From: J Bodyw Mov Ther. 2010 Jan;14(1):55-64.

Anma therapy is a traditional style of Japanese massage, one of touch and manual therapies, and one of the most popular complimentary alternative therapies therapies in Japan. It was brought from China in the 6th century and, while based on the theory of Chinese medicine, it developed in Japan according to Japanese preference and has recently come to include theories of Western medicine. The purpose of this study was to clarify the physical and psychological effects of Anma therapy.

Fifteen healthy female volunteers in their fifth decade, with chronic muscle stiffness in the neck and shoulder, received two interventions: 40-min Anma therapy and 40-min rest intervention. The design was cross-over design. Participants were randomly divided into two groups. Group A was started on Anma therapy from the first day followed by the rest intervention after a 3-day interval. The order of the Anma therapy and the rest intervention reversed for Group B. Visual Analogue Scale score for muscle stiffness in the neck and shoulder, state anxiety score, and salivary cortisol concentration levels and secretory immunoglobulin A were measured pre- and post-interventions.

Anma therapy significantly reduced Visual Analogue Scale scores and state anxiety scores. Secretory immunoglobulin A concentration levels increased significantly across both groups. Anma therapy reduced muscle stiffness in the neck and shoulder and anxiety levels in this pilot study of 50-year-old females

From: J Manipulative Physiol Ther. 2010 Feb;33(2):96-101

The purpose of this study was to examine the effect of manipulative therapy on the shoulder girdle, in addition to usual care provided by the general practitioner, on the outcomes of physical examination tests for the treatment of shoulder complaints.

In clinical practice, a dysfunction of the shoulder girdle can be treated by manipulative therapy, which aim is to restore normal functioning of the shoulder girdle. To date, with only 1 randomized trial favoring manipulative therapy for the shoulder girdle, the evidence for the effectiveness of manipulative treatment in the treatment of shoulder complaints is scarce. Therefore, the authors conducted a randomized trial to study the effect of manipulative therapy for the shoulder girdle in addition to usual care by the general practitioner in the treatment of shoulder complaints. The design of this study and the main patient-experienced results are already published. The results indicate that additional manual therapy for the structures of the shoulder girdle accelerates recovery of patient-experienced shoulder symptoms and reduces their severity. In the present article, the results for the physical examination outcome measures are presented.

In the clinical research of musculoskeletal complaints, physical testing of pain and mobility by the physician are important outcomes. However, this concerns mostly multiple physical examination tests and multiple outcome measures. This requires multiple statistical testing. Together with small study sizes (more outcomes than patients), this may lead to spurious significant results from randomized trials affecting the interpretability of the outcome of the trial.

The challenge is to reduce the number of variables in such a way that they are clinically sensible and statistically manageable. To overcome the aforementioned problems with pain and mobility as outcome measures of our randomized trial, we tried to reduce the individual physical examination tests for pain and mobility to relevant components. In this study, we used a physical assessment of pain and mobility of the shoulder and shoulder girdle as outcome measures. They consist primarily of the assessment of active and passive limitations in shoulder movement and pain experienced during these movements and a physical examination of the cervicothoracic spine, consisting of passive movements of the neck and pain experienced in these movements. The authors used factor analysis to identify relevant components from these variables thereby reducing the number of outcome measures in a clinically meaningful sense and to increase statistical power. The purpose of this study was to examine the effect of manipulative therapy on the shoulder girdle, in addition to usual care provided by the general practitioner, on the outcomes of physical examination tests for the treatment of shoulder complaints.

This was a randomized controlled trial in a primary care setting in the Netherlands. A total of 150 participants were recruited from December 2000 until December 2002. All patients received usual care by the general practitioner. Usual care included one or more of the following depending on the needs of the patient: information/advice, oral analgesics or nonsteroidal antiinflammatory drugs, corticosteroid injections, exercises, and massage. In addition to usual care, the intervention group received manipulative therapy, up to 6 treatment sessions in a 12-week period. Twenty-four physical examination tests were done at baseline and after 6, 12, and 26 weeks. Factor analysis was done to reduce the number of outcome measures.

The factor analysis resulted in 4 factors: “shoulder pain,” “neck pain,” “shoulder mobility,” and “neck mobility.” At 6 weeks, no significant differences between groups were found. At 12 weeks, the mean changes of all 4 factors favored the intervention group; the factors “shoulder pain” and “neck pain” reached statistical significance. At 26 weeks, differences in the factors “shoulder pain”, “shoulder mobility”, and “mobility neck” statistically favored the intervention group.

In clinical trials concerning treatment of shoulder complaints, factor analysis is useful for the reduction of multiple outcomes of physical examination data and therefore increases statistical power. On the basis of the factors derived from physical examination tests of the shoulder and the cervicothoracic spine, the authors conclude that manipulative therapy, in addition to usual care by the general practitioner, diminishes the severity of the pain in the shoulder and neck and improves the mobility of the shoulder and the cervicothoracic spine. Results were most prominent at 26 weeks after initiation of treatment.

