Pain matters for central sensitization: sensory and psychological parameters in patients with fibromyalgia syndrome

Gender differences in clinical presentations and sensory profiles in patients with fibromyalgia: implications of peripheral and central mechanisms

Introduction

Fibromyalgia has a high female predominance and research work has been focussing mainly on women.

Objectives

We aimed to answer (1) gender differences in pain scores and quality of life, (2) any gender-specific subgroups defined by quantitative sensory testing (QST), and (3) correlations of QST parameters with pain intensity and questionnaire scores.

Methods

We evaluated clinical presentations and QST profiles from 38 male and 38 age-matched female patients.

Results

Women reported significantly higher scores in average daily pain, daily sleep interference score, average weekly pain, weekly sleep interference score, and revised fibromyalgia impact questionnaire (rFIQ). Based on LOGA classification, L0G2, mechanical allodynia or hyperalgesia without abnormal sensory loss, was the most common QST subtype which accounted for 28.9% of men and 26.3% of women. Approximately 34.2% of men and 26.3% of women displayed loss of function of small fibres with an increased cold or warm detection threshold. Cold detection threshold was negatively correlated with pain intensity and functional impairment, suggesting a peripheral mechanism. Central sensitization, defined as allodynia and hyperalgesia to thermal or mechanical stimuli, was found in two-thirds of male and female patients. Mechanical pain sensitivity was positively correlated with the severity of pain and associated symptoms in women, but not men.

Conclusion

There was a marked gender difference in reported pain and quality of life. We have confirmed that central sensitization is a major mechanism for women. Our data suggested an important role of small fibre pathology in both men and women.

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.

Spatial Distribution Dynamics of Sensory Disturbances in the Treatment of Obesity-Related Meralgia Paresthetica Using Transcutaneous Electrical Nerve Stimulation

Background: To date, there have been no studies on the dynamics of areas of pain, paraesthesia and hypoesthesia after the use of various transcutaneous electrical nerve stimulation in the treatment of meralgia paresthetica. Methods: In this pilot study, we observed 68 patients with obesity-related bilateral meralgia paresthetica. Pain syndrome, paraesthesia symptoms, and hypoesthesia were evaluated using 10-point scores. In addition, pain drawing (PD) was used to determine the area of the spatial distribution of pain syndrome and paraesthesia symptoms, and body drawing was used to determine the area of hypoesthesia. Sham TENS was performed in the control group, and effective TENS was performed in the treatment group. The treatment group consisted of two subgroups. One subgroup underwent HF-LA TENS, and the second subgroup underwent LF-HA TENS. Results: Despite the greatest analgesic effect observed from HF-LA TENS, which was assessed using scoring methods, during and after treatment, the reduction in the area of pain and paraesthesia symptoms and the area of hypoesthesia was moderate, short-term, and reversible. In contrast, LF-HA TENS had a pronounced analgesic and sustained anti-paraesthesia effect, manifested by a noticeable decrease in pain and paraesthesia symptoms area in PD, gradually increasing during the first 2 months of follow-up and accompanied by an irreversible prolonged decrease in the area of hypoesthesia. Conclusion: The areas of paraesthesia and hypoesthesia correlate with affective reactions to long-term chronic pain, which noticeably regress under the influence of LF-HA TENS compared to HF-LA TENS.

Pain sensitization in fibromyalgia. Cross-sectional associations between quantitative sensory testing of pain sensitization and fibromyalgia disease burden

BACKGROUND

Whether fibromyalgia burden is related to measures of sensitization, assessed by quantitative sensory testing (QST), is not clear. We examine the associations between sensitization and fibromyalgia disease burden as measured by the polysymptