Pain intensity and pressure pain thresholds after a light dynamic physical load in patients with chronic neck-shoulder pain

Background

To investigate the development of pain intensity and pressure pain thresholds during and 24 h after a light dynamic physical load among patients with chronic neck-shoulder pain.

Methods

Twenty-six patients with chronic neck-shoulder pain and 12 healthy controls were included. The participants arm-cycled on an ergometer. Effort was rated with the Borg Rating of Perceived Exertion scale (RPE), and pain intensity with an numeric rating scale (NRS). Pressure pain thresholds were measured by an algometer. Participants started a pain diary 1 week before the physical exercise and continued until 1 week after. Pain intensity was assessed before, during and the following two evenings after arm-cycling. Pressure pain thresholds were assessed before, 15 min after, 105 min after and 24 h after.

Results

The chronic pain group showed increased pain intensity during, and the following two evenings after the arm cycling, and decreased pain thresholds immediately after the arm cycling involving painful regions. In the patient group there were no impact on pain thresholds in the neck the following day.

Conclusions

Patients with chronic neck-shoulder pain reported increased pain intensity during and in the evenings after a light dynamic load involving painful regions. In addition, they showed decreased pain thresholds close to the exercise, indicating mechanical hyperalgesia.

Association of insomnia severity with well-being, quality of life and health care costs: A cross-sectional study in older adults with chronic pain (PainS65+)

BACKGROUND

Insomnia is one of the most common complaints in chronic pain. This study aimed to evaluate the association of insomnia with well-being, quality of life and health care costs.

METHODS

The sample included 2790 older individuals (median age = 76; interquartile range [IQR] = 70-82) with chronic pain. The participants completed a postal survey assessing basic demographic data, pain intensity and frequency, height, weight, comorbidities, general well-being, quality of life and the insomnia severity index (ISI). Data on health care costs were calculated as costs per year (€ prices) and measured in terms of outpatient and inpatient care, pain drugs, total drugs and total health care costs.

RESULTS

The overall fraction of clinical insomnia was 24.6% (moderate clinical insomnia: 21.9% [95% CI: 18.8-23.3]; severe clinical insomnia: 2.7% [95% CI: 1.6-3.2]). Persons who reported clinical insomnia were more likely to experience pain more frequently with higher pain intensity compared to those reported no clinically significant insomnia. Mean total health care costs were € 8469 (95% CI: €4029-€14,271) for persons with severe insomnia compared with € 4345 (95% CI: €4033-€4694) for persons with no clinically significant insomnia. An association between severe insomnia, well-being, quality of life, outpatient care, total drugs costs and total health care costs remained after controlling for age, sex, pain intensity, frequency, body mass index and comorbidities using linear regression models.

CONCLUSIONS

Our results determine an independent association of insomnia with low health-related quality of life and increased health care costs in older adults with chronic pain.

SIGNIFICANCE

The concurrence and the severity of insomnia among older adults with chronic pain were associated with decreased well-being and quality of life, and increased health care costs to society.

Does psychotherapy work? An umbrella review of meta-analyses of randomized controlled trials

OBJECTIVE

To map and evaluate the evidence across meta-analyses of randomized controlled trials (RCTs) of psychotherapies for various outcomes.

METHODS

We identified 173 eligible studies, including 247 meta-analyses that synthesized data from 5157 RCTs via a systematic search from inception to December 2016 in the PubMed, PsycINFO and Cochrane Database of Systematic Reviews. We calculated summary effects using random-effects models, and we assessed between-study heterogeneity. We estimated whether large studies had significantly more conservative results compared to smaller studies (small-study effects) and whether the observed positive studies were more than expected by chance. Finally, we assessed the credibility of the evidence using several criteria.

RESULTS

One hundred and ninety-nine meta-analyses were significant at P-value ≤ 0.05, and almost all (n = 196) favoured psychotherapy. Large and very large heterogeneity was observed in 130 meta-analyses. Evidence for small-study effects was found in 72 meta-analyses, while 95 had evidence of excess of significant findings. Only 16 (7%) provided convincing evidence that psychotherapy is effective. These pertained to cognitive behavioural therapy (n = 6), meditation therapy (n = 1), cognitive remediation (n = 1), counselling (n = 1) and mixed types of psychotherapies (n = 7).

CONCLUSIONS

Although almost 80% meta-analyses reported a nominally statistically significant finding favouring psychotherapy, only a few meta-analyses provided convincing evidence without biases.

Illness beliefs among patients with chronic widespread pain - associations with self-reported health status, anxiety and depressive symptoms and impact of pain

Background

Chronic widespread pain (CWP) is a disabling condition associated with a decrease in health. Illness beliefs are individual and are acquired during life. Constraining beliefs may prevent patients from regaining health. Understanding these patients’ illness beliefs may be a way to improve the health care they are offered. The aim of this study was to describe illness beliefs among patients with CWP and associations with self-reported health, anxiety and depressive symptoms, and impact of pain.

Method

In this cross-sectional study, questionnaires were sent by mail to 330 patients including socio-demographic information, the Illness Perception Questionnaire (IPQ-R), the Short-Form General Health Survey (SF-36) and the Hospital Anxiety and Depression Scale (HADS). Data were analysed using descriptive statistics, non-parametric tests and linear regression analyses.

Results

Patients experienced and related a high number of symptoms to CWP (mean (SD) 9 (3)). The patients believed their illness to be long lasting, to affect their emotional well being, and to have negative consequences for their lives. Some 72% reported having severe or very severe pain, and impact of pain according to SF-36 was negatively correlated to several illness beliefs dimensions, anxiety- and depressive symptoms. In regression analyses, the Identity, Consequences and Personal control dimensions of IPQ-R and Anxiety- and Depressive symptoms explained 32.6–56.1% of the variance in the two component scores of SF-36.

