Eye Pain and Dry Eye in Patients with Fibromyalgia.

Objectives: The aim of this study was to examine visual function and eye symptoms in fibromyalgia patients, with a particular focus on dry eye syndrome and eye pain. Methods: A tertiary care center-based cross-sectional study was carried out in chronic musculoskeletal pain patients diagnosed with fibromyalgia. Chronic musculoskeletal pain patients without fibromyalgia were enrolled as a comparison group. Self-reported eye pain was investigated with the McGill pain questionnaire and the numeric rating scale. In addition, we assessed corrected visual acuity, vision-related quality of life, and self-reported dry eye syndrome. Results: A total of 90 musculoskeletal pain patients were included, with 66 patients fulfilling American College of Rheumatology 1990 criteria for fibromyalgia. Sixty-seven percent (95% confidence interval [CI] = 56%-78%) of the fibromyalgia patients reported eye pain, and 62% (95% CI = 43%-81%) of those were without fibromyalgia diagnosis. Sixty-seven percent (95% CI = 56%-78%) of the fibromyalgia patients reported an experience of dry eye compared with 76% (95% CI = 57%-95%) in the nonfibromyalgia group. Vision-related quality of life was noticeably reduced in both groups. Conclusions: Eye pain and dry eye are common in chronic pain patients, with comparable prevalence in musculoskeletal pain patients with and without fibromyalgia.

Conditioned pain modulation in patients with nonspecific chronic back pain with chronic local pain, chronic widespread pain, and fibromyalgia.

Findings considering conditioned pain modulation (CPM) in chronic back pain (CBP) are contradictory. This might be because many patients with CBP report pain in further areas of the body, and altered CPM might influence spatial extent of pain rather than CBP per se. Therefore, we compared CPM in patients with CBP with different pain extent. Patients with fibromyalgia syndrome (FMS), for whom CPM impairment is reported most consistently, were measured for comparison. Based on clinical evaluation and pain drawings, patients were categorized into chronic local back pain (CLP; n = 53), chronic widespread back pain (CWP; n = 32), and FMS (n = 92). Conditioned pain modulation was measured by the difference in pressure pain threshold (test stimuli) at the lower back before and after tonic heat pain (conditioning stimulus). We also measured psychosocial variables. Pressure pain threshold was significantly increased in CLP patients after tonic heat pain (P < 0.001) indicating induction of CPM. Conditioned pain modulation in CLP was significantly higher than that in CWP and FMS (P < 0.001), but CPM in CWP and FMS did not differ. Interestingly, a higher number of painful areas (0-10) were associated with lower CPM (r = 0.346, P = 0.001) in CBP but not in FMS (r = -0.013, P = 0.903). Anxiety and depression were more pronounced in FMS than in CLP or CWP (P values <0.01). Our findings suggest that CPM dysfunction is associated with CWP and not with FMS as suggested previously. FMS seems to differ from CWP without FMS by higher psychosocial burden. Moreover, patients with CBP should be stratified into CLP and CWP, and centrally acting treatments targeting endogenous pain inhibition seem to be more indicated the higher the pain extent.

Altered pressure pain thresholds and increased wind-up in adult patients with chronic back pain with a history of childhood maltreatment: a quantitative sensory testing study.

