Somatosensory attentional modulations during pain-related movement execution.

Pain serves to protect against bodily threat, and therefore initiates protective responses such as attending toward threat-relevant information. Since pain is often exacerbated by executing movements, these motor actions may serve as cues for pain. Up to date, however, pain-related attention during movement remains largely unexplored. While it has been shown that the preparation of a pain-related movement leads to enhanced processing of somatosensory information, it is unclear how the actual execution of a movement interacts with somatosensory attention. In the current study, we examined whether somatosensory processing is enhanced at a moving body part when the movement is expected to be associated with pain. Participants were asked to execute hand movements which were occasionally followed by a pain stimulus. To measure somatosensory attention, a task-irrelevant, innocuous tactile probe was presented on either hand to evoke a somatosensory evoked potential (SEP). The results showed an elevation of the N120 SEP at the hand performing a potentially painful movement, indicating heightened attention toward tactile information at the threatened moving hand compared to the non-threatened hand. Additionally, the P200 SEP also showed enlarged responses when performing a pain-related movement compared to a no-pain-related movement. These results show that not only the anticipation, but also the execution of pain-related movements, may modulate the processing of somatosensory input, driven by attentional processes.

Do sociodemographic features, pain sensitivity or pain catastrophizing relate to clinic-based adherence to physiotherapy in people suffering from chronic spinal pain? Secondary analysis of a randomized clinical trial.

PURPOSE: Examining whether socio-demographic variables, pain or functionality are related to the degree of clinic-based therapy adherence in patients suffering from nonspecific chronic spinal pain (nCSP). DESIGN: Secondary analysis of a randomized clinical trial. SETTING: University hospital of Ghent and Brussels. METHODS: Dutch speakers, 18-65 years old, experiencing nCSP for at least 3 months. 120 participants were randomly allocated to two interventional groups, of which 94 completed all therapy sessions. MAIN OUTCOME MEASURES: Degree of clinic-based adherence, defined as the amount of completed therapy sessions. RESULTS: Demographic data (sex, age or education) were not significantly associated with adherence in the total sample or the neuroscience group. For the traditional physiotherapy group, educational level was associated with attendance of at least 50% of the therapy sessions. Regarding pain-, belief- and function-related measures, only the association between change in kinesiophobia and adherence was significant for the traditional physiotherapy group. CONCLUSIONS: Factors related to therapy adherence in the total group or the neuroscience group could not be found. Educational level and change in kinesiophobia were however related to therapy adherence in the traditional physiotherapy group.

Evaluating abdominal core muscle fatigue: Assessment of the validity and reliability of the prone bridging test.

The aims of this study were to research the amplitude and median frequency characteristics of selected abdominal, back, and hip muscles of healthy subjects during a prone bridging endurance test, based on surface electromyography (sEMG), (a) to determine if the prone bridging test is a valid field test to measure abdominal muscle fatigue, and (b) to evaluate if the current method of administrating the prone bridging test is reliable. Thirty healthy subjects participated in this experiment. The sEMG activity of seven abdominal, back, and hip muscles was bilaterally measured. Normalized median frequencies were computed from the EMG power spectra. The prone bridging tests were repeated on separate days to evaluate inter and intratester reliability. Significant differences in normalized median frequency slope (NMFslope ) values between several abdominal, back, and hip muscles could be demonstrated. Moderate-to-high correlation coefficients were shown between NMFslope values and endurance time. Multiple backward linear regression revealed that the test endurance time could only be significantly predicted by the NMFslope of the rectus abdominis. Statistical analysis showed excellent reliability (ICC=0.87-0.89). The findings of this study support the validity and reliability of the prone bridging test for evaluating abdominal muscle fatigue.

Does muscle morphology change in chronic neck pain patients? - A systematic review.

