Central sensitivity syndromes: mounting pathophysiologic evidence to link fibromyalgia with other common chronic pain disorders

Small Fibre Pathology in Fibromyalgia: A review

Fibromyalgia syndrome (FMS) presents a complex and challenging disorder in both the diagnosis and treatment, with emerging evidence suggesting a role of small fibre pathology (SFP) in its pathophysiology. The significance of the role of SFP in FMS remains unclear; however, recent evidence suggests degeneration and dysfunction of the peripheral nervous system, particularly small unmyelinated fibres, which may influence pathophysiology and underlying phenotype. Both skin biopsy and corneal confocal microscopy (CCM) have consistently demonstrated that ~ 50% of people with FMS have SFP. CCM, a non-invasive measure of small nerve fibres has detected small fibre loss, correlating with neuropathic pain descriptors. Additionally, quantitative sensory testing has shown abnormalities, primarily in pain pressure/mechanical pain thresholds. This narrative review provides a comprehensive understanding of the pathophysiological dimensions of FMS with a clear focus on small nerve fibres and the peripheral nervous system, offering a roadmap for future research.

Eating concerns in youth with functional abdominal pain disorders

OBJECTIVES

Adolescents with functional abdominal pain (FAP) often experience pain and other gastrointestinal symptoms in the context of eating, which may place them at risk for eating disorders. This study compared disordered eating and its sequalae in adolescents with FAP to those with chronic headache.

METHODS

Participants in this retrospective chart review study were 270 adolescents and young adults (mean age 15.9; standard deviation [SD] = 1.63; 60% female) attending an intensive, interdisciplinary pain treatment program, including 135 youth with FAP and an age- and gender-matched control group with a primary pain diagnosis of chronic headache. Information was extracted related to eating- and weight-related symptoms.

RESULTS

Independent t-tests and χ2 analyses found that compared with adolescents with chronic headache, patients with FAP showed significantly more eating pathology as reflected by scores on the Eating Attitudes Test-26 (EAT-26) (p < 0.001), endorsement of pain-related restrictive eating (p < 0.01), eating disorder history (p < 0.001), and avoidant restrictive food intake disorder (ARFID) diagnoses (p < 0.001). Compared to those with chronic headache, significantly more patients with FAP had lost 10 pounds or more (p < 0.01) and a higher proportion were underweight (p < 0.001). Among all participants, a history of exclusion diets used to manage symptoms significantly increased the risk for ARFID (p < 0.001).

CONCLUSION

The results of this study highlight the increased risk of eating-related concerns among youth with FAP, as well as the judicious use of exclusion diets to manage symptoms in these patients.

The effect of fibromyalgia syndrome on female patients diagnosed with chronic migraine

OBJECTIVE

To compare pain, quality of life, sleep, anxiety and depression, central sensitization, and functionality between chronic migraine (CM) patients with comorbid fibromyalgia syndrome (FMS) and patients with CM alone.

METHOD

Thirty three female patients with CM and thirty three female patients with CM+FMS were enrolled in the study. Demographic and clinical characteristics of the patients were recorded. FM was diagnosed based on the 2016 American College of Rheumatology diagnostic criteria. All participants were evaluated with Allodynia Symptom Checklist, Short Form-36 (SF-36), Pittsburgh Sleep Quality Index (PSQI), Hospital Anxiety and Depression Scale (HADS), Migraine Disability Assessment (MIDAS) and Headache Impact Test (HIT-6) questionnaires, and Central Sensitization Inventory (CSI). FM patients were also evaluated with Fibromyalgia Impact Questionnaire (FIQ).

RESULTS

The average number of headache days was significantly higher in patients with CM+FMS (p = 0.006). Among migraine accompanying symptoms, the number of patients with phonophobia was significantly higher in patients with CM+FMS (p = 0.008). While CSI score was 39.0 ± 11.7 in CM patients, it was 52.2 ± 9.2 in CM+FMS patients. CSI scores were higher in CM+FMS patients (p < 0.001). SF-36 sub-cores, including physical function, energy/fatigue, emotional well-being, and general health scores, were lower in CM+FMS patients (p < 0.05). Sleep duration was significantly lower and use of medication to sleep was more common in same group (p < 0.05). FIQ score in CM+FMS patients was associated with quality of life scores, sleep quality, anxiety, and central sensitization scores (p < 0.05).

CONCLUSION

In patients with chronic migraine, FMS comorbidity negatively affects the quality of life and significantly increases central sensitization.

Laryngeal and Global Somatosensation in Primary Muscle Tension Dysphonia

INTRODUCTION

Primary muscle tension dysphonia (pMTD) is a functional voice disorder that reduces communicative abilities and adversely impacts occupational productivity and quality of life. Patients with pMTD report increased vocal effort, fatigue, discomfort, and odynophonia. Although laryngeal and paralaryngeal muscle tension and hyperfunction are the most commonly proposed mechanisms underlying these symptoms, recent studies suggest pMTD may have more to do with the somatosensory system. However, relationships between voice symptoms and somatosensory mechanisms are poorly understood, creating challenges for mechanistic-based pMTD management. The first objective was to compare laryngeal, paralaryngeal, and global somatosensation between subjects with and without pMTD. The second was to determine relationships between pMTD symptoms and somatosensation.

METHODS

Fifty-two (20 pMTD and 32 control) subjects underwent laryngeal sensory testing with aesthesiometers, as well as peripheral mechanosensory and dynamic temporal summation testing to paralaryngeal and limb regions. Voice symptom severities (vocal effort, fatigue, discomfort, and odynophonia) were collected on 100-mm visual analog scales before and after laryngeal sensory testing. Participants also completed the Central Sensitization Inventory.

RESULTS

Patients with pMTD reported significantly higher laryngeal sensations (P = 0.0072) and voice symptom severities (P < 0.001) compared with the control group, and had significantly more vocal tract discomfort postlaryngeal sensory testing compared with the prelaryngeal sensory testing timepoint (P = 0.0023). However, there were no significant group differences in laryngeal airway protection responses suggestive of peripheral laryngeal hypersensitivities (P = 0.444). There were also no significant group differences on paralaryngeal or global sensitivities (P > 0.05), and no correlations between severity of voice symptoms and perceptual laryngeal sensations or hypersensitivities (P > 0.05).

CONCLUSION

Patients with pMTD perceive more sensitivities in the larynx and feel more sensations related to the voice (vocal effort, fatigue, discomfort, and pain). However, in general, patients with pMTD do not have abnormal peripheral laryngeal hypersensitivities, increased global somatosensation, or heightened central sensitivity. The lack of significant correlations between peripheral laryngeal hypersensitivities and voice symptom severity ratings suggests these outcome variables target distinct mechanistic constructs.

The Central Sensitization Inventory Measures Thoughts and Emotions

To determine if the Central Sensitization Inventory questionnaire (CSI) functions as a mental health measure among a cross-section of people seeking musculoskeletal specialty care, we asked: (1) What is the association of CSI total score and item groupings identified in factor analysis with mental health measures? and (2) What is the association between specific CSI items that represent each factor well and specific mental health measures? One hundred and fifty-seven adults seeking specialty care for musculoskeletal symptoms completed the CSI, a measure of catastrophic thinking, and 3 measures of distress (symptoms of health anxiety, general anxiety, and depression). Exploratory factor analysis was used to identify item groupings. Exploratory factor analysis identified 4 item groupings (factors): (1) thoughts and feelings (mental health), accounting for 52% of the variation in the CSI, (2) urinary and visual symptoms (15%) (3) body aches (10%), and (4) jaw pain (8.1%). More than half the variation in both the CSI total score (51%) and the thoughts and feelings factor (57%) were accounted for by variation in measures of catastrophic thinking and distress. Specific items that account for large amounts of the variation in the CSI also had notable correlations with mental health measures. The strong relationship between the CSI and thoughts and emotions suggests that the CSI functions largely as a mental health measure. If the concept of central sensitization is to help people get and stay healthy, it will depend on evidence that central sensitization can be measured and quantified distinct from mental health.