Childhood maltreatment (CM) has been associated with an increased risk of nonspecific chronic low back pain (nsCLBP). However, the mechanisms underlying this association are unclear. Therefore, this study considered whether distinct types of CM are accompanied by specific alterations in somatosensory function. A total of 176 subjects with nsCLBP and 27 pain-free controls (PCs) were included. The Childhood Trauma Questionnaire (CTQ) was used to categorize patients into 2 groups (abused/neglected vs nonabused/nonneglected) for 5 types of CM (emotional abuse, physical abuse, sexual abuse, emotional neglect, and physical neglect). The standardized quantitative sensory testing protocol of the "German Research Network on Neuropathic Pain" was performed to obtain comprehensive profiles on somatosensory function, including detection and pain thresholds, pain sensitivity, and assessments of temporal summation (wind-up). Between 17.7% and 51.4% of subjects with nsCLBP reported CM, depending on the type of CM. Childhood Trauma Questionnaire subscores for emotional and sexual abuse were significantly higher in subjects with nsCLBP than in PCs. Compared with PCs, subjects with CM showed reduced pressure pain thresholds (PPTs), irrespective of the type of CM. Regarding distinct types of CM, subjects with nsCLBP with emotional abuse reported significantly higher wind-up than those without, and sexual abuse was accompanied by enhanced touch sensitivity. Our findings suggest that CM is nonspecifically associated with a decreased PPT in nsCLBP. Emotional abuse apparently leads to enhanced spinal pain summation, and sexual abuse leads to enhanced touch sensitivity. These results emphasize the importance of emotional abuse in nsCLBP and suggest that CM can induce long-term changes in adult somatosensory function.

Eye Movement Desensitization and Reprocessing vs. Treatment-as-Usual for Non-Specific Chronic Back Pain Patients with Psychological Trauma: A Randomized Controlled Pilot Study.

OBJECTIVE: Eye movement desensitization and reprocessing (EMDR)-an evidence-based approach to eliminate emotional distress from traumatic experiences-was recently suggested for the treatment of chronic pain. The aim of this study was to estimate preliminary efficacy of a pain-focused EMDR intervention for the treatment of non-specific chronic back pain (CBP). DESIGN: Randomized controlled pilot study. METHODS: 40 non-specific CBP (nsCBP) patients reporting previous experiences of psychological trauma were consecutively recruited from outpatient tertiary care pain centers. After baseline assessment, patients were randomized to intervention or control group (1:1). The intervention group received 10 sessions standardized pain-focused EMDR in addition to treatment-as-usual (TAU). The control group received TAU alone. The primary outcome was preliminary efficacy, measured by pain intensity, disability, and treatment satisfaction from the patients' perspective. Clinical relevance of changes was determined according to the established recommendations. Assessments were conducted at the baseline, posttreatment, and at a 6-month follow-up. Intention-to-treat analysis with last observation carried forward method was used. Registered with http://ClinicalTrials.gov (NCT01850875). RESULTS: Estimated effect sizes (between-group, pooled SD) for pain intensity and disability were d = 0.79 (CI95%: 0.13, 1.42) and d = 0.39 (CI95%: -0.24, 1.01) posttreatment, and d = 0.50 (CI95%: 0.14, 1.12) and d = 0.14 (CI95%: -0.48, 0.76) at 6-month follow-up. Evaluation on individual patient basis showed that about 50% of the patients in the intervention group improved clinically relevant and also rated their situation as clinically satisfactory improved, compared to 0 patients in the control group. CONCLUSION: There is preliminary evidence that pain-focused EMDR might be useful for nsCBP patients with previous experiences of psychological trauma, with benefits for pain intensity maintained over 6 months.

Chronic Widespread Back Pain is Distinct From Chronic Local Back Pain: Evidence From Quantitative Sensory Testing, Pain Drawings, and Psychometrics.

OBJECTIVES: Whether chronic localized pain (CLP) and chronic widespread pain (CWP) have different mechanisms or to what extent they overlap in their pathophysiology is controversial. The study compared quantitative sensory testing profiles of nonspecific chronic back pain patients with CLP (n=48) and CWP (n=29) with and fibromyalgia syndrome (FMS) patients (n=90) and pain-free controls (n = 40). MATERIALS AND METHODS: The quantitative sensory testing protocol of the "German-Research-Network-on-Neuropathic-Pain" was used to measure evoked pain on the painful area in the lower back and the pain-free hand (thermal and mechanical detection and pain thresholds, vibration threshold, pain sensitivity to sharp and blunt mechanical stimuli). Ongoing pain and psychometrics were captured with pain drawings and questionnaires. RESULTS: CLP patients did not differ from pain-free controls, except for lower pressure pain threshold (PPT) on the back. CWP and FMS patients showed lower heat pain threshold and higher wind-up ratio on the back and lower heat pain threshold and cold pain threshold on the hand. FMS showed lower PPT on back and hand, and higher comorbidity of anxiety and depression and more functional impairment than all other groups. DISCUSSION: Even after long duration CLP presents with a local hypersensitivity for PPT, suggesting a somatotopically specific sensitization of nociceptive processing. However, CWP patients show widespread ongoing pain and hyperalgesia for different stimuli that is generalized in space, suggesting the involvement of descending control systems, as also suggested for FMS patients. Because mechanisms in nonspecific chronic back pain with CLP and CWP differ, these patients should be distinguished in future research and allocated to different treatments.