BACKGROUND: Neck pain is a common disabling worldwide health problem with a high socio-economic burden. Changes underlying the transition to, or the maintenance of a chronic state are still barely understood. Increasing evidence suggests that morphological muscle changes, including changes in cross-sectional area (CSA) or fatty infiltration, play a role in chronic neck pain. However, a structured overview of the current evidence of morphological changes is lacking. OBJECTIVE: To systematically review the morphological muscle changes in patients with chronic neck pain, including those with whiplash-associated disorders (WAD) and chronic idiopathic neck pain. STUDY DESIGN & METHODS: A systematic review using the PRISMA-guidelines. RESULTS: Fourteen of 395 papers were included after extensive screening. Most studies were of moderate methodological quality. A higher CSA was found in all flexor muscles in both patients with WAD and patients with chronic idiopathic neck pain, except for the deeper flexor muscles in patients with chronic idiopathic neck pain. The cervical extensor muscles show an increased CSA at the highest cervical segments in patients with WAD, while most studies in patients with chronic idiopathic neck pain report a decreased CSA in all extensor muscles. Fatty infiltration, which could be accountable for an increased CSA, of both cervical extensors and flexors seems to occur only in patients with WAD. CONCLUSION: Some evidence is available for changes in muscle morphology, however more high quality prospective and cross-sectional research is needed to confirm these changes and to identify potential underlying causes that need yet to be discovered.

Identifying prognostic factors predicting outcome in patients with chronic neck pain after multimodal treatment: A retrospective study.

OBJECTIVES: This study was conducted to identify possible prognostic factors to predict drop-out and favorable outcome in patients following a multimodal treatment program at an outpatient rehabilitation clinic. METHODS: A retrospective cohort study was conducted on 437 patients with chronic neck pain involved in an exercise-based rehabilitation program of an outpatient rehabilitation center between January 2008 and November 2011. Prognostic factors were analyzed through a univariate and a multivariate logistic regression analysis. RESULTS: Multivariate logistic regression revealed that a higher age (OR=0.960), presence of headache (OR=0.436) or low back pain (OR=0.525), and having low levels of depression (OR=1.044) increase the odds to complete the multimodal treatment program. A high NDI-score (OR=0.945), a high NRS-score for pain in the upper extremities (OR=0.862), a low NRS score for pain in the neck (OR=1.372), and a trauma in the patient's history (OR=0.411) decrease the odds of having a favorable outcome after the given treatment program. CONCLUSION: It is important to assess these prognostic factors as they may help therapists to identify patients with a good prognosis or patients at risk. For those at risk, this would allow the treatment approach to be redirected to address their specific needs.

Articular dysfunction patterns in patients with mechanical low back pain: A clinical algorithm to guide specific mobilization and manipulation techniques.

Recent systematic reviews have demonstrated reasonable evidence that lumbar mobilization and manipulation techniques are beneficial. However, knowledge on optimal techniques and doses, and its clinical reasoning is currently lacking. To address this, a clinical algorithm is presented so as to guide therapists in their clinical reasoning to identify patients who are likely to respond to lumbar mobilization and/or manipulation and to direct appropriate technique selection. Key features in subjective and clinical examination suggestive of mechanical nociceptive pain probably arising from articular structures, can categorize patients into distinct articular dysfunction patterns. Based on these patterns, specific mobilization and manipulation techniques are suggested. This clinical algorithm is merely based on empirical clinical expertise and complemented through knowledge exchange between international colleagues. The added value of the proposed articular dysfunction patterns should be considered within a broader perspective.

Muscle functional MRI analysis of trunk muscle recruitment during extension exercises in asymptomatic individuals.

The present study examined the activity levels of the thoracic and lumbar extensor muscles during different extension exercise modalities in healthy individuals. Therefore, 14 subjects performed four different types of extension exercises in prone position: dynamic trunk extension, dynamic-static trunk extension, dynamic leg extension, and dynamic-static leg extension. Pre- and post-exercise muscle functional magnetic resonance imaging scans from the latissimus dorsi, the thoracic and lumbar parts of the longissimus, iliocostalis, and multifidus were performed. Differences in water relaxation values (T2-relaxation) before and after exercise were calculated (T2-shift) as a measure of muscle activity and compared between extension modalities. Linear mixed-model analysis revealed higher lumbar extensor activity during trunk extension compared with leg extension (T2-shift of 5.01 ms and 3.55 ms, respectively) and during the dynamic-static exercise performance compared with the dynamic exercise performance (T2-shift of 4.77 ms and 3.55 ms, respectively). No significant differences in the thoracic extensor activity between the exercises could be demonstrated. During all extension exercises, the latissimus dorsi was the least activated compared with the paraspinal muscles. While all extension exercises are equivalent effective to train the thoracic muscles, trunk extension exercises performed in a dynamic-static way are the most appropriate to enhance lumbar muscle strength.