From: Conf Proc IEEE Eng Med Biol Soc. 2009;1:7269-72

There is sound evidence available showing the association between computer use and the risk of developing neck pain and musculoskeletal disorders. Consistent use of computers is one of the major risk factors for neck and shoulder disorders in the workplace. One of the most recent forecasts of computer adoption estimates that there were more than a billion computers in use at the end of 2008. This report also forecasts a 12.3% compound annual growth rate between 2003 and 2015. Driven by lower prices and global demand especially in developing countries it is expected that there will be over 2 billion computer users by 2015. A study of 512 office workers found the 12 month prevalence of neck pain to be 45.5%. Reports of the lifetime prevalence of neck pain in the general population range from 67-80%. As computer adoption increases we can expect a corresponding increase in the prevalence of neck pain if appropriate countermeasures are not employed.

Over time poor neck posture results in pain, muscle aches, tension and headache and can lead to long term complications such as osteoarthritis. Physiological and biomechanical stress due to sustained postures limit important musculoskeletal stimuli that are essential for normal musculoskeletal development. Most upper extremity disorders and symptoms (neck, shoulder, elbow and wrist pain) are associated with computer use at workstations in positions of poor posture. Along with the sitting position, placement of computer monitors and keyboards and the number of hours spent working at computer workstations are important factors in the etiology of cervical disorders associated with computer use. Other workplace risk factors include the number of hours per week of computer use and the time spent in a non-neutral posture at a computer.

A detailed survey at Harvard University showed that more then half of students experienced pain and discomfort while using a computer. The three factors significantly associated with computer-related upper extremity and neck pain among the students were female gender, eight or more years of using a computer 10 or more hours a week, and using a computer for more than 20 hours per week. Most of the students in the study reported that pain in the neck and upper extremity was related to computer use and the posture assumed while using a computer. Most of them adopted a better posture by adjusting the workstation and keyboard, while some took a break when feeling uncomfortable during their work on the computer. Workplace studies, of both cross-sectional and prospective design, consistently identified a relationship between the number of hours per week of computer use and musculoskeletal pain and disorders or the upper extremity and neck.

Trapezius Myositis/Spasm, Paraspinal/Rheomboid Spasm, Cervical Radiculopathy, Thoracic Outlet Syndrome, Bicipital Tendonitis, and Rotator Cuff Tendonitis are all common upper extremity and cervical musculoskeletal disorders associated with use of computers in poor posture. Tension neck syndrome and thoracic outlet syndrome are the most common problems associated with computer use and the major cause is prolonged sitting with the neck and back in flexed positions. These conditions are commonly reported for a person sitting in front of a computer for more then 4 hours which is common in office environments.

Cervical flexion is a complex mechanism as there are eight joints involved in head/neck flexion, the skull and C1 through T1 vertebrae. The angle between a vertical line passing through C7 and the line from C7 to the tragus is called the cranial-vertebral angle or C7-tragus angle. In a normal sitting posture, the cranial-vertebral angle is usually 30°, 40° is considered more appropriate during computer use, a posture beyond 40° is not recommended. A normal posture is observed if the subject is standing erect and they are looking at a visual target 15 degrees below eye level. The C6-C7 vertebrae are the most mobile vertebrae in the spine and most prone to be affected by poor posture adapted while using a computer. C6-C7 are also important because they support and stabilize the head during its movement in all planes of motion. Moreover, the line of gravity passes through the C6-C7 vertebrae while sitting in a good posture. For these reasons the authors measured head and neck angle by placing an accelerometer device at the C7, directly measuring the cranial-vertebral angle.

Accelerometers are miniature, inexpensive and low-power. They have been used extensively for the measurement of human movement and are entirely suitable for monitoring posture. While a number of posture monitoring systems have been described, the authors intention was to create a single sensor biofeedback system, thus reducing the cost and inconvenience of the system. By using an accelerometer, cranial-vertebral angle could be directly measured. Feedback was to initially consist of a colour coded signal and beep when outside of acceptable thresholds. However, proprioceptive acuity of cervical spine rotation has been shown to be related to neck pain. The addition of a visual biofeedback reference was included as a means to improve the subject’s recognition of their neck angle.

The percentage of time spent in positions defined as bad posture (outside of the set thresholds) was compared with and without biofeedback. Over the 5 hour periods the percentage of time spent in bad posture decreased significantly without biofeedback. This represents an 82% overall decrease in time spent in bad posture. With biofeedback all subjects experienced a significant reduction in time spent in positions of bad posture.

This system is designed to measure the changes in neck angle while working on a computer workstation and to alert the user to correct their position when they are outside of this threshold. The results from data collected during this study suggest that participants were able to maintain better neck posture when working with the biofeedback system. Other issues remain which have not been evaluated in this study. In the system evaluated the cervical angle relative to gravity was the only parameter measured and does not take the thoracic or lumbar regions into account. Time lapse monitoring of sitting posture over time suggests that cervical and thoracic postural changes occur in a similar manner. Further evaluation of the effect of cervical feedback on the lumbar and thoracic spine would clarify if the impact on these regions is similarly positive as reported here. In this study cervical movement was only monitored in the saggital plane, however, a complete system could provide feedback in other planes of movement.

The Cinderella Hypothesis suggests that the cause of chronic muscular pain in computer use is due to the combination of low but static loads and activation of muscle fibres outside the normal recruitment pattern. The lack of sufficient rest in the active muscles, causes damage to the muscle fibres belonging to the early recruited “Cinderella” motor units. Future work will examine EMG activity with and without biofeedback to determine if improved neck posture results in greater rest of the trapezoid muscle in particular.