The Course of the Spatial Extent of Pain in Nonspecific Chronic Back Pain: A Prospective Population-based Cohort Study With Clinical Evaluation.

OBJECTIVES: Longitudinal population-based studies on the natural course of nonspecific chronic back pain (nsCBP) concerning the spatial extent of pain are scarce. This study aims to assess the natural course of nsCBP patients concerning their spatial extent of pain and physical impairment over time. METHODS: Analyses were based on a prospective, population-based survey with clinical evaluation. A representative population-based sample of 4000 German adults was sent a pain questionnaire. Patients mentioning nsCBP in the questionnaire were invited to a comprehensive clinical evaluation, including 1- and 2-year follow-ups. On the basis of pain drawings, the course of the spatial extent of pain over time was classified as "constant-local," "constant-widespread," "constant-amelioration," "constant-spreading," or "variable." Physical impairment was assessed by the Back Performance Scale as an objective clinical assessment tool that measures self-reported activity limitation in daily functioning caused by nsCBP. RESULTS: Pain drawings and physical assessment from 3 visits were available from 165 patients. The course of the spatial extent of pain was constant-local in 39.4% and constant-widespread in 18.2% of all patients, whereas 11.5% reported a variable course. Constant-amelioration was observed in 18.2% and constant-spreading was observed in 12.7%. Physical impairment remained unchanged over the time in all groups and was worst in the constant-widespread group. DISCUSSION: Most nsCBP patients report a stable pain extent over the time of the study, whereas a constant spread of pain is observed only in a minority of nsCBP patients. These findings challenge the concept of a continuous transition from local to widespread pain.

Shank Muscle Strength Training Changes Foot Behaviour during a Sudden Ankle Supination.

BACKGROUND: The peroneal muscles are the most effective lateral stabilisers whose tension braces the ankle joint complex against excessive supination. The purpose of this study was to identify the morphological and biomechanical effects of two machine-based shank muscle training methods. METHODS: Twenty-two healthy male recreationally active sports students performed ten weeks of single-set high resistance strength training with 3 training sessions per week. The subjects conducted subtalar pronator/supinator muscle training (ST) with the right leg by using a custom-made apparatus; the left foot muscles were exercised with machine-based talocrural plantar and dorsiflexor training (TT). Muscle strength (MVIC), muscle volume and foot biomechanics (rearfoot motion, ground reaction forces, muscle reaction times) during a sudden ankle supination were recorded before and after the intervention. RESULTS: Compared to TT, ST resulted in significantly higher pronator (14% vs. 8%, P<0.01) and supinator MVIC (25% vs. 12%, P<0.01). During sudden foot inversions, both ST and TT resulted in reduced supination velocity (-12%; P<0.01). The muscle reaction onset time was faster after the training in peroneus longus (PL) (P<0.01). Muscle volume of PL (P<0.01) and TA (P<0.01) increased significantly after both ST and TT. CONCLUSION: After both ST and TT, the ankle joint complex is mechanically more stabilised against sudden supinations due to the muscle volume increase of PL and TA. As the reduced supination velocities indicate, the strength training effects are already present during free-fall. According to a sudden ankle supination in standing position, both machine-based dorsiflexor and pronator strength training is recommended for enhancing the mechanical stability of the ankle.

Distinct quantitative sensory testing profiles in nonspecific chronic back pain subjects with and without psychological trauma.