The functional coupling of the deep abdominal and paraspinal muscles: the effects of simulated paraspinal muscle contraction on force transfer to the middle and posterior layer of the thoracolumbar fascia.

The thoracolumbar fascia (TLF) consists of aponeurotic and fascial layers that interweave the paraspinal and abdominal muscles into a complex matrix stabilizing the lumbosacral spine. To better understand low back pain, it is essential to appreciate how these muscles cooperate to influence lumbopelvic stability. This study tested the following hypotheses: (i) pressure within the TLF's paraspinal muscular compartment (PMC) alters load transfer between the TLF's posterior and middle layers (PLF and MLF); and (ii) with increased tension of the common tendon of the transversus abdominis (CTrA) and internal oblique muscles and incremental PMC pressure, fascial tension is primarily transferred to the PLF. In cadaveric axial sections, paraspinal muscles were replaced with inflatable tubes to simulate paraspinal muscle contraction. At each inflation increment, tension was created in the CTrA to simulate contraction of the deep abdominal muscles. Fluoroscopic images and load cells captured changes in the size, shape and tension of the PMC due to inflation, with and without tension to the CTrA. In the absence of PMC pressure, increasing tension on the CTrA resulted in anterior and lateral movement of the PMC. PMC inflation in the absence of tension to the CTrA resulted in a small increase in the PMC perimeter and a larger posterior displacement. Combining PMC inflation and tension to the CTrA resulted in an incremental increase in PLF tension without significantly altering tension in the MLF. Paraspinal muscle contraction leads to posterior displacement of the PLF. When expansion is combined with abdominal muscle contraction, the CTrA and internal oblique transfers tension almost exclusively to the PLF, thereby girdling the paraspinal muscles. The lateral border of the PMC is restrained from displacement to maintain integrity. Posterior movement of the PMC represents an increase of the PLF extension moment arm. Dysfunctional paraspinal muscles would reduce the posterior displacement of the PLF and increase the compliance of the lateral border. The resulting change in PMC geometry could diminish any effects of increased tension of the CTrA. This study reveals a co-dependent mechanism involving balanced tension between deep abdominal and lumbar spinal muscles, which are linked through the aponeurotic components of the TLF. This implies the existence of a point of equal tension between the paraspinal muscles and the transversus abdominis and internal oblique muscles, acting through the CTrA.

The sacroiliac joint: an overview of its anatomy, function and potential clinical implications.

This article focuses on the (functional) anatomy and biomechanics of the pelvic girdle and specifically the sacroiliac joints (SIJs). The SIJs are essential for effective load transfer between the spine and legs. The sacrum, pelvis and spine, and the connections to the arms, legs and head, are functionally interrelated through muscular, fascial and ligamentous interconnections. A historical overview is presented on pelvic and especially SIJ research, followed by a general functional anatomical overview of the pelvis. In specific sections, the development and maturation of the SIJ is discussed, and a description of the bony anatomy and sexual morphism of the pelvis and SIJ is debated. The literature on the SIJ ligaments and innervation is discussed, followed by a section on the pathology of the SIJ. Pelvic movement studies are investigated and biomechanical models for SIJ stability analyzed, including examples of insufficient versus excessive sacroiliac force closure.

The thoracolumbar fascia: anatomy, function and clinical considerations.

In this overview, new and existent material on the organization and composition of the thoracolumbar fascia (TLF) will be evaluated in respect to its anatomy, innervation biomechanics and clinical relevance. The integration of the passive connective tissues of the TLF and active muscular structures surrounding this structure are discussed, and the relevance of their mutual interactions in relation to low back and pelvic pain reviewed. The TLF is a girdling structure consisting of several aponeurotic and fascial layers that separates the paraspinal muscles from the muscles of the posterior abdominal wall. The superficial lamina of the posterior layer of the TLF (PLF) is dominated by the aponeuroses of the latissimus dorsi and the serratus posterior inferior. The deeper lamina of the PLF forms an encapsulating retinacular sheath around the paraspinal muscles. The middle layer of the TLF (MLF) appears to derive from an intermuscular septum that developmentally separates the epaxial from the hypaxial musculature. This septum forms during the fifth and sixth weeks of gestation. The paraspinal retinacular sheath (PRS) is in a key position to act as a 'hydraulic amplifier', assisting the paraspinal muscles in supporting the lumbosacral spine. This sheath forms a lumbar interfascial triangle (LIFT) with the MLF and PLF. Along the lateral border of the PRS, a raphe forms where the sheath meets the aponeurosis of the transversus abdominis. This lateral raphe is a thickened complex of dense connective tissue marked by the presence of the LIFT, and represents the junction of the hypaxial myofascial compartment (the abdominal muscles) with the paraspinal sheath of the epaxial muscles. The lateral raphe is in a position to distribute tension from the surrounding hypaxial and extremity muscles into the layers of the TLF. At the base of the lumbar spine all of the layers of the TLF fuse together into a thick composite that attaches firmly to the posterior superior iliac spine and the sacrotuberous ligament. This thoracolumbar composite (TLC) is in a position to assist in maintaining the integrity of the lower lumbar spine and the sacroiliac joint. The three-dimensional structure of the TLF and its caudally positioned composite will be analyzed in light of recent studies concerning the cellular organization of fascia, as well as its innervation. Finally, the concept of a TLC will be used to reassess biomechanical models of lumbopelvic stability, static posture and movement.