Prevention of workplace injuries due to poor ergonomics is a rapidly growing area of interest to health care professionals, employers and employees in this modern era. This study describes the preliminary evaluation of a new minimally invasive system for the correction of posture at the workplace. The rational for sensor placement based on cervical geometry has been discussed. The developed system provides the user with biofeedback data to assist in the maintenance of good computer workstation posture. Further work will address the other issues related to the evaluation of this single accelerometer based biofeedback system.

Tags: neck, posture, cervical, poor, computer

From: Ann Fam Med. 2009 Sep-Oct;7(5):446-54

Complaints of arm, neck, and shoulder pain are very common in Western societies. In the Netherlands the estimated 12-month prevalence in the general population was 31% for neck pain, 30% for shoulder pain, 11% for elbow pain, and 18% for wrist or hand pain. Studies have reported that of the respondents with noninflammatory musculoskeletal pain, about 30% to 45% contacted their general practitioner. In Dutch general practice, incidence data for patients with nontraumatic arm, neck, or shoulder complaints show 97 consultations per 1,000 registered persons annually.

Common management options for patients with nontraumatic arm, neck, and shoulder complaints are watchful waiting, additional diagnostic tests, prescription of medication, referral for physiotherapy, a corticosteroid injection, and referral for medical specialist care. Use of these 6 management options shows wide variation, however, both between and within diagnostic groups. Until now, no studies have evaluated the determinants that contribute to variation in the management of these complaints. Part of this variation may be explained by the diagnosis, which, because of its natural course and available treatment, usually guides management. Also, patient and complaint characteristics may influence management. In the Netherlands guidelines issued by the Dutch College of General Practitioners are available for epicondylitis and shoulder complaints; in both guidelines, management advice is partly based on differences in the levels of hindrance (pain severity and functional limitations). In other study populations, patient and complaint characteristics reported to be associated with management options are distress, poor perceived health, age, and sex. Additionally, indicators of poor prognosis can play a role in management decisions. In our earlier study in this population, indicators of poor prognosis were long duration of the complaints at baseline, having musculoskeletal comorbidity, recurrent complaint, low social support, and a high somatization level.

The authors wanted to evaluate associations between diagnosis and characteristics of the patient, complaint, and general practitioner, as well as 6 common management decisions, in patients with nontraumatic arm, neck, and shoulder complaints at the time of the first consultation with their physician. They undertook an observational cohort study set in 21 Dutch general practices, including 682 patients with nontraumatic complaints of arm, neck, and shoulder. The outcome measure was application (yes/no) of a specific management option: watchful waiting, additional diagnostic tests, prescription of medication, corticosteroid injection, referral for physiotherapy, and referral for medical specialist care. Separate multilevel analyses showed that overall, the diagnostic category, having long duration of complaints, and reporting many functional limitations were most frequently associated with the choice of a management option. For watchful waiting, only complaint variables played a role (long duration of complaints, high complaint severity, many functional limitations, recurrent complaint). All these variables were negatively associated with watchful waiting. When opting for 1 of the 5 other management options, several physician characteristics played a role as well. Less clinical experience was associated with additional diagnostic tests and referral to a medical specialist. General practitioners working in a solo practice more frequently referred to a medical specialist. General practitioners working in a rural area more frequently referred for physiotherapy. Female General practitioners prescribed medication less frequently. Physicians with special interest in musculoskeletal complaints gave corticosteroid injections more frequently.

Diagnostic category, long duration of complaints, and high functional limitations were key variables in management decisions with arm, neck, and shoulder complaints complaints. In addition, several physician characteristics played a role as well.

Tags: arm, pain,, neck, pain,, shoulder, pain

From: Pain. 2008 Oct 31;139(3):588-93

Trapezius myalgia – chronic pain from the upper trapezius muscle – is frequent in female employees in monotonous stressful jobs, potentially due to chronic overload of type I muscle fibers. In this study, the authors investigated the intra-individual distribution of trapezius muscle fiber size, and hypothesized that females with myalgia compared with matched healthy controls have a higher percentage of grossly hypertrophied type I fibers with poor capillarization.

Forty-two female office workers with trapezius myalgia and 20 healthy matched controls participated in the study. Standard histochemical methods were used to determine fiber size, fiber type, and capillarization. Type I megafiber were defined as at least twice the size of the median type I fiber size of each individual. The main finding was that trapezius myalgia had a significantly higher proportion of type I megafibers than healthy matched controls, in spite of no significant difference in overall type I fiber size. In trapezius myalgia and healthy matched controls type I megafibers were located in 46% and 11% of the females, respectively. Capillarization of the overall type I fiber pool was not different between healthy matched controls and trapezius myalgia, but was significantly lower in type I megafibers of both groups. The percentage of megafibers was positively related to age and weekly working hours, indicating an effect of long-term exposure. In conclusion, this study shows that trapezius myalgia is associated with a significantly higher percentage of grossly hypertrophied type I muscle fibers with poor capillarization – type I megafibers.