Conclusion

Constraining illness beliefs in patients with CWP are related to worse health status, especially in cases of high number of physical or mental symptoms, beliefs of negative consequences or the illness affecting them emotionally. Identification and understanding of these beliefs may reduce patients’ suffering if they are taken into consideration in rehabilitation programs and in development of new evidence-based interventions aimed at increasing health in patients with CWP.

Biomarkers alterations in trapezius muscle after an acute tissue trauma: A human microdialysis study

Aims

Alteration in muscle milieu has been proposed as one of the main contributors underlying chronic musculoskeletal pain (CMP). Microdialysis (MD) provides real-time information on release of pain and metabolic biomarkers in muscle. However, insertion of MD probe causes a local tissue trauma, which may affect the tissue milieu. Whether an acute tissue trauma alter pain and metabolite biomarkers in trapezius muscle of patients with CMP is not known. Hence, this study investigated changes in muscle metabolites following MD probe insertion in patients with CMP in comparison with healthy controls.

Methods

Nineteen patients (11 women and 8 men; 41.4 years) with CMP and 20 pain-free volunteers (10 women and 10 men; 36.5 years) were recruited (project approval number: 2013/151- 31). Baseline pressure pain thresholds (PPT) at trapezius muscle were obtained bilaterally with a reference point at the tibialis muscle. Pain questionnaires were used for determining levels of anxiety and depression and catastrophizing impact. Interstitial samples were collected from trapezius muscles by aid of MD (20 kDa cut-off) during a period of 40 min. Collected dialysates at 2 time-points of 20 and 40 min were stored at −70 °C until analysis. Concentrations of glucose, lactate, pyruvate, glycerol, and glutamate were analyzed by ISCUSSflex. P ≤ 0.05 was considered significant.

Results

No potential case with respect to anxiety, depression or catastrophizing impact was found. Lower PPTs were found in CMP group (P ≤ 0.05). Significantly lower levels of pyruvate were found in CMP group at both 20 min (P = 0.003) and 40 min (P = 0.006). Gender-based analysis indicated higher concentrations of glutamate in female patients with CMP.

Conclusions

This study was first to demonstrate metabolite alterations during trauma phase of MD in trapezius muscles of CPM compared with healthy controls. This model proved beneficial for investigating pain and metabolic biomarkers during acute phase of MD.

Different DHEA-S Levels and Response Patterns in Individuals with Chronic Neck Pain, Compared with a Pain Free Group-a Pilot Study

Objective

To test, in this pilot study, whether DHEA-S (Dehydroepiandrosterone, sulfated form) plasma levels are lower among persons with chronic neck pain, compared to control persons, and to investigate the DHEA-S response after a physical exercise.

Subjects

Included were 12 persons with chronic neck pain and eight controls without present pain, all 18 and 65 years of age. Exclusion criteria for both groups were articular diseases or tendinosis, fibromyalgia, systemic inflammatory and neuromuscular diseases, pain conditions due to trauma, or severe psychiatric diseases.

Design and methods

The participants arm-cycled on an ergometer for 30 minutes. Blood samples were taken before, 60 minutes, and 150 minutes after this standardized physical exercise.

Results

The estimated plasma DHEA-S levels at baseline were 2.0 µmol/L (95% confidence interval [CI] 1.00; 4.01) in the pain group and 4.1 µmol/L (95% CI2.0; 8.6) in the control group, adjusted for sex, age, body mass index (BMI), and Shirom-Melamed Burnout Questionnaire (SMBQ), with a ratio of 0.48 ( P  = 0.094).

Conclusions

In this pilot study, the plasma DHEA-S levels appeared to be lower among the persons with chronic neck pain, compared with the control group. It was indicated that DHEA-S decreased during the physical exercise in the control group, and either increased or was unaffected in the chronic pain group.

Prevalence of different pain categories based on pain spreading on the bodies of older adults in Sweden: a descriptive-level and multilevel association with demographics, comorbidities, medications, and certain lifestyle factors (PainS65+)

Background and objective

There is limited knowledge about the prevalence of pain and its relation to comorbidities, medication, and certain lifestyle factors in older adults. To address this limitation, this cross-sectional study examined the spreading of pain on the body in a sample of 6611 subjects ≥65 years old (mean age = 75.0 years; standard deviation [SD] = 7.7) living in southeastern Sweden.

Methods

Sex, age, comorbidities, medication, nicotine, alcohol intake, and physical activity were analyzed in relation to the following pain categories: local pain (LP) (24.1%), regional pain medium (RP-Medium) (20.3%), regional pain heavy (RP-Heavy) (5.2%), and widespread pain (WSP) (1.7%).

Results

RP-Medium, RP-Heavy, and WSP were associated more strongly with women than with men (all p<0.01). RP-Heavy was less likely in the 80–84 and >85 age groups compared to the 65–69 age group (both p<0.01). Traumatic injuries, rheumatoid arthritis/osteoarthritis, and analgesics were associated with all pain categories (all p<0.001). An association with gastrointestinal disorders was found in LP, RP-Medium, and RP-Heavy (all p<0.01). Depressive disorders were associated with all pain categories, except for LP (all p<0.05). Disorders of the central nervous system were associated with both RP-Heavy and WSP (all p<0.05). Medication for peripheral vascular disorders was associated with RP-Medium (p<0.05), and hypnotics were associated with RP-Heavy (p<0.01).