Evaluation of Central Sensitisation in Bladder Pain Syndrome: A Systematic Review

INTRODUCTION AND HYPOTHESIS

Bladder pain syndrome (BPS) is a debilitating condition characterised by exaggerated bladder sensations and altered bladder function. It is still unknown whether the condition is a peripheral sensory problem or due to abnormal central sensory processing as seen in central sensitisation. This systematic review, which followed a published and Prospective Register of Systematic Reviews-registered protocol (CRD42021229962), is aimed at establishing the scope of central sensitisation in patients with BPS to aid optimal management and treatment.

METHODS

Four databases were searched, and appraisal of the identified studies was conducted by two independent reviewers based on eligibility criteria: patients with BPS being investigated for central sensitisation with or without comparison of controls, English-language articles, full text and publication in a peer-reviewed journal. The Methodological Index for non-Randomised Studies was used to determine study quality. We identified 763 papers in total, with 15 studies included in the final analysis. All studies were observational and had a low risk of bias. Measures included in the evaluation of CS were questionnaires, urodynamics, and quantitative sensory testing methods.

RESULTS

There was evidence of central sensitisation in patients with BPS in all papers evaluated (15 out of 15). In addition, more significant central sensitisation correlated with severe disease presentation (3 out of 3 papers) and concomitant chronic pain conditions (5 out of 5 papers).

CONCLUSIONS

Central sensitisation plays an integral role in BPS patient pathology. Many secondary measures are used to evaluate this condition. Stratification of patients based on their pathology (peripheral, central or a combination of the two) will aid in implementing an individualised management strategy.

Chronic nonspecific multiple-sites pain [CNMSP] of unknown etiology: Biopsychosocial method of evaluation for the primary care level

Background

Understanding and dealing with chronic nonspecific pain (CNP) is the important entity at primary care hospital. Chronic nonspecific multiple-site pain [CNMSP] of unknown etiology creates diagnostic and therapeutic challenges for primary care physicians due to lack of guidance regarding evaluation and treatment.

Aims and Objectives

To classify and formulate the evaluation, treatment strategies, and prediction of prognosis of patients with CNMSP of unknown etiology.

Methods

Patients present with CNMSP of more than 3-month duration without any obvious medical cause. The biopsychosocial [BPS] model with 3P model was applied to see the biological, psychological, and social factors behind persistence. Finally, patients were classified into four groups for evaluation response to treatment and relapse rates in 12-month follow-up.

Results

Of the total 243 patients of CNMSP, 243 [96.3%] were females. Sixty [24.7%] patients had short duration, and 183 [75.3%] had long duration. Headache was in 115 [47%], low back pain ± leg pain in 96 [39.4%], cervical pain ± shoulder/arm pain in 83 [34.1%], and diffuse body pain in 50 [20.5%] in various combinations. A total of 155 [63.8%] patients had high somatization-sensitization index (SSI), and 144 [59.3%] had low ferritin level. Group 1 [high SSI and low ferritin] had 37.9% of patients, group 2 [high SSI and normal ferritin] had 25.9% of patients, group 3 [low to medium SSI with low ferritin] had 21.4% of patients, and group 4 [low to medium SSI with normal ferritin] had 14.8% of patients. Response to pain symptoms was better in group 1, and relapse rate was higher in group 2.

Conclusion

CNMSP of unknown etiology itself is a heterogeneous entity, and assessment based on the BPS model can be very useful to understand the treatment plan and outcome of these patients.

Night time heart rate predicts next-day pain in fibromyalgia and primary back pain

Introduction

Primary chronic pain is pain that persists for over 3 months without associated measurable tissue damage. One of the most consistent findings in primary chronic pain is its association with autonomic hyperactivation. Yet whether the autonomic hyperactivation causes the pain or results from it is still unclear. It is also unclear to what extent autonomic hyperactivation is related to experienced pain intensity in different subtypes or primary chronic pain.

Objectives

Our first aim was to test lagged relationships between the markers of autonomic activation (heart rate) and pain intensity to determine its directionality. The main question here was whether autonomic biomarkers predict pain intensity or whether pain intensity predicts autonomic biomarkers. The second aim was to test whether this relationship is different between people with primary back pain and people with fibromyalgia.

Methods

Sixty-six patients with chronic pain were observed over an average of 81 days. Sleep heart rate and heart rate variability were measured with a wearable sensor, and pain intensity was assessed from daily subjective reports.

Results

The results showed a predictive relationship between sleep heart rate and next-day pain intensity (P < 0.05), but not between daily pain intensity and next night heart rate. There was no interaction with the type of chronic pain.

Conclusions

These findings suggest that autonomic hyperactivation, whether stress-driven or arising from other causes, precedes increases in primary chronic pain. Moreover, the present results suggest that autonomic hyperactivation is a common mechanism underlying the pain experience in fibromyalgia and chronic back pain.

Exercise-induced hypoalgesia in chronic neck pain: A narrative review

Chronic neck pain (CNP) is a worldwide health problem with several risk factors. One of the most widely used treatments for managing this condition is therapeutic exercise, which could generate a response called exercise-induced hypoalgesia (EIH). There is no consensus on the best exercise modality to induce hypoalgesia. Therefore, this review aims to analyze and synthesize the state-of-the-art about the hypoalgesic effect of exercise in subjects with CNP. We included articles on EIH and CNP in patients older than 18 years, with pain for more than three months, where the EIH response was measured. Articles that studied CNP associated with comorbidities or measured the response to treatments other than exercise were excluded. The studies reviewed reported variable results. Exercise in healthy subjects has been shown to reduce indicators of pain sensitivity; however, in people with chronic pain, the response is variable. Some investigations reported adverse effects with increased pain intensity and decreased pain sensitivity, others found no clinical response, and some even reported EIH with decreased pain and increased sensitivity. EIH is an identifiable, stimulable, and helpful therapeutic response in people with pain. More research is still needed on subjects with CNP to clarify the protocols and therapeutic variables that facilitate the EIH phenomenon. In addition, it is necessary to deepen the knowledge of the intrinsic and extrinsic factors that influence EIH in people with CNP.

A Pilot Study of Functional Brain Magnetic Resonance Imaging in BPS/IC Patients: Evidence of Central Sensitization

Bladder pain syndrome/Interstitial cystitis (BPS/IC) is characterized by increased activity in bladder afferent pathways, recruitment of silent nociceptive neurons, and sensitization of the brain areas responsible for pain amplification. Default mode network (DMN) is a set of regions activated during the resting state, which reflect the brain's intrinsic activity. Conversely, the sensorimotor network (SMN) plays a key role in structural neuroplasticity. This study aimed to evaluate DMN and SMN activity in BPS/IC patients, both with and without bladder noxious stimulus, using functional brain magnetic resonance imaging (MRI). Six BPS/IC female patients underwent 3 Tesla fMRI brain scanners. Acquisitions consisted of 10-minute blood oxygen level-dependent echo-planar imaging. The first acquisition was with an empty bladder, painless, and the second was with suprapubic pain. Data were processed using the independent component analysis method with the MELODIC tool from the functional brain MRI of the Brain Software Library (FSL). A semi-quantitative analysis was performed afterward. The patients' age was 42.6 ± 5 years, pain intensity was 7 ± 0.7 (0-10), day and night frequency were 9.2 ± 2.2 and 2.8 ± 1.0, and maximal bladder capacity was 260 ± 54 mL. One patient was unable to complete the study. All patients showed a comparable DMN activation in both empty and full bladder states, and all presented high SMN activation whether the bladder was empty or full. The activation of DMN at both bladder states, empty and full, and constant SMN activation without and with pain supports the role of these networks in BPS/IC. Similar findings have been reported in other chronic pain syndromes.

Pain in Adolescence: Maternal and Paternal Factors Affecting Adolescents' Pain in Norway-A Cross-Sectional Study

BACKGROUND

Pain in adolescence is considered a worldwide concern. Adolescents' pain affects family functioning. However, bidirectional associations should be considered as parental determinates such as pain, stress, and sociodemographic factors are also shown to influence pain in adolescence.

