Musculoskeletal Pain Disorders Research Articles

Injections of Algesic Solutions into Muscle Activate the Lateral Reticular Formation: A Nociceptive Relay of the Spinoreticulothalamic Tract.

Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subsequent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6% hypertonic saline, pH 4.0 acetate buffer, or 0.05% capsaicin) was made into the gastrocnemius muscle and the distribution of immunolabeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to muscles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial laminae. Numerous neurons were immunolabeled in the brainstem, predominantly in the lateral reticular formation (LRF). Labeled neurons were found bilaterally in the caudalmost ventrolateral medulla, where neurons responsive to noxious stimulation of cutaneous and visceral structures lie. Immunolabeled neurons in the LRF continued rostrally and dorsally along the intermediate reticular nucleus in the medulla, including the subnucleus reticularis dorsalis caudally and the parvicellular reticular nucleus more rostrally, and through the pons medial and lateral to the motor trigeminal nucleus, including the subcoerulear network. Immunolabeled neurons, many of them catecholaminergic, were found bilaterally in the nucleus tractus solitarii, the gracile nucleus, the A1 area, the CVLM and RVLM, the superior salivatory nucleus, the nucleus locus coeruleus, the A5 area, and the nucleus raphe magnus in the pons. The external lateral and superior lateral subnuclei of the parabrachial nuclear complex were consistently labeled in experimental data, but they also were labeled in many control cases. The internal lateral subnucleus of the parabrachial complex was labeled moderately. Few immunolabeled neurons were found in the medial reticular formation, however, but the rostroventromedial medulla was labeled consistently. These data are discussed in terms of an interoceptive, multisynaptic spinoreticulothalamic path, with its large receptive fields and role in the motivational-affective components of pain perceptions.

Effectiveness of extracorporeal shockwave therapy in three major tendon diseases.

BackgroundExtracorporeal shockwave therapy is a conservative treatment for several painful musculoskeletal disorders. The aim of the study was the assessment of the relief from pain by the shockwave therapy in a population of consecutive patients affected by specific pathologies.Materials and methodsA group of consecutive patients were studied and treated. They were affected by calcific tendonitis of the shoulder (129 patients), chronic Achilles tendinopathy (102 patients), and lateral epicondylitis of the elbow (80 subjects). Each patient had 3 applications with a monthly interval, and was followed up at 1, 6, and 12 months after treatment. Results were evaluated by the numeric rating scale (NRS) in all cases, the Constant Murley Score for the assessment of the shoulder function, the American Orthopaedic Foot and Ankle Society Score for subjects affected by chronic Achilles tendinopathy, and the Oxford Elbow Score for those affected by a lateral epicondylitis of the elbow.ResultsOne year after treatment, the results were considered satisfactory with an almost complete resolution of symptoms. There were statistically significant results at the 12-month follow-ups regarding the mean NRS score (from 6.25 to 0.2), the Constant Murley Score (from 66.7 to 79.4), the Oxford Elbow Score (from 28 to 46), and the AOFAS (from 71 to 86).ConclusionsExtracorporeal shockwave therapy may be considered a safe, economic, and effective treatment for several chronic musculoskeletal disorders, allowing satisfactory pain relief and improvement of function ability.Level of evidenceLevel IV.

Altered Central Sensitization and Pain Modulation in the CNS in Chronic Joint Pain.

Musculoskeletal pain disorders are the second largest contributor to global disability underlining the significance of effective treatments. However, treating chronic musculoskeletal pain, and chronic joint pain (osteoarthritis (OA)) in particular, is challenging as the underlying peripheral and central pain mechanisms are not fully understood, and safe and efficient analgesic drugs are not available. The pain associated with joint pain is highly individual, and features from radiological imaging have not demonstrated robust associations with the pain manifestations. In recent years, a variety of human quantitative pain assessment tools (quantitative sensory testing (QST)) have been developed providing new opportunities for profiling patients and reaching a greater understanding of the mechanisms involved in chronic joint pain. As joint pain is a complex interaction between many different pain mechanisms, available tools are important for patent profiling and providing the basic knowledge for development of new drugs and for developing pain management regimes.

