An overview of offset analgesia and the comparison with conditioned pain modulation : a systematic literature review

Background: Offset analgesia (OA) is an increasingly described phenomenon to measure endogenous pain inhibition, in which a greater decrease in pain intensity is experienced than would be predicted by the decrease in painful stimulation. The temporal filtering in this OA phenomenon differs from the spatial filtering in the commonly described conditioned pain modulation (CPM). Yet, the knowledge on the efficacy of OA in chronic pain patients is scarce, compared to CPM efficacy. Objective: This systematic review has been conducted to provide an overview of the current knowledge regarding OA, and to compare it to CPM. Study Design: A systematic review of research studies that investigated the application or mechanisms of OA. Setting: The present study took place at Ghent University and the University of Antwerp. Methods: This systematic review follows the PRISMA guidelines. The electronic databases Pubmed and Web of Science were searched in January 2015. Full text clinical reports addressing OA were included. The checklists for randomized controlled trials, case-control studies, and cohort-studies provided by the Dutch Institute for Healthcare Improvement and the Dutch Cochrane Centre were used to assess methodological quality. The articles received a level of evidence A1, A2, B, C, or D, based on study design and risk of bias. These levels were used to determine the strength of conclusion (level 1 to 4). Results: Seventeen articles met the inclusion criteria. Sixteen studies used quantitative sensory testing to provoke OA; however, differences in protocols are present. OA can function as a non-opioid mediated assessment tool for endogenous pain inhibition, and activates brain regions such as periaqueductal gray (PAG), dorsolateral prefontral cortex, insula, medulla, pons and cerebellum, indicating strong brain derived pain modulation. The primary somatosensory cortex is, conversely, less activated during OA. OA is decreased in neuropathic patients. Nonetheless, evidence for the influence of individual factors on OA is limited. OA and CPM seem to rely on different mechanisms. Limitations: Search strategy was taken wide, wherefore a large variety of research perspectives were included. Conclusions: This systematic review displays OA as a temporal filtering mechanisms that is more brain-derived compared to the spatial assessment method CPM. There is strong evidence for reduced OA in neuropathic patients, however, evidence regarding OA in (sub) acute and central sensitization patients, and the influence of personal factors on OA is currently scarce and needs further investigation

Inventory of personal factors influencing conditioned pain modulation in healthy people: a systematic literature review

Background: Conditioned pain modulation (CPM) is believed to play an important role in the development and exacerbation of chronic pain, because dysfunction of CPM is associated with a shift in balance between pain facilitation and pain inhibition. In many patients with central sensitization, CPM is less efficacious. Besides that, efficacy of CPM is highly variable in healthy people. Consequently, it seems that several individual variables may influence CPM. A systematic review examining personal factors influencing CPM was conducted. Methods: This systematic review follows the PRISMA guidelines. Pubmed and Web of Science were searched using different synonyms of CPM. Full-text clinical reports addressing the influence of personal factors on CPM in healthy adults were included. Checklists for RCTs and case-control studies provided by the Dutch Institute for Healthcare Improvement (CBO) and the Dutch Cochrane Centre were utilized to assess methodological quality. Levels of evidence and strength of conclusion were assigned using the CBO guidelines. Results: Forty-six articles were identified that reported the influence of personal factors on CPM. Quality assessment revealed 10 studies with a methodological quality less than 50% wherefore they were excluded (21.8%), resulting in a general total methodological quality score of 72.5%. Overall younger adult age, male gender, ovulatory phase, positive expectations, attention to the conditioning stimulus, and carrier of the 5-HTTLPR long allele result in better CPM. Conclusion: It is advised for future studies to take these factors into account. Further research regarding the influence of oral contraceptives, catastrophizing, information about conditioning stimulation, distraction, physical activity, and genetics on CPM magnitude is required

Foci of segmentally contracted sarcomeres in trapezius muscle biopsy specimens in myalgic and nonmyalgic human subjects : preliminary results

Objective The myofascial trigger point hypothesis postulates that there are small foci of contracted sarcomeres in resting skeletal muscle. Only one example, in canine muscle, has been published previously. This study evaluated human muscle biopsies for foci of contracted sarcomeres. Setting The Departments of Rehabilitation Sciences and Physiotherapy at Ghent University, Ghent, Belgium. Subjects Biopsies from 28 women with or without trapezius myalgia were evaluated, 14 in each group. Methods Muscle biopsies were obtained from regions of taut bands in the trapezius muscle and processed for light and electron microscopy and for histochemical analysis. Examination of the biopsies was blinded as to group. Results A small number of foci of segmentally contracted sarcomeres were identified. One fusiform segmental locus involved the entire muscle fiber in tissue from a myalgic subject. Several transition zones from normal to contracted sarcomeres were found in both myalgic and nonmyalgic subjects. The distance between Z-lines in contracted sarcomeres was about 25–45% of the same distance in normal sarcomeres. Z-lines were disrupted and smeared in the contracted sarcomeres. Conclusions A small number of foci of segmentally contracted sarcomeres were found in relaxed trapezius muscle in human subjects, a confirmation of the only other example of spontaneous segmental contraction of sarcomeres (in a canine muscle specimen), consistent with the hypothesis of trigger point formation and with the presence of trigger point end plate noise

Evidence for exercise training in autonomic function modulation in patients with chronic obstructive pulmonary disease (COPD) : a systematic review

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The Effects of Aerobic Exercise in Patients with Early-Onset Dementia: A Scoping Review

BACKGROUND: Early-onset dementia (EOD) defines all dementia related conditions with an onset before the age of 65 years. EOD places a large and distressing psychological, emotional and financial burden on the individuals themselves and their caregivers. For various reasons, diagnostic and treatment strategies for EOD are very challenging. There is a general agreement that not only the human body but also the mind benefits from physical activity and/or exercise. Especially aerobic exercise has shown to have favorable effects on cognitive functions in healthy older adults, as well as in patients with MCI and dementia. However, there are major differences in age, physical fitness level and clinical presentation between EOD and late-onset dementia. Therefore, one cannot just assume that the same type and intensity of exercise will lead to similar effects in the former population. By conducting this scoping review, the authors aimed to identify the evidence on the effectiveness of aerobic exercise on physical and mental health outcomes in individuals with EOD, display gaps in this context, and formulate related directions for future research. SUMMARY: There are a number of reasons to assume that aerobic exercise might be extremely valuable within individuals with EOD. However, this scoping review led to the surprising and striking finding that not a single study so far has investigated the effects of physical exercise on cognition, physical performance and feelings of well-being and quality of life in EOD. Although nowadays the disease is increasingly recognized, coping and (non-pharmacological) treatment strategies for EOD are virtually non-existent. KEY MESSAGES: Exercise intervention studies in EOD are lacking. With this scoping review the authors hope to inspire researchers in the field for related directions for future research. The potential beneficial effects of aerobic exercise in individuals with EOD should be explored and assessed extensively. Secondarily, decent guidelines for non-pharmacological treatment and coping strategies should be developed, with the aim of supporting people with EOD and their caregivers