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  • 1.
    Alföldi, Peter
    et al.
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Wiklund, Tobias
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Comorbid insomnia in patients with chronic pain: a study based on the Swedish quality registry for pain rehabilitation (SQRP)2014In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 36, no 20, p. 1661-1669Article in journal (Refereed)
    Abstract [en]

    Purpose: This study investigates the prevalence of insomnia and its relationship to other symptoms and health aspects in patients with chronic pain. Methods: Patients with chronic pain conditions (n = 845) referred to a multidisciplinary pain centre completed surveys provided by the Swedish quality registry for pain rehabilitation (SQRP). The SQRP collects data on socio-demographics, health status, symptoms of pain, mood and insomnia and life satisfaction. Results: The majority of patients (65.3%) had clinical insomnia according to the insomnia severity index (ISI). Insomnia correlated significantly but weakly with pain, depression, anxiety and coping; the strongest multivariate correlations were found with depression and anxiety followed by pain interference and pain severity. Pain intensity, depression and anxiety correlated stronger than ISI with respect to the two investigated aspects of health. Conclusions: The prevalence of insomnia is high in patients with chronic pain conditions, but the level of importance in relation to other symptoms for health aspects is low, and the associations with other important symptoms are relatively weak. One way to increase the effects of multimodal rehabilitation programs may be to provide interventions directed specifically at insomnia rather than focusing only on interventions that address pain, depression and anxiety. Implications for Rehabilitation The prevalence of insomnia is high in patients with complex chronic pain conditions. Relatively low correlations existed between insomnia and pain intensity, depression, anxiety and other psychological aspects. Pain intensity, anxiety and depression were more important for perceived health aspects than insomnia. One way to increase the effects of multimodal rehabilitation programs may be to also include interventions directed directly to insomnia.

  • 2.
    Antepohl, Wolfram
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Kiviloog, Liisa
    Andersson, Jan
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Cognitive impairment in patients with chronic whiplash-associated disorder - A matched control study2003In: NeuroRehabilitation (Reading, MA), ISSN 1053-8135, E-ISSN 1878-6448, Vol. 18, no 4, p. 307-315Article in journal (Refereed)
    Abstract [en]

    Aim: To verify the occurrence of cognitive impairment in patients with chronic whiplash-associated disorder (WAD) and to provide a more detailed description of the impairment's character and context. Methods: Thirty (30) patients with chronic WAD and 30 matched healthy controls completed a cognitive test battery. Four computerised tests were used: a) two different types of cognitive tasks (reaction time vs. working memory) and b) two types of information processing (verbal vs. spatial). Before testing and after every randomised subtest, subjects rated their pain level on a visual analogue scale. Results: A worse overall performance among patients with WAD and, specifically, worse results concerning working memory tasks were found. Post-hoc testing revealed a statistically significant difference concerning the single variable "verbal reaction time". Pain intensity among patients increased significantly during testing. Pain intensity after the subtest for verbal mental reaction time (independent of test sequence) was significantly correlated with results in this subtest, the more pain, the more time was needed. Conclusion: Compared to healthy controls, patients performed worse overall. Concerning verbal reaction time, the impairment was correlated with pain intensity. The findings support the hypothesis that pain might be one important factor leading to cognitive impairment in patients with chronic WAD.

  • 3.
    Aspegren Kendall, Sally
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Brolin-Magnusson, Kerstin
    Sörén, Birgitta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Physiotherapy.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Henriksson, Karl-Gösta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Neurophysiology. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    A pilot study of body awareness programs in the treatment of fibromyalgia syndrome2000In: Arthritis Care and Research, ISSN 0893-7524, E-ISSN 1529-0123, Vol. 13, no 5, p. 304-311Article in journal (Refereed)
    Abstract [en]

    Objective. To compare in a pilot study the effect of two physical therapies, the Mensendieck system (MS) and body awareness therapy (BAT) according to Roxendal, in fibromyalgia patients and to investigate differences in effect between the two interventions. Methods. Twenty female patients were randomized to either MS or BAT in a program lasting 20 weeks. Evaluations were tender point examination and questionnaires, including visual analog scales (pain intensity at worst site, muscular stiffness, evening fatigue, and global health), Fibromyalgia Impact Questionnaire (FIQ), Coping Strategies Questionnaire, Quality of Life Scales, Arthritis Self-Efficacy Scale (ASES), and disability before, immediately after, and at 6 and 18 months followup. Results. The BAT group had improved global health at 18 months followup, but lower results than the MS group. The MS group had improved FIQ, ASES other symptoms, and pain at worst site at 18 months followup. Conclusion. In the present pilot study, MS was associated with more positive changes than BAT.

  • 4.
    Aspegren Kendall, Sally
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Börgesson, A
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Karlsson, E
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    The effect of a session of exercise of moderate intensity level on pressure pain thresholds in healthy women2003In: Advances in Physiotherapy, ISSN 1403-8196, E-ISSN 1651-1948, Vol. 5, no 1, p. 15-20Article in journal (Refereed)
    Abstract [en]

    The aim of this investigation was to study in healthy women the effect of a moderately intensive physical exercise session on the pressure pain thresholds of tendon, bone and muscle. Twenty-four healthy women in the 7-14th day of the menstruation cycle took part in a 60-min exercise class. Pressure pain thresholds were measured by electronic algometer at four points before and after the class. Habitual exercise habits and perceived class exercise intensity were recorded. There was no change in pressure pain sensitivity at any site. Increased pressure pain thresholds tended to be linked to older age and later day in the follicular phase of the menstrual cycle. In conclusion, a single session of moderate exercise in an exercise setting outside the healthcare system or the laboratory did not increase pressure pain thresholds at group level in healthy women.

  • 5.
    Aspegren Kendall, Sally
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Ekselius, L
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Sörén, B
    Bengtsson, Ann
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Rheumatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Feldenkrais intervention in fibromyalgia patients: A pilot study2001In: Journal of Musculoskeletal Pain, ISSN 1058-2452, E-ISSN 1540-7012, Vol. 9, no 4, p. 25-35Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate the effect of the Feldenkrais intervention, in fibromyalgia patients. Methods: Twenty fibromyalgia patients started Feldenkrais intervention done as one individual and two group sessions weekly for 15 weeks. Nineteen started a group-based pain education program followed by a pool program. Test and self-report questionnaires were administered at the start, at six month follow up, and at the end of intervention. Results: After the Feldenkrais intervention improvement in balance and trends to better lower extremity muscle function were shown, but the improvements were not maintained. Conclusions: No sustained benefit of the Feldenkrais intervention compared to a pool program was seen. Methodological problems are discussed. ⌐ 2001 by The Haworth Press, Inc. All rights reserved.

  • 6.
    Aspegren Kendall, Sally
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Elert, Jessica
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Ekselius, Lisa
    Department of Neuroscience, Psychiatry, University Hospital, Uppsala, Sweden.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Are perceived muscle tension, electromyographic hyperactivity and personality traits correlated in the fibromyalgia syndrome?2002In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 34, no 2, p. 73-79Article in journal (Refereed)
    Abstract [en]

    The study was performed to investigate the relationship between perceived muscle tension and electromyographic hyperactivity and to what extent electromyographic (EMG) hyperactivity relates to personality traits in fibromyalgics. Thirty-six females with fibromyalgia performed isokinetic maximal forward flexions of the shoulder combined with surface EMG recordings of the trapezius and infraspinatus muscles. Signal amplitude ratio and peak torque were calculated in the initial and endurance test phases. Pain intensity, perceived general and local shoulder muscle tension, and personality traits using the Karolinska Scales of Personality were assessed pre-test. Neither perceived muscle tension nor muscular tension personality trait correlated with EMG muscle hyperactivity. Perceived general muscle tension correlated with aspects of anxiety proneness (including muscle tension) of the Karolinska Scales of Personality. Pain intensity interacted with many of the variables. We propose that when patients with fibromyalgia report muscle tension that they may be expressing something other than physiological muscle tension.

  • 7.
    Aspegren Kendall, Sally
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Pain and Occupational Centre, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Henriksson, Karl-Gösta
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Hurtig, Ingrid
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Raak, Ragnhild
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Ann
    Linköping University, Department of Molecular and Clinical Medicine, Rheumatology. Linköping University, Faculty of Health Sciences.
    Sören, Birgitta
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Wahren, Lis Karin
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Differences in sensory thresholds in the skin of women with fibromyalgia syndrome: A comparison between ketamine responders and ketamine non-responders2003In: Journal of Musculoskeletal Pain, ISSN 1058-2452, E-ISSN 1540-7012, Vol. 11, no 2, p. 3-9Article in journal (Refereed)
    Abstract [en]

    Objectives: To compare detection and pain thresholds in the skin of female fibromyalgia patients who were either ketamine responders or ketamine nonresponders.

    Methods: Detection thresholds to innocuous warmth, of cold, heat or cold pain, and touch and dynamic touch sensation were determined in the skin. Pressure pain thresholds, local and widespread pain intensity, and pain duration were also registered.

    Results: Ketamine nonresponse was associated with more pronounced hypersensitivity for thermal pain [especially cold pain] than ketamine response.

    Conclusions: Blockade of N-metyl-D-aspartic acid receptors by ketamine and the recording of pain thresholds in the skin, especially for cold pain, might reveal different mechanisms of allodynia.