Hypnotherapy and accupressure for brachial neuralgia

Background Pain management is concerned with the reduction of suffering and enhanced quality of life rather than a reduction of pain complaint. Persistent pain may be associated with morbidity such as emotional distress, physical disability, and sleep disturbance. Despite the prevalence of pain in musculoskeletal disorders, effective first line treatments are not without moderate to severe side effects. The aim of this study is to compare the efficacy of clinical hypnotherapy with acupressure in reducing major unresolved chronic pain; brachial neuralgia.

Reference Values of the Pain Disability Index in Patients With Painful Musculoskeletal and Spinal Disorders: A Cross-national Study.

Cross-sectional study. To examine reference data for the Pain Disability Index (PDI) in Dutch and Canadian patient samples with a variety of musculoskeletal pain disorders and to test which potential factors are independently associated with the PDI score. The PDI is a widely used generic instrument for measuring disability related to pain. It is unknown whether patients with spinal and other musculoskeletal diagnoses have different levels of disability when scored on the PDI. Patients were referred to secondary and tertiary care centers in the Netherlands and Alberta, Canada, between 2009 and 2013. All patients filled out a baseline questionnaire including demographics and the PDI. After first consultation with a medical doctor, diagnoses were set by the medical specialist. Univariate general linear models were used to examine correlations between PDI scores and age, sex, country of residence, diagnosis, and work status. In total 6997 patients were included in this study: 1302 Canadian and 5695 Dutch patients. Mean PDI score of the total group was 37.8 ± 14.2. Reference values are presented and clustered into the following diagnostic groups: spinal nerve and intervertebral disc disorders; nonspecific back pain; rheumatic soft-tissue pain (widespread pain or fibromyalgia); spinal stenosis; and whiplash-associated disorder. The PDI score was significantly and relevantly associated with pain intensity (η explained variance from 20% to 25%), but not relevantly associated with age, sex, country of residence, and diagnostic group (η<3%). In the working subgroup, adding "current sick leave" as covariate increased the explained variance to 34%. Reference values of the PDI are presented. Patient ratings of disability on the PDI are relevantly associated with pain intensity and work status, but not with nationality or diagnostic group. Only minimal differences were identified between the various musculoskeletal diagnoses included. N/A.

Prevalence of Musculoskeletal Disorders for Nurses in Hospitals, Long-Term Care Facilities, and Home Health Care

The aim of this study was to determine the prevalence of musculoskeletal pain and reported injuries for nurses and nursing aides. Nurses and nursing aides suffer from work-related pain and musculoskeletal disorders (MSDs). Although there have been a plethora of studies on MSDs, an overall understanding of the prevalence of MSDs and pain can lead to better prioritization of research needs with respect to the health care industry. A total of 132 articles on prevalence of MSD pain and injuries were included in the review. All articles were published in peer-reviewed English-speaking journals and subjected to a quality review. Reported prevalence of MSD pain for nurses and nursing aides was highest in the low back, followed by shoulders and neck. However, the majority of the studies have been concentrated on 12-month pain in the low back and predominantly in hospitals. Few researchers have investigated pain in the upper and lower extremities (less than 27% of the studies). Even fewer researchers have evaluated reported injuries or even subjective lost-time injuries (less than 15% of the studies). MSD pain in the nursing profession has been widely investigated worldwide, with a major focus on low-back pain. Given new directions in health care, such as patients who live longer with more chronic diseases, bariatric patients, early mobility requirements, and those who want to be at home during sickness, higher prevalence levels may shift to different populations--home health care workers, long-term care workers, and physical therapists--as well as shift to different body regions, such as shoulders and upper extremities.