Conclusion

More than 50% of older adults suffered from different pain spread categories. Women were more likely to experience greater spreading of pain than men. A noteworthy number of common comorbidities and medications were associated with increased likelihood of pain spread from LP to RP-Medium, RP-Heavy, and WSP. Effective management plans should consider these observed associations to improve functional deficiency and decrease spreading of pain-related disability in older adults.

Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients

BACKGROUND

A randomized, double-blinded, placebo-controlled study was conducted to investigate if single monosodium glutamate (MSG) administration would elevate muscle/serum glutamate concentrations and affect muscle pain sensitivity in myofascial temporomandibular disorders (TMD) patients more than in healthy individuals.

METHODS

Twelve myofascial TMD patients and 12 sex- and age-matched healthy controls participated in two sessions. Participants drank MSG (150 mg/kg) or NaCl (24 mg/kg; control) diluted in 400 mL of soda. The concentration of glutamate in the masseter muscle, blood plasma and saliva was determined before and after the ingestion of MSG or control. At baseline and every 15 min after the ingestion, pain intensity was scored on a 0-10 numeric rating scale. Pressure pain threshold, pressure pain tolerance (PPTol) and autonomic parameters were measured. All participants were asked to report adverse effects after the ingestion.

RESULTS

In TMD, interstitial glutamate concentration was significantly greater after the MSG ingestion when compared with healthy controls. TMD reported a mean pain intensity of 2.8/10 at baseline, which significantly increased by 40% 30 min post MSG ingestion. At baseline, TMD showed lower PPTols in the masseter and trapezius, and higher diastolic blood pressure and heart rate than healthy controls. The MSG ingestion resulted in reports of headache by half of the TMD and healthy controls, respectively.

CONCLUSION

These findings suggest that myofascial TMD patients may be particularly sensitive to the effects of ingested MSG. WHAT DOES THIS STUDY ADD?': Elevation of interstitial glutamate concentration in the masseter muscle caused by monosodium glutamate (MSG) ingestion was significantly greater in myofascial myofascial temporomandibular disorders (TMD) patients than healthy individuals. This elevation of interstitial glutamate concentration in the masseter muscle significantly increased the intensity of spontaneous pain in myofascial TMD patients.

Prevalence of Different Pain Categories Based on Pain Spreading in Older Adults in Sweden: A Multilevel Association With Socio-Demographic Characteristics, Comorbidities and Drug Consumption (Pain S65+)

Introduction

Understanding of factors related to chronic pain in elderly is limited.

Objectives and aims

To estimate the prevalence of pain categories based on spreading of pain on the body and to investigate how such spreading is related to demographic variables, pain intensity, comorbidities and medication in an elderly general population in southeastern Sweden.

Methods

A total of 6611 adults aged ≥ 65 years participated (mean age = 76.2; SD = 7.4). Pain categories were assessed by a self-reported postal questionnaire covering 45 anatomical predefined pain regions along with demographics, pain intensity during previous seven days, comorbidities and medication. Poisson regression models with robust error variance were used for data analyzing.

Results

The prevalence of pain spreading categories was: chronic local pain (CLP) 16%; chronic regional pain medium (CRP-Medium) 17%; chronic regional pain heavy (CRP-Heavy) 5% and chronic widespread pain (CWSP) 2%. Overall, increased prevalence for CRP-Heavy and CWSP in subjects 75–79 years old compared to those 65–69, 70–74, 80–84 and ≥ 85 years were revealed. In men, 75–79 years old, CRP-Heavy was more common than in the other pain categories. In women, 75–79 years old CWSP, was more common than in the other pain categories. Pain intensity was strongly associated with all pain categories (P < 0.001). CLP was associated with trauma, rheumatoid arthritis, cancer, prescribed and non-prescribed analgesics. CRP-Medium was associated with rheumatoid arthritis, CRP-Heavy with rheumatoid arthritis and lung diseases and CWSP with rheumatoid arthritis and prescribed analgesics (P < 0.001).

Conclusions

Our findings elucidate heterogeneity of pain in elderly which has to be further investigated.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Protein alterations in women with chronic widespread pain—A proteomic study of the trapezius muscle

Aim

This study aims to investigate the proteome of trapezius muscle biopsies of women with chronic widespread pain (CWP) compared to female pain-free controls using proteomic tools. CWP has a high prevalence (10%) resulting in prominent negative individual and societal consequences. There is no clear consensus concerning the etiology behind CWP although alterations in the central processing of nociception maintained by peripheral nociceptive input has been suggested.

Methods

Two-dimensional gel electrophoresis (2-DE) analysis and nano-liquid chromatography/mass spectrometry (nLC/MS) was used to study the proteome differences of biopsies from the trapezius muscle between 18 female patients diagnosed with CWP and 19 healthy female controls.

Results

The proteomic analysis revealed 17 proteins to be statistically significantly expressed between the two groups by which 12 were up-regulated and 5 were down-regulated in the CWP group compared to healthy controls. Many of the proteins were important enzymes in metabolic pathways like the glycolysis and gluconeogenesis (Triosephosphate isomerase, Glyceraldehyde-3-phosphate dehydrogenase, Pyruvate kinase isoenzyme M1/M2 and Fructose-bisphosphate aldolase A, all up-regulated in CWP). Other proteins are associated with muscle damage (Ankyrin repeat domain-containing protein 2, down-regulated in CWP), muscle recovery (Alpha-crystallin B chain, up-regulated in CWP) stress and inflammation (carbonic anhydrase 3, up-regulated in CWP). The contractile and structural proteins found have been associated with various types of myopathies (Actin alpha skeletal muscle, up-regulated, Troponin T slow skeletal muscle and Desmin, down-regulated in CWP).