  • 8.
    Bendelin, Nina
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Öberg, Jörgen
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Arts and Sciences.
    Hesser, Hugo
    Linköping University, The Swedish Institute for Disability Research. Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences.
    Andersson, Gerhard
    Linköping University, The Swedish Institute for Disability Research. Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Pain and Rehabilitation Centre.
    Internet-delivered intervention for relapse prevention after pain management program2009Conference paper (Other academic)
  • 9.
    Bernfort, Lars
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences. Region Östergötland, Heart and Medicine Center, Allergy Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Rahmqvist, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Husberg, Magnus
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Levin, Lars-Åke
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Chronic pain in an elderly population in Sweden: Impact on costs and quality of life2015Report (Other academic)
    Abstract [en]

    Chronic pain among elderly people has long been a well-known problem, in terms of both societal costs and the quality of life of affected individuals. To estimate the magnitude of the problems associated with chronic pain in an elderly population, data on both costs and quality of life were gathered. A postal questionnaire was sent out to a stratified sample of 10 000 inhabitants 65 years and older in Linköping and Norrköping. The survey included questions on demographics, habits, and life situation, and different kinds of questions and instruments related to well-being (e.g., quality-of-life and pain-specific questions). In the questionnaire respondents were asked whether they were receiving any help—informal care—from a relative. If they answered yes, they were asked for permission to contact the informal caregiver and to provide contact details. The amount of informal care provided by relatives to persons with chronic pain was investigated by use of a questionnaire directed to the caregiving relatives, containing questions about time spent providing informal care.

    Data on costs were collected from registers of consumption of health care, drugs, and municipal services.

    The results of the study showed a very clear association between existence and severity of chronic pain and societal costs. The study population was subdivided into three groups with respect to having chronic pain or not, and a pain intensity during the last week of 0–4 (mild), 5–7 (moderate), or 8–10 (severe) on a scale of 0–10. Taking all costs (health care, drugs, municipal services, and informal care) into account, persons in the severe chronic pain group consumed on average 72% more resources than persons in the moderate chronic pain group and 143% more than those in the no or mild chronic pain group. Differences were most pronounced concerning municipal services and informal care costs.

    Even more alarming are the results on the quality of life of persons in the different groups. On the EQ-5D index, the average value for persons in the no or mild chronic pain group was 0.82. For those in the moderate chronic pain group the average value was 0.64, and for those in the severe chronic pain group the average value was only 0.38. EQ-VAS resulted in less pronounced but still clearly significant differences.

    It is concluded that this study, reaching a rather large part of the target population, shows that existence and severity of chronic pain among people 65 years and older affects costs to society and the quality of life of affected individuals in a massive way.

  • 10.
    Bernfort, Lars
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences. Region Östergötland, Heart and Medicine Center, Allergy Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Rahmqvist, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Husberg, Magnus
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Levin, Lars-Åke
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Health Sciences.
    Severity of chronic pain in an elderly population in Sweden-impact on costs and quality of life2015In: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 156, no 3, p. 521-527Article in journal (Refereed)
    Abstract [en]

    Chronic pain is associated with large societal costs, but few studies have investigated the total costs of chronic pain with respect to elderly subjects. The elderly usually require informal care, care performed by municipalities, and care for chronic diseases, all factors that can result in extensive financial burdens on elderly patients, their families, and the social services provided by the state. This study aims to quantify the societal cost of chronic pain in people of age 65 years and older and to assess the impact of chronic pain on quality of life. This study collected data from 3 registers concerning health care, drugs, and municipal services and from 2 surveys. A postal questionnaire was used to collect data from a stratified sample of the population 65 years and older in southeastern Sweden. The questionnaire addressed pain intensity and quality of life variables (EQ-5D). A second postal questionnaire was used to collect data from relatives of the elderly patients suffering from chronic pain. A total of 66.5% valid responses of the 10,000 subjects was achieved; 76.9% were categorized as having no or mild chronic pain, 18.9% as having moderate chronic pain, and 4.2% as having severe chronic pain. Consumed resources increased with the severity of chronic pain. Clear differences in EQ-5D were found with respect to the severity of pain. This study found an association between resource use and severity of chronic pain in elderly subjects: the more severe the chronic pain, the more extensive (and expensive) the use of resources.

  • 11.
    Biurrun Manresa, Jose A.
    et al.
    Aalborg University, Denmark.
    Sörensen, Jan
    Linköping University, Department of Medical and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Faculty of Medicine and Health Sciences.
    Andersen, Ole K.
    Aalborg University, Denmark.
    Arendt-Nielsen, Lars
    Aalborg University, Denmark.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Dynamic Changes in Nociception and Pain Perception After Spinal Cord Stimulation in Chronic Neuropathic Pain Patients2015In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 31, no 12, p. 1046-1053Article in journal (Refereed)
    Abstract [en]

    Objectives: Patients with an implanted spinal cord stimulation (SCS) system for pain management present an opportunity to study dynamic changes in the pain system in a situation where patients are not stimulated (ie, experiencing severe pain) compared with a situation in which patients have just been stimulated (ie, pain free or greatly reduced pain). The aims of this study were (1) to determine if there are differences in nociceptive withdrawal reflex thresholds (NWR-T) and electrical pain thresholds (EP-T) before and after SCS; and (2) to establish if these differences are related to psychological factors associated with chronic pain. Methods: Seventeen volunteers with chronic neuropathic pain participated in the experiment. Electrical stimuli were applied to assess the NWR-T and the EP-T. In addition, psychological factors (ie, pain characteristics, depression, anxiety, and disability indexes) were also recorded. The NWR-T and EP-T were assessed with the SCS system off (at least 8 h before the experiment), and then reassessed 1 hour after the SCS system was turned on. Results: Ongoing pain intensity ratings decreased (P=0.018), whereas the NWR-T increased (P=0.028) after the SCS was turned on, whereas no significant difference was found for EP-T (P=0.324). Psychological factors were significant predictors for EP-T but not for NWR-T. Discussion: The results of this study suggest that pain relief after SCS is partially mediated by a decrease in the excitability of dorsal horn neurons in the spinal cord.

  • 12.
    Björk, Mathilda
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Thyberg, Ingrid
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology . Linköping University, Faculty of Health Sciences.
    Peolsson, Mchael
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Multivariate relationships between pain intensity and other aspects of health in rheumatoid arthritis: cross sectional and five year longitudinal analyses (the Swedish TIRA project)2008In: Disability and Rehabilitation, ISSN 0963-8288, Vol. 30, no 19, p. 1429-1438Article in journal (Refereed)
    Abstract [en]

    Objectives: This study analyses the relationships between pain intensity and other aspects of health commonly used to assess disease activity and disability in early rheumatoid arthritis and examines whether such relationships were different between women and men.

    Subjects and methods: This study included the 189 patients (69% women) with early RA (symptoms <12 months at diagnosis) still remaining in the Swedish TIRA cohort 5 years after inclusion. Disease activity and disability was assessed 3, 6, 12, 18, 24, 36, 48, and 60 months (M0-M60) after inclusion by erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), number of swollen and tender joints, physicians global assessment of disease activity (PGA), grip force average over 10 seconds (Grippit), Grip Ability Test (GAT), Signals of Functional Impairment (SOFI) in hand, lower limb and upper limb, Health Assessment Questionnaire (HAQ), and pain intensity measured with a visual analogue scale (VAS). The variables were divided into meaningful blocks according to the correlation structure in a principal component analysis (PCA) at M60. Using hierarchical partial least squares (PLS) analyses, this study investigated the blocks cross-sectionally to test for correlations with pain intensity at M0 and M60. The blocks at M0 were also used as predictors of pain intensity at M60 in a hierarchical PLS.

    Results: The strongest relationship was found between pain intensity and the second block, consisting of HAQ and SOFI-lower limb at the cross-sectional analyses in both women and men. The block representing disease activity (i.e., ESR, CRP, PGA, and swollen and tender joints) had the weakest relation to pain intensity. According to the longitudinal analyses, the disease activity variables (block 1) at M0 had the strongest relationship to pain intensity at M60 in men. In contrast, HAQ and SOFI-lower limb (block 2) at M0 had a strong relation to pain intensity in women.

  • 13.
    Björk, Mathilda
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Thyberg, Ingrid
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, Faculty of Health Sciences.
    Rikner, Klas
    Department of Rehabilitation, School of Health Sciences, Jönköping University, and Centre for Public Sector Research, Göteborg University.
    Balogh, Istvan
    Department of Occupational and Environmental Medicine, University Hospital Lund, Lund.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Pain and Occupational Centre, Pain and Rehabilitation Centre.
    Sick leave before and after diagnosis of rheumatoid arthritis in relation to referens: A report from the Swedish TIRA project2009In: Journal of Rheumatology, ISSN 0315-162X, E-ISSN 1499-2752, Vol. 36, no 6, p. 1170-1179Article in journal (Refereed)
    Abstract [en]

    Objective. Our study describes sick leave during 3 years before and 3 years after diagnosis of rheumatoid arthritis (RA) in relation to referents and identifies predictors for sick leave during the third year after diagnosis of RA.

    Methods. One hundred twenty patients (76% women) from the Swedish early RA study TIRA were included. Disease activity and disability were registered regularly during 3 years in TIRA. Referents were matched for sex, age, and home town. Sick leave data were obtained for patients 3 years before and 3 years after diagnosis and for the referents for the corresponding 6 years.

    Results. No differences were seen between patients and referents regarding sick leave during the first 2 years, whereas sick leave increased in patients 6 months before diagnosis, from 30% to 53%. During the 3 years after diagnosis, sick leave among patients was rather stable, varying between 50% and 60%, even though disability pension increased and sickness benefit decreased. Sick leave before diagnosis, disability 1 year after diagnosis, and type of work were identified as predictors for sick leave during the third year after diagnosis.

    Conclusion. Not surprisingly, sick leave in patients increased the year before diagnosis. Although disease activity and disability diminished after diagnosis, the patients’ sick leave remained essentially unchanged. Sick leave 3 years after diagnosis was foremost predicted by earlier sick leave, disability, and type of work.