Psychological trauma is associated with an increased risk for chronification of nonspecific chronic back pain (nsCLBP) independent of posttraumatic stress disorder (PTSD). However, the mechanisms underlying the role of psychological trauma in nsCLBP are less clear than in PTSD. Therefore, this study considered whether psychological trauma exposure (TE) is accompanied by specific alterations in pain perception. The study included 56 participants with nsCLBP and TE (nsCLBP-TE), 93 participants with nsCLBP without TE (nsCLBP-W-TE), and 31 pain-free controls. All participants underwent a thorough clinical evaluation. The standardized quantitative sensory testing protocol of the "German Research Network on Neuropathic Pain" was used to obtain comprehensive profiles on somatosensory functions in painful (back) and non-painful areas (hand). The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. Psychological trauma was validated by structured clinical interview. Trauma-associated symptom severity, anxiety, and depressive symptomatology were assessed by self-report questionnaires. Differences in somatosensory function were seen only for pressure pain thresholds. Compared with controls, nsCLBP-TE revealed hyperalgesia generalized in space with lower thresholds in painful and non-painful areas, whereas nsCLBP-W-TE demonstrated localized alterations with decreased thresholds only in the pain-affected area of the back (P ≤ 0.006). Our findings suggest an augmented central pain processing in nsCLBP-TE (alterations in painful and non-painful areas), whereas nsCLBP-W-TE show only local changes (alterations only in the painful area) suggesting regional sensitization processes. This finding might explain why TE without PTSD is associated with an increased prevalence of chronic pain.

Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): reference data for the trunk and application in patients with chronic postherpetic neuralgia.

Age- and gender-matched reference values are essential for the clinical use of quantitative sensory testing (QST). To extend the standard test sites for QST-according to the German Research Network on Neuropathic Pain-to the trunk, we collected QST profiles on the back in 162 healthy subjects. Sensory profiles for standard test sites were within normal interlaboratory differences. QST revealed lower sensitivity on the upper back than the hand, and higher sensitivity on the lower back than the foot, but no systematic differences between these trunk sites. Age effects were significant for most parameters. Females exhibited lower pressure pain thresholds (PPT) than males, which was the only significant gender difference. Values outside the 95% confidence interval of healthy subjects (considered abnormal) required temperature changes of >3.3-8.2 °C for thermal detection. For cold pain thresholds, confidence intervals extended mostly beyond safety cutoffs, hence only relative reference data (left-right differences, hand-trunk differences) were sufficiently sensitive. For mechanical detection and pain thresholds, left-right differences were 1.5-2.3 times more sensitive than absolute reference data. The most sensitive parameter was PPT, where already side-to-side differences >35% were abnormal. Compared to trunk reference data, patients with postherpetic neuralgia exhibited thermal and tactile deficits and dynamic mechanical allodynia, mostly without reduced mechanical pain thresholds. This pattern deviates from other types of neuropathic pain. QST reference data for the trunk will also be useful for patients with postthoracotomy pain or chronic back pain.

Everyday physical activity in ambulatory heart transplant candidates: the role of expected health benefits, social support, and potential barriers.

BACKGROUND: Physical activity (PA) is recommended for stable patients with advanced heart failure (HF). PURPOSE: We evaluated expected health benefits of PA and social support as facilitators of PA, and physical symptom distress and psychological distress (depression, anxiety) as barriers to PA. Additionally, we investigated if facilitators of PA are of particular importance for patients who report barriers. METHOD: We analyzed data assessed at time of waitlisting in 231 ambulatory patients (53.4 ± 10.3 years, 18 % women) who were enrolled in the multisite Waiting for a New Heart Study in 1 Austrian and 16 German hospitals. Self-reported everyday PA scores (number of activities, duration of activities) was regressed on demographic characteristics and indicators of disease severity (ejection fraction, peak oxygen consumption), facilitators (expected health benefits of PA, perceived emotional support, perceived support for PA), and barriers to PA (physical symptom distress, psychological distress). Interaction terms of facilitators with barriers were also examined. RESULTS: PA was positively associated with higher peak oxygen consumption, validating self-reported PA. Regarding facilitators, expected health benefits of PA were independently associated with higher PA (p values < 0.001). There were no main effects for social support on PA. Regarding barriers, depression tended to be associated with fewer activities (p = 0.068). However, in the presence of barriers (depression, physical symptoms), feeling supported for being physically active was positively associated with PA (p values < 0.05). CONCLUSION: Interventions to improve PA may benefit from strengthening positive expectations of health outcomes associated with everyday PA and fostering PA-specific social support for those distressed by HF symptoms or depression.