From: Spine: 2009 Aug 1;34(17): 1863-8

Nonspecific neck, shoulder, arm pain is a very common symptom in the general population. It causes suffering for individuals as well as high societal costs in form of sick leave, disability pensions, health care utilization, and loss of productivity. Reviews have reported that the 12-month prevalence of neck pain range from 14% up to 78% and that the 12-month prevalence of shoulder pain range from 5% to 47%. It is important to understand whether the magnitude of different pain conditions are changing in order to plan and provide appropriate health care as well as preventive measures. However, differences in case definitions and study methodologies are considerable, making it difficult to establish time trends for neck, shoulder and arm pain. The authors are not aware of any published studies that have attempted to investigate time trends by repeatedly following the prevalence in a given geographical area.

Neck, shoulder, arm pain is more common among females. A summary of data from epidemiological studies in the general population found a median ratio between females and males of 1.4 for neck pain and 1.3 for shoulder pain. Treaster and Burr concluded that females do have higher prevalence than males for many types of upper extremity musculoskeletal disorders, even after controlling for the type of data source self reporting, plant/worker compensation records or physical examinations and confounders such as age. The reasons behind the prevalence differences are poorly understood, and it is still unclear whether this gender gap has been constant over time, or is increasing or decreasing.

Several studies have reported that both comorbid low back pain and comorbid psychological distress are common. Both a national study and a cross national study have shown that about two-third of individuals with musculoskeletal pain reported pain in at least 2 regions. The link between symptoms in different bodily regions may involve shared pathology, common mechanical risk factors, or some aspects of psychological distress. To the authors knowledge, no studies have reported whether the prevalence of neck, shoulder, arm pain with concurrent low back pain or psychological distress has changed over time.

This article presents data on the prevalence of neck, shoulder, arm pain, neck, shoulder, arm pain with concurrent low back pain, and neck, shoulder, arm pain with concurrent psychological distress, from the Stockholm Public Health Surveys that have been carried out every 4 years since 1990.

It has been hypothesized that the prevalence of musculoskeletal pain is increasing, but the evidence has been both sparse and equivocal. In contrast to an earlier study that found a 2 to 4 fold increase of pain in 2 surveys conducted 40 years apart, the results in the present article indicated a slight rise in the prevalence of neck, shoulder, arm pain, which may indicate a similar but weaker time trend.

A possible explanation for the increased rates of neck, shoulder, arm pain could be higher exposures in working life. However, both national and regional work environment surveys indicate that, broadly speaking, physical workload has been quite stable over time. In contrast, there are indications of increased problems with psychosocial factors. At the same time, it is generally acknowledged that mental or psychosocial demands have also increased outside the workplace. Altogether, the relative importance of exposures may to some extent have shifted from strenuous physical work to monotonous sedentary work and psychosocial factors. However, the total magnitude of exposure is still quite extensive and may contribute to maintaining or even increasing the prevalence of neck, shoulder, arm pain. There has also been discussion of whether a higher prevalence of pain is because of random fluctuations in answers to such questions or because general cultural influence has affected awareness and reporting of musculoskeletal symptoms.

Musculoskeletal symptoms in several areas of the body are common. It has been shown to be positively related to outcomes such as health care utilization, impaired work role functioning, and delayed return to work. The increased prevalence of neck, shoulder, arm pain with concurrent low back pain was similar compared to solely neck, shoulder, arm pain. This finding might be explained by shared pathology for the 2 body regions as well as common mechanical and psychological risk factors for pain or disorders.

The prevalence of neck, shoulder, arm pain with concurrent psychological distress was rather low. However, the prevalence increased about 2 fold over the 16 year period, and more for males than for females. It could be argued that the increase in prevalence is only because of an increased prevalence of psychological distress. However, national data from the Swedish Work Environment Authority, obtained by yearly interviews 1998-2008, show that the trends are similar for physical disorders compared with nonphysical disorders. Psychological factors and mental health problems have been described as being intimately associated with musculoskeletal pain. Several different explanations for the association between musculoskeletal pain and mental health have been proposed: first, that mental health problems either may cause pain or are expressed as pain; second, pain causes mental health problems; and third, psychiatric disorders such as depression may share common pathogenic mechanisms with pain. On the other hand, it is rather clear that the experience of pain interacts with psychological factors that influence emotion and behavior, and this in turn shapes the course of pain development. Consequently, the results in the present study are quite worrying.

At the beginning of the 2000s, mental health problems passed musculoskeletal disorders as the most common cause of sickness absence in the County of Stockholm, and in 2006 mental health problems became for the first time the most common cause of early retirement in Sweden. The media attention paid to this development may have contributed to an increased awareness (and acceptance?) of these conditions in the general population, and in turn influenced the willingness to report symptoms of psychological distress.

Finally, the results show that females have a higher prevalence of neck, shoulder, arm pain than males, which is in concordance with previous studies. Generally, the observed increases in prevalence of neck, shoulder, arm pain as well as concurrent conditions were similar among females and males. The gender gap did not seem to have changed over time.