  • 14.
    Björk, Mathilda
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Occupational Therapy. Linköping University, Faculty of Health Sciences. The Vårdal Foundation, The Swedish Institute for Health Sciences.
    Thyberg, Ingrid
    Linköping University, Department of Molecular and Clinical Medicine, Rheumatology. Linköping University, Faculty of Health Sciences.
    Skogh, Thomas
    Linköping University, Department of Molecular and Clinical Medicine, Rheumatology. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Pain and Occupational Centre, Pain and Rehabilitation Centre.
    Hand Function and Activity Limitation According to Health Assessment Questionnaire in Patients with Rheumatoid Arthritis and Healthy Referents: 5-Year Followup of Predictors of Activity Limitation (The Swedish TIRA Project)2007In: Journal of Rheumatology, ISSN 0315-162X, E-ISSN 1499-2752, Vol. 34, no 2, p. 296-302Article in journal (Refereed)
    Abstract [en]

    Objective: This study identifies baseline predictors of future activity limitation in rheumatoid arthritis (RA). To reinforce the utility of instruments assessing functional ability/activity limitation, we used reference data from healthy referents.

    Methods: This study includes 189 patients (69% women) with recent-onset RA (onset of joint swelling not more than 12 months at diagnosis) in a prospective cohort ("the Swedish TIRA project") during 27 months from 1996 through 1998. Regular followups were done for a period of 5 years, and 123 healthy persons (50% women) were recruited as referents. Hand function was assessed by the "grip ability test (GAT)" and "signals of functional impairment" (SOFI). Grip force was measured with the electronic device GrippitTM. Activity limitation was assessed with the Swedish version of the Health Assessment Questionnaire (HAQ).

    Results: Throughout the study and for both sexes, GAT, grip force, SOFI-hand, and HAQ were significantly different for the patients compared to healthy referents. In the healthy referents, HAQ was mainly related to age and GAT, whereas in RA HAQ was most obviously linked to grip force. Five years after diagnosis only 8% of HAQ outcome was explained by the baseline measures: HAQ, grip force, SOFI-lower limb, sex, walking speed, and GAT.

    Conclusion: Our study provides valuable reference data for several functional ability and activity limitation measures. The HAQ score was explained by different variables in healthy referents compared to patients with RA. Five years after diagnosis only 8% of HAQ outcome was explained by the variables assessed at inclusion.

  • 15.
    Borg, Jörgen
    et al.
    Uppsala Universitet.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Stibrant Sunnerhagen, Katharina
    Göteborgs universitet.
    Rehabiliteringsmedicin - bakgrund och aktuell roll i sjukvården2006In: Rehabiliteringsmedicin-Teori och praktik / [ed] Borg, Jörgen, Lund: Studentlitteratur , 2006, 1, p. 11-19Chapter in book (Other academic)
    Abstract [sv]

              Kapitel om rehabiliteringsmedicinens utveckling och nuvarande plats i sjukvården samt begrepp och metodik inleder boken. I två delar ges därefter rehabiliteringsmedicinska aspekter på de dominerande sjukdomsgrupperna - komplexa smärttillstånd respektive skador och sjukdomar i nervsystemet. Som avslutning beskrivs bland annat  stressrelaterade tillstånd. Läroboken är avsedd för grundutbildning av läkare, arbetsterapeuter och sjukgymnaster, logopeder samt för läkare under AT-tjänstgöring. Den är också lämplig som introduktion i specialistutbildningen i rehabiliteringsmedicin, geriatrik, neurologi och smärtlindring. Vidareutbildningar av olika vårdyrkesgrupper kan ha nytta av boken och den kan också användas som referenslitteratur av yrkesverksamma med intresse för rehabiliteringsmedicin.

  • 16.
    Bromley Milton, Maria
    et al.
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Börsbo, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. County Hospital Ryhov, Jönköping, Sweden.
    Rovner, Graciela
    University of Gothenburg, Sweden.
    Lundgren-Nilsson, Åsa
    University of Gothenburg, Sweden.
    Stibrant-Sunnerhagen, Katharina
    University of Gothenburg, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Is Pain Intensity Really That Important to Assess in Chronic Pain Patients? A Study Based on the Swedish Quality Registry for Pain Rehabilitation (SQRP)2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 6Article in journal (Refereed)
    Abstract [en]

    Background

    Incorporating the patient's view on care and treatment has become increasingly important for health care. Patients describe the variety of consequences of their chronic pain conditions as significant pain intensity, depression, and anxiety. We hypothesised that intensities of common symptoms in chronic pain conditions carry important information that can be used to identify clinically relevant subgroups. This study has three aims: 1) to determine the importance of different symptoms with respect to participation and ill-health; 2) to identify subgroups based on data concerning important symptoms; and 3) to determine the secondary consequences for the identified subgroups with respect to participation and health factors.

    Methods and Subjects

    This study is based on a cohort of patients referred to a multidisciplinary pain centre at a university hospital (n = 4645, participation rate 88%) in Sweden. The patients answered a number of questionnaires concerning symptoms, participation, and health aspects as a part of the Swedish Quality Registry for Pain Rehabilitation (SQRP).

    Results

    Common symptoms (such as pain intensity, depression, and anxiety) in patients with chronic pain showed great variability across subjects and 60% of the cohort had normal values with respect to depressive and anxiety symptoms. Pain intensity more than psychological symptoms showed stronger relationships with participation and health. It was possible to identify subgroups based on pain intensity, depression, and anxiety. With respect to participation and health, high depressive symptomatology had greater negative consequences than high anxiety.

    Conclusions

    Common symptoms (such as pain intensity and depressive and anxiety symptoms) in chronic pain conditions carry important information that can be used to identify clinically relevant subgroups.

  • 17.
    Bäckryd, Emmanuel
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Region Östergötland, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Carlsson, Anders K
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Olausson, Patrik
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Multivariate proteomic analysis of the cerebrospinal fluid of patients with peripheral neuropathic pain and healthy controls: a hypothesis-generating pilot study2015In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 8, p. 321-333Article in journal (Refereed)
    Abstract [en]

    Pain medicine lacks objective biomarkers to guide diagnosis and treatment. Combining two-dimensional gel proteomics with multivariate data analysis by projection, we exploratively analyzed the cerebrospinal fluid of eleven patients with severe peripheral neuropathic pain due to trauma and/or surgery refractory to conventional treatment and eleven healthy controls. Using orthogonal partial least squares discriminant analysis, we identified a panel of 36 proteins highly discriminating between the two groups. Due to a possible confounding effect of age, a new model with age as outcome variable was computed for patients (n=11), and four out of 36 protein spots were excluded due to a probable influence of age. Of the 32 remaining proteins, the following seven had the highest discriminatory power between the two groups: an isoform of angiotensinogen (upregulated in patients), two isoforms of alpha-1-antitrypsin (downregulated in patients), three isoforms of haptoglobin (upregulated in patients), and one isoform of pigment epithelium-derived factor (downregulated in patients). It has recently been hypothesized that the renin–angiotensin system may play a role in the pathophysiology of neuropathic pain, and a clinical trial of an angiotensin II receptor antagonist was recently published. It is noteworthy that when searching for neuropathic pain biomarkers with a purely explorative methodology, it was indeed a renin–angiotensin system protein that had the highest discriminatory power between patients and controls in the present study. The results from this hypothesis-generating pilot study have to be confirmed in larger, hypothesis-driven studies with age-matched controls, but the present study illustrates the fruitfulness of combining proteomics with multivariate data analysis in hypothesis-generating pain biomarker studies in humans.

  • 18.
    Bäckryd, Emmanuel
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Östergötlands Läns Landsting, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Do low levels of Beta-endorphin in the cerebrospinal fluid indicate defective top-down inhibition in patients with chronic neuropathic pain? A cross-sectional, comparative study2014In: Pain medicine (Malden, Mass.), ISSN 1526-2375, E-ISSN 1526-4637, Vol. 15, no 1, p. 111-119Article in journal (Refereed)
    Abstract [en]

    Objective

    Pain medicine still lacks mechanism-specific biomarkers to guide diagnosis and treatment, and defective top-down modulation is an important factor in the pathophysiology of chronic pain conditions. Using modern analytical tools and advanced multivariate statistical analysis, the aim of this study was to revisit two classical potential biomarkers of pro- and anti-nociception in humans (substance P and beta-endorphin), focusing particularly on the cerebrospinal fluid (CSF).

    Design

    Cross-sectional, comparative, observational study.

    Subjects

    Patients with chronic, post-traumatic and/or post-surgical, neuropathic pain refractory to conventional treatment (N = 15) and healthy controls (N = 19) were included.

    Methods

    Samples were taken from CSF and blood, and levels of substance P and beta-endorphin were investigated using a Luminex technology kit.

    Results

    We found low levels of beta-endorphin in the CSF of neuropathic pain patients (66 ± 11 pcg/mL) compared with healthy controls (115 ± 14 pcg/mL) (P = 0.017). Substance P levels in the CSF did not differ (20 ± 2 pcg/mL, 26 ± 2, P = 0.08). However, our multivariate data analysis showed that belonging to the patient group was associated with low levels of both substances in the CSF. A higher correlation between the levels of beta-endorphin and substance P in CSF was found in healthy controls than in patients (rs = 0.725, P < 0.001 vs rs = 0.574, P = 0.032).

    Conclusions

    Patients with chronic neuropathic pain due to trauma or surgery had low levels of beta-endorphin in the CSF. We speculate that this could indicate a defective top-down modulation of pain in chronic neuropathic pain. Our results also illustrate the importance of taking a system-wide, multivariate approach when searching for biomarkers.

  • 19.
    Bäckryd, Emmanuel
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Sörensen, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Nerve block as analgesia forneoplastic brachial plexopathy2010In: European Journal of Palliative Care, ISSN 1352-2779, E-ISSN 1479-0793, Vol. 17, no 5, p. 218-220Article in journal (Other academic)
    Abstract [en]

    Brachial plexus nerve blocks are performed to treat patients with chronic pain referable to the brachial plexus. The needle insertion and trajectory are based on palpation of surface landmarks. Occasionally, the surface landmarks are difficult to identify owing to body habitus or anatomic alterations secondary to surgery or radiation therapy. The intent of this manuscript is to describe a technique for brachial plexus block guided with computed tomography and to report our initial results for regional pain management.