Effects of eye movement desensitization and reprocessing (EMDR) treatment in chronic pain patients: a systematic review.

OBJECTIVE: This study systematically reviewed the evidence regarding the effects of eye movement desensitization and reprocessing (EMDR) therapy for treating chronic pain. DESIGN: Systematic review. METHODS: We screened MEDLINE, EMBASE, the Cochrane Library, CINHAL Plus, Web of Science, PsycINFO, PSYNDEX, the Francine Shapiro Library, and citations of original studies and reviews. All studies using EMDR for treating chronic pain were eligible for inclusion in the present study. The main outcomes were pain intensity, disability, and negative mood (depression and anxiety). The effects were described as standardized mean differences. RESULTS: Two controlled trials with a total of 80 subjects and 10 observational studies with 116 subjects met the inclusion criteria. All of these studies assessed pain intensity. In addition, five studies measured disability, eight studies depression, and five studies anxiety. Controlled trials demonstrated significant improvements in pain intensity with high effect sizes (Hedges' g: -6.87 [95% confidence interval (CI95 ): -8.51, -5.23] and -1.12 [CI95 : -1.82, -0.42]). The pretreatment/posttreatment effect size calculations of the observational studies revealed that the effect sizes varied considerably, ranging from Hedges' g values of -0.24 (CI95 : -0.88, 0.40) to -5.86 (CI95 : -10.12, -1.60) for reductions in pain intensity, -0.34 (CI95 : -1.27, 0.59) to -3.69 (CI95 : -24.66, 17.28) for improvements in disability, -0.57 (CI95 : -1.47, 0.32) to -1.47 (CI95 : -3.18, 0.25) for improvements in depressive symptoms, and -0.59 (CI95 : -1.05, 0.13) to -1.10 (CI95 : -2.68, 0.48) for anxiety. Follow-up assessments showed maintained improvements. No adverse events were reported. CONCLUSIONS: Although the results of our study suggest that EMDR may be a safe and promising treatment option in chronic pain conditions, the small number of high-quality studies leads to insufficient evidence for definite treatment recommendations.

The prevalence rate and the role of the spatial extent of pain in nonspecific chronic back pain--a population-based study in the south-west of Germany.

OBJECTIVE: To determine the prevalence of chronic back pain in the general population and to establish an evidence-based subclassification system for chronic back pain based on pain extent. DESIGN: Representative population-based survey. SETTING: South-western Germany. SUBJECTS: Four-thousand representative residents were contacted. The corrected response rate was 61.8% (N = 2,408). Those suffering from chronic back pain (pain ≥45 days/last 3 months) were invited to a clinical evaluation. OUTCOME MEASURES: Chronic back pain, spatial extent of pain, sociodemographic and clinical variables. RESULTS: Age- and sex-adjusted prevalence rate for chronic back pain was 17.7%. Analyzing pain extent, we found that only 19.6% suffered strictly from chronic local back pain, while the majority indicated additional pain regions. Thus, we developed a subclassification system based on pain extent that consists of four more homogeneous groups (19.6% strict chronic local pain, 42.1% chronic regional pain, 24.3% common chronic widespread pain, 13.9% extreme chronic widespread pain). Interestingly, in this system, increasing pain extent was significantly associated with higher distress, as reflected by sociodemographic (e.g., lower education, lower social class, and higher application rate for disability pension) and clinical variables (e.g., higher pain intensity, more pain medication, more consultations, higher impairment, and lower quality of life). CONCLUSIONS: Chronic back pain is prevalent and usually involves additional pain areas outside of the back. This challenges the concept of chronic back pain as a distinct entity. To identify patients who are distressed by chronic back pain, a four-class taxonomy based on pain drawings is both feasible and clinically useful.