OBJECTIVES

This study explored the associations between maternal and paternal sociodemographic factors, pain, and stress and adolescents' pain, and stress on adolescents' pain.

METHODS

In total, 508 school-based Norwegian adolescents with a corresponding parent were included. All adolescents completed an electronic survey during school hours, and their respective parents responded electronically. The survey included sociodemographic data, the Perceived Stress Questionnaire, and the Brief Pain Inventory.

RESULTS

Herein, 385 adolescents reported an average pain of 2.1 (SD, 1.9), and 308 of the participating parents reported an average pain of 1.6 (SD, 1.8). Regressions stratified by parental gender revealed nonsignificant associations in fathers' study variables predicting adolescents' pain. However, having the highest maternal educational level (p ≤ 0.01) and working part-time (p ≤ 0.01) were associated with lower pain in adolescents.

CONCLUSIONS

The findings of this study demonstrated that sociodemographic factors such as high educational status in mothers and mothers working part-time were associated with lower pain in Norwegian adolescents. These findings highlight the importance of a holistic approach to pain management in adolescence.

DC/TMD Axis I diagnostic subtypes in TMD patients from Confucian heritage cultures: a stratified reporting framework

OBJECTIVES

This study proposed a conceptual framework for reporting Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I conditions and investigated the prevalence of TMD subtypes/categories in patients from Confucian heritage cultures. Variances in gender, age, and TMD chronicity between Chinese (CN) and Korean (KR) patients were also explored.

MATERIALS AND METHODS

Subjects were recruited from consecutive patients seeking care at two University-based centers in Beijing and Seoul. Eligible patients completed a demographic survey as well as the DC/TMD Symptom Questionnaire and were clinically examined according to the DC/TMD methodology. Axis I diagnoses were subsequently rendered with the DC/TMD algorithms and documented using the stratified reporting framework. Statistical evaluations were performed with chi-square, Mann-Whitney U tests, and logistic regression analysis (α = 0.05).

RESULTS

Data of 2008 TMD patients (mean age 34.8 ± 16.2 years) were appraised. Substantial differences in female-to-male ratio (CN > KR), age (KR > CN), and TMD duration (KR > CN) were observed. Ranked frequencies of the most common Axis I diagnoses were: CN - disc displacements (69.7%) > arthralgia (39.9%) > degenerative joint disease (36.7%); KR - disc displacements (81.0%) > myalgia (60.2%) > arthralgia (56.1%). Concerning TMD categories, notable differences in the prevalence of intra-articular (CN 55.1% > KR 15.4%) and combined (KR 71.8% > CN 33.4%) TMDs were discerned.

CONCLUSIONS

Though culturally similar, the two countries require disparate TMD care planning/prioritization. While TMJ disorders in children/adolescents and young adults should be emphasized in China, the focus in Korea would be on TMD pain in young and middle-aged adults.

CLINICAL RELEVANCE

Besides culture, other variables including socioeconomic, environmental, and psychosocial factors can influence the clinical presentation of TMDs. Chinese and Korean TMD patients exhibited significantly more intra-articular and combined TMDs respectively.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Central Pain Sensitization in Patients with Chronic Plaque Psoriasis

BACKGROUND

Central sensitization (CS) is a condition characterized by a disproportionate response to pain stimuli, and is associated with chronic pain conditions such as fibromyalgia, but also with inflammatory arthropathies such as rheumatoid arthritis and psoriatic arthritis (PsA). CS has never been investigated in patients with psoriasis. The aim of this study is to investigate CS in patients with chronic plaque psoriasis.

METHODS

This research involved a cross-sectional observational study of adult patients with moderate-to-severe psoriasis consecutively attending the outpatient clinic of the University Hospital of Verona. Demography, measures of disease severity or activity [i.e., Psoriasis Area and Severity Index (PASI), Disease Activity in Psoriatic Arthritis (DAPSA)], diagnosis of PsA, hypertension, and diabetes were collected. Central Sensitization Inventory (CSI), Dermatology Life Quality Index (DLQI), General Anxiety Disorder-7 (GAD-7), and Patient Health Questionnaire-9 (PHQ-9) were administered.

RESULTS

A total of 194 patients, including 115 (59%) men, with mean age of 54 ± 13 years, mean PASI of 12.7 ± 6.7, and mean DAPSA of 14.4 ± 3.8 were included. In total, 134 patients (79%) had only psoriasis while 60 (31%) had psoriasis and PsA; 19 (10%) patients had CSI score ≥ 40, which is the threshold for diagnosing CS. The proportion of CS ≥ 40 was higher in patients with PsA compared with psoriasis (17% versus 7%, p = 0.031). The mean CSI score in patients with PsA was higher compared with those with only psoriasis (27.5 ± 13.5 versus 20.7 ± 13.7, p = 0.002). An association between CSI and DLQI [β = 1.25 (95% CI 0.85-1.66)], PASI [β = 1.22 (95% CI 0.74-1.65)], GAD-7 [β = 2.07 (95% CI 1.69-2.45)] and PHQ-9 [β = 2.16 (95% CI 1.76-2.54)] was found independently from age, gender, diabetes, and PsA.

CONCLUSIONS

Central sensitization may be associated with psoriasis, particularly in those with high PASI, concomitant PsA, anxiety, depression, and severe quality of life impairment.

Feasibility, Acceptability, and Efficacy of Home-Based Transcranial Direct Current Stimulation on Pain in Older Adults with Alzheimer's Disease and Related Dementias: A Randomized Sham-Controlled Pilot Clinical Trial

Although transcranial direct current stimulation (tDCS) is emerging as a convenient pain relief modality for several chronic pain conditions, its feasibility, acceptability, and preliminary efficacy on pain in patients with Alzheimer's disease and related dementias (ADRD) have not been investigated. The purpose of this pilot study was to assess the feasibility, acceptability, and preliminary efficacy of 5, 20-min home-based tDCS sessions on chronic pain in older adults with ADRD. We randomly assigned 40 participants to active (n = 20) or sham (n = 20) tDCS. Clinical pain intensity was assessed using a numeric rating scale (NRS) with patients and a proxy measure (MOBID-2) with caregivers. We observed significant reductions of pain intensity for patients in the active tDCS group as reflected by both pain measures (NRS: Cohen's d = 0.69, p-value = 0.02); MOBID-2: Cohen's d = 1.12, p-value = 0.001). Moreover, we found home-based tDCS was feasible and acceptable intervention approach for pain in ADRD. These findings suggest the need for large-scale randomized controlled studies with larger samples and extended versions of tDCS to relieve chronic pain on the long-term for individuals with ADRD.

Validity Testing of the Head and Neck Lymphedema and Fibrosis Symptom Inventory

Background: Lack of reliable and valid tools significantly impacts early identification and timely treatment of lymphedema and fibrosis (LEF) in the head and neck cancer population. To address this need, we developed and reported a patient-reported outcome measure (Head and Neck Lymphedema and Fibrosis Symptom Inventory [HN-LEF SI]). This article reports the construct validity (convergent and divergent validity) testing of the tool. Materials and Methods: A prospective, longitudinal, instrument validation study was conducted in patients with a newly diagnosed oral cavity or oropharyngeal cancer. Participants completed the HN-LEF SI and six carefully selected self-report measures at pretreatment, end-of-treatment, and every 3 months up to 12 months after treatment. Spearman correlations were used. Results: A total of 117 patients completed the study. Patterns of correlations of the HN-LEF SI scores with the established self-report measure scores were consistent with expected convergent and divergent validity. Conclusion: Evidence from this work supports the construct validity of the HN-LEF SI.

Effect of central sensitization inventory on the number of painful sites and pain severity in a Japanese regional population cohort

BACKGROUND

To investigate the association between the central sensitization inventory (CSI), a screening tool for central sensitization, and the number of painful sites and the severity of pain in locomotive organs in an epidemiological study in the elderly.