  • 20.
    Bäckryd, Emmanuel
    et al.
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Sörensen, Jan
    Linköping University, Department of Medical and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Faculty of Medicine and Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ziconotide Trialing by Intrathecal Bolus Injections: An Open-Label Non-Randomized Clinical Trial in Postoperative/Posttraumatic Neuropathic Pain Patients Refractory to Conventional Treatment2015In: Neuromodulation (Malden, Mass.), ISSN 1094-7159, E-ISSN 1525-1403, Vol. 18, no 5, p. 404-413Article in journal (Refereed)
    Abstract [en]

    Objectives: The aim of this open-label, non-randomized, clinical trial was to evaluate the feasibility of trialing ziconotide by intrathecal bolus injections. Material and Methods: Twenty-three patients, who had peripheral neuropathic pain refractory to pharmacological treatment and were under consideration for Spinal Cord Stimulation, received up to three ziconotide bolus injections according to a comprehensive algorithm. After a first injection of 2.5g, the patients progressed in the algorithm depending on the presence or absence of pain reduction and significant adverse events. A patient was considered a "responder" if experiencing pain reduction and no significant adverse event on two consecutive occasions at the same dosage. Results: We found a low proportion of responders (13%). However 30% of patients experienced greater than= 30% pain reduction on a least one injection, yielding a number needed to treat of similar to 3 for clinically significant pain relief. Pain intensity changed significantly over time (0-6h) (p = 0.047) after a mean ziconotide dose of 2.75 mu g. Adverse events were as expected, and no serious adverse event occurred. We did not find any statistical association between response to Spinal Cord Stimulation and response to ziconotide. Conclusions: Ziconotide bolus injection trialing seems feasible, but the proportion of responders in the present study was low. Adverse events were as expected, and no serious adverse event occurred. The predictive power of ziconotide bolus trialing remains unclear, and the pharmacological profile of ziconotide (slow tissue penetration due to high hydrophilicity) calls the rationale for bolus trialing into question.

  • 21.
    Börsbo, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Peolsson, Michael
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Impact of the interaction between selfefficacy, symptoms and catastrophizing on disability, quality of life and health in chronic pain patients2010In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 32, no 17, p. 1387-1396Article in journal (Refereed)
    Abstract [en]

    This study investigates the interactions between self-efficacy–including subcomponents–and symptoms (pain, depression, and anxiety), catastrophizing, disability, quality of life, and health in a population of chronic pain patients. The study used 433 chronic pain patients including 47 patients with spinal cord injuryrelated pain, 150 with chronic whiplash-associated disorders, and 236 with fibromyalgia. The participants answered a postal questionnaire that provided background data, pain intensity and duration, and psychological- and health-related items. In the multivariate context, depression, anxiety, catastrophizing, and disability were intercorrelated. Self-efficacy correlated positively with variables of quality of life and general health. These two groups of variables were negatively correlated. The pain variables–duration of pain, pain intensity, and spreading of pain–formed a third group of variables. Self-efficacy function was negatively correlated to these three pain variables. When regressing disability, quality of life, and health, we found that self-efficacy had a positive impact whereas symptoms, catastrophizing, and pain had a negative influence on these aspects. Different patterns of influencing variables were discerned for the three different analyses, and specific patterns of the subscales of self-efficacy corresponded to specific patterns of negative factors for the outcome of disability, quality of life, and health.

    Perspective: This article presents the complex interaction of psychological factors and symptoms and their positive and negative influence on disability, quality of life, and health. The results indicate that it might be important to assess and influence both enhancing and detoriating factors to ensure an effective pain management programme.

  • 22.
    Börsbo, Björn
    et al.
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Liedberg, Gunilla M
    Linköping University, Department of Social and Welfare Studies, Division of Health, Activity and Care. Linköping University, Faculty of Health Sciences.
    Wallin, Mia
    Linköping University, Department of Social and Welfare Studies, Division of Health, Activity and Care. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Subgroups based on thermal and pressure pain thresholds in women with chronic whiplash display differences in clinical presentation - an explorative study2012In: Journal of pain research, ISSN 1178-7090, Vol. 5, p. 511-521Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the presence of subgroups in chronic whiplash-associated disorders (WAD) based on pain thresholds for pressure (PPT), cold (CPT), and heat (HPT) and to compare these subgroups with respect to symptomatology, disability, and health aspects. Methods: Two groups of female subjects – patients with chronic WAD (n = 28) and healthy controls (CON; n = 29) – were investigated. Quantitative sensory testing (QST) for thermal thresholds and algometry for PPT at four sites in the body (over the trapezius and tibialis anterior bilaterally) were determined. Habitual pain intensities, psychological strain, disability, and health aspects were registered using a questionnaire.Results: A cluster analysis based on PPT, CPT, and HPT identified two subgroups of chronic WAD: one sensitive subgroup (s-WAD; n = 21), and one less sensitive subgroup (ls-WAD; n = 6). S-WAD displayed widespread hyperalgesia, whereas ls-WAD had localized hyperalgesia in the neck area, with tendencies to supernormal values in remote areas of the body. Generally, s-WAD had a significantly worse situation than the CON with respect to symptomatology, disability, and health aspects. The ls-WAD group was intermediary between s-WAD and CON in these aspects.Conclusion: Different explanations, eg, severity of the pain condition per se, etiological factors, and pre-trauma differences in pain sensitivity, may exist for the differences in pain thresholds between the two subgroups. Future research should investigate the role of pain thresholds in the chronic stage to determine the efficacy of treatment interventions.

  • 23.
    Börsbo, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Peolsson, Michael
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Catastrophizing, depression, and pain: Correlation with and influence on quality of life and health: A study of chronic whiplash-associated disorders2008In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 40, no 7, p. 562-569Article in journal (Refereed)
    Abstract [en]

    Objective: The aims of this study were: (i) to classify subgroups according to the degree of pain intensity, depression, and catastrophizing, and investigate distribution in a group of patients with chronic whiplash-associated disorders; and (ii) to investigate how these subgroups were distributed and inter-related multivariately with respect to consequences such as health and quality of life outcome measures.

    Design: Descriptive cross-sectional study.

    Patients: A total of 275 consecutive chronic pain patients with whiplash-associated disorders who were referred to a university hospital.

    Methods: The following data were obtained by means of self-report questionnaires: pain intensity in neck and shoulders, background history, Beck Depression Inventory, the catastrophizing scale of Coping Strategy Questionnaire, Life Satisfaction Checklist, the SF-36 Health Survey, and the EuroQol.

    Results: Principal component analysis was used to recognize subgroups according to the degree of pain intensity, depression, and catastrophizing. These subgroups have specific characteristics according to perceived health and quality of life, and the degree of depression appears to be the most important influencing factor.

    Conclusion: From a clinical point of view, these findings indicate that it is important to assess patients for intensity of pain, depression, and catastrophizing when planning a rehabilitation programme. Such an evaluation will help individualize therapy and intervention techniques so as to optimize the efficiency of the programme.

  • 24.
    Börsbo, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Peolsson, Michael
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine .
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    The complex interplay between pain intensity, depression, anxiety and catastrophizing with respect to quality of life and disability2009In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 31, no 19, p. 1605-1613Article in journal (Refereed)
    Abstract [en]

    Purpose: To identify subgroups of chronic pain patients based on the occurrence of depression, anxiety, and catastrophizing and the duration of pain and pain intensity. In addition to this, to investigate the relationship between the subgroups with respect to background variables, diagnosis, pain-related disability, and perceived quality of life.

    Methods: This study used 433 chronic pain patients including 47 patients with spinal cord injury related pain, 150 with chronic whiplash associated disorders, and 236 with fibromyalgia. The participants answered a postal questionnaire that provided background data, pain intensity and duration and psychological and health related items.

    Results: Based on depression, anxiety, catastrophizing, pain intensity and duration, we identified subgroups of chronic pain patients that differed with respect to perceived quality of life, disability and diagnosis. The psychological factors, especially depression, significantly influenced perceived quality of life and disability. Pain intensity and duration play a minor role with respect to quality of life although pain intensity is associated contributes more to perceived disability.

    Conclusions: The results of this study highlight the importance of not looking at chronic pain patients as a homogenous entity. A detailed assessment, including psychological factors with emphasis on depressive symptoms, might be essential for planning and carrying through treatment and rehabilitation.

  • 25.
    Christidis, Nikolaos
    et al.
    Karolinska Institute, Sweden; SCON, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Region Östergötland, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Larsson, Anette
    University of Gothenburg, Sweden; .
    Palstam, Annie
    University of Gothenburg, Sweden.
    Mannerkorpi, Kaisa
    University of Gothenburg, Sweden; .
    Bileviciute-Ljungar, Indre
    Karolinska Institute, Sweden.
    Lofgren, Monika
    Karolinska Institute, Sweden.
    Bjersing, Jan
    University of Gothenburg, Sweden.
    Kosek, Eva
    Karolinska Institute, Sweden; Stockholm Spine Centre, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ernberg, Malin
    Karolinska Institute, Sweden; SCON, Sweden.
    Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle - A Microdialysis Study2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 12, p. e0143856-Article in journal (Refereed)
    Abstract [en]

    Objective Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions. Material and Methods 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1 beta, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0-100) and fatigue Borgs Rating of Perceived Exertion Scale; 6-20) were assessed before and during the entire microdialysis session. Results The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P &lt; .001) and induced fatigue in both groups (P &lt; .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P &lt; .001). The levels of IL-1 beta did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P &lt; .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (Ps &lt; .001). There were no correlations between pain or fatigue and cytokine levels after contractions. Conclusion There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1 beta, IL-6, IL-8, and TNF do not seem to play an important role in maintenance of muscle pain in fibromyalgia.