Conclusions

In conclusion, the expression of these proteins belonging to the protein groups, contractile, stress and inflammatory, structural, and metabolic, suggests abnormalities and alterations in the myalgic trapezius muscle.

Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study

Purpose

The mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle.

Methods

Microdialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography—mass spectrometry (GC–MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann–Whitney U test of group difference in individual metabolites was also performed.

Results

A large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle.

Conclusion

This study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

Decreased muscle concentrations of ATP and PCR in the quadriceps muscle of fibromyalgia patients--a 31P-MRS study

BACKGROUND AND METHODS

Fibromyalgia (FMS) has a prevalence of approximately 2% in the population. Central alterations have been described in FMS, but there is not consensus with respect to the role of peripheral factors for the maintenance of FMS. 31P magnetic resonance spectroscopy (31P-MRS) has been used to investigate the metabolism of phosphagens in muscles of FMS patients, but the results in the literature are not in consensus. The aim was to investigate the quantitative content of phosphagens and pH in resting quadriceps muscle of patients with FMS (n = 19) and in healthy controls (CONTROLS; n = 14) using (31) P-MRS. It was also investigated whether the concentrations of these substances correlated with measures of pain and/or physical capacity.

RESULTS

Significantly lower concentrations of adenosine triphosphate (ATP) and phosphocreatinine (PCr; 28-29% lower) were found in FMS. No significant group differences existed with respect to inorganic phosphate (Pi), Pi/PCr and pH. The quadriceps muscle fat content was significantly higher in FMS than in CONTROLS [FMS: 9.0 ± 0.5% vs.

CONTROLS

6.6 ± 0.6%; (mean ± standard error); P = 0.005]. FMS had significantly lower hand and leg capacity according to specific physical test, but there were no group differences in body mass index, subjective activity level and in aerobic fitness. In FMS, the specific physical capacity in the leg and the hand correlated positively with the concentrations of ATP and PCr; no significant correlations were found with pain intensities.

CONCLUSIONS

Alterations in intramuscular ATP, PCr and fat content in FMS probably reflect a combination of inactivity related to pain and dysfunction of muscle mitochondria.

Experimental myalgia induced by repeated infusion of acidic saline into the human masseter muscle does not cause the release of algesic substances

BACKGROUND

Animal studies have shown that two repeated intramuscular injections of acidic saline induce mechanical allodynia that lasts for 4 weeks with spread to the contralateral side. In this study, we tested the hypothesis that two repeated intramuscular infusions of acidic saline into the human masseter muscle is associated with pain, mechanical allodynia and release of algesic substances. Eighteen healthy volunteers participated. On day 1, 2.5 mL of acidic saline (pH 3.3) was infused into one of the masseter muscles and isotonic saline (pH 6.0) into the other (randomized and single-blind). Two days later, intramuscular microdialysis was performed to sample serotonin, glutamate, pyruvate, lactate and glucose, during which the saline infusions were repeated. Pain and pressure pain thresholds (PPTs) were recorded before and after infusions on both days.

RESULTS

Pain intensity induced by the infusions was higher after acidic than that after isotonic saline (p < 0.05). PPTs were decreased on both sides after microdialysis compared with baseline day 1 (p's < 0.05), but there were no differences in PPTs between sides at any time point. The levels of serotonin, glutamate, pyruvate, lactate or glucose did not change significantly during microdialysis.

CONCLUSION

Infusion of acidic saline caused low levels of muscle pain, but no mechanical allodynia and no increased release of algesic substances. The value of this model appears modest, but future studies could be performed with larger sample size and higher flow rate before definite conclusions about the validity of the model for craniofacial myalgia can be drawn.

A personal computer-based system for real-time analysis of surface EMG signals during static and dynamic contractions

This paper describes a prototype system that uses an advanced data acquisition processor in combination with a personal computer (PC) to analyse surface electromyogram (EMG) signals on-line and in real-time. The system is able to calculate the average power and estimate the mean frequency of the power spectrum of surface EMGs during static and repeated isokinetic contractions with a high degree of standardization. Selection of parameters as well as implementation of future parameters is easy to perform, since the system is software-based. The system has been tested both with known (sine waves, filtered white noise) and physiological (surface EMG) signals. The system gave the expected results in different test situations.

Pain sensitivity changes in chronic pain patients with and without spinal cord stimulation assessed by nociceptive withdrawal reflex thresholds and electrical pain thresholds

Background and aim

Previous studies have shown that patients with chronic pain had significantly lower nociceptive withdrawal reflex thresholds (NWR-T) and electrical pain thresholds (EP-T) than healthy controls. Patients with chronic pain and implanted spinal cord stimulator (SCS) system presents an opportunity to study dynamic pain sensitivity changes in a situation where patients just have been stimulated (i.e., pain-free or greatly reduced pain) and compare with the situation where patients are not stimulated (i.e., experiencing severe pain).

Methods

Seventeen volunteers with chronic neuropathic pain and a SCS implanted for pain relief participated in the experiment. Volunteers were asked to turn off the SCS and refrain from medication at least 8 h before the experiment. Electrical stimulation (train-of-five 1-ms pulses delivered at 200 Hz) was applied to the arc of the foot in order to elicit the NWR and electromyographic responses were recorded from tibialis anterior muscle. A staircase procedure was used to assess the NWR-T and a Visual-Analog-Scale (VAS) scale (range 0–10) was used to assess the EP-T. After the initial testing, the SCS was turned on, and thresholds were reassessed after 1 h. Paired t-tests were used to compare the thresholds before and after the SCS was turned on. All values are presented as mean ± SD.