Effects of eye movement desensitization and reprocessing (EMDR) on non-specific chronic back pain: a randomized controlled trial with additional exploration of the underlying mechanisms.

BACKGROUND: Non-specific chronic back pain (CBP) is often accompanied by psychological trauma, but treatment for this associated condition is often insufficient.Nevertheless, despite the common co-occurrence of pain and psychological trauma, a specific trauma-focused approach for treating CBP has been neglected to date. Accordingly, eye movement desensitization and reprocessing (EMDR), originally developed as a treatment approach for posttraumatic stress disorders, is a promising approach for treating CBP in patients who have experienced psychological trauma.Thus, the aim of this study is to determine whether a standardized, short-term EMDR intervention added to treatment as usual (TAU) reduces pain intensity in CBP patients with psychological trauma vs. TAU alone. METHODS/DESIGN: The study will recruit 40 non-specific CBP patients who have experienced psychological trauma. After a baseline assessment, the patients will be randomized to either an intervention group (n = 20) or a control group (n = 20). Individuals in the EMDR group will receive ten 90-minute sessions of EMDR fortnightly in addition to TAU. The control group will receive TAU alone. The post-treatment assessments will take place two weeks after the last EMDR session and six months later.The primary outcome will be the change in the intensity of CBP within the last four weeks (numeric rating scale 0-10) from the pre-treatment assessment to the post-treatment assessment two weeks after the completion of treatment.In addition, the patients will undergo a thorough assessment of the change in the experience of pain, disability, trauma-associated distress, mental co-morbidities, resilience, and quality of life to explore distinct treatment effects. To explore the mechanisms of action that are involved, changes in pain perception and pain processing (quantitative sensory testing, conditioned pain modulation) will also be assessed.The statistical analysis of the primary outcome will be performed on an intention-to-treat basis. The secondary outcomes will be analyzed in an explorative, descriptive manner. DISCUSSION: This study adapts the standard EMDR treatment for traumatized patients to patients with CBP who have experienced psychological trauma. This specific, mechanism-based approach might benefit patients. TRIAL REGISTRATION: This trial has been registered with ClinicalTrials.gov (NCT01850875).

Alterations in endogenous pain modulation in endurance athletes: an experimental study using quantitative sensory testing and the cold-pressor task.

There is evidence for long-term alterations in pain tolerance among athletes compared with normally active controls. However, scientific data on pain thresholds in this population are inconsistent, and the underlying mechanisms for the differences remain unclear. Therefore, we assessed differences and similarities in pain perception and conditioned pain modulation (CPM) at rest in endurance athletes and normally active controls. The standardised quantitative sensory testing protocol (QST) of the 'German-Research-Network-on-Neuropathic-Pain' was used to obtain comprehensive profiles on somatosensory functions. The protocol consisted of thermal and mechanical detection as well as pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. CPM (the diffuse-noxious-inhibitory-control-like effect) was measured using 2 tonic heat pain test stimuli (at the temperature exceeding a subjective pain rating of 50/100) separated by a 2-min cold-pressor task (CPM-TASK; conditioning stimulus). Pain ratings were measured with a numerical rating scale. Endurance capacity was validated by assessment of maximum oxygen uptake (VO2max). Participants included 25 pain-free male endurance athletes (VO2max>60mL/min∗kg) and 26 pain-free normally active controls (VO2max<45mL/min∗kg) matched based on age and body mass index. Athletes were significantly less sensitive to mechanical pain but showed higher sensitivity to vibration (P<0.05). In athletes, CPM was significantly less activated by the conditioning stimuli (P<0.05) when compared with normally active controls. Our data show that somatosensory processing in athletes differs in comparison with controls, and suggest that the endogenous pain inhibitory system may be less responsive. This finding may explain the paradoxical propensity of athletes to develop chronic widespread pain.

Subgroups of musculoskeletal pain patients and their psychobiological patterns - the LOGIN study protocol.

