Pressure pain sensitivity maps of the neck-shoulder and the low back regions in men and women

Background

Musculoskeletal pain in the low back and neck-shoulder regions is a major problem among the working population all over the world. The prevalence of musculoskeletal pain is found to be higher among women. Women also have lower pressure pain thresholds (PPTs) than men. Pressure pain topography aims at mapping the spatial distribution of PPT within a muscle in an attempt to track changes in mechanical sensitivity. In order to assess gender differences in the pain topography, it is necessary to map the distribution in both healthy men and women. The aim of this study was to assess PPT maps from the cervico-thoracic and lumbar regions in men and women.

Methods

Eleven men and eleven women without any known musculoskeletal disorders participated in the study. PPT was measured twice at 36 points over the trapezius muscle of the dominant arm, at 36 points over the trapezius muscle on the contralateral side and at 12 points over the spine between the left and right trapezius. Further, 11 points were measured over the erector spinae muscle on the left side of the spine between the first and the fifth lumbar vertebrae, 11 on the right side and 5 points on the spine itself. The measurements on each trapezius muscle were divided according to anatomical subdivisions. Three-way and two-way ANOVAs were used to analyse the differences in PPTs with the following factors: gender, locations and sub-divisions (only for cervico-thoracic region).

Results

There were no differences between left and right side in neither the cervico-thoracic nor the lumbar region, but there were (large effect) differences between the subdivisions in the trapezius with the lowest values in the upper part (P < 0.001; partial η² = 0.19). Women had (small effect) lower PPT in both cervico-thoracic and lumbar regions (P ≤ 0.001; partial η² = 0.02 for both regions), but gender had no effect on neither location nor subdivisions.

Conclusions

The pain topography was not found to be different between genders in the cervico-thoracic and lumbar regions. This study can be used as basis for further clinical studies on musculoskeletal disorders.

Fibromyalgia: diagnosis and treatment options

BACKGROUND

Fibromyalgia is a widespread, chronic pain disorder that includes a complex constellation of somatic and emotional symptoms. Controlled clinical trials for both medication and nonmedication therapies have led to sound, evidence-based recommendations for the care of patients with fibromyalgia.

OBJECTIVE

This review article was designed to provide updated information from database literature searches on fibromyalgia epidemiology, including gender differences, psychological comorbidity, and treatment with medication and nonmedication therapies.

METHODS

A literature review was performed by identifying fibromyalgia articles published in English from January 2000 to October 2008 using the PubMed and EMBASE databases. Search terms included fibromyalgia, exercise, gender, nonpharmacologic, placebo-controlled, randomized, and treatment.

RESULTS

New epidemiologic data support important differences in fibromyalgia symptom severity between the sexes and the important role of comorbid psychological distress. Physicians diagnose fibromyalgia in women at an approximately 3- to 6-fold rate compared with men. Well-conducted clinical trials and recently published treatment guidelines reinforce effective treatment with medication and nonpharmacologic therapy. The strongest evidence suggests effective treatment of fibromyalgia with duloxetine and milnacipran. Studies also report efficacy with gabapentin, pramipexole, pregabalin, tramadol, and IV tropisetron. Nonpharmacologic treatments should include fitness and strengthening exercise, as well as warm-water therapy and psychological pain management techniques.

CONCLUSIONS

Fibromyalgia is a common, disabling, chronic pain condition that predominantly affects women. Symptoms can be effectively treated using both drug and nondrug therapies. In general, treatment benefits in fibromyalgia appear largely independent of patient sex.

Sex, gender, and pain: a review of recent clinical and experimental findings

Sex-related influences on pain and analgesia have become a topic of tremendous scientific and clinical interest, especially in the last 10 to 15 years. Members of our research group published reviews of this literature more than a decade ago, and the intervening time period has witnessed robust growth in research regarding sex, gender, and pain. Therefore, it seems timely to revisit this literature. Abundant evidence from recent epidemiologic studies clearly demonstrates that women are at substantially greater risk for many clinical pain conditions, and there is some suggestion that postoperative and procedural pain may be more severe among women than men. Consistent with our previous reviews, current human findings regarding sex differences in experimental pain indicate greater pain sensitivity among females compared with males for most pain modalities, including more recently implemented clinically relevant pain models such as temporal summation of pain and intramuscular injection of algesic substances. The evidence regarding sex differences in laboratory measures of endogenous pain modulation is mixed, as are findings from studies using functional brain imaging to ascertain sex differences in pain-related cerebral activation. Also inconsistent are findings regarding sex differences in responses to pharmacologic and non-pharmacologic pain treatments. The article concludes with a discussion of potential biopsychosocial mechanisms that may underlie sex differences in pain, and considerations for future research are discussed.

PERSPECTIVE

This article reviews the recent literature regarding sex, gender, and pain. The growing body of evidence that has accumulated in the past 10 to 15 years continues to indicate substantial sex differences in clinical and experimental pain responses, and some evidence suggests that pain treatment responses may differ for women versus men.

Gender differences in the mu rhythm during empathy for pain: an electroencephalographic study

Our recent magnetoencephalography study demonstrated that the mu rhythm can reliably indicate sensorimotor resonance during the perception of pain in others (Cheng, Y., Yang, C.Y., Lin, C.P., Lee, P.L., Decety, J., 2008b. The perception of pain in others suppresses somatosensory oscillations: a magnetoencephalography study. NeuroImage 40, 1833-1840). The current study further investigated the neurophysiological mechanism underpinning empathy for pain in relation with gender through the measurements of the electroencephalographic mu suppression in healthy female (N=16) and male (N=16) adults during the observation of body parts in painful or no-painful situations. The results demonstrate that both genders exhibited sensorimotor activation related to pain empathy. However, females showed stronger mu suppressions than males when watching the painful as well as the non-painful situations. Further, the mu suppression for pain empathy was positively correlated with the scoring on the personal distress subscale of the interpersonal reactivity index only in the female participants. The present findings suggest the existence of a gender difference in pain empathy in relation with the sensorimotor cortex resonance. The mu rhythm can be a potential biomarker of empathic mimicry.