Exercise, Not to Exercise, or How to Exercise in Patients With Chronic Pain? Applying Science to Practice

Exercise is an effective treatment strategy in various chronic musculoskeletal pain disorders, including chronic neck pain, osteoarthritis, headache, fibromyalgia and chronic low back pain. Although exercise can benefit those with chronic pain (CP), some patients (eg, those with fibromyalgia, myalgic encephalomyelitis/chronic fatigue syndrome and chronic whiplash associated disorders) encounter exercise as a pain inducing stimulus and report symptom flares due to exercise. This paper focuses on the clinical benefits and detrimental effects of exercise in patients with CP. It summarizes the positive and negative effects of exercise therapy in migraine and tension-type headache and provides an overview of the scientific evidence of dysfunctional endogenous analgesia during exercise in patients with certain types of CP. Further, the paper explains the relationship between exercise and recovery highlighting the need to address recovery strategies as well as exercise regimes in the rehabilitation of these patients. The characteristics, demands and strategies of adequate recovery to compensate stress from exercise and return to homeostatic balance will be described. narrative review. Exercise is shown to be effective in the treatment of chronic tension-type headache and migraine. Aerobic exercise is the best option in migraine prophylaxis, whereas specific neck and shoulder exercises is a better choice in treating chronic tension-type headache. Besides the consensus that exercise therapy is beneficial in the treatment of CP, the lack of endogenous analgesia in some CP disorders should not be ignored. Clinicians should account for this when treating CP patients. Furthermore, optimizing the balance between exercise and recovery is of crucial merit in order to avoid stress-related detrimental effects and achieve optimal functioning in patients with CP. Exercise therapy has found to be beneficial in CP, but it should be appropriately and individually tailored with emphasis on prevention of symptom flares and applying adequate recovery strategies.

Proprioception in musculoskeletal rehabilitation. Part 2: Clinical assessment and intervention

IntroductionProprioception can be impaired in gradual-onset musculoskeletal pain disorders and following trauma. Understanding of the role of proprioception in sensorimotor dysfunction and methods for assessment and interventions is of vital importance in musculoskeletal rehabilitation. In Part 1 of this two-part Masterclass we presented a theory-based overview of the role of proprioception in sensorimotor control, causes and findings of altered proprioception in musculoskeletal conditions, and general principles of assessment and interventions. PurposeThe aim of this second part is to present specific methods for clinical assessment and interventions to improve proprioception in the spine and extremities. ImplicationsClinical assessment of proprioception can be performed using goniometers, inclinometers, laser-pointers, and pressure sensors. Manual therapy, taping, and bracing can immediately enhance proprioception and should be used to prepare for exercise interventions. Various types of exercise (active joint repositioning, force sense, co-ordination, muscle performance, balance/unstable surface, plyometric, and vibration training) should be employed for long-term enhancement of proprioception.

Functional Assessment in Greek Tension-Type Headache Sufferers: Validity, Reliability, Responsiveness and Psychometrics of the Migraine Disability Assessment Questionnaire (MIDAS)

Introduction: Functional assessment in painful musculoskeletal disorders such as tension - type headache requires valid, reliable and sensitive instruments. MIDAS (Migraine Disability Assessment questio nnaire) is an internationally well - known functional index which has not been validated in Greek headache sufferers. Aims: The aim of the study was to assess headache related disability in Greek tension - type headache sufferers using MIDAS. The validity, rel iability, responsiveness and psychometrics of the Greek MIDAS version were examined. Study Design : A multicenter prospective design was followed. Place and Duration of Study: The study took place in a medical rehabilitation unit and two physiotherapy priva te practices in Athens, from January - December 2010. Methodology: A sample of 121 patients ( 101 women, age: 39.4 + 12.7; 20 men, age: 35.5 + 8.8,

A Knowledge Translation Perspective on the Two Quantitative Sensory Tests and their Usability with Clinicians