From: Cephalalgia. 2009 Jun 8. [Epub ahead of print]

Spatial changes in pressure pain hypersensitivity are present throughout the cephalic region (temporalis muscle) in both chronic tension type headache and unilateral migraine. The aim of this study was to assess pressure pain sensitivity topographical maps on the trapezius muscle in 20 patients with chronic tension type headache and 20 with unilateral migraine in comparison with 20 healthy controls in a blind design. For this purpose, a pressure algometer was used to assess pressure pain thresholds over 11 points of the trapezius muscle: four points in the upper part of the muscle, two over the levator scapulae muscle, two in the middle part, and the remaining three points in the lower part of the muscle. Pressure pain sensitivity maps of both sides were depicted for patients and controls.

Chronic tension type headache patients showed generalized lower pressure pain thresholds levels compared with both migraine patients and controls. The migraine group had also lower pressure pain thresholds than healthy controls. The most sensitive location for the assessment of pressure pain thresholds was the neck portion of the upper trapezius muscle in both patient groups and healthy controls. Pressure pain thresholds was negatively related to some clinical pain features in both chronic tension type headache and unilateral migraine patients. Side-to-side differences were found in strictly unilateral migraine, but not in those subjects with bilateral pain, i.e. chronic tension type headache. These data support the influence of muscle hyperalgesia in both chronic tension type headache and unilateral migraine patients and point towards a general pressure pain hyperalgesia of neck and shoulder muscles in headache patients, particularly in chronic tension type headache.

From: BMC Musculoskelet Disord. 2009 Mar 2;10:28

Temporomandibular disorders are musculoskeletal pain conditions characterised by pain and dysfunction in the jaw-face muscles and/or the temporomandibular joint. Musculoskeletal pain conditions occurring at various locations may share pathophysiological mechanisms. Co-morbidity between temporomandibular disorders, headaches and neck/shoulder pain has been reported in temporomandibular disorders patient samples as well as in samples drawn from the general population. Low back pain, one of the most common pain conditions in humans, has been associated with other pains such as neck pain and headaches, which has been interpreted as a tendency for symptoms to cluster in some individuals. The source of these patterns is not known, but neurobiological sensitization processes, genetically determined vulnerability and psychological factors are commonly given as possible explanations. Results of a 3-year prospective study showed a significantly increased risk of developing a new pain condition with presence of a pain condition at baseline. A more recent prospective study based on patients with non-painful temporomandibular disorders indicated a dose-response relationship between the number of pain sites at baseline (head, back, chest, stomach) and the risk of onset of dysfunctional temporomandibular disorders pain among women. Frequency of headaches was found to have a dose-response relationship with occurrence of musculoskeletal symptoms (e.g. pain in neck, shoulders and low back) in a Norwegian population.

The authors have recently shown that patients with long-term spinal pain (neck, shoulder and/or low back) significantly more often have signs and symptoms of temporomandibular disorders than do matched controls. The associations remained statistically significant also after exclusion of those who reported jaw pain. It is not known whether co-morbidity between temporomandibular disorders and neck pain, shoulder pain and/or low back pain occurs within the whole range of variation in symptom frequency and severity. Most analyses in this field have involved dichotomized samples, not taking variations of symptom severity into consideration. The aim of the present study was to test whether a reciprocal dose-response relation exists between frequency and severity of neck pain, shoulder pain and/or low back pain and temporomandibular disorders. The authors tested the following null hypotheses:

1. Occurrence of frequent temporomandibular disorders symptoms and headaches does not differ significantly between study groups with varying frequency and severity of neck pain, shoulder pain and/or low back pain.

2. Presence of frequent neck pain, shoulder pain and/or low back pain does not differ significantly between study groups with varying frequency and severity of temporomandibular disorders symptoms.

The operational definition of ‘spinal pain’ was pain in the neck, shoulders and/or low back. Symptoms in the jaw-face region, head, neck, shoulder and low back regions were assessed by questionnaire. Presence of symptoms was stated for frequency (never; not now, but previously; once or twice a month; once or twice a week; several times a week; daily), duration (< 1 month; 1 month–1 year; 1–5 years; > 5 years) and intensity. The subjects were also asked to estimate the impact of jaw symptoms, headaches, neck-shoulder pain and low back pain on activities of daily living. Intensity and activities of daily living was assessed using the 11-point Numerical Rating Scale.

Presence and severity of temporomandibular disorders was evaluated for the separate symptoms and according to the Helkimo Anamnestic dysfunction Index. This classification grades the severity of symptoms in the jaw-face region into mild (i.e. temporomandibular joint sounds during opening and closing of the jaw and/or tiredness/stiffness in the jaws) or severe (i.e. pain, temporomandibular joint locking and/or difficulties in opening the mouth wide).

The present study showed a dose-response relation between frequency and severity of spinal pain and temporomandibular disorders. The pattern was evident in both directions, the prevalence of frequent temporomandibular disorders symptoms and headaches increasing with increasing frequency/severity of spinal pain, and the prevalence of frequent pain in the neck, shoulders and/or low back increasing with increasing frequency and severity of temporomandibular disorders symptoms. The test for trends showed significant dose-response associations in both directions. The two tested null hypotheses were therefore rejected.