METHODS

A total of 379 individuals who underwent musculoskeletal disease screening were enrolled in this study. The CSI was used to assess symptoms of central sensitization. The number and location of painful sites and the severity of pain were evaluated using pain mapping and a numerical rating scale (NRS) at 37 sites. We investigated the association between the number of painful sites and CSI score, and the association between the severity of low back pain or knee pain and CSI score.

RESULTS

There was a positive correlation between CSI score and the number of painful sites. The CSI score was significantly higher in those with significant low back pain than in those without pain, and the high-CSI group tended to have a greater number of painful sites. Comparison of CSI scores between participants with low back pain alone and those with low back pain and posterior lower leg pain showed that the latter group had a significantly higher CSI score than the former group. The CSI score in participants with radiographic evidence of knee osteoarthritis was significantly higher in those with knee pain than in those without pain.

CONCLUSIONS

The results of this study suggest that participants with significant low back pain and a higher number of painful sites are more susceptible to the influence of central sensitization. In addition, CSI score was higher in participants with low back pain and posterior lower leg pain than in those with low back pain alone, suggesting that the spread of pain may be due to central sensitization.

Chronic Pain: Clinical Updates and Perspectives

The International Association for the Study of Pain (IASP) has defined pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage, which also comprises a subjective component [...].

Visual Sensitivity in Complex Regional Pain Syndrome and Fibromyalgia: An Online Study

Perceptual anomalies can provide insights into underlying pathologies even when they are not the main symptom of many clinical conditions. Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions associated with changes in the central nervous system, possibly leading to enhanced visual sensitivity. It is unclear whether this occurs more than for people with other types of pain. We examined visual sensitivity elicited by different stimuli and in daily life, through an online study of people with CRPS (n = 57), fibromyalgia (n = 74), other pain (n = 50), and no pain (n = 89). Respondents rated changes in pain, discomfort, or distress from viewing patterns with different spatial frequencies (lower-order visual processing), and reversible figures (bistable images; higher-order visual processing). We assessed visual sensitivity in daily life using the Leiden Visual Sensitivity Scale and Visual Discomfort Scale. Respondents with CRPS or fibromyalgia reported more visual discomfort than pain-related and pain-free controls while viewing striped patterns and a circle, with no effect of spatial frequency. They reported more pain while viewing a nonreversible square, but not reversible figures (Necker Cube, Duck/Rabbit). Finally, they reported more daily visual sensitivity than pain-related and pain-free controls. Suppressing visual cortical activity might benefit people with CRPS or fibromyalgia.

Characteristics of clusters with contrasting relationships between central sensitization-related symptoms and pain

The central sensitization inventory (CSI) evaluates the central sensitization (CS)-related symptoms associated with increased pain sensitivity. However, the CSI includes items that are not directly related to pain. In this study, 146 patients with pain were classified into subgroups by k-means cluster analysis based on the short form of the central sensitization inventory (CSI9) and pain scores. In addition, inter-group and multiple comparisons were performed to examine the characteristics of each group. As a result of this study, there were three subgroups (clusters 1, 2, and 3) in which the CSI9 and pain intensity were both low, moderate, and high, and one subgroup (cluster 4) in which only CSI9 was high and pain intensity was low. Two subgroups with high CSI9 scores but contrasting pain intensities (clusters 3 and 4) were extracted; the pattern of CS-related symptoms in these two groups was very similar, with no differences in most of the non-pain factors. It is necessary to consider these points when interpreting the clinical condition of a patient with pain when using the assessment of CS-related symptoms.

The Definition, Assessment, and Prevalence of (Human Assumed) Central Sensitisation in Patients with Chronic Low Back Pain: A Systematic Review

Central sensitisation is assumed to be one of the underlying mechanisms for chronic low back pain. Because central sensitisation is not directly assessable in humans, the term 'human assumed central sensitisation' (HACS) is suggested. The objectives were to investigate what definitions for HACS have been used, to evaluate the methods to assess HACS, to assess the validity of those methods, and to estimate the prevalence of HACS. Database search resulted in 34 included studies. Forty different definition references were used to define HACS. This review uncovered twenty quantitative methods to assess HACS, including four questionnaires and sixteen quantitative sensory testing measures. The prevalence of HACS in patients with chronic low back pain was estimated in three studies. The current systematic review highlights that multiple definitions, assessment methods, and prevalence estimates are stated in the literature regarding HACS in patients with chronic low back pain. Most of the assessment methods of HACS are not validated but have been tested for reliability and repeatability. Given the lack of a gold standard to assess HACS, an initial grading system is proposed to standardize clinical and research assessments of HACS in patients with a chronic low back.

A large-scale population-based epidemiological study on the prevalence of central sensitization syndromes in Japan

A cross-sectional study of 21,665 Japanese residents was performed to investigate the prevalence of central sensitization syndromes (CSS). CSS were assessed using the Central Sensitization Inventory (CSI-A). CSS were defined as a CSI-A score of 40 or higher. Age, sex, district, 10 CSS-related diseases (CSI-B), lifestyle, and mental factors were rated in a self-reported survey. The prevalence of CSS and its relationship with potential factors were examined by sex using descriptive and logistic regression models. The prevalence of CSS was 4.2% in all participants and was significantly higher in women (4.9%) than in men (2.7%). Adjusted odds ratios correlated with CSS for an age of 80–97 years versus 60–79 years (2.07 and 2.89), one or more CSI-B diseases (3.58 and 3.51), few sleeping hours (2.18 and 1.98), high perceived stress (5.00 and 4.91), low (2.94 and 2.71) and high (0.45 and 0.66) resilience versus moderate resilience, and exercise habits (0.68 and 0.55) in men and women (all P < 0.05). The relationship between CSS and age 20 and 59 years, ex-smokers, coffee intake, and alcohol intake differed by sex. The prevalence of CSS was estimated to be low in the healthy population. CSS correlated with CSS-related diseases and some positive and negative factors.

Comorbid Conditions in Temporomandibular Disorders Myalgia and Myofascial Pain Compared to Fibromyalgia

The impact of comorbidities in fibromyalgia (FM) and temporomandibular disorders (TMD) have been well documented, but whether TMD sub-diagnoses myalgia (MYA) and myofascial pain with referral (MFP) differ regarding comorbidity is unclear. We aimed to elucidate this by studying the presence and associations of comorbidities in FM, MFP and MYA. An extended version of the Diagnostic Criteria for TMD axis II questionnaire was used to examine demographics, pain and comorbidities in 81 patients with FM, 80 with MYA, and 81 with MFP. Patients with MFP and FM reported a higher percentage of irritable bowel syndrome (IBS), depression, anxiety, somatic symptoms, perceived stress, and insomnia compared to MYA. Patients with FM had more IBS, depression, and somatic symptom disorder versus MFP. After adjusting for confounding variables, participants with anxiety, somatic symptoms disorder, pain catastrophizing, and perceived stress, as well as a greater number of comorbidities, were more likely to have MFP than MYA, whereas FM participants were more associated with IBS, somatic symptoms and insomnia compared to MFP. The number of comorbidities was significantly associated with widespread pain but not pain duration, body mass index or being on sick leave. In conclusion, patients with MFP were more similar to those with FM regarding comorbidity and should be differentiated from MYA in clinical settings and pain management.

Corneal neuropathic pain in irritable bowel syndrome: clinical findings and in vivo corneal confocal microscopy

PURPOSE

Ocular discomfort is a common symptom in central sensitization syndromes. The aim of this study was to evaluate ocular surface discomfort and related corneal changes in patients with irritable bowel syndrome.

METHODS

Twenty-nine patients with IBS (20 female, 9 male, mean age: 45.3 ± 10.1 years) and 37 healthy control subjects (25 female, 12 male, mean age: 44.95 ± 9.76 years) were included. A detailed ophthalmological examination was performed to all participants including tear break-up time (TBUT) and Schirmer test I with anesthetic (SIT). Ocular discomfort was evaluated using the ocular surface disease index (OSDI) questionnaire and corneal sensation was evaluated with Cochet-Bonnet esthesiometer. Corneal subbasal nerve plexus was evaluated with in vivo corneal confocal microscopy (IVCM).