Background: Knowledge Translation (KT) in health service can be conceptualized as evidence based knowledge transfer to clinical practice. KT puts evidence-informed innovations into practice and evaluates the effectiveness innovations. The use of Quantitative Sensory Testing (QST) is rare in clinics despite its scientific evidence and potential benefit for patient care. Appropriate KT plan can reduce the gap between scientific evidence and clinical practice. This KT project aimed to develop and conduct beta testing of two KT tools (created knowledge) with the target population (clinicians) who treat musculoskeletal pain disorders. Methods: This paper explores how evidence-informed innovations (knowledge creation) may work in action process model of KT. The whole process may be defined as “knowledge-to-action” process, and it is a dynamic interaction between researchers, clinicians and stakeholders. We used Ovid database (e.g. MEDLINE, EMBASE, AMED, PsycINFO) for literature review and KT tool production ((knowledge creation). This KT project evaluated two KT tools (manual and video) by administering the survey with 12 clinicians. Results: Overall rating of the KT tools (manual and video) = 5.75 out of 6. All responses from 12 clinicians were affirmative answer and minimum 75% inquires strongly agreed on all components/topics. Clinicians supported implementation of the two QST techniques for the clinical setting and their feedback assisted in the strategy for implementation. Conclusions: Evaluation of KT through the wide lens of the “knowledge-to-action” process creates awareness of the value of clinicians and research based evidence. It justifies opportunities and pathways of KT for QST in clinic. The study with a KT model reflected clinical perspective of knowledge has a potential role in successful KT intervention. The future directed models may allow clinicians and stakeholders to analyse complex situation in health service, and it may help to identify target KT strategies to solve the practical problem for implementing two reliable, feasible and economic QST in clinical practice.

Gastrointestinal Adverse Effects due to Use of Non-Steroidal Anti- Inflammatory Drugs (NSAIDs) in Non-Traumatic Painful Musculoskeletal Disorders

Background: The present study aims at investigation of the gastrointestinal adverse drug reactions (ADRs) with use of NSAIDs in patients of Non-Traumatic musculoskeletal painful disorders. Our study is unique in terms that it aims at investigations and evaluations of the gastrointestinal adverse drug reactions (ADRs) with use of NSAIDs in patients of non-traumatic musculoskeletal painful disorders, where most of the concurrent and concomitant risk factors like hepatobiliary system, renal system are mostly excluded, along with a dedicated follow up of large population included in our study. Non-Steroidal anti-inflammatory drugs (NSAIDs) such as Diclofenac sodium, Ibuprofen and others are effective for non-traumatic musculoskeletal painful disorders ranging from acute to chronic conditions. NSAIDs are probably most commonly used medications by medical fraternity worldwide for relief from acute, recurring or chronic pain conditions and are easily available in India in many forms as over-the-counter analgesic. Prolonged unsupervised use of these medications leads to disturbance in achieving pain relief and risk of gastrointestinal symptoms ranging from dyspepsia to acute and chronic gastrointestinal ulcer. The most frequent ADRs due to NSAIDs use was gastrointestinal effects leading to discontinuation of treatment. The other ADRs for which NSAIDs are blamed widely are alteration of renal or cardiac parameters in a small subset of patients. Renal and cardiac side effects are well documented and evaluated by clinicians prior to administration of NSAIDs, but the gastrointestinal adverse reactions are overlooked by medical fraternity while

Effects of exercise on pain of musculoskeletal disorders: a systematic review

Work related musculoskeletal disorders are a major concern for public health and pain is the most important symptom. The aim of this study was to verify the effectiveness of workplace exercises to control musculoskeletal pain and its frequency, intensity, duration and type of exercises used. The search was conducted systematically in Medline, Pubmed, Embase, Bireme, Web of Knowledge and Pedro databases. The keywords "workplace", "exercise" and "musculoskeletal disorders" were used combined. Randomized control trials which performed worksite exercises were selected and the studies were assessed by their methodological soundness. Ten articles were selected which investigated the resistance training, cardio respiratory exercises, Pilates, stretching, postural orientation and exercises for relaxation. Workplace resistance training performed at 70-85% RM, three times a week for 20 minutes promotes reduction of the pain in shoulders, wrists, cervical, dorsal and lumbar spine. However, there is no consensus regarding the total duration of the intervention for the decrease of musculoskeletal pain in these regions. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment, Systematic Review of RCTs (Randomized and Controlled Clinical Studies).