The authors have previously shown that patients with long-term pain in the neck, shoulders and/or low back have a sevenfold risk of reporting pain and dysfunction in the jaw-face region and a fivefold risk of having clinical signs of temporomandibular disorders, compared with matched controls. This finding was recently supported in a cross-sectional analysis based on almost 30,000 adults in the USA, indicating a strong relationship between reported pain in the neck, shoulders and/or low back and jaw-face pain. The present study shows a stepwise positive correlation between severity of spinal pain and pain and dysfunction in the jaw-face region. This dose-response-like pattern should not be interpreted as a sign of exposure and outcome. However, it strengthens previous results of an association between temporomandibular disorders and spinal pain and may point to common underlying biological or psychological mechanisms. It should be emphasized that the results are derived from a cross-sectional study and do not show causality. Owing to the study design we have no information about the temporal sequence of the examined disorders, an essential element in assessing causality. Studies with a prospective design have indicated that presence of a pain condition increases the risk of contracting temporomadibular disorder pain. In a recent prospective study the risk for onset of facial pain, meeting research diagnostic criteria for temporomadibular disorders, was almost four times higher among adolescents with back pain at baseline, than among those without back pain. Papageorgiou et al. followed a cohort without low back pain at baseline and noted that musculoskeletal pain at other sites predicted future episodes of low back pain. These results are interesting, but so far there is no sufficient evidence to conclude that back pain precedes temporomandibular disorders, or vice versa. Psychological factors are often co-morbid with chronic pain conditions. The temporal sequence of pain and depression is however not clear. In a review addressing this question the majority of studies indicated that depression was a consequence rather than an antecedent of pain. Longitudinal studies on these issues are therefore warranted.

It has been suggested that generalized pain (i.e. fibromyalgia) is at one end of a continuum. Vierck presents temporomandibular pain as an example of a focal pain condition where the nociceptive sensory input may contribute to development of generalized hypersensitivity and related susceptibility to further load. In line with this hypothesis one experimental study reports signs of mechanical allodynia in the hindpaw following nociceptive stimuli applied to the masseter muscle of rats. Other experimental studies have shown that perceived muscle pain intensity and distribution is influenced by the stimulation rate (temporal summation) and the number of stimulated afferents (spatial summation). Temporal summation has been shown in temporomandibular disorders patients, as well as in other chronic pain conditions, suggesting a generalized hyperexcitability of the central nociceptive system. In a large population sample grouped with respect to frequency of reported headaches a dose-response pattern was demonstrated between headache frequency and 1-year prevalence of musculoskeletal symptoms (with locations including neck, shoulders, elbows, wrist/hands, chest/abdomen, upper back, low back, hips, knees, ankles/feet). The contribution of input from the craniofacial nervous system in spreading pain may therefore be of significance and more experimental and clinical studies are needed.

Recent studies have shown that genetic polymorphism, with influence on the metabolism of catecholamines, is highly associated with pain sensitivity and the risk for developing temporomandibular disorders. Central sensitization may be one possible explanation for co-morbidity between pain conditions at different locations, as well as presence of allodynia and hyperalgesia. Reflex connections between nociceptors and the fusimotor-muscle spindle system may also be involved in the pathophysiologic mechanisms related to pain and dysfunction.

The allocation of subjects in the present study to different pain in the neck, shoulders and/or low back groups was based on the participants’ reports of pain frequency in the questionnaire. For example, if a subject reported daily shoulder pain, but infrequent low back pain, the grouping was done according to the frequency of shoulder pain. Subjects who had been referred to a rehabilitation programme and who were on sick leave were considered to have more severe spinal pain than subjects with frequent pain but not on sick leave. Symptom description in self-report questionnaires may be a limitation in a strict dose-response discussion; however, frequency as well as intensity and duration of pain and dysfunction are important variables in health care seeking behaviour. Similarly, in this study, pain severity in the separate neck-shoulder pain and low back pain groups demonstrates stepwise increased mean values of reported pain intensity and impact on activities of daily living. In the sub-sample test with symptoms of temporomandibular disorders as independent variable, we included none of the patients from the rehabilitation center. The severity of the temporomandibular disorders symptoms is reflected by the reported interference of jaw symptoms with daily living. The formation of groups, aiming at discrete severity categories (dose), therefore seems valid also with regard to the mean intensity level and the impact of the symptoms on daily living.

The study shows a reciprocal positive dose-response pattern between frequency and severity of neck-shoulder pain and low back pain and temporomandibular disorders. The results indicate a strong co-morbidity between these two conditions, suggesting that they may share risk factors or that they may influence each other. The authors agree with the recently advocated view of a need for hypothesis-based studies on specific pain -pain co-morbidities, but also on pain-dysfunction co-morbidities. The present results are of significance for physicians and dentists, both of whom are expected to manage patients with pain and dysfunction. Collaboration as well as a costing system for cooperation in the diagnosis and management of the two conditions is warranted. Researchers of pain conditions should include the jaw-face region in their efforts to comprehend the pain patient’s case history.

From: Med Lav. 2009 Jan-Feb;100(1):29-34

Musculoskeletal disorders are a common problem among computer users. Many epidemiological studies have shown that ergonomic factors and aspects of work organization play an important role in the development of these disorders. The authors carried out a cross-sectional survey to estimate the prevalence of musculoskeletal symptoms among university students using personal computers and to investigate the features of occupational exposure and the prevalence of symptoms throughout the study course. Another objective was to assess the students’ level of knowledge of computer ergonomics and the relevant health risks.