Changes in microcirculation of the trapezius muscle during a prolonged computer task.

The aim of this study is to investigate if there is a change in oxygen saturation and blood flow in the different parts of the trapezius muscle in office workers with and without trapezius myalgia during a standardized computer task. Twenty right-handed office workers participated; ten were recruited based on pain in the trapezius and ten as matching controls. Subjects performed a combination of typing and mousing tasks for 60 min at a standardized workstation. Muscle tissue oxygenation and blood flow data were collected from the upper trapezius (UT), the middle trapezius (MT) and the lower trapezius (LT), both on the left and right side at seven moments (at baseline and every tenth minute during the 1-h typing task) by use of the oxygen to see device. In all three parts of the trapezius muscle, the oxygen saturation and blood flow decreased significantly over time in a similar pattern (p < 0.001). Oxygenation of the left and right UT was significantly higher compared to the other muscle parts (p < 0.001). Oxygen saturation for the MT was significantly lower in the cases compared to the control group (p = 0.027). Blood flow of the UT on the right side was significantly lower than the blood flow on the left side (p = 0.026). The main finding of this study was that 1 h of combined workstation tasks resulted in decreased oxygen saturation and blood flow in all three parts of the trapezius muscle. Future research should focus on the influence of intervention strategies on these parameters.

Functional reorganization of cervical flexor activity because of induced muscle pain evaluated by muscle functional magnetic resonance imaging.

There is mounting evidence of an association between chronic neck pain and impaired cervical flexor muscle performance. It is likely that the deep cervical flexors demonstrate changes very early after the onset of pain, but evidence is currently lacking. This study investigated the effect of experimental neck muscle pain on the activation of the cervical flexor muscles during the performance of craniocervical flexion (CCF) by use of muscle functional magnetic resonance imaging. Activity of the longus colli (Lco), longus capitis (Lca) and sternocleidomastoid (SCM) muscles were investigated bilaterally and at three cervical levels (C0-C1, C2-C3 and C6-C7) in 14 healthy subjects. Measurements were performed at rest and after the performance of CCF without and with induced pain of the upper trapezius (intramuscular injection of hypertonic saline). In the non-pain condition, the Lca (p = 0.005) and Lco (p = 0.029) were significantly more active during CCF compared to SCM. In the pain condition, the activity of the Lco and Lca was reduced bilaterally and at multiple levels (p ≤ 0.009), whereas the left SCM showed increased activity at only the C6-C7 level (p ≤ 0.001). The results suggest that local excitation of nociceptive afferents causes an immediate reorganization of the cervical flexor muscle activity similar to that identified in clinical populations.

The effect of unilateral muscle pain on recruitment of the lumbar multifidus during automatic contraction. An experimental pain study.

Changes in control of the multifidus muscle are a likely contributor to low back pain (LBP), however, the underlying mechanisms of these changes are not well understood. To date it remains uncertain if pain has a selective effect on the multifidus muscles, in line with the observations of the selective changes in structure in acute LBP, or a more generalized effect. The objective of this study is to help to elucidate whether acute unilateral muscle pain alters the activation of the multifidus specific at the level and side of the pain or has a more widespread effect. An experimental pain protocol using hypertonic saline was applied to induce unilateral low back muscle pain. Automatic activity of the multifidus muscle during arm lifts was evaluated with dynamic ultrasound measurement, by assessing muscle thickness change during contraction. Multifidus activity of 15 healthy subjects was compared in a non-pain and in a pain condition, at different spinal levels (L3-L4-L5) and at both body sides. Unilateral induced pain at one segmental level reduced muscle thickness increase during contraction, at both body sides and at different lumbar levels. These results do suggest that unilateral pain may have a more widespread effect on multifidus muscle recruitment, affecting the left and right muscles, at different lumbar levels.