THU0136 Acupuncture in the Treatment of Rheumatoid Arthritis: Results of A Randomized Controlled Trial

BackgroundAcupuncture is commonly used by patients in India with chronic painful musculoskeletal disorders. There are, however, few well-designed studies of its efficacy.ObjectivesThis study describes a randomized controlled trial to evaluate...

A History of Dry Needling

Objectives: To trace the development of the practice and theoretical basis of dry needling by means of an examination of the literature.Findings: The term dry needling arose from the need to provide a contrast to the injection of a fluid through a hypodermic syringe [now sometimes referred to as wet needling]. Dry needling does not involve the injection of any substance, merely the insertion of a needle. The history of dry needling is inextricably bound up with the search for effective treatment of painful musculoskeletal disorders. In particular, it was the research into the use of injections, to both cause and relieve pain in muscular tissue, that led to the development of trigger point theory and then to the use of dry needling as a treatment.Conclusions: A search of the literature reveals that the important clinical finding that simple dry needling of tender points could produce profound and long-lasting relief of musculoskeletal pain had been published in 1941 and again in 1947. This provoked little interest in the wider academic or clinical community until the focus on acupuncture in the 1970s and the publication of a scientific explanation of the nature of myofascial trigger points in the 1970s and 1980s. Since 2000, there has been a surge in academic interest in dry needling and its use has expanded into the allied health professions of physiotherapy, osteopathy, and chiropractic.

Region-specific tendon properties and patellar tendinopathy: a wider understanding.

Patellar tendinopathy is a common painful musculoskeletal disorder with a very high prevalence in the athletic population that can severely limit or even end an athletic career. To date, the underlying pathophysiology leading to the condition remains poorly understood, although reports suggesting that patellar tendinopathy most frequently concerns the proximal posterior region of the tendon has prompted some researchers to examine region-specific tendon properties for a better understanding of the etiology and potential risk factors associated with the condition. However, to date, research concerning the in vivo region-specific tendon properties in relation to patellar tendinopathy is very scarce, perhaps due to the lack of validated techniques that can determine such properties in vivo. In recent years, a technique has been developed involving an automated tendon-tracking program that appears to be very useful in the determination of region-specific tendon properties in vivo. In terms of regional variations in tendon properties, previous research has demonstrated differences in structural, mechanical, and biochemical properties between the discrete regions of the patellar tendon, but the extent to which these regional variations contribute to patellar tendinopathy remains elusive. In addition, with respect to treatment strategies for patellar tendinopathy, previous research has utilized a wide range of interventions, but the use of eccentric exercise (EE) and/or heavy-slow resistance (HSR) training appear to be most promising. However, the optimal program design variables of EE and HSR training that induce the most favorable effects are yet to be determined. This review article provides a detailed discussion of all of the above to allow a better understanding of the etiology and potential risk factors associated with the condition as well as the most effective treatment strategies. First, a comprehensive literature review is provided with respect to region-specific structural, mechanical, and biochemical properties, in association with patellar tendinopathy. Second, the automated tendon-tracking methodology is outlined to assist future researchers in the determination of region-specific tendon properties. Finally, potential treatment strategies are discussed, particularly with regards to the use of EE and HSR training for the management of patellar tendinopathy.

Ulnar nerve neurodynamic test: study of the normal sensory response in asymptomatic individuals.