  • 26. Crenshaw, A.G.
    et al.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Heiden, M.
    Karlsson, S.
    Fridén, J.
    Intramuscular pressure and electromyographic responses of the vastus lateralis muscle during repeated maximal isokinetic knee extensions.2000In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 170, p. 119-126Article in journal (Refereed)
  • 27.
    Cöster, Lars
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rheumatology . Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Kendall, Sally
    Multidisciplinary Pain Centre Copenhagen University Hospital, Copenhagen, Denmark.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Henriksson, Chris
    Department of Clinical and Experimental Medicine Linköping University.
    Henriksson, Karl-Gösta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Bengtsson, Ann
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rheumatology . Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Chronic widespread musculoskeletal pain - A comparison of those who meet criteria for fibromyalgia and those who do not2008In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 12, no 5, p. 600-610Article in journal (Refereed)
    Abstract [en]

    Fibromyalgia is currently classified as chronic widespread pain with widespread allodynia to pressure pain. There are few data describing pain characteristics, quality of life, consequences for daily living, and psychosocial status in patients who meet the classification criteria for fibromyalgia proposed by the American College of Rheumatology compared with patients with chronic widespread pain but not widespread allodynia. This study used a randomly selected sample from the general population. A postal questionnaire and a pain mannequin were sent to 9952 people. The response rate was 76.7%. The pain drawings showed that 345 people had widespread pain, that is, they noted pain in all four extremities and axially. Clinical examination, which included a manual tender point examination, was performed in 125 subjects. These people answered commonly used questionnaires on pain, quality of life, coping strategies, depression, and anxiety. Compared with chronic widespread pain without widespread allodynia, fibromyalgia was associated with more severe symptoms/consequences for daily life and higher pain severity. Similar coping strategies were found. Chronic widespread pain without widespread allodynia to pressure pain was found in 4.5% in the population and fibromyalgia in 2.5%. © 2007 European Federation of Chapters of the International Association for the Study of Pain.

  • 28.
    Dawson, Andreas
    et al.
    Malmö University, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Region Östergötland, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    List, Thomas
    Malmö University, Sweden; Skåne University Hospital, Sweden.
    Svensson, Peter
    Aarhus University, Denmark.
    Ernberg, Malin
    Karolinska Institute, Sweden; Aarhus University Hospital, Denmark.
    Effects of Experimental Tooth Clenching on Pain and Intramuscular Release of 5-HT and Glutamate in Patients With Myofascial TMD2015In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 31, no 8, p. 740-749Article in journal (Refereed)
    Abstract [en]

    Objectives: It has been suggested that tooth clenching may be associated with local metabolic changes, and is a risk factor for myofascial temporomandibular disorders (M-TMD). This study investigated the effects of experimental tooth clenching on the levels of 5-HT, glutamate, pyruvate, and lactate, as well as on blood flow and pain intensity, in the masseter muscles of M-TMD patients. Methods: Fifteen patients with M-TMD and 15 pain-free controls participated. Intramuscular microdialysis was performed to collect 5-HT, glutamate, pyruvate, and lactate and to assess blood flow. Two hours after the insertion of a microdialysis catheter, participants performed a 20-minute repetitive tooth clenching task (50% of maximal voluntary contraction). Pain intensity was measured throughout. Results: A significant effect of group (P less than 0.01), but not of time, was observed on 5-HT levels and blood flow. No significant effects of time or group occurred on glutamate, pyruvate, or lactate levels. Time and group had significant main effects on pain intensity (P less than 0.05 and less than 0.001). No significant correlations were identified between: (1) 5-HT, glutamate, and pain intensity; or between (2) pyruvate, lactate, and blood flow. Discussion: This experimental tooth clenching model increased jaw muscle pain levels in M-TMD patients and evoked low levels of jaw muscle pain in controls. M-TMD patients had significantly higher levels of 5-HT than controls and significantly lower blood flow. These 2 factors may facilitate the release of other algesic substances that may cause pain.

  • 29.
    Dawson, Andreas
    et al.
    Malmö University, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Östergötlands Läns Landsting, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    List, Thomas
    Malmö University, Sweden.
    Svensson, Peter
    Aarhus University, Denmark.
    Ernberg, Malin
    Karolinska Institutet, Huddinge, Sweden.
    Pain and intramuscular release of algesic substances in the masseter muscle after experimental tooth-clenching exercises in healthy subjects2013In: Journal of Orofacial Pain, ISSN 1064-6655, E-ISSN 1945-3396, Vol. 27, no 4, p. 350-360Article in journal (Refereed)
    Abstract [en]

    AIMS:

    To investigate whether experimental tooth clenching leads to a release of algesic substances in the masseter muscle.

    METHODS:

    Thirty healthy subjects (16 females, 14 males) participated. During two sessions, separated by at least 1 week, intramuscular microdialysis was performed to collect masseter muscle 5-hydroxytryptamine (5-HT) and glutamate as well as the metabolic markers pyruvate and lactate. Two hours after the start of microdialysis, participants were randomized to a 20-min repetitive experimental tooth-clenching task (50% of maximal voluntary contraction) or a control session (no clenching). Pain and fatigue were measured throughout. The Friedman and Wilcoxon tests were used for statistical analyses.

    RESULTS:

    No alterations were observed in the concentrations of 5-HT, glutamate, pyruvate, and lactate over time in the clenching or control session, or between sessions at various time points. Pain (P < .01) and fatigue (P < .01) increased significantly over time in the clenching session and were significantly higher after clenching than in the control session (P < .01).

    CONCLUSION:

    Low levels of pain and fatigue developed with this experimental tooth-clenching model, but they were not associated with an altered release of 5-HT, glutamate, lactate, or pyruvate. More research is required to elucidate the peripheral release of algesic substances in response to tooth clenching.

  • 30.
    Ekman, Bertil
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Internal Medicine. Östergötlands Läns Landsting, MC - Medicincentrum, EMT-endo.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Arnqvist, Hans
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Cell biology. Östergötlands Läns Landsting, MC - Medicincentrum, EMT-endo.
    Growth hormone substitution titrated to obtain IGF-I levels in the physiological range in hypopituitary adults: Effects upon dynamic strength, endurance and EMG2003In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 90, no 5-6, p. 496-504Article in journal (Refereed)
    Abstract [en]

    We studied the effects of individualised growth hormone (GH) substitution, aiming at normal insulin-like growth factor I (IGF-I) levels, on biomechanical output and surface electromyogram (EMG) of isokinetic muscle strength and endurance performance in 18 hypopituitary adults and compared with 17 matched healthy controls. The muscle function tests consisted of isokinetic contractions of the right knee extensors, from which torque and EMG were recorded. Three patients were excluded from the final analysis of the muscle function tests due to technical errors and one control subject moved from the area during the study. We found that GH-deficient adults without GH substitution were weaker and had less endurance than healthy control subjects. At the group level, plasma levels of IGF-I were normalised but generally no significant effects upon biomechanical output and EMG were found after dose titration and 6 months of a constant GH dose. However, subjects with the largest changes in IGF-I had significantly better biomechanical output and EMG compared to those with small changes in IGF-I. This finding may indicate that the net increase in IGF-I levels is critical for improvements in biomechanical output, EMG and perception of fatigue to occur.

  • 31.
    Ekman, Bertil
    et al.
    Linköping University, Department of Medicine and Care, Internal Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Arnqvist, Hans J.
    Linköping University, Department of Medicine and Care, Internal Medicine. Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Improved muscle function in GH substituted adults is related to increase in circulating IGF-IManuscript (preprint) (Other academic)
    Abstract [en]

    We studied the effects of individualized growth hormone substitution, aiming at normal IGF-I levels, on biomechanical output and EMG of isokinetic muscle strength and endurance performance in 18 hypopituitary adults compared with matched controls. The muscle function tests consisted of isokinetic contractions of the dght knee extensors, and torque and EMG were recorded. Plasma levels of IGF-I were normalized, and peak torque at 90° s-1, and peak torque endurance level increased after dose titration and 6 months constant GH-dose. The change in IGF-I correlated positively with the changes in biomechanical output and EMG variables and a negative correlation existed with the perception of fatigue. Despite improvement during GH-substitution the patients still had about 10-20 % less muscle strength and endurance compared with the controls at the study end. In summary we found that individualized GH substitution improves muscle function and that the net increase in IGF-I levels indicates generally increases in biomechanical output and EMG variables and a lower perception of fatigue.

  • 32.
    Elert, Jessica
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Aspegren Kendall, Sally
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Larsson, Barbro
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Månsson, Bjarne
    Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Chronic pain and difficulty in relaxing postural muscles in patients with fibromyalgia and chronic whiplash associated disorders2001In: Journal of Rheumatology, ISSN 0315-162X, E-ISSN 1499-2752, Vol. 28, no 6, p. 1361-1368Article in journal (Refereed)
    Abstract [en]

    Objective. To investigate if muscle tension according to the surface electromyogram (EMG) of the shoulder flexors is increased in consecutive patients with fibromyalgia (FM) or chronic whiplash associated disorders (WAD). Methods. A total of 59 consecutive patients with FM (n = 36) or chronic WAD (n = 23) performed 100 maximal isokinetic contractions combined with surface electromyography of the trapezius and infraspinatus. A randomized group of pain-free female (n = 27) subjects served as control group. Peak torque initially (Pti) and absolute and relative peak torque at endurance level (PTe, PTer) were registered as output variables, together with the EMG level of unnecessary muscle tension, i.e., the signal amplitude ratio (SAR). Results. The patient groups had a higher level of unnecessary tension initially and at the endurance level. The patients had lower absolute output (PTi and PTe), but the relative levels (PTer) did not differ comparing all 3 groups. Subjects with FM had significantly higher body mass index (BMI) than the other groups. BMI did not influence the SAR but correlated positively with PTi. Conclusion. The results confirmed earlier findings that groups of patients with chronic pain have increased muscle tension and decreased output during dynamic activity compared to pain-free controls. However, the results indicated there is heterogeneity within groups of patients with the same chronic pain disorder and that not all patients with chronic pain have increased muscle tension.