RESULTS

There was no significant difference between the groups for age, gender distribution, and visual acuity. OSDI scores were significantly higher (p = 0.008) and TBUT was significantly reduced in patients with IBS compared to controls (p = 0.001 for right eye, p = 0.014 for left eye). However, there was no significant difference in corneal touch sensation and SIT results between the groups. IVCM revealed that corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length were significantly reduced in patients with IBS (p < 0.001, p < 0.001, and p = 0.023, respectively).

CONCLUSION

Patients with IBS have increased dry eye-associated ocular surface complaints and nerve fiber loss in corneal subbasal nerve plexus. IBS should be remembered in the differential diagnosis, when there is discordance between the level of ocular surface discomfort and dry eye disease associated corneal findings.

Association between central sensitivity syndrome and psychological factors in people with presurgical low back pain: A cross-sectional study

BACKGROUND

Low back pain (LBP) is a major problem; it causes significant burden, incurs considerable economic and human costs, and adversely affects the quality of life (QoL). Central sensitivity syndrome (CSS) is known as a group of overlapping conditions that share a common pathophysiological mechanism of central sensitization. Previous studies have shown that CSS is present in several disorders. However, it has been studied for people with presurgical LBP. The purpose of the study was to investigate the proportion of patients with CSS for presurgical LBP and to analyse the association of CSS with clinical symptoms and psychological factors.

METHODS

Data of demographics, the central sensitization inventory (CSI), psychological measures, clinical symptoms of 238 patients with presurgical LBP were evaluated. The patients were divided into two groups depending on the CSI scores (≥40 and < 40). The two groups were compared, and the correlation between the CSI scores and other outcomes was analysed. Furthermore, multiple regression analysis was performed to identify factors contributing to the CSI scores.

RESULTS

13.0% of participants were CSS. All outcomes were significantly different between the groups and significant associations were found between the CSI scores and all other outcomes. In addition, Pain Catastrophizing Scale (PCS) was most significant associated scale for the CSI scores.

CONCLUSION

We found that certain patients had CSS with presurgical LBP. The CSI scores were significantly associated with the majority of the factors. The PCS was the factor with the most influence on the CSI scores.

Validation of the Leiden Visual Sensitivity Scale and Visual Discomfort Scale in Chronic Pain Conditions

Discomfort provoked by normally innocuous visual stimuli has been reported by people with chronic pain. Visual discomfort may be higher in pain conditions in which central sensitization is implicated, such as Complex Regional Pain Syndrome (CRPS) and fibromyalgia. In an online study, we validated the Leiden Visual Sensitivity Scale (L-VISS) and Visual Discomfort Scale (VDS) in people with CRPS (n = 57), fibromyalgia (n = 75), and general chronic pain (n = 53); investigated whether these groups and pain-free controls (n = 125) differed in visual discomfort; and evaluated the effect of age. The L-VISS and VDS had good internal consistency. Both scales were positively related with experimentally induced visual distortions for mid-spatial frequency striped patterns, suggesting good construct validity. The scales were positively related with each other, and dissociated between the pain and pain-free groups in similar ways, suggesting good construct validity. There was no relationship between age and L-VISS scores and a small negative relationship between age and VDS scores. Visual discomfort was highest in the fibromyalgia group, followed by the CRPS group. This research confirms the utility of the L-VISS and VDS for measuring visual sensitivity in chronic pain and adds to evidence that central sensitization is an important mechanism of visual discomfort.

Transcutaneous electrical nerve stimulation (TENS): towards the development of a clinic-friendly method for the evaluation of excitatory and inhibitory pain mechanisms

Background: Temporal summation and conditioned pain modulation (CPM) can be measured using a thermode and cold pressor test (CPTest). Unfortunately, these complex and expensive tools are ill-suited for routine clinical assessments.

Aims: We aimed to compare the temporal summation and CPM obtained with the thermode + CPTest paradigm to those obtained with a novel paradigm using transcutaneous electrical nerve stimulation (TENS).

Methods: We assessed temporal summation and CPM in 29 healthy participants, using two paradigms (random order): TENS, and thermode + CPTest. In the TENS paradigm, both the conditioning stimulus (CS) and the test stimulus (TS) were delivered using TENS; in the thermode + CPTest paradigm, the CS consisted of a CPTest and the TS was delivered using a thermode. We compared the average temporal summation and CPM evoked by the two paradigms.

Results: Average temporal summation was similar for both modalities (P = 0.90), and the number of participants showing temporal summation was similar in both paradigms (19 with thermode vs. 18 with TENS; P = 1.00). Average CPM response was larger following the thermode + CPTest than following the TENS (P = 0.005), and more participants showed CPM with the thermode + CPTest paradigm compared to the TENS paradigm (24 vs. 14; P = 0.01).

Conclusions: Both paradigms were roughly equivalent in the ability to evoke temporal summation (although response to one modality did not predict response to the other), but the TENS paradigm appeared to be less apt to induce a CPM response than the thermode + CPTest paradigm.

Slowly repeated evoked pain (SREP) as a central sensitization marker in episodic migraine patients

Migraine headache is a pain condition characterized by severe and recurrent unilateral head pain. Among other mechanisms, central pain sensitization processes seem to be involved in the disorder. An experimental protocol based on slowly repeated evoked pain (SREP) has been shown to indicate pain sensitization in fibromyalgia patients and differentiate these patients from healthy individuals and rheumatoid arthritis patients. This study examined SREP sensitization in migraine patients and explored its potential usefulness as a central sensitization marker. The SREP protocol was administered to 40 episodic migraine (EM) patients not currently experiencing a headache and 40 healthy controls. SREP consisted of a series of 9 suprathreshold painful pressure stimuli of 5 s duration and a 30 s interstimulus interval. SREP sensitization was indexed by the increase in pain ratings across the stimuli. Pain threshold, pain tolerance and temporal summation of pain were also assessed. SREP sensitization was observed in EM, but not in healthy individuals (p < .001). SREP differentiated between EM and healthy individuals with up to 75% diagnostic accuracy. Pain threshold, pain tolerance and temporal summation of pain did not show significant discriminative ability. An SREP index value of 0.5 was the most sensitive cut-off for detecting central pain sensitization when prioritizing diagnostic sensitivity (0.88). Results provide evidence for SREP as a possible central sensitization marker with potential clinical utility in migraine patients. Inclusion of SREP in Quantitative Sensory Testing protocols may enhance the assessment of altered pain modulation in different pain conditions.

Lack of correlation between central sensitization inventory and psychophysical measures of central sensitization in individuals with painful temporomandibular disorder

OBJECTIVE

To assess the correlation between the Central Sensitization Inventory (CSI) scores and the results of psychophysical tests and psychosocial questionnaires according to the presence of painful temporomandibular disorder (TMD).

DESIGN

It was a cross-sectional study involving 146 participants, aged 20-65 years. Painful TMD was classified using the Research Diagnostic Criteria for Temporomandibular Disorders. CSI was applied to assess "central sensitization-related symptoms", as has been suggested. Wind-up ratio, pressure pain threshold and conditioned pain modulation were used as psychophysical tests to evaluate signs and symptoms of central sensitization. Psychosocial factors were assessed by the presence of non-specific physical symptoms, depressive and anxiety symptoms. The sample was divided into two groups: Control (n = 31); Painful TMD (n = 115). Descriptive statistics characterized the sample. Correlation analysis were performed using Pearson's and Spearman's correlation coefficients (α = 5%).

RESULTS

Of the total sample, 78.8 % presented painful TMD, and the mean (standard deviation) age was 37.4 (±11.5) years. Anxiety symptoms (p = 0.028) and non-specific physical symptoms (p < 0.001) were more frequent in the painful TMD group than in controls. Painful TMD patients presented higher scores of the CSI (p < 0.001) and lower pressure pain thresholds (p ≤ 0.020) compared to controls. CSI scores were significantly correlated with psychosocial measures (p < 0.001) but not with psychophysical tests (p ≥ 0.089).