MRI analysis of muscle/fat index of the superficial and deep neck muscles in an asymptomatic cohort.

All muscles of the neck have a role in motion and postural control of the cervical region. The aim of this study was to investigate the difference in muscle/fat index between (1) cervical flexors and extensors and (2) deep and superficial neck muscles. Twenty-six healthy subjects participated in the study. Magnetic resonance imaging (MRI) was used to quantify muscle fat indices in different cervical flexor and extensor muscles at the C4-C5 level. Overall, the ventral muscles had a significantly lower fat content compared with the dorsal muscles (P < or = 0.001). For the cervical extensors, significant differences between the muscle/fat index of the deep and superficial muscles were found (P < or = 0.001). For the cervical flexors, there were no significant differences between the different muscles. The higher fat content in the dorsal muscles can be explained by a discrepancy in function between the spine extensors and flexors, reflected in a different muscle fiber distribution. The rather small differences between superficial and deep neck muscles are in line with recent findings that have demonstrated that both muscles groups exhibit phasic activity during isometric muscles contractions and the presumption that there is no difference in fiber type distribution between superficial and deep neck muscles.

Does soccer participation lead to genu varum?

Little is known about the relationship between sport participation and body adaptations during growth. Our aim was to investigate whether soccer participation in youth is associated with the degree of genu varum. The design was a retrospective cohort study. Three hundred and thirty-six male soccer players, and 458 male non-soccer players (aged from 8 to 18) were recruited and included in the study. The intercondylar (IC) or intermalleolar (IM) distance were clinically measured with a specifically designed instrument. The results of this study revealed a statistically significant increase in degree of genu varum in both groups from the age of 14. However, at the age of 16-18 years a significant higher degree of genu varum was observed in the soccer players compared to the non-soccer players (P = 0.028). Intense soccer participation increases the degree of genu varum in males from the age of 16. Since genu varum predisposes to injuries, efforts to reduce the development of genu varum in male soccer players are warranted.

Individual and work related risk factors for neck pain among office workers: a cross sectional study.

Work related neck disorders are common problems in office workers, especially among those who are intensive computer users. It is generally agreed that the etiology of work related neck disorders is multidimensional which is associated with, and influenced by, a complex array of individual, physical and psychosocial factors. The aim of the current study was to estimate the one-year prevalence of neck pain among office workers and to determine which physical, psychological and individual factors are associated with these prevalences. Five hundred and twelve office workers were studied. Information was collected by an online questionnaire. Self-reported neck pain during the preceding 12 months was regarded as a dependent variable, whereas different individual, work-related physical and psychosocial factors were studied as independent variables. The 12 month prevalences of neck pain in office workers was 45.5%. Multivariate analysis revealed that women had an almost two-fold risk compared with men (OR = 1.95, 95% CI 1.22-3.13). The odds ratio for age indicates that persons older than 30 years have 2.61 times more chance of having neck pain than younger individuals (OR = 2.61, 95% CI 1.32-3.47). Being physically active decreases the likelihood of having neck pain (OR = 1.85, 95% CI 1.14-2.99). Significant associations were found between neck pain and often holding the neck in a forward bent posture for a prolonged time (OR = 2.01, 95% CI 1.20-3.38), often sitting for a prolonged time (OR = 2.06, 95% CI 1.17-3.62) and often making the same movements per minute (OR = 1.63, 95% CI 1.02-2.60). Mental tiredness at the end of the workday (OR = 2.05, 95% CI 1.29-3.26) and shortage of personnel (OR = 1.71, 95% CI 1.06-2.76) are significantly associated with neck pain. The results of this study indicate that physical and psychosocial work factors, as well as individual variables, are associated with the frequency of neck pain. These association patterns suggest also opportunities for intervention strategies in order to stimulate an ergonomic work place setting and increase a positive psychosocial work environment.