Cross-sectional study. To describe and analyze normal sensory responses to the ulnar upper-limb neurodynamic test (ULNT3) and to investigate the influence of sex and arm dominance. Neurodynamic tests are commonly used in the clinical evaluation of patients with musculoskeletal pain disorders. While the normal responses of other upper-limb neurodynamic tests have been previously investigated, there are no studies that have reported the normal responses for the ULNT3. A total of 68 asymptomatic individuals between 18 and 50 years of age volunteered to participate in the study. Of these, 57 (29 women, 28 men) were eligible for the study. The variables measured were pain intensity using a numeric rating scale, shoulder abduction angle, and quality and distribution of symptoms at the point of pain tolerance of the ULNT3. There were statistically significant differences in pain intensity and shoulder abduction angle between the sexes, with women having higher perceived pain and lower shoulder angle than men (P<.05). There was a significant difference of 6.6° (95% confidence interval: 1.1°, 12.1°) in shoulder abduction angle during the ULNT3 (P<.05) between the dominant arm and nondominant arm. The symptoms most often described during application of the ULNT3 were stretching (90%), followed by pain, and the most frequent location of symptoms was the anteromedial half of the forearm. The results of this study provide the normal shoulder abduction angle and quality and distribution of symptoms for the ULNT3. These data can be used by clinicians as a reference when using the ULNT3 in their clinical reasoning and decision making.

The role of stress in absenteeism: cortisol responsiveness among patients on long-term sick leave.

ObjectiveThis study aimed to (1) See whether increased or decreased variation relate to subjective reports of common somatic and psychological symptoms for a population on long-term sick leave; and (2) See if this pattern in variation is correlated with autonomic activation and psychological appraisal.MethodsOur participants (n = 87) were referred to a 3.5-week return-to-work rehabilitation program, and had been on paid sick leave >8 weeks due to musculoskeletal pain, fatigue and/or common mental disorders. An extensive survey was completed, addressing socio-demographics, somatic and psychological complaints. In addition, a physician and a psychologist examined the participants, determining baseline heart rate, medication use and SCID-I diagnoses. During the 3.5-week program, the participants completed the Trier Social Stress Test for Groups. Participants wore heart rate monitors and filled out Visual Analogue Scales during the TSST-G.ResultsOur participants presented a low cortisol variation, with mixed model analyses showing a maximal increase in free saliva cortisol of 26% (95% CI, 0.21–0.32). Simultaneously, the increase in heart rate and Visual Analogue Scales was substantial, indicating autonomic and psychological activation consistent with intense stress from the Trier Social Stress Test for Groups.ConclusionsThe current findings are the first description of a blunted cortisol response in a heterogeneous group of patients on long-term sick leave. The results suggest lack of cortisol reactivity as a possible biological link involved in the pathway between stress, sustained activation and long-term sick leave.

Occupational rehabilitation programs for musculoskeletal pain and common mental health disorders: study protocol of a randomized controlled trial.

BackgroundLong-term sick leave has considerably negative impact on the individual and society. Hence, the need to identify effective occupational rehabilitation programs is pressing. In Norway, group based occupational rehabilitation programs merging patients with different diagnoses have existed for many years, but no rigorous evaluation has been performed. The described randomized controlled trial aims primarily to compare two structured multicomponent inpatient rehabilitation programs, differing in length and content, with a comparative cognitive intervention. Secondarily the two inpatient programs will be compared with each other, and with a usual care reference group.Methods/designThe study is designed as a randomized controlled trial with parallel groups. The Social Security Office performs monthly extractions of sick listed individuals aged 18–60 years, on sick leave 2–12 months, with sick leave status 50% - 100% due to musculoskeletal, mental or unspecific disorders. Sick-listed persons are randomized twice: 1) to receive one of two invitations to participate in the study or not receive an invitation, where the latter “untouched” control group will be monitored for future sick leave in the National Social Security Register, and 2) after inclusion, to a Long or Short inpatient multicomponent rehabilitation program (depending on which invitation was sent) or an outpatient cognitive behavioral therapy group comparative program. The Long program consists of 3 ½ weeks with full rehabilitation days. The Short program consists of 4 + 4 full days, separated by two weeks, in which a workplace visit will be performed if desirable. Three areas of rehabilitation are targeted: mental training, physical training and work-related problem solving. The primary outcome is number of sick leave days. Secondary outcomes include time until full sustainable return to work, health related quality of life, health related behavior, functional status, somatic and mental health, and perceptions of work. In addition, health economic evaluation will be performed, and the implementation of the interventions, expectations and experiences of users and service providers will be investigated with different qualitative methods.Trial registrationClinicalTrials.gov: NCT01926574.