  • 33.
    Elert, Jessica
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Physiotherapy.
    Sterner, Ylva
    Nyberg, Vanja
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Lack of gender differences in the ability to relax between repetitive maximum isokinetic shoulder forward flexions: A population-based study among northern Swedes2000In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 83, no 4-5, p. 246-256Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to analyse the effects of gender and age in a population-based sample of clinically healthy subjects on: (1) strength, endurance and perception of fatigue, (2) mean frequency (MNF) of the electromyogram (EMG), and (3) the ability to relax between active contractions (signal amplitude ratio, SAR) of the surface EMG of an isokinetic shoulder forward flexion test. With this aim we have analysed aspects of the validity of MNF as an indicator of fatigue, using peak torque as a criterion variable. The subjects were 27 men and 28 women (age range: 20-60 years), who were obtained by random sample from the official census lists (participation rate: 66%). The peak torque and surface EMG of two portions of the trapezius, deltoid and infraspinatus muscles were recorded throughout 100 repetitive maximal isokinetic shoulder forward flexions. No significant differences in the perception of fatigue and relative endurance levels of peak torque and work were found between males and females. Males were significantly stronger than females and, on average, females produced approximately 60% of the output of the males, 76% after normalisation for body mass. The men had significantly lower MNF endurance levels for three of the investigated muscles. When controlled for age and body mass, the men had a significantly higher MNF of the deltoid muscle than did the females. These differences were only found for the deltoid muscle. Significant correlations existed between the MNF of the four muscles and biomechanical output, indicating criterion validity for the MNF variable with respect to fatigue. There were no significant effects of gender or age on the ability to relax between repetitive contractions (SAR). The higher prevalence of musculoskeletal complaints of the neck-shoulder region in females cannot be explained by a higher intrinsic muscle tension. Age, gender, body mass index and biomechanical output can have significant effects upon MNF. These effects are important considerations in the interpretation of MNF, for instance in ergonomic situations.

  • 34.
    Elert, Jessica
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Sydnerth, S-B.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Åbjörnsson, L.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Aspects of criterion validity and sensitivity of the BAS-health scale in chronic pain patients - a pilot study of patients at a multidisciplinary pain centre.1999In: Advances in Physics, ISSN 0001-8732, E-ISSN 1460-6976, Vol. 1, p. 83-97Article in journal (Refereed)
  • 35.
    Ernberg, M.
    et al.
    Karolinska Institutet, Huddinge, Sweden.
    Castrillon, E.E.
    Aarhus University, Denmark.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre. Östergötlands Läns Landsting, Heart and Medicine Centre, Occupational and Environmental Medicine Centre.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    List, T.
    Malmö University, Sweden.
    Svensson, P.
    Aarhus University and Aarhus University Hospital, Denmark.
    Experimental myalgia induced by repeated infusion of acidicsaline into the human masseter muscle does not cause the release of algesic substances2013In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 17, no 4, p. 539-550Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

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

    RESULTS:

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

    CONCLUSION:

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

  • 36.
    Ernberg, Malin
    et al.
    Karolinska Institute, Sweden; SCON, Sweden.
    Christidis, Nikolaos
    Karolinska Institute, Sweden; SCON, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Bileviciute-Ljungar, Indre
    Karolinska Institute, Sweden; Danderyd Hospital, Sweden.
    Löfgren, Monika
    Karolinska Institute, Sweden; Danderyd Hospital, Sweden.
    Larsson, Anette
    University of Gothenburg, Sweden; University of Gothenburg, Sweden.
    Palstam, Annie
    University of Gothenburg, Sweden.
    Bjersing, Jan
    University of Gothenburg, Sweden.
    Mannerkorpi, Kaisa
    University of Gothenburg, Sweden; University of Gothenburg, Sweden.
    Kosek, Eva
    Karolinska Institute, Sweden; Stockholm Spine Centre, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Effects of 15 weeks of resistance exercise on pro-inflammatory cytokine levels in the vastus lateralis muscle of patients with fibromyalgia2016In: Arthritis Research & Therapy, ISSN 1478-6354, E-ISSN 1478-6362, Vol. 18, no 137Article in journal (Refereed)
    Abstract [en]

    Background: This study aimed at investigating the effect of a resistance exercise intervention on the interstitial muscle levels of pro-inflammatory cytokines in fibromyalgia (FMS) and healthy controls (CON). Methods: Twenty-four female patients with FMS (54 +/- 8 years) and 27 female CON (54 +/- 9 years) were subjected to intramuscular microdialysis of the most painful vastus lateralis muscle before and after 15 weeks of progressive resistance exercise twice per week. Baseline dialysates were sampled in the resting muscle 140 min after insertion of the microdialysis catheter. The participants then performed repetitive dynamic contractions (knee extension) for 20 min, followed by 60 min rest. Pain intensity was assessed with a 0-100 mm visual analogue scale (VAS), and fatigue was assessed with Borgs RPE throughout microdialysis. Dialysates were sampled every 20 min and analyzed with Luminex for interleukin (IL)-1 beta, tumor necrosis factor (TNF) alpha, IL-6, and IL-8. Results: At both sessions and for both groups the dynamic contractions increased pain (P amp;lt; 0.012) and fatigue (P amp;lt; 0.001). The levels of TNF were lower in the FMS group than the CON group at both sessions (P amp;lt; 0.05), but none of the other cytokines differed between the groups. IL-6 and IL-8 increased after the dynamic contractions in both groups (P amp;lt; 0.010), while TNF increased only in CON (P amp;lt; 0.05) and IL-1 beta did not change. Overall pain intensity was reduced after the 15 weeks of resistance exercise in FMS (P amp;lt; 0.05), but there was no changes in fatigue or cytokine levels. Conclusion: Progressive resistance exercise for 15 weeks did not affect the interstitial levels of IL-1 beta, TNF, IL-6, and IL-8 in the vastus lateralis muscle of FMS patients or CON.

  • 37.
    Ertzgaard, Per
    et al.
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Rehabilitation Medicine. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Ohberg, Fredrik
    Umeå University, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Grip, Helena
    Umeå University, Sweden.
    A new way of assessing arm function in activity using kinematic Exposure Variation Analysis and portable inertial sensors - A validity study2016In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 21, p. 241-249Article in journal (Refereed)
    Abstract [en]

    Portable motion systems based on inertial motion sensors are promising methods, with the advantage compared to optoelectronic cameras of not being confined to a laboratory setting. A challenge is to develop relevant outcome measures for clinical use. The aim of this study was to characterize elbow and shoulder motion during functional tasks, using portable motion sensors and a modified Exposure Variation Analysis (EVA) and evaluate system accuracy with optoelectronic cameras. Ten healthy volunteers and one participant with sequel after stroke performed standardised functional arm tasks. Motion was registered simultaneously with a custom developed motion sensor system, including gyroscopes and accelerometers, and an optoelectronic camera system. The EVA was applied on elbow and shoulder joints, and angular and angular velocity EVA plots was calculated. The EVA showed characteristic patterns for each arm task in the healthy controls and a distinct difference between the affected and unaffected arm in the participant with sequel after stroke. The accuracy of the portable system was high with a systematic error ranging between -1.2 degrees and 2.0 degrees. The error was direction specific due to a drift component along the gravity vector. Portable motion sensor systems have high potential as clinical tools for evaluation of arm function. EVA effectively illustrates joint angle and joint angle velocity patterns that may capture deficiencies in arm function and movement quality. Next step will be to manage system drift by including magnetometers, to further develop clinically relevant outcome variables and apply this for relevant patient groups. (C) 2015 Elsevier Ltd. All rights reserved.

  • 38.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Förekomst av kroniska/långvariga smärtor2006In: Rehabiliteringsmedicin Teori och praktik / [ed] Jörgen Borg,Björn Gerdle, Gunnar Grimby, Katharina Stibrant Sunnerhagen, Lund: Studenltitteratur , 2006, 1, p. 73-77Chapter in book (Other academic)
    Abstract [sv]

        Kapitel om rehabiliteringsmedicinens utveckling och nuvarande plats i sjukvården samt begrepp och metodik inleder boken. I två delar ges därefter rehabiliteringsmedicinska aspekter på de dominerande sjukdomsgrupperna - komplexa smärttillstånd respektive skador och sjukdomar i nervsystemet. Som avslutning beskrivs bland annat  stressrelaterade tillstånd. Läroboken är avsedd för grundutbildning av läkare, arbetsterapeuter och sjukgymnaster, logopeder samt för läkare under AT-tjänstgöring. Den är också lämplig som introduktion i specialistutbildningen i rehabiliteringsmedicin, geriatrik, neurologi och smärtlindring. Vidareutbildningar av olika vårdyrkesgrupper kan ha nytta av boken och den kan också användas som referenslitteratur av yrkesverksamma med intresse för rehabiliteringsmedicin.