Results

The NWR-T were significantly higher after the SCS was turned on (before: 16.3 ±8.1 mA; after: 19.0 ± 10.9 mA; p = 0.028). EP-T did not show any significant differences (before: 3.2 ± 1.5 mA; after: 2.9 ± 2.0 mA; p = 0.324).

Conclusion

Results showed a higher NWR-T after the SCS was turned on, which indicates a depression of spinal nociception. Moreover, the NWR-T was able to detect ongoing and relatively quick changes in pain sensitivity.

Neuropsychological Aspects of Driving After Brain Lesion: Simulator Study and On-Road Driving

Twenty-nine patients with brain lesion and 29 matched controls participated in the study. The patients were socially well recovered with a high rate of employment. Compared with the controls, they performed significantly worse on a neuropsychological test battery, especially on executive and cognitive functions. Patients drove as well as controls in predictable situations in the advanced simulator used. In unpredictable situations, they demonstrated longer reaction times and safety margins, as well as difficulties in allocating processing resources to a secondary task. The patients showed significantly less attention, worse traffic behavior, and less risk awareness when driving in real traffic. Forty-one percent of the patients did not pass the driving test. The neuropsychological test battery was factor analyzed into four factors: executive capacity, cognitive capacity, automatic attentional capacity, and simple perceptual-motor capacity. The second factor was the mast significant with a simultaneous capacity test predicting driving performance with 78% confidence.

Responses of algesic and metabolic substances to 8 h of repetitive manual work in myalgic human trapezius muscle

The trapezius muscle often develops pain as the result of repetitive and stressful work tasks although it is unclear to what extent this pain is due to alterations in muscle concentrations of algesic/nociceptive substances. Twenty women with chronic neck- and shoulder pain (TM) whose work required highly repetitive work tasks and 20 pain-free female colleagues (CON) were studied during and after a full 8-hour workday. We collected microdialysates from their dominant/most painful trapezius muscle; concentrations of serotonin, glutamate, lactate, pyruvate, potassium, bradykinin, and cytokines and blood flow were determined. In addition, we measured surface electromyogram, task exposure level, pain intensity, perceived mental stress, and urine-cortisol. In connection to the clinical neck and shoulder examination, we determined pressure pain thresholds (PPTs) over the trapezius and tibialis muscles. TM had higher concentrations of glutamate (71+/-42 vs. 36+/-15 micromol l(-1)) and pyruvate (187+/-89 vs. 125+/-63 micromol l(-1)) than CON. Interstitial serotonin was higher in TM (before work: 10.6+/-10.8 vs. 2.2+/-1.2 nM; after work: 9.2+/-8.3 vs. 1.5+/-2.9 nM). The trapezius blood flow during the working day was higher in TM than in CON. TM had lower PPT and higher pain intensity throughout the working day. No differences in EMG, task exposure level, mental stress, or urine-cortisol in the groups were found. These findings support the idea that peripheral nociceptive processes are activated in occupationally active subjects, who are diagnosed with trapezius myalgia. In contrast, no sign of low blood flow or increased stress or muscle activity markers were found in TM.

Women with fibromyalgia: work and rehabilitation

PURPOSE

To explore disability in women with fibromyalgia with a focus on their work situation.

METHOD

Review of literature on work status of women with fibromyalgia.

RESULTS

Major differences exist between studies in reported disability and in the percentages of women working. Limitations caused by pain, fatigue, decreased muscle strength, and endurance influence work capacity. However, 34 - 77% of the women work. Individual adjustments in the work situation are reported. When the women find a level that matches their ability, they continue to work and find satisfaction in their work role. Many factors besides degree of impairment or disability influence whether clients with longstanding pain can remain in their work role or return to work after sickness leave.

CONCLUSION

The total life situation, other commitments, type of work tasks, the ability to influence the work situation, and the physical and psychosocial work environment are important factors in determining whether a person can remain in a work role. More knowledge is needed about how to adjust work conditions for people with partial work ability to the benefit of society and the individual.

Non-invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application

AIM

To evaluate a specially developed photoplethysmographic (PPG) technique, using green and near-infrared light sources, for simultaneous non-invasive monitoring of skin and muscle perfusion.

METHODS

Evaluation was based on assessments of changes in blood perfusion to various provocations, such as post-exercise hyperaemia and hyperaemia following the application of liniment. The deep penetrating feature of PPG was investigated by measurement of optical radiation inside the muscle. Simultaneous measurements using ultrasound Doppler and the new PPG application were performed to elucidate differences between the two methods. Specific problems related to the influence of skin temperature on blood flow were highlightened, as well.

RESULTS

Following static and dynamic contractions an immediate increase in muscle perfusion was shown, without increase in skin perfusion. Liniment application to the skin induced a rapid increase in skin perfusion, but not in muscle. Both similarities and differences in blood flow measured by Ultrasound Doppler and PPG were demonstrated. The radiant power measured inside the muscle, by use of an optical fibre, showed that the near-infrared light penetrates down to the vascular depth inside the muscle.

CONCLUSIONS

The results of this study indicate the potentiality of the method for non-invasive measurement of local muscle perfusion, although some considerations still have to be accounted for, such as influence of temperature on blood perfusion.

Shoulder pain and its consequences in paraplegic spinal cord-injured, wheelchair users

STUDY DESIGN

Cross-sectional.

OBJECTIVES

To describe the consequences of shoulder pain on activity and participation in spinal cord-injured paraplegic wheelchair users. To describe the prevalence and type of shoulder pain.

SETTING

Two spinal cord injury (SCI) centres in Sweden.