A questionnaire was distributed to 183 students attending the lectures for second and fourth year courses of the Faculty of Architecture. Data concerning personal characteristics, ergonomic and organizational aspects of computer use, and the presence of musculoskeletal symptoms in the neck and upper limbs were collected. Exposure to risk factors such as daily duration of computer use, time spent at the computer without breaks, duration of mouse use and poor workstation ergonomics was significantly higher among students of the fourth year course.

Neck pain was the most commonly reported symptom (69%), followed by hand/wrist (53%), shoulder (49%) and arm (8%) pain. The prevalence of symptoms in the neck and hand/wrist area was signifcantly higher in the students of the fourth year course. In this survey we found high prevalence of musculoskeletal symptoms among university students using computers for long time periods on a daily basis. Exposure to computer related ergonomic and organizational risk factors, and the prevalence of musculoskeletal symptoms both seem to increase significantly throughout the study course. Furthermore, they found that the level of perception of computer related health risks among the students was low. Our findings suggest the need for preventive intervention consisting of education in computer ergonomics.

From: Spine. 2009 Feb 15;34(4):413-8

Musculoskeletal disorders are one of the important health problems in the world. With the exception of back pain, neck and shoulder pain is one of the prevalent disorders in workplaces and a common reason for abseentism, job change, and disability pension.

The incidence and prevalence of neck and shoulder pain have a broad range in different studies, depending on which data collection method is used (self-reported questionnaire, medical examination, sickness absence). Neck and shoulder pain is a dynamic entity that can change over time, but few longitudinal studies have been performed on workplace populations to address the above-mentioned issues.

The relation between neck and shoulder pain and physical as well as psychosocial factors at work have been studied and approved (with different consistency) in different surveys. Most of these studies are cross-sectional and related to high-income and industrialized countries. There is little information about neck and shoulder pain in the general population in developing and low-income countries. There are even fewer studies in working populations.

The main aim of this longitudinal investigation was to determine the incidence of sick leave because of neck and shoulder pain in a large population of Iranian workers, and to study its relation with physical and psychosocial factors at work, lifestyle, and previous pain. An additional aim was to compare risk factors for future sick leave versus risk factors for self-reported neck and shoulder pain in the cross-sectional baseline study.

Our study shows an extremely low incidence of neck and shoulder pain compared with previous studies. A limited number of longitudinal studies on the incidence of neck and shoulder pain have been conducted in high-income countries. However, to our knowledge there are no such studies from middle or low income countries. In this study, we used sickness absence because of neck and shoulder pain as our outcome.

There are several difficulties when trying to compare studies on sickness absence, since not only the study design but also outcome measures, terminology, and insurance systems (among nations as well as over time) differ widely.

In the literature, there are different views on the importance of self-reported symptoms. One view emphasizes the progression of these disorders from development of symptoms, followed by reporting symptoms and seeking health care, and then finally the need for sick leave and resulting disability. Health outcomes such as symptoms, care-seeking, and sick leave overlap, but give different windows of the magnitude of the problem. In addition to the severity of a disorder, care-seeking is probably influenced by family situation and occupation, as well as activities during leisure time and in society.

IKCo has a young population of employees; the average age at baseline in 2003 was 29.6 years. All employees undergo a pre-employment medical examination and there are some restrictions regarding the employment of people with certain diseases. Our study population is a young selected group of probably very healthy workers, which of course, might influence the incidence of sick leave. Job insecurity could be another important factor. Iran is a country with a high rate of unemployment and people are very keen to keep their jobs, which might also affect the incidence of sick leave.

According to insurance legislation in Iran, sickness benefit is payable in cases of disease, or injuries, that reduce work capacity. For 3 days or less, a general medical certificate (from within or outside the insurance system) may be accepted by the company or any other insurance system. In cases of sickness absence lasting more than 3 days, medical certificates must be confirmed by physicians who are approved by the insurance system. For long-term sickness absence (>60 days), sickness benefit is payable based on a confirmation of diagnosis by the expert medical board at the insurance organization. Sickness benefit is payable by the insurance organization from the first day of accident and the fourth day of disease. The insurance system pays 70% of the salary but it does not include overtime. Most workers in industries have overtime and they are dependent on this part of the salary.

In Iran, there is no time limit for sickness benefit payment, and it will continue as long as the insurance organization expert committee approves it. In severe cases where employees have partially or completely lost their work ability, this committee will give them partial or complete disability pension. There is no part-time sickness absence and benefit in Iran.

Low incidence and high prevalence give rise to the theory that maybe most workers continue to work regardless of pain and disability. Such behavior has been reported from different countries, among both sexes, and for various illnesses. Working when ill referred to as presenteeism or sickness attendance has been reported for LBP and neck and shoulder pain. Studies show that presenteeism is most common among professionals, e.g., physicians and nurses, whose work ethic of commitment and responsibility to serve others may be considered more important than their own needs. Sickness presenteeism has also been observed in organizations where the absent employee cannot be easily replaced; thus sick leave causes negative consequences for the absentee, workmates or a third party. Financial loss, accumulated work tasks and job security could also be main reasons. A study by Hansson et al shows that reporting sick is neither undertaken lightly nor for short-term reasons only. Instead, personal history and anticipated spine-related pain in the future, as well as workplace and labor market factors, are also important considerations.