  • 39.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Björk, Jonas
    Competence Centre for Clinical Research Lund University Hospital.
    Cöster, Lars
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rheumatology . Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Henriksson, Karl-Gösta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Henriksson, Chris
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Social and Welfare Studies.
    Bengtsson, Ann
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rheumatology . Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Prevalence of widespread pain and associations with work status: A population study2008In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 9Article in journal (Refereed)
    Abstract [en]

    Background. This population study based on a representative sample from a Swedish county investigates the prevalence, duration, and determinants of widespread pain (WSP) in the population using two constructs and estimates how WSP affects work status. In addition, this study investigates the prevalence of widespread pain and its relationship to pain intensity, gender, age, income, work status, citizenship, civil status, urban residence, and health care seeking. Methods. A cross-sectional survey using a postal questionnaire was sent to a representative sample (n = 9952) of the target population (284,073 people, 18-74 years) in a county (Östergötland) in the southern Sweden. The questionnaire was mailed and followed by two postal reminders when necessary. Results. The participation rate was 76.7% (n = 7637), the non-participants were on the average younger, earned less money, and male. Women had higher prevalences of pain in 10 different predetermined anatomical regions. WSP was generally chronic (90-94%) and depending on definition of WSP the prevalence varied between 4.8-7.4% in the population. Women had significantly higher prevalence of WSP than men and the age effect appeared to be stronger in women than in men. WSP was a significant negative factor - together with age 50-64 years, low annual income, and non-Nordic citizen - for work status in the community and in the group with chronic pain. Chronic pain but not the spreading of pain was related to health care seeking in the population. Conclusion. This study confirms earlier studies that report high prevalences of widespread pain in the population and especially among females and with increasing age. Widespread pain is associated with prominent effects on work status. © 2008 Gerdle et al, licensee BioMed Central Ltd.

  • 40.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Björk, Jonas
    Lunds Universitet.
    Henriksson, Chris
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Occupational Therapy.
    Bengtsson, Ann
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Rheumatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Prevalence of current and chronic pain and their influences upon work and healthcare-seeking: A population study2004In: Journal of Rheumatology, ISSN 0315-162X, E-ISSN 1499-2752, Vol. 31, no 7, p. 1399-1406Article in journal (Refereed)
    Abstract [en]

    Objective. To investigate the prevalence of current and chronic pain and their relationship to pain intensity, sex, age, income, employment status, citizenship, marital status, urban residence, occupational activity, and healthcare-seeking based on a representative sample from a Swedish county. Methods. A cross-sectional survey using a postal questionnaire was sent to a representative sample (n = 9952) of the target population (284,073 people, age 18-74 yrs) in a county (Östergötland) in southern Sweden. A questionnaire was mailed and followed by 2 postal reminders if necessary. Results. The participation rate was 76.7% (n = 7637), nonparticipants were on average younger, male, and earned less money. The overall point prevalence of pain was 48.9%. The corresponding one-month period prevalence was 63.0%, and pain on several occasions during the previous 3 months was reported by 61.3% of participants. The prevalence of chronic pain (pain > 3 months) was 53.7%. Female sex, age, and sick leave/early retirement were generally of significant importance in the regressions of pain. No sex factor was found in the regressions of pain frequency and pain intensity. Chronic pain - especially frequent and intensive pain - showed clear associations with healthcare-seeking and occupational activity. Conclusion. High prevalence of current pain (48.9%) and chronic pain (53.7%) were found in this community-based study. Being female, older, and on sick leave or early retirement were generally of significant importance in the regressions of pain. Chronic pain showed clear associations with healthcare-seeking and occupational activity, indicating considerable socioeconomic costs.

  • 41.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Boivie, Jörgen
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Neurology. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
    Johansson, Eva
    Umeå Universitet.
    Inledning2006In: Metoder för behandling av långvarig smärta - en systematisk litteraturöversikt / [ed] Statens beredning för medicinsk utvärdering, Stockholm: Statens beredning för medicinsk utvärdering (SBU) , 2006, 2, p. 47-107Chapter in book (Other academic)
    Abstract [sv]

      

    Syftet med rapporten är att sammanfatta det vetenskapliga underlaget rörande effekter, biverkningar samt kostnadseffektivitet för metoder som används för att behandla långvarig, icke-cancerrelaterad smärta. Behandling som innebär öppen kirurgi har exkluderats från genomgången.

  • 42.
    Gerdle, Björn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ernberg, Malin
    Karolinska Institute, Department of Dental Medicine, Section of Orofacial Pain and Jaw Function / Scandinavian Centre for Orofacial Neuroscience (SCON), Stockholm, Sweden.
    Mannerkorpi, Kaisa
    Section of Physiotherapy, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden / University of Gothenburg Centre for Person-Centred Care (GPCC), Sahlgrenska Academy, Gothenburg, Sweden.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Kosek, Eva
    Department of Clinical Neuroscience and Osher Centre for Integrative Medicine, Karolinska Institute, Stockholm, Sweden.
    Christidis, Nikolaos
    Karolinska Institute, Department of Dental Medicine, Section of Orofacial Pain and Jaw Function / Scandinavian Centre for Orofacial Neuroscience (SCON), Stockholm, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Increased Interstitial Concentrations of Glutamate and Pyruvate in Vastus Lateralis of Women with Fibromyalgia Syndrome Are Normalized after an Exercise Intervention: a Case-Control Study2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 10, p. 14article id e0162010Article in journal (Refereed)
    Abstract [en]

    Background Fibromyalgia syndrome (FMS) is associated with central alterations, but controversies exist regarding the presence and role of peripheral factors. Microdialysis (MD) can be used in vivo to study muscle alterations in FMS. Furthermore for chronic pain conditions such as FMS, the mechanisms for the positive effects of exercise are unclear. This study investigates the interstitial concentrations of algesics and metabolites in the vastus lateralis muscle of 29 women with FMS and 28 healthy women before and after an exercise intervention. Methods All the participants went through a clinical examination and completed a questionnaire. In addition, their pressure pain thresholds (PPTs) in their upper and lower extremities were determined. For both groups, MD was conducted in the vastus lateralis muscle before and after a 15-week exercise intervention of mainly resistance training of the lower limbs. Muscle blood flow and interstitial muscle concentrations of lactate, pyruvate, glutamate, glucose, and glycerol were determined. Results FMS was associated with significantly increased interstitial concentrations of glutamate, pyruvate, and lactate. After the exercise intervention, the FMS group exhibited significant decreases in pain intensity and in mean interstitial concentrations of glutamate, pyruvate, and glucose. The decrease in pain intensity in FMS correlated significantly with the decreases in pyruvate and glucose. In addition, the FMS group increased their strength and endurance. Conclusion This study supports the suggestion that peripheral metabolic and algesic muscle alterations are present in FMS patients and that these alterations contribute to pain. After an exercise intervention, alterations normalized, pain intensity decreased (but not abolished), and strength and endurance improved, all findings that suggest the effects of exercise are partially peripheral.

  • 43.
    Gerdle, Björn
    et al.
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Forsgren, Mikael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Bengtsson, Ann
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Rheumatology.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Sören, B.
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Rheumatology.
    Karlsson, Anette
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences.
    Brandejsky, Vaslav
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Lund, Eva
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Östergötlands Läns Landsting, Center for Diagnostics, Department of Radiology in Linköping.
    Decreased muscle concentrations of ATP and PCR in the quadriceps muscle of fibromyalgia patients – A 31P-MRS study2013In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 17, no 8, p. 1205-1215Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND METHODS:

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

    RESULTS:

    Significantly lower concentrations of adenosine triphosphate (ATP) and phosphocreatinine (PCr; 28-29% lower) were found in FMS. No significant group differences existed with respect to inorganic phosphate (Pi), Pi/PCr and pH. The quadriceps muscle fat content was significantly higher in FMS than in Controls [FMS: 9.0 ± 0.5% vs. Controls: 6.6 ± 0.6%; (mean ± standard error); P = 0.005]. FMS had significantly lower hand and leg capacity according to specific physical test, but there were no group differences in body mass index, subjective activity level and in aerobic fitness. In FMS, the specific physical capacity in the leg and the hand correlated positively with the concentrations of ATP and PCr; no significant correlations were found with pain intensities.

    CONCLUSIONS:

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

  • 44.
    Gerdle, Björn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Östergötlands Läns Landsting, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Ernberg, Malin
    Karolinska Institutet, Huddinge, Sweden.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Chronic musculoskeletal pain: review of mechanisms and biochemical biomarkers as assessed by the microdialysis technique2014In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 7, p. 313-326Article, review/survey (Refereed)
    Abstract [en]

    Chronic musculoskeletal pain conditions are multifaceted, and approximately 20% of the adult population lives with severe chronic pain, with a higher prevalence in women and in lower income groups. Chronic pain is influenced by and interacts with physical, emotional, psychological, and social factors, and a biopsychosocial framework is increasingly applied in clinical practice. However, there is still a lack of assessment procedures based on the activated neurobiological pain mechanisms (ie, the biological part of the biopsychosocial model of pain), which may be a necessary step for further optimizing outcomes after treatments for patients with chronic pain. It has been suggested that chronic pain conditions are mainly driven by alterations in the central nervous system with little or no peripheral stimuli or nociception. In contrast, other authors argue that such central alterations are driven by peripheral alterations and nociceptive input. Microdialysis is an in vivo method for studying local tissue alterations and allows for sampling of substances in the interstitium of the muscle, where nociceptor free nerve endings are found close to the muscle fibers. The extracellular matrix plays a key role in physiologic functions of cells, including the primary afferent nociceptor. The present review mainly concerns the results of microdialysis studies and how they can contribute to the understanding of activated peripheral nociceptive and pain mechanisms in humans with chronic pain. The primary aim was to review molecular studies using microdialysis for the investigation of human chronic muscle pain, ie, chronic masticatory muscle pain, chronic trapezius myalgia, chronic whiplash-associated disorders, and chronic widespread pain/fibromyalgia syndrome. Several studies clearly showed elevated levels of serotonin, glutamate, lactate, and pyruvate in localized chronic myalgias and may be potential biomarkers. These results indicate that peripheral muscle alterations are parts of the activated pain mechanisms in common chronic pain conditions. Muscle alterations have been reported in fibromyalgia syndrome and chronic widespread pain, but more studies are needed before definite conclusions can be drawn. For other substances, results are inconclusive across studies and patient groups.