Poster #M240 BEHAVIORAL EFFECTS OF THE NOVEL BENZODIAZEPINE POSITIVE ALLOSTERIC MODULATOR SH-053-2′F-S-CH3 IN AN IMMUNE-MEDIATED NEURODEVELOPMENTAL DISRUPTION MODEL

Pepper (Capsicum) is an annual herbaceous plant belonging to the Solanaceae family. It is a popular fruit that has been grown and consumed for millennia and is found today in most parts of the world for food and also used as traditional medicine. The popularity of capsicum is because it is a highly nutritious, flavorful, and beneficial crop. Numerous epidemiological studies and interventional trials have found that capsicum can reduce many diseases, such as coronary heart disease and cancer. Studies also confirmed the antiinflammatory property of pepper and investigated it against neurological pain and musculoskeletal pain disorders. The health benefits of capsicum are a result of the various antioxidants and phytochemicals found in capsicum. These beneficial compounds vary in concentrations, depending on factors such as agronomic factors, genotype, and environmental issues. These compounds can also be affected by factors such as disinfecting after postharvest, storage method, and cooking. Although capsicum is highly nutritious, it is important to consider that moderation is important as the use of some types of capsicum, such as jalapenos and other chillis, contain capsaicin which can cause discomfort or digestive issues if consumed in excess.

Opioid Receptors and Their Ligands in the Musculoskeletal System and Relevance for Pain Control

Interest in opioid drugs like morphine, as the oldest and most potent pain-killing agents known, has been maintained through the years. One of the most frequent chronic pain sensations people experience is associated with pathological conditions of the musculoskeletal system. Chronic musculoskeletal pain is a major health problem, and an adequate management requires understanding of both peripheral and central components, with more attention drawn to the former. Intense experimental and clinical research activities resulted in important knowledge on the mechanisms and functions of the endogenous opioid system located in the periphery. This review describes the occurrence and distribution of endogenous opioids and their receptors in the musculoskeletal system, and their role in pain control in musculoskeletal disorders, such as rheumatoid arthritis and osteoarthritis. Using different techniques, including immunohistochemistry, electron microscopy or radioimmunoassay, expression of enkephalins, dynorphin, β-endorphin, and endomorphins was demonstrated in musculoskeletal tissues of animals and humans. Localization of opioid peptides was found in synovial membrane, periosteum, bone and bone marrow, loose connective tissue, the paratenon and musculotendinous junction of the achilles tendon. Animal and human studies have also demonstrated expression of µ, δ and κ opioid receptor proteins in musculoskeletal tissues using radioligand binding assays, autoradiography, electrophysiology, immunohistochemistry and Western blotting. Opioid receptor gene expression was reported based on polymerase chain reaction and in situ hybridization techniques. Combining morphological and quantitative approaches, important evidence that the musculoskeletal apparatus is equipped with a peripheral opioid system is provided. Demonstration of the occurrence of an endogenous opioid system in bone and joint tissues represents an essential step for defining novel pharmacological strategies to attain peripheral control of pain in musculoskeletal disorders.