BACKGROUND: Pain conditions of the musculoskeletal system are very common and have tremendous socioeconomic impact. Despite its high prevalence, musculoskeletal pain remains poorly understood and predominantly non-specifically and insufficiently treated.The group of chronic musculoskeletal pain patients is supposed to be heterogeneous, due to a multitude of mechanisms involved in chronic pain. Psychological variables, psychophysiological processes, and neuroendocrine alterations are expected to be involved. Thus far, studies on musculoskeletal pain have predominantly focused on the general aspects of pain processing, thus neglecting the heterogeneity of patients with musculoskeletal pain. Consequently, there is a need for studies that comprise a multitude of mechanisms that are potentially involved in the chronicity and spread of pain. This need might foster research and facilitate a better pathophysiological understanding of the condition, thereby promoting the development of specific mechanism-based treatments for chronic pain. Therefore, the objectives of this study are as follows: 1) identify and describe subgroups of patients with musculoskeletal pain with regard to clinical manifestations (including mental co-morbidity) and 2) investigate whether distinct sensory profiles or 3) distinct plasma levels of pain-related parameters due to different underlying mechanisms can be distinguished in various subgroups of pain patients. METHODS/DESIGN: We will examine a population-based chronic pain sample (n = 100), a clinical tertiary care sample (n = 100) and pain-free patients with depression or post-traumatic stress disorder and pain-free healthy controls (each n = 30, respectively). The samples will be pain localisation matched by sex and age to the population-based sample. Patients will undergo physical examination and thorough assessments of mental co-morbidity (including psychological trauma), perceptual and central sensitisation (quantitative sensory testing), descending inhibition (conditioned pain modulation, the diffuse noxious inhibitory control-like effect), as well as measurement of the plasma levels of nerve growth factor and endocannabinoids. DISCUSSION: The identification of the underlying pathophysiologic mechanisms in different subgroups of chronic musculoskeletal pain patients will contribute to a mechanism-based subgroup classification. This will foster the development of mechanism-based treatments and holds promise to treat patients more sufficient.

Pain perception in athletes compared to normally active controls: a systematic review with meta-analysis.

This study systematically reviewed differences in pain perception between athletes and normally active controls. We screened MEDLINE, Sport-Discus, EMBASE, Web of Science, PsycINFO, PSYNDEX, and the citations of original studies and systematic reviews. All studies on experimentally induced pain that compared pain perception between athletes and normally active controls were eligible. The main outcome measures were pain tolerance and pain threshold. Effects are described as standardized mean differences and were pooled using random-effects models. Fifteen studies including 899 subjects met the inclusion criteria. Twelve of these studies assessed pain tolerance, and 9 studies examined pain threshold. A meta-analysis of these studies revealed that athletes possessed higher pain tolerance compared to normally active controls (effect size calculated as Hedges' g=0.87, 95% confidence interval [CI(95)] 0.53-1.21; P<0.00001), whereas available data on pain threshold were less uniform (Hedges' g=0.69, CI(95) 0.16-1.21; P=0.01). After exclusion of studies with high risk of bias, differences between groups in pain threshold were not significant any longer. Our data suggest that regular physical activity is associated with specific alterations in pain perception. Psychological and biological factors that may be responsible for these alterations are discussed.

The prevalence and type of Axis-I and Axis-II mental disorders in subjects with non-specific chronic back pain: results from a population-based study.