METHODS

All subjects with paraplegia due to an SCI of more than 1 year living in the counties of Uppsala and Linköping, Sweden were contacted by mail and asked to fill in a questionnaire (89 subjects). Those of the responding 56 subjects with current shoulder pain were asked to participate in further examination and interviews. A physiotherapist examined 13 subjects with shoulder pain in order to describe type and site of impairment. To describe consequences of shoulder pain on activity and participation, the Constant Murley Scale (CMS), the Wheelchair Users Shoulder Pain Index (WUSPI) the Klein & Bell adl-index and the Canadian Occupational Performance Measure (COPM) were used.

RESULTS

Out of all respondents, 21 had shoulder pain (37.5%). Data from 13 of those subjects were used in the description of type and consequences of shoulder pain. Findings of muscular atrophy, pain, impingement and tendinits were described. We found no difference in ADL-performance with, respectively without, shoulder pain (P=0.08) using the Klein & Bell adl-index. No correlation was found between the various descriptions of impairment, activity limitations and participation restriction (P>0.08). All together 52 problems with occupational performance due to shoulder pain were identified using the COPM. Of these, 54% were related to self-care activities.

CONCLUSION

The consequences of shoulder pain in paraplegic wheelchair users are mostly related to wheelchair activities. Since the wheelchair use itself presumably cause shoulder problems, this will become a vicious circle. More research is needed in order to reduce shoulder problems in wheelchair users.

A pilot study of body awareness programs in the treatment of fibromyalgia syndrome

OBJECTIVE

To compare in a pilot study the effect of two physical therapies, the Mensendieck system (MS) and body awareness therapy (BAT) according to Roxendal, in fibromyalgia patients and to investigate differences in effect between the two interventions.

METHODS

Twenty female patients were randomized to either MS or BAT in a program lasting 20 weeks. Evaluations were tender point examination and questionnaires, including visual analog scales (pain intensity at worst site, muscular stiffness, evening fatigue, and global health), Fibromyalgia Impact Questionnaire (FIQ), Coping Strategies Questionnaire, Quality of Life Scales, Arthritis Self-Efficacy Scale (ASES), and disability before, immediately after, and at 6 and 18 months follow-up.

RESULTS

The BAT group had improved global health at 18 months follow-up, but lower results than the MS group. The MS group had improved FIQ, ASES other symptoms, and pain at worst site at 18 months follow-up.

CONCLUSION

In the present pilot study, MS was associated with more positive changes than BAT.

An estimation of the influence of force decrease on the mean power spectral frequency shift of the EMG during repetitive maximum dynamic knee extensions

Frequency analysis of myoelectric (ME) signals, using the mean power spectral frequency (MNF), has been widely used to characterize peripheral muscle fatigue during isometric contractions assuming constant force. However, during repetitive isokinetic contractions performed with maximum effort, output (force or torque) will decrease markedly during the initial 40-60 contractions, followed by a phase with little or no change. MNF shows a similar pattern. In situations where there exist a significant relationship between MNF and output, part of the decrease in MNF may per se be related to the decrease in force during dynamic contractions. This study estimated force effects on the MNF shifts during repetitive dynamic knee extensions. Twenty healthy volunteers participated in the study and both surface ME signals (from the right vastus lateralis, vastus medialis, and rectus femoris muscles) and the biomechanical signals (force, position, and velocity) of an isokinetic dynamometer were measured. Two tests were performed: (i) 100 repetitive maximum isokinetic contractions of the right knee extensors, and (ii) five gradually increasing static knee extensions before and after (i). The corresponding ME signal time-frequency representations were calculated using the continuous wavelet transform. Compensation of the MNF variables of the repetitive contractions was performed with respect to the individual MNF-force relation based on an average of five gradually increasing contractions. Whether or not compensation was necessary was based on the shape of the MNF-force relationship. A significant compensation of the MNF was found for the repetitive isokinetic contractions. In conclusion, when investigating maximum dynamic contractions, decreases in MNF can be due to mechanisms similar to those found during sustained static contractions (force-independent component of fatigue) and in some subjects due to a direct effect of the change in force (force-dependent component of fatigue). In order to compare MNF shifts during sustained static and repetitive dynamic contractions it is necessary to estimate the force-dependent component of fatigue of dynamic contractions. Our results are preliminary and have to be confirmed in larger experiments using single dynamic contractions when determining the MNF-force relationship of the unfatigued situation.

Test-retest reliability of EMG and peak torque during repetitive maximum concentric knee extensions

The aim of this study was to investigate the reliability of peak torque and surface electromyography (EMG) variable's root mean square (RMS) and mean frequency (MNF) during an endurance test consisting of repetitive maximum concentric knee extensions. Muscle fatigue has been quantified in several ways, and in isokinetic testing it is based on a set of repetitive contractions. To assess test-retest reliability, two sets of 100 dynamic maximum concentric knee extensions were performed using an isokinetic dynamometer. The two series were separated by 7-8 days. The subjects relaxed during the passive flexion phase. Twenty (10 men and 10 women) clinically healthy subjects volunteered. Peak torque and EMG from rectus femoris, vastus medialis, vastus lateralis and biceps femoris were recorded. RMS and MNF were calculated from the EMG signal. The reliability was calculated with intraclass correlation coefficient ICC (1.1) and standard error of measurements (SEM). The reliability of peak torque was good (ICC=0.93) and SEM showed low values. ICC was good for absolute RMS of rectus femoris (ICC>/=0.80), vastus medialis (ICC>/=0.88) and vastus lateralis (ICC>/=0.82) and MNF of rectus femoris (ICC>/=0.82) and vastus medialis (ICC>/=0.83). Peak torque, and MNF and RMS of rectus femoris and vastus medialis are reliable variables obtained from an isokinetic endurance test of the knee extensors.