CONCLUSION

The CSI scores did not correlate with psychophysical measures of central sensitization but were positively correlated with the results of psychosocial questionnaires.

Central sensitization inventory scores correlate with pain at rest in patients with hip osteoarthritis: a retrospective study

Background

Patients with persistent pain due to osteoarthritis (OA) complain of multiple symptoms that cannot be explained solely by structural changes. A poor correlation exists between structural and inflammatory changes in OA and pain levels. Central sensitization (CS) has been identified as a factor that induces chronic pain in patients with OA. Although it is important to identify osteoarthritis patients with CS components, the prevalence and characteristics of CS, especially those in patients with hip OA, are not well understood. Thus, we aimed to determine the prevalence and characteristics of CS in patients with hip OA, in this study.

Methods

The CS Inventory (CSI), used as a non-invasive routine clinical tool to evaluate the presence of CS 1 month before surgery in 100 patients with hip OA, was measured at our outpatient clinic, and the data were retrospectively reviewed. We determined the number of patients with a CSI score of 40 points or higher and assessed the relationships between the CSI score and clinical factors (including age, duration of hip pain, degree pain at rest and on activity, by using the visual analogue scale [VAS] and the Harris Hip Score) using the Spearman’s correlation coefficient.

Results

The mean age of participants was 63.9 ± 11.6 years, and there were 15 men and 85 women. All patients had hip OA, categorised as advanced and terminal stage (Tönnis grade 2–3) on preoperative plain radiography. The mean duration of hip pain was 4.2 ± 4.4 years. The mean CSI score was 19.5 ± 11.3 and 5 (5.0%) of the patients had a score of 40 or more points. CSI scores correlated significantly only with VAS pain at rest (r = 0.348, P < 0.001).

Conclusion

In this study, 1 out of every 20 hip OA patients had CS components. CSI scores were significantly correlated with pain at rest in hip OApatients. CS approaches to hip OA may be one of the treatment options for pain at rest.

Associations between Paraspinal Muscle Morphology, Disc Degeneration, and Clinical Features in Patients with Lumbar Spinal Stenosis

Objective

The purpose of this study was to examine the relationships between intervertebral disc degeneration in the lumbar spine, paraspinal muscle morphology, and clinical features in patients with lumbar spinal stenosis (LSS).

Methods

A total of 52 patients with LSS participated in this study. Magnetic resonance imaging was used to assess intervertebral disc degeneration at L4/5 and to measure the standardized cross-sectional areas (SCSAs) of the multifidus and erector spinae muscles. The intensity of low back pain (LBP) and lower limb pain, the level of disability, and the quality of life (QoL) were evaluated using patient-reported outcome measures. The associations between the image findings and clinical features, including the disability score, the pain score for low back pain, and the QoL score, were calculated using Spearman's rank correlation coefficient.

Results

No associations were found between disc degeneration and clinical features. However, disc degeneration and the SCSA of the multifidus muscle (r=-0.38, P <0.01) and of the erector spinae muscle (r=-0.29, P=0.04) were significantly associated. Analysis of the associations between muscle morphology and clinical features found that the SCSA of the multifidus muscle was associated with LBP (r=0.31, P=0.03).

Conclusions

These results suggest that there is some correlation between atrophy of the multifidus and pain intensity. Consequently, focusing on the CSA of the multifidus muscle may help to clarify the causes of LBP in patients with LSS. However, because of the cross-sectional nature of this study, causal relationships could not be determined and further research is needed.

Standard Correction of Vision Worsens EMG Activity of Pericranial Muscles in Chronic TMD Subjects

Recent studies showed an evident correlation between the stomatognathic system and the visual system. These results suggest that subjects who are affected by both temporomandibular (TMD) disorders and refractive disorders present with altered control of pericranial musculature tone and higher open-eye electromyographic (EMG) values. The objective of this work was to evaluate the effects of standard vision correction on EMG in subjects suffering from TMD compared with application of the same vision treatments to non-TMD subjects. 40 subjects were enrolled in this study. The test group included 20 myopic subjects and also included patients with TMD. The control group included 20 healthy myopic subjects. All of the participants underwent a complete ocular examination and a sEMG analysis. The results showed that TMD subjects with vision disorders that are corrected with standard glasses present EMG values that are significantly higher than those presented by non-TMD subjects with vision disorders and standard glasses. Infact, in TMD subjects, eye correction did not have a positive effect on the stomatognathic or pericranial musculature.

Irritable bowel, chronic widespread pain, chronic fatigue and related syndromes are prevalent and highly overlapping in the general population: DanFunD

Prevalence of functional somatic syndromes (FSS) in the general population varies with observed overlap between syndromes. However, studies including a range of FSS are sparse. We investigated prevalence and characteristics of various FSS and the unifying diagnostic construct bodily distress syndrome (BDS), and identified mutual overlap of the FSS and their overlap with BDS. We included a stratified subsample of 1590 adults from a randomly selected Danish general population sample (n = 7493). Telephonic diagnostic interviews performed by three trained physicians were used to identify individuals with FSS and BDS. Prevalence of overall FSS was 9.3%; 3.8% for irritable bowel, 2.2% for chronic widespread pain, 6.1% for chronic fatigue, 1.5% for whiplash associated disorders, and 0.9% for multiple chemical sensitivity. Prevalence of BDS was 10.7% where 2.0% had the multi-organ type. FSS were highly overlapping with low likelihood of having a “pure” type. Diagnostic agreement of FSS and BDS was 92.0%. Multi-syndromatic FSS and multi-organ BDS were associated with female sex, poor health, physical limitations, and comorbidity. FSS are highly prevalent and overlapping, and multi-syndromatic cases are most affected. BDS captured the majority of FSS and may improve clinical management, making the distinction between multi- and mono-syndromatic patients easier.

Oral Health and Fibromyalgia Syndrome: A Systemic Review

Fibromyalgia is a syndrome currently considered idiopathic and multifactorial rheumatic that causes an increase in muscle tension and is characterized by muscle pain and chronic fibrous tissues-widespread, fluctuating and migrating-associated with stiffness, asthenia, cognitive disorders, insomnia or sleep disorders, alterations in sensitivity to stimuli. In affected patients, there may be anxiety or depressive disorder development. The aim of this study is, with the help of an interdisciplinary team, to evaluate the correlations between this syndrome and oral health. A literature review was conducted, analyzing the most common scientific databases, more than 200 studies were obtained. Subsequently to the application of filters and revision by the authors, only 18 articles were considered eligible for this review. From the results, it is clear that the correlations between fibromyalgia and oral health mainly concern pain in the oro-maxillofacial district, especially in the temporomandibular joint. This certainly could help for faster diagnosis of the syndrome, which is currently difficult to identify.

Conus coronatus and Conus frigidus Venom: A New Source of Conopeptides with Analgesic Activity

BACKGROUND

Cone snails are a natural source of complex peptides with analgesic properties called conotoxins. These peptides are secreted in a complex venomic mixture and are predominantly smaller than 5 kDa. The present study aimed to document the analgesic activity of two species of Conus coronatus (C. coronatus) and Conus frigidus (C. frigidus) venom collected off the Iranian coast in a mouse behavioral test.

METHODS

Conotoxin containing fractions was extracted from the venom ducts and initially purified by column chromatography. The analgesic effect of the fractions was determined on formalin pain model and hot-plate test.

RESULTS

The results led to the identification of four fractions with analgesic activity in C. coronatus and two in C. frigidus. Only one fraction was able to reduce the flinching and licking in both acute pain and chronic pain phases of the formalin test. Moreover, the activity of this fraction remained 30 minutes on the hot-plate test. Purification of the fractions was carried out by RP-HPLC. LC-ESI-MS analysis of the fractions showed that the conotoxins of the analgesic fraction had molecular weights not previously reported.

CONCLUSION

The findings give insight into the venom of two previously under-investigated Conus species and reveal the therapeutic potential of the containing conopeptides.