  • 45.
    Gerdle, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gronlund, Christer
    Umeå University Hospital.
    Karlsson, Stefan J
    Umeå University Hospital.
    Holtermann, Andreas
    National Research Centre Working Environment, Copenhagen.
    Roeleveld, Karin
    Norwegian University Science and Technology.
    Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia2010In: BMC MUSCULOSKELETAL DISORDERS, ISSN 1471-2474, Vol. 11, no 42Article in journal (Refereed)
    Abstract [en]

    Background: fibromyalgia is a relatively common condition with widespread pain and pressure allodynia, but unknown aetiology. For decades, the association between motor control strategies and chronic pain has been a topic for debate. One long held functional neuromuscular control mechanism is differential activation between regions within a single muscle. The aim of this study was to investigate differences in neuromuscular control, i.e. differential activation, between myalgic trapezius in fibromyalgia patients and healthy controls. Methods: 27 fibromyalgia patients and 30 healthy controls performed 3 minutes bilateral shoulder elevations with different loads (0-4 Kg) with a high-density surface electromyographical (EMG) grid placed above the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. Results: the median frequency of the differential activations was significantly lower, and the average duration of the differential activations significantly longer in fibromyalgia compared with controls at the two lowest load levels (0-1 Kg) (p andlt; 0.04), but not at the two highest load levels (2 and 4 Kg). Conclusion: these findings illustrate a different neuromuscular control between fibromyalgia patients and healthy controls during a low load functional task, either sustaining or resulting from the chronic painful condition. The findings may have clinical relevance for rehabilitation strategies for fibromyalgia.

  • 46.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gullacksen, Ann-Christine
    Malmö Högskola.
    Multimodal rehabilitering2006In: Metoder för behandling av långvarig smärta - En systematisk litteraturöversikt / [ed] Statens beredning för medicinsk utvärdering, Stockholm: Statens beredning för medicinsk utvärdering (SBU) , 2006, 2, p. 159-213Chapter in book (Other academic)
    Abstract [sv]

    Syftet med rapporten är att sammanfatta det vetenskapliga underlaget rörande effekter, biverkningar samt kostnadseffektivitet för metoder som används för att behandla långvarig, icke-cancerrelaterad smärta. Behandling som innebär öppen kirurgi har exkluderats från genomgången.

  • 47.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gullacksen, Ann-Christine
    Malmö Högskola.
    Rehabilitering vid kronisk smärta-särskilt multimodal rehabiltiering2006In: Rehabiliteringsmedicin - Teori och praktik / [ed] Jörgen Borg,Björn Gerdle, Gunnar Grimby, Katharina Stibrant Sunnerhagen, Lund: Studentlitteratur , 2006, 1, p. 97-107Chapter in book (Other academic)
    Abstract [sv]

      Kapitel om rehabiliteringsmedicinens utveckling och nuvarande plats i sjukvården samt begrepp och metodik inleder boken. I två delar ges därefter rehabiliteringsmedicinska aspekter på de dominerande sjukdomsgrupperna - komplexa smärttillstånd respektive skador och sjukdomar i nervsystemet. Som avslutning beskrivs bland annat  stressrelaterade tillstånd. Läroboken är avsedd för grundutbildning av läkare, arbetsterapeuter och sjukgymnaster, logopeder samt för läkare under AT-tjänstgöring. Den är också lämplig som introduktion i specialistutbildningen i rehabiliteringsmedicin, geriatrik, neurologi och smärtlindring. Vidareutbildningar av olika vårdyrkesgrupper kan ha nytta av boken och den kan också användas som referenslitteratur av yrkesverksamma med intresse för rehabiliteringsmedicin.

  • 48.
    Gerdle, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Hilgenfeldt, Ulrich
    University of Heidelberg.
    Larsson, Britt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Kristiansen, Jesper
    National Research Centre for the Working Environment.
    Sogaard, Karen
    National Research Centre for the Working Environment.
    Rosendal, Lars
    Cyncron A/S.
    Bradykinin and kallidin levels in the trapezius muscle in patients with work-related trapezius myalgia, in patients with whiplash associated pain, and in healthy controls - A microdialysis study of women2008In: PAIN, ISSN 0304-3959, Vol. 139, no 3, p. 578-587Article in journal (Refereed)
    Abstract [en]

    The origins of chronic Muscle pain development and maintenance are debated regarding the relative contributions of peripheral nociception and central pain processing. Bradykinin (BKN) and kallidin (KAL) have been suggested to be algesic kinins involved in muscle pain. This in vivo study investigates whether there were significant differences in interstitial muscle concentrations of BKN and KAL between chronic work-related trapezius myalgia (TM), chronic whiplash associated disorders (WAD), and healthy controls (CON). These subjects were studied Lit rest, during a 20-min repetitive low-force exercise and recovery. The interstitial concentrations of BKN and KAL of trapezius were determined using the microdialysis technique. The interstitial concentration of KAL was overall significantly higher in TM than in CON. [KAL] and [BKN] increased significantly during the brief exercise in all groups. The increase in [BKN] during exercise was significantly higher in TM than in the other two groups,whereas the increase in [KAL] during exercise was highest in WAD. In chronic pain, positive correlations existed between the two kinins and the difference in pain intensity between recovery and baseline. In this in vivo study of two groups of patients with chronic pain clinically involving the trapezius muscle, we found alterations - most prominent in TM in the interstitial concentrations of BKN and KAL. The results indicated that the two kinins were involved in aspects of hyperalgesia.

  • 49.
    Gerdle, Björn
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Karlsson, S
    Crenshaw, AG
    Elert, Jessica
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Physiotherapy.
    Fridén, J
    The influences of muscle fibre proportions and areas upon EMG during maximal dynamic knee extensions2000In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 81, no 1-2Article in journal (Refereed)
    Abstract [en]

    This study is an investigation of the relationship between muscle morphology and surface electromyographic (EMG) parameters [mean frequency of the power spectrum (MNF), signal amplitude (root mean square, RMS) and the signal amplitude ratio (SAR, i.e. the ratio between the RMS level during the passive part of the contraction cycle and the RMS level during the active part of the contraction cycle)] during 100 maximal dynamic knee extensions at 90░.s-1. Each contraction cycle comprised of 1 s of active knee extension and 1 s of passive knee flexion. The surface EMG was recorded from the vastus lateralis muscle. Twenty clinically healthy subjects participated in the study, and muscle biopsy samples of the vastus lateralis were obtained from 19 of those subjects. The relationships between muscle morphology and EMG were investigated at three stages of the test: initially, during the fatigue phase (initial 40 contractions), and at the endurance level (the final 50 contractions). Major findings on correlations are that SAR and MNF tended to correlate positively with the proportion of type 1 fibres, and RMS correlated positively with the proportion of type 2 muscle fibres. The muscle fibre areas showed little correlation with the EMG variables under investigation. The results of the present study showed that the three EMG variables of a dynamic endurance test that were investigated (RMS, MNF and SAR were clearly correlated with the proportions of the different fibre types, but only to a small extent with fibre areas. These findings contradict some of the theoretical models of the EMG, especially for parameters in the frequency domain.

  • 50.
    Gerdle, Björn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Kristiansen, Jesper
    National Research Centre Working Environm, Denmark.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Saltin, Bengt
    University of Copenhagen, Denmark.
    Sogaard, Karen
    University of Southern Denmark, Denmark.
    Sjogaard, Gisela
    University of Southern Denmark, Denmark.
    Algogenic substances and metabolic status in work-related Trapezius Myalgia: a multivariate explorative study2014In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 15, no 357Article in journal (Refereed)
    Abstract [en]

    Background: This study compares the levels of algesic substances between subjects with trapezius myalgia (TM) and healthy controls (CON) and explores the multivariate correlation pattern between these substances, pain, and metabolic status together with relative blood flow changes reported in our previous paper (Eur J Appl Physiol 108: 657-669, 2010). Methods: 43 female workers with (TM) and 19 females without (CON) trapezius myalgia were - using microdialysis - compared for differences in interstitial concentrations of interleukin-6 (IL-6), bradykinin (BKN), serotonin (5-HT), lactate dehydrogenas (LDH), substance P, and N-terminal propeptide of procollagen type I (PINP) in the trapezius muscle at rest and during repetitive/stressful work. These data were also used in multivariate analyses together with previously presented data (Eur J Appl Physiol 108: 657-669, 2010): trapezius muscle blood flow, metabolite accumulation, oxygenation, and pain development and sensitivity. Results: Substance P was significantly elevated in TM (p=0.0068). No significant differences were found in the classical algesic substances (p: 0.432-0.926). The multivariate analysis showed that blood flow related variables, interstitial concentrations of metabolic (pyruvate), and algesic (BKN and K+) substances were important for the discrimination of the subjects to one of the two groups (R-2: 0.19-0.31, pless than0.05). Pain intensity was positively associated with levels of 5-HT and K+ and negatively associated with oxygenation indicators and IL-6 in TM (R-2: 0.24, pless than0.05). A negative correlation existed in TM between mechanical pain sensitivity of trapezius and BKN and IL-6 (R-2: 0.26-0.39, pless than0.05). Conclusion: The present study increased understanding alterations in the myalgic muscle. When considering the system-wide aspects, increased concentrations of lactate, pyruvate and K+ and decreased oxygenation characterized TM compared to CON. There are three major possible explanations for this finding: the workers with pain had relatively low severity of myalgia, metabolic alterations preceded detectable alterations in levels of algesics, or peripheral sensitization and other muscle alterations existed in TM. Only SP of the investigated algesic substances was elevated in TM. Several of the algesics were of importance for the levels of pain intensity and mechanical pain sensitivity in TM. These results indicate peripheral contribution to maintenance of central nociceptive and pain mechanisms and may be important to consider when designing treatments.

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