Quantitative sensory testing in fibromyalgia patients and in healthy subjects: identification of subgroups

OBJECTIVE

To determine perception and pain thresholds in patients with fibromyalgia syndrome and in healthy controls, and to investigate whether patients with fibromyalgia syndrome can be grouped with respect to thermal hyperalgesia and whether these subgroups differ from healthy controls and in clinical appearance.

DESIGN

The authors conducted a quasi-experimental clinical study.

SUBJECTS

Twenty-nine women patients with fibromyalgia syndrome and 21 healthy pain-free age-matched women participated in the study.

METHODS

Quantitative sensory testing using a Thermotest instrument was performed on the dorsum of the left hand. Sleep and pain intensity were rated using visual analog scales.

RESULTS

Cold and heat pain but not perception thresholds differed significantly between patients with fibromyalgia syndrome and healthy subjects. Based on thermal pain thresholds, two subgroups could be identified in fibromyalgia syndrome using cluster analysis.

CONCLUSION

Patients with fibromyalgia syndrome were subgrouped by quantitative sensory testing (i.e., thermal pain thresholds). Subgroups show clinical differences in pain intensities, number of tender points, and sleep quality. Cold pain threshold was especially linked to these clinical aspects.

Prospective study of trigeminal sensibility after whiplash trauma

Trigeminal sensory impairment is frequent in whiplash cases. The pathophysiology is unknown. The purpose of the present investigation was to prospectively study the trigeminal sensibility for temperature and vibration and to evaluate their relationship with the clinical symptoms. Thirty-four of 43 patients with whiplash injury were investigated through quantitative sensory tests with a mean of 6 weeks and 71 months after injury. Sensory disturbances over the trigeminal skin area persisted over the years ( r = 0.764. p < 0.000). At follow-up, a significant correlation ( r = 0.614, p < 0.000) was found between the sensory disturbances and the symptoms related to the central nervous system, whereas no significant relationship was found with the musculoskeletal symptoms. Trigeminal sensory impairment can either be explained by dysfunction in the central nervous system or by inhibitory mechanisms secondary to pain.

Wheelchair seating intervention. Results from a client-centred approach

PURPOSE

The aim of this study was to analyse the effects of wheelchair intervention from a client-centred perspective.

METHOD

Results from 38 consecutive active wheelchair users visiting the wheelchair-seating department at the University Hospital in Linköping, Sweden, were analysed and described. All clients had defined problems related to wheelchair seating. Back pain was estimated before intervention and at follow-up, using a Visual Analogue Scale. The effect of intervention on different aspects of wheelchair functionality, seating and occupational performance was estimated by the clients at follow-up.

RESULTS

Two initial main problem areas were identified among the group; seating discomfort (87%) and back pain (63%). Back pain was significantly reduced at follow-up (p<0.001). Problems initially defined by the clients, e.g. seating discomfort, were affected positively, in 79% of all clients, as estimated by the clients at follow-up. No significant correlation was found between the initial cause of intervention or the highest ranked wheelchair functionality aspect and final acceptance of intervention.

CONCLUSIONS

The results from this study confirm the possibility of reducing, or even eliminating, common secondary problems such as back pain and discomfort, related to wheelchair seating by individually adjusted measures. Further research and development in this field is both necessary and cost-effective.

Early interdisciplinary rehabilitation programme for whiplash associated disorders

PURPOSE

To assess the clinical outcomes of a multidisciplinary rehabilitation programme for early intervention of chronic whiplash associated disorders (WAD). The primary aim of the programme was to increase levels of activity and independence in patients suffering WAD.

METHODS

Ninety subjects with purported chronic symptoms associated with whiplash associated disorder (WAD) were referred to a multi-centre multi-modal 5- and 8-week rehabilitation programme in 1997-1998, during which prospective and retrospective functional and psychological evaluations were conducted, the follow-up was to 6 months.

RESULTS

Subjects indicated they were satisfied with the programme. Retrospective evaluation indicated increased ability to cope with and control pain and, to some extent, psychological aspects. The pain intensity in the neck and upper back were significantly decreased at 6 months follow-up. However, for most of the functional and psychological markers, no significant changes were found.

CONCLUSIONS

A multi-modal rehabilitation programme for the chronic suffering attributed to WAD had positive effects according to several aspects of the retrospective evaluations, but according to most of the aspects evaluated prospectively the programme does not appear to have significant benefits.

Chronic pain and difficulty in relaxing postural muscles in patients with fibromyalgia and chronic whiplash associated disorders

OBJECTIVE

To investigate if muscle tension according to the surface electromyogram (EMG) of the shoulder flexors is increased in consecutive patients with fibromyalgia (FM) or chronic whiplash associated disorders (WAD).

METHODS

A total of 59 consecutive patients with FM (n = 36) or chronic WAD (n = 23) performed 100 maximal isokinetic contractions combined with surface electromyography of the trapezius and infraspinatus. A randomized group of pain-free female (n = 27) subjects served as control group. Peak torque initially (Pti) and absolute and relative peak torque at endurance level (PTe, PTer) were registered as output variables, together with the EMG level of unnecessary muscle tension, i.e., the signal amplitude ratio (SAR).

RESULTS

The patient groups had a higher level of unnecessary tension initially and at the endurance level. The patients had lower absolute output (PTi and PTe), but the relative levels (PTer) did not differ comparing all 3 groups. Subjects with FM had significantly higher body mass index (BMI) than the other groups. BMI did not influence the SAR but correlated positively with PTi.