Examination of pain threshold and neuropeptides in patients with acute suicide risk

INTRODUCTION

One of the main challenges in suicide prevention is the limited understanding of the biological mechanisms underlying suicide. Recent findings suggest impairments in pain processing in acutely suicidal patients. However, little is known about the biological factors that may drive these discrete physiological abnormalities. In this study, we examined plasma peptides involved in analgesic and inflammatory responses and physical pain threshold in acutely suicidal patients.

METHODS

Thirty-seven depressed patients of both sexes hospitalized for severe suicidal ideation or a recent suicide attempt were characterized clinically including history of suicidal ideation and behavior. Psychological and physical pain, and pressure pain threshold was also measured. Plasma levels of β-endorphin, neurotensin, agouti-related protein (AgRP), C-reactive protein (CRP), adrenocorticotropic hormone (ACTH), and brain-derived neurotrophic factor (BDNF) were run in Milliplex multiplex assays.

RESULTS

The number of lifetime suicide attempts was positively correlated with β-endorphin (r = 0.702; p = 0.007), and neurotensin (r = 0.728, p = 0.007) plasma levels. Higher pain threshold was measured in the suicide attempt group as compared to the suicidal ideation group. Pain threshold was strongly and negatively associated with CRP plasma levels (r = -0.548; p < 0.001). In patients reporting chronic pain, lower AgRP levels and lower pain threshold were observed (t = 4.472; p = 0.001).

CONCLUSION

Our results suggest that abnormalities in the opioid and neurotensin systems may underlie the increase in pain threshold found in suicide attempters, and possibly risk for suicidal behavior. Targeting pain circuits and systems may provide therapeutic mechanisms for suicide prevention.

Translation and cross-cultural adaptation of the Polish Central Sensitization Inventory

Objectives

The Central Sensitization Inventory (CSI) is a new, simple clinimetric instrument intended to help doctors who deal with pain of unclear origin. It may be particularly useful when there is a large component of neuropathic pain and to assess non-specific symptoms associated with the phenomenon of central sensitization known under the common name of the central sensitization syndrome. The aim of this study is to perform translation of the CSI into Polish, its cultural adaptation and its preparation for further validation. The proposed adaptation of the scale may be applied both at the clinical level and at the level of primary care.

Material and methods

The CSI translation process took place in several stages. Firstly, the text of the questionnaire was translated from English to Polish by five independent translators. Secondly, the optimal version of the text was determined and, at the third stage, it was submitted to a linguist in order to assess it in the context of the idiomatic and semantic clarity. Thirdly, the translation was passed on to a native speaker who verified the congruence of the Polish translation with its original version. At a later stage, the effect of translating the scale and its usefulness were discussed by a group of experts in order to adapt a cultural tool. The final step was to provide it to be completed and evaluated by twenty anonymous patients with the aim of pre-assessing the level of its understanding.

Results

The final result of the undertaken activities is the Polish version of the CSI ready for validation.

Conclusions

After the multistage preparation and thorough verification of the Polish questionnaire at conceptual, empirical, semantic and idiomatic levels, necessary due to numerous cultural and linguistic differences, the Polish translation of the CSI seems to be a product ready for further validation and introduction to clinical practice.

The important role of central sensitization in chronic musculoskeletal pain seen in different rheumatic diseases

OBJECTIVE

This study explored the role of central sensitization (CS) pain in patients with various rheumatic diseases using the CS inventory (CSI).

METHODS

A total of 193 patients of mean age 50.72 ± 9.65 years were included; they were divided into four different groups in terms of their rheumatic diseases. Patients with rheumatoid arthritis (RA), spondyloarthropathy (SpA), osteoarthritis (OA), and fibromyalgia syndrome (FMS) were evaluated in tertiary care rheumatology/pain medicine settings. Disease duration and activity, the Bath Ankylosing Spondylitis Disease Activity Index, the Disease Activity Score-28, and pain severity (evaluated using a visual analog scale) were assessed, and the Turkish version of the CSI administered.

RESULTS

CS syndromes were present in almost half the patients (45% of SpA, 41% of RA, 62% of OA, and 94% of FMS patients). We found no significant relationship between disease activity and the CSI-A scores in SpA or RA patients (p = 0.731 and p = 0.390, respectively). As expected, the CSI-A scores were highest in the FMS group (p = 0.000), but were similar in the other groups (p < 0.05). CS-related syndromes (CSI-B conditions) were present at similar frequencies in the RA, SpA, and OA groups, but were less common in the FMS group (p = 0.000).

CONCLUSIONS

The CSI usefully detects CS pain in patients with rheumatic diseases. Treatment of such pain can enhance the quality of daily life in patients with rheumatic diseases.Key Point• Central sensitization pain is common in patients with rheumatic diseases including rheumatoid arthritis, spondyloarthropathies, and osteoarthritis.

Chronic Systemic Symptoms in Head and Neck Cancer Patients

The systemic effects and manifestations of disease and treatment have been of interest for millennium. Until recently, basic and clinical research is just now reaching a watershed. Systemic symptoms usually do not occur in isolation but rather in clusters; however, much of the cutting-edge research pertaining to the etiology, mechanism, manifestations, and moderators of systemic symptoms in humans has been directed at individual symptoms, thus creating silos of knowledge. Breaching these silos and bridging the knowledge from disparate arenas of investigation to build a comprehensive depiction of acute and chronic systemic symptoms has been a challenge. In addition, much of the recent work in systemic symptoms has been conducted in the setting of nonmalignant disease. The degree to which the findings from other chronic disease processes can be translated into the oncologic realm is unknown. This article will explore inflammation as a major contributing factor to systemic symptoms and sickness behavior, discuss the most common manifestations in cancer survivors, and, where available, discuss specific data pertaining to head and neck cancer survivors.

Noninvasive experimental bladder pain assessment in painful bladder syndrome

OBJECTIVE

To compare bladder sensitivity between patients with pelvic pain and patients who were pain free, undergoing noninvasive, controlled bladder distension via diuresis. We also sought to measure potential mechanisms underlying bladder sensitivity.

DESIGN

Prospective observational study.

SETTING

Community teaching hospital.

POPULATION

Reproductive-age women with non-bladder chronic pelvic pain (CPP, n = 23), painful bladder syndrome (PBS, n = 23), and pelvic pain-free controls (n = 42) METHODS: Participants were compared on cystometric capacity, pelvic floor pressure-pain thresholds (PPTs), pelvic muscle function, O'Leary-Sant bladder questionnaire, and psychosocial instruments using Wilcoxon rank-sum tests. Multivariate regression was used to identify factors underlying bladder pain phenotypes.

MAIN OUTCOME MEASURES

Pelvic floor pain thresholds; self-reported bladder distension pain.

RESULTS

Participants with PBS exhibited higher bladder distension pain than those with CPP, with both groups reporting higher pain levels than controls (P < 0.05). No significant associations were found between bladder distension pain and pelvic muscle structure or pain sensitivity measures; however, bladder distension pain positively correlates with both vaginal PPTs adjacent to the bladder (r = 0.46) and pain with transvaginal bladder palpation (r = 0.56). Pain at maximal distension was less influenced by somatic sensitivity than bladder symptoms (r = 0.35 versus r = 0.59; P < 0.05). Multivariate regression identified three independent components of bladder symptoms in PBS: bladder distension pain, bladder sensation, and somatic symptoms.

CONCLUSIONS

Diuresis-induced bladder pain differentiates CPP from PBS. Experimental bladder pain is not predicted by pelvic floor sensitivity. Compared with patient-reported outcomes it appears less influenced by psychological factors. Further study is needed to determine whether screening for experimental bladder pain sensitivity could predict future risk of PBS.

TWEETABLE ABSTRACT

Controlled, water ingestion-provoked bladder pain can objectively identify visceral pain sensitivity.

Cross-cultural adaptation and validity of the Italian version of the Central Sensitization Inventory

BACKGROUND

Central sensitization (CS) is an important feature in patients with chronic pain. The Central Sensitization Inventory (CSI) was developed with the goal of detecting the patients' symptoms related to CS.