OBJECTIVE: To investigate the prevalence and the type of mental comorbidity in a population-based sample of subjects with non-specific chronic back pain. DESIGN: Representative population-based survey. SETTING: The city of Heidelberg (in southwestern Germany) and 10 adjacent communities. PATIENTS: From a random sample of individuals (N = 2,000), 1,091 subjects completed a questionnaire including a pain assessment. Of those, 188 subjects (17%) fulfilled the criteria for chronic back pain (≥45 days of back pain in the last 3 months) and were subsequently invited to undergo a detailed clinical examination; 131 subjects (70%) agreed to participate. The Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) (SCID-I + II) was used to assess current (defined as the previous 4 weeks) mental comorbidity and was completed in 110 subjects (84%) with non-specific chronic back pain. INTERVENTION: N/A. OUTCOME MEASURES: DSM-IV mental comorbidity diagnoses. RESULTS: The overall prevalence of mental comorbidity of Axis-I and -II disorders were 35.5% and 15.5%, respectively. Of Axis-I disorders, anxiety disorders (20.9%) and affective disorders (12.7%) were the most frequent. Of Axis-II disorders, 9.1% of diagnoses was of the Cluster C category (anxious/inhibited). Compared with the general population, the total rate of Axis-I comorbidity was significantly higher, while the total rate for Axis-II personality disorders was only slightly different. CONCLUSIONS: The consistent diagnoses of anxiety, fear, and avoidance in these subjects indicate that also primary care health professionals should consider anxiety disorders in patients with chronic pain, in addition to the affective disorders that are most frequently self-reported in pain patients.

Quantitative sensory testing profiles in chronic back pain are distinct from those in fibromyalgia.

OBJECTIVES: Alterations in the central nervous system leading to higher pain sensitivity have been shown in both chronic back pain (CBP) and fibromyalgia syndrome (FMS). The aim of this study was to disclose commonalities and differences in the pathophysiology of FMS and CBP. METHODS: We used the quantitative sensory testing protocol of the German Research Network on Neuropathic Pain to obtain comprehensive profiles of somatosensory functions. The protocol comprised thermal and mechanical detection and pain thresholds, vibration thresholds, and pain sensitivity to sharp and blunt mechanical stimuli. We studied 21 FMS patients (mean pain duration: 13.4 y), 23 CBP subjects (mean pain duration: 15.9 y), and 20 healthy controls (HCs). Each participant received the test battery on the back and on the dorsal hand (pain-free control site). RESULTS: On the back, FMS patients showed increased thermal and mechanical pain sensitivity compared with HCs and CBP participants. On the hand dorsum, FMS patients showed higher mechanical pain sensitivity compared with CBP participants and HCs and higher cold pain sensitivity compared with HCs. CBP participants showed increased pressure pain sensitivity and lower vibration sensitivity on the back, but no significant differences on the hand dorsum compared with HCs. DISCUSSION: FMS patients showed increased sensitivity for different pain modalities at all measured body areas, suggesting central disinhibition as a potential mechanism. CBP participants in contrast, showed localized alterations within the affected segment possibly due to peripheral sensitization.

Alaris AEP monitor's "Click Detection" does not help to detect inadvertent disconnection of headphones during anesthesia.

UNLABELLED: Auditory evoked potentials (AEP) can be suppressed by anesthetics dose dependently, but may fail to be registered because of the absence of adequate auditory stimuli. The Alaris AEP monitor includes the "Click Detection" (CD) (generating the message "NO AEP" or "LOW AEP") to detect the loss of auditory stimuli. We investigated the accuracy of the CD in 17 patients awake (AWAKE) and during anesthesia (ANESTHESIA) with accurately placed headphones (HP) and after disconnected HP (No HP) over 5 min each, respectively. Alaris AEP ARX index, CD, and Bispectral Index were recorded each minute. Changes were evaluated with the Friedman and Wilcoxon test. Sensitivity (SEN) and specificity (SPE) and receiver operating characteristic curve were analyzed for the accuracy of the CD. During AWAKE after disconnection of the HP, Alaris AEP ARX index decreased significantly (P < 0.05). The CD was able to detect No HP after 2 min with a SEN of 88% and a SPE of 97%. During ANESTHESIA, no changes were found after HP disconnection. CD detected No HP with a SEN of 100% and a SPE of 20%. The CD of the Alaris AEP monitor is not able to detect unnoticed disconnection of HP during ANESTHESIA. IMPLICATIONS: Signal transmission of auditory evoked potentials can be suppressed by anesthetics, but also by disconnection of headphones. In the present study, we demonstrate that even the Alaris AEP monitor with the very new feature "Click Detection" was not able to detect the loss of headphones during general anesthesia with propofol and remifentanil.