CONCLUSION

The results confirmed earlier findings that groups of patients with chronic pain have increased muscle tension and decreased output during dynamic activity compared to pain-free controls. However, the results indicated there is heterogeneity within groups of patients with the same chronic pain disorder and that not all patients with chronic pain have increased muscle tension.

Fibre type proportion and fibre size in trapezius muscle biopsies from cleaners with and without myalgia and its correlation with ragged red fibres, cytochrome-c-oxidase-negative fibres, biomechanical output, perception of fatigue, and surface electromyography during repetitive forward flexions

In the literature enlarged/increased cross-sectional area (CSA) of type I muscle fibres has been reported as a morphological mark of work-related localised myalgia in the descending part of the trapezius muscle of women. These studies did not use enough subjects or lacked an adequate control group. The recording of surface electromyograms (EMG) is central to the research field of work-related myalgia. However, the influence of intrinsic muscle properties such as the effect of muscle fibre distribution upon surface EMG has to be better understood in order properly to evaluate this method as a possible diagnostic and preventive tool. This study had two aims. Firstly, it investigated the muscle fibre distribution and CSA in work-related myalgia in trapezius muscles. Secondly, the multivariate relationships among muscle morphology and histochemistry [ragged-red (RR) fibres, and cytochrome-c-oxidase-negative-fibre changes] EMG, perceived fatigue, and biomechanical output of shoulder flexions were analysed. The raw data have been presented in an earlier study. The participants in this study were 25 female cleaners with work-related myalgia of the trapezius muscle and 25 female cleaners not experiencing work-related myalgia of this muscle. The control group comprised 21 healthy female teachers who had not been exposed to highly repetitive work or static muscle work. Smaller CSA of type II fibres were found in cleaners compared to teachers. In this study the CSA of type I fibres of the trapezius muscles associated with myalgia were no greater than in muscles without myalgia. The prevalence of RR fibres together with age, fibre type proportions, CSA and working as a cleaner correlated with the ability to relax as recorded electromyographically. The relative mean frequency of the EMG of the trapezius muscle correlated with the prevalence of RR fibres, but it did not correlate with the proportions and CSA of different fibre types. Low biomechanical outputs and low signal amplitude increases of the EMG during the test were associated with high proportions of type -IIB fibres. The smaller CSA of type II fibres in cleaners might have reflected a different muscle activation pattern due to different occupational demands in cleaners than in teachers. Morphological or histopathological variables can influence the three EMG variables investigated.

Survival with pain: an eight-year follow-up of war-wounded refugees

The aim of this study was to investigate the nature of chronic pain in male war-wounded refugees and to examine the relationship between chronic pain and psychiatric symptoms. A culturally heterogeneous group of 44 war-wounded refugees were investigated during hospitalization, shortly after arrival, and followed up after two years. This study is an additional follow-up after eight years. The data collection methods used were structured interviews and physical examination. The measures of outcome were: Visual Analogue Scale (VAS) grading of pain; clinical categorization of pain into nociceptive or neurogenic; Hopkins Symptom Check List (HSCL-25); Post Traumatic Symptom Scale (PTSS-10). Chronic pain was found in 32 (73%) out of 44 subjects. The pain was purely nociceptive and neurogenic in 53% and 25%, respectively. The frequency of psychiatric symptoms was significantly related to the mean intensity of pain. War-wounded refugees display psychiatric symptoms and chronic pain in a complex pattern. Further research is needed as a basis for pain rehabilitation programmes suitable for this group.

Mean frequency and signal amplitude of the surface EMG of the quadriceps muscles increase with increasing torque--a study using the continuous wavelet transform

The continuous wavelet transform (CWT), a time-frequency method, was used when calculating mean frequency of the power spectrum (MNF) and signal amplitude (RMS) of the surface EMG to investigate their relationships to force during a gradually increasing knee extension (ramp). Based upon the CWT, MNF was redefined to include time dependence on the EMG signal frequency contents, the short-time MNF (STMNF). Surface EMG was recorded from vastus lateralis, rectus femoris and vastus medialis in 21 clinically healthy subjects during a brief, gradually increasing contraction up to 100% of a maximum voluntary contraction (MVC), with a duration of approximately 10 s. The relationships between the EMG variables and force using linear regression were determined for each subject. For vastus lateralis, we also investigated if certain aspects of the muscle morphology (i.e., proportions and areas of different fibre types) influenced the EMG-force relationship. For the majority of subjects (17-18 out of 21 subjects) there were significant positive correlations between STMNF and force in the three muscles. No sex differences were found in intercepts or regression coefficients of STMNF. The muscle morphology had a significant influence on the STMNF-force intercept and the regression coefficient. Positive and highly significant linear correlations between RMS and force were found for all subjects and all three muscles.In conclusion, time frequency methods can be applied when investigating EMG during brief contractions associated with non-stationarity. In a great majority of the subjects, and in the three muscles, significant linear force dependencies were found for STMNF. Thus, when evaluating muscle fatigue, e.g., in ergonomic situations, it is important to consider the force level as one factor that can influence the results. Morphological variables (fibre proportions and fibre areas) influenced the STMNF-force relationship in vastus lateralis.

Anterior tibial translation during different isokinetic quadriceps torque in anterior cruciate ligament deficient and nonimpaired individuals

STUDY DESIGN

Factorial quasi-experimental design.

OBJECTIVES

To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors.

BACKGROUND

The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation.

METHODS AND MEASURES

Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60 degrees x s(-1)), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject.

RESULTS

The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group.

CONCLUSIONS

An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.