OBJECTIVES

This study aimed at cross-culturally adapting the CSI into Italian, and at assessing its structural and construct validity in patients with different chronic pain disorders.

DESIGN

Clinimetric study.

METHODS

The Italian version of the CSI (CSI-I) was generated following forward and backward translations, expert committee review, and pilot-testing. Patients with pain for ≥3 months were eligible if diagnosed with: low back pain (LBP), temporomandibular disorder (TMD), hand osteoarthritis (HOA), fibromyalgia (FM), or rheumatoid arthritis (RA). Structural validity was assessed with exploratory factor analysis and parallel analysis based on minimum rank factor analysis; construct validity was evaluated by testing ten hypotheses on: 1) expected differences between relevant subgroups, 2) expected correlations with other instruments measuring pain intensity, physical functioning, psychological functioning, headache symptoms, and pain self-efficacy.

RESULTS

220 patients were included: 35% with LBP, 17% with TMD, 19% with HOA, 9% with FM, and 20% with RA. Factor analyses revealed that the CSI-I is a unidimensional instrument. Construct validity was satisfactory since 80% of the hypotheses were met.

CONCLUSIONS

The CSI-I was successfully developed and exhibited satisfactory validity in patients with chronic pain. Its reliability, responsiveness and content validity should be investigated in future studies. Until robust evidence indicates a strong relationship between CS and the CSI-I, caution should be adopted in claiming that the CSI-I measures CS.

Up to a quarter of patients with certain chronic recalcitrant tendinopathies may have central sensitisation: a prospective cohort of more than 300 patients

Introduction

To identify the possible prevalence of 'central sensitisation', in patients with chronic recalcitrant lower limb tendinopathy conditions, with the Central Sensitisation Inventory (CSI) questionnaire.

Methods

Patients with chronic lower limb tendinopathy conditions treated within a single hospital outpatient clinic specialising in tendinopathy were identified from clinical records. As part of routine care, self-reported numerical markers of pain, global function (using the EuroQol-5D (EQ-5D) questionnaire) and the CSI score to investigate the possibility of central sensitisation were completed.

Results

A total of 312 suitable patients with chronic lower limb tendinopathy and similar conditions were identified, who had completed a CSI questionnaire. Of these, 108 presented with greater trochanteric pain syndrome, 12 with patella tendinopathy, 33 with non-insertional Achilles tendinopathy, 48 with insertional Achilles tendinopathy and 110 with plantar fasciitis. A total of 66% of the patients were female, the median age was 54.9 years and the median duration of symptoms was 24 months. There was a median CSI score of 25%, with statistically significant differences noted between the different conditions studied. Overall, 20% of patients scored above a threshold of 40% on CSI questionnaire, indicating that central sensitisation was possible. Greater trochanteric pain syndrome and plantar fasciitis had the highest proportions in the conditions studied. Weak correlations were found between CSI and other pain scores studied.

Conclusion

The CSI questionnaire may identify up to a quarter of patients with some chronic lower limb tendinopathy and associated conditions as being more likely to have central sensitisation, and these proportions differed between conditions. The clinical significance of this is unclear, but worth further study to see if/how this may relate to treatment outcomes. These are results from a single hospital clinic dealing with patients with chronic tendinopathy, and comparison with a control group is currently lacking. However, on the information presented here, the concept of central sensitisation should be considered in patients being treated for chronic tendinopathy.

A systematic review and meta-analysis of the prevalence of small fiber pathology in fibromyalgia: Implications for a new paradigm in fibromyalgia etiopathogenesis

OBJECTIVES

Fibromyalgia is a condition which exhibits chronic widespread pain with neuropathic pain features and has a major impact on health-related quality of life. The pathophysiology remains unclear, however, there is increasing evidence for involvement of the peripheral nervous system with a high prevalence of small fiber pathology (SFP). The aim of this systematic literature review is to establish the prevalence of SFP in fibromyalgia.

METHODS

An electronic literature search was performed using MEDLINE, EMBASE, PubMed, Web of Science, CINAHL and the Cochrane Library databases. Published full-text, English language articles that provide SFP prevalence data in studies of fibromyalgia of patients over 18years old were included. All articles were screened by two independent reviewers using a priori criteria. Methodological quality and risk of bias were evaluated using the critical appraisal tool by Munn et al. Overall and subgroup pooled prevalence were calculated by random-effects meta-analysis with 95% CI.

RESULTS

Database searches found 935 studies; 45 articles were screened of which 8 full text articles satisfied the inclusion criteria, providing data from 222 participants. The meta-analysis demonstrated the pooled prevalence of SFP in fibromyalgia is 49% (95% CI: 38-60%) with a moderate degree of heterogeneity, (I²= 68%). The prevalence estimate attained by a skin biopsy was 45% (95% CI: 32-59%, I²= 70%) and for corneal confocal microscopy it was 59% (95% CI: 40-78%, I²= 51%).

CONCLUSION

There is a high prevalence of SFP in fibromyalgia. This study provides compelling evidence of a distinct phenotype involving SFP in fibromyalgia. Identifying SFP will aid in determining its relationship to pain and potentially facilitate the development of future interventions and pharmacotherapy.

You'd Better Believe It: The Conceptual and Practical Challenges of Assessing Malingering in Patients With Chronic Pain

Chronic pain is a prevalent and costly condition, with many patients receiving income support and funded treatment. Given that pain cannot be assessed objectively, patients may be suspected of exaggerating their pain and disability to receive additional funding. Although numerous methods of detecting malingering have been suggested, it is unclear whether clinicians can reliably identify malingering in patients with chronic pain. The present focus article was developed to assess the theoretical basis and empirical support for proposed methods of detecting malingering in patients with chronic pain. Five approaches were identified: the evaluation of behavioral signs, effort testing, pen and paper measures, symptom validity tests, and combined methods. An examination of the literature revealed that proposed assessment tools have little theoretical basis or empirical support in patients with chronic pain. Additionally, assessment tools are inconsistent with advances in pain science and scores or observations are likely to be influenced by the typical features of chronic pain, including fear-avoidance and central sensitization. Clinicians should be aware that as yet neither subjective clinical opinions nor clinical detection methods can reliably identify malingering in patients with chronic pain. Perspective: There is interest in the development of assessment tools to detect malingering in patients with chronic pain. An evaluation of methods reveals theoretical and empirical limitations that undermine the usefulness of these approaches. As yet, there is no reliable way for clinicians to identify malingering in patients with chronic pain.

Usefulness of the pain sensitivity questionnaire to discriminate the pain behaviour of chronic pain patients

BACKGROUND

Chronic pain is no longer an effective warning system, but a syndrome with co-morbidities and many causes, needing a careful evaluation. Questions remain about the pain behaviour of chronic pain patients compared with patients with acute pain, or healthy subjects that we investigated.

METHODS

We compared three populations: healthy (HS, n=280), with acute pain (AP=110 patients), and chronic pain (CP=280 patients) by assessing their pain behaviour with the pain sensitivity questionnaire (PSQ-total and PSQ-minor). The influence of central sensitisation syndrome (CSS) on chronic pain behaviour, including catastrophising, was further investigated by using the central sensitisation inventory.

RESULTS

Compared with the AP patients and HS, the CP patients exhibited significantly higher catastrophising scores; higher PSQ-minor scores [29.0 (21.0-39.0), than for AP 24.0 (14.0-32.5), and for healthy subjects 25.0 (17.0-34.0); and PSQ-total scores of for CP, 63.5 for AP, and 64.0 for HS. No significant difference was observed between the HS and AP populations. Significant differences were observed between the CP patients with and without CSS. The median PSQ-minor for patients with CSS was 33.0 and without CSS was 25.0 (P<0.05); the median PSQ-total for patients with CSS was 82.0 and without CSS was 65 (P<0.05). The CP patients without CSS did not show any significant difference compared with the AP and HS groups, except for catastrophising.

CONCLUSIONS

This study highlights the influence of CSS in the results of PSQ and catastrophising by chronic pain patients in comparison with healthy controls and acute pain patients.

CLINICAL TRIAL REGISTRATION

P2014/134.