Although most studies show that recurrence of neck and shoulder pain is common, our study only has 6 cases with more than 1 episode of neck and shoulder pain during the 4-year follow-up. One possible explanation for this contradictory result might be that most employees in our cohort continue doing their job despite having pain.

We have no information about the care-seeking behavior of employees who suffer pain but are not sick-listed. Such information could perhaps help to increase our knowledge of health behavior and reasons for sick-listing.

The low incidence of neck and shoulder pain becomes more complex when we compare it with incidence of low back pain in the same cohort. Although the prevalence of neck/shoulder and back pain were similar at baseline, the 1-year incidence of low back pain was 20 times higher than the incidence of neck and shoulder pain. This gives rise to the hypothesis that there are different health behaviors and norms for different musculoskeletal disorders.

Sick leave in a certain country depends not only on individual health behavior; it can also be affected by the approval of physicians and the insurance system. It seems that physicians in Iran easily agree to approve low back pain on the basis of patient reports alone, as compared with neck and shoulder pain, where different tests are recommended and requested before a final decision is made.

The participation rate in the baseline study was high (79.8%) but the difference in incidence between participants and nonparticipants in the follow-up study is considerable (0.8% compared with 4.2%). Reports from the human resource department revealed no obvious differences in demographic or workplace factors between participants and nonparticipants. A severe bias can be introduced in studies with a low response rate. At least in this study, healthy workers were more likely to participate.

neck and shoulder pain and disorders are more prevalent among women compared with men. Cassou et al showed that prevalence and incidence of neck and shoulder pain were twice as high in women as in men. In our study, women reported neck and shoulder pain 2 times more than men in the baseline survey, but only 4 sick-listed cases were detected in the follow-up study. At IKCo, women work as office workers and technicians, and as a whole there are low sick leave rates in these jobs.

Pain in the neck or shoulder in the baseline study was a significant factor for being on sick leave because of neck/shoulder pain. This is more significant for having disabling pain compared with nondisabling pain. Although the number of cases is small (i.e., there is a wide confidence interval), this significance is rather interesting.

With regard to the questions we asked in the baseline study about pain in different regions of extremities, our analysis (not included in this paper) shows that having pain in these regions of upper limbs, including the elbow and wrist, does not constitute a risk factor for neck and shoulder pain sick leave.

As far as low back pain is concerned, studies show that workers with low back pain and concurrent musculoskeletal complaints from another anatomic region (including spinal comorbidity) are more likely to remain sick-listed than subjects with solely low back pain. On the other hand, Ijzelenberg et al did not find that concurrent low back pain and neck and shoulder pain increased the risk of sickness absence.

In a study by Bergstrom et al, the most consistent risk factors for new episodes of sick leave because of neck or back pain found during 2 periods of follow-up (18 months and 3 years) were blue-collar work and several earlier episodes of neck or back pain assessed at baseline. In this study we did not find any significant relation between previous back pain and the risk of future sick leave because of neck and shoulder pain.

The results of our study on comorbidity in sick leave cases show that comorbidity is more prevalent in sick leave cases because of neck and shoulder pain (e.g., high rate of depression, previous sickness absence and spine pain, demands for changing jobs) than in other employees, although further studies are required to improve this hypothesis.

During the 4-year follow-up, 2200 employees left the company. The main reason for this in more than 80% of the cases was retirement. In Iran, all employees who have 30 years of work experience or are above the age of 60, can retire. Among industrial workers, this duration was 25 years at the start of the study period. In accordance with new rules that were approved by the government during our study period, all employees with more than 20 years of hard physical work experience (based on a national expert committee’s definitions) could also retire. For this reason, a large number of workers retired during the 4 years. A small number of employees left the company and transferred to other plants outside IKCo. It is logical to assume that those who left the company, taken as a whole, were older than other participants, and this may affect the incidence of sick leave.

In the baseline study, age and work experience were risk factors for self-reported neck and shoulder pain but there was no significant relation with sick leave; with considering the total number of employees and the number of retired employees it cannot describe the reason or at least the main reason for the low incidence.

In the baseline study, several physical and psychosocial risk factors at work for neck and shoulder pain were found. In this study of sick leave, repetitive work, sitting position at work, and unattractive work were the only factors that influenced the outcome and remained as risk factors.

Different studies have shown relations between physical and psychosocial factors at work, and both incidence and prevalence of neck and shoulder pain. In 1 review, the risk factors for sick leave because of neck and shoulder pain were shown to be poor social support and low decision latitude over work content and organizational factors. Former studies have also shown that there is a difference between these factors in self-reported pain and sickness absence because of pain. Our study is also in line with these reports.

In this study we only measured risk factors at the beginning of the project in 2003. IKCo is a large company with its special characteristics. Compared with other companies in Iran, it is more stable and prestigious; nevertheless, like most companies IKCo undergoes different changes such as reorganization, downsizing and outsourcing programs that affect physical and psychosocial work factors. The exposures for the specific individuals may have changed and may thereby bias the results. Repeated measurement of exposures is one possible way of helping to identify this dynamic pattern and its influence on the outcome.

IKCo is a company with various jobs, including specialists, technicians, office workers, and unskilled workers, but there is no guarantee that it is representative of other industries and populations of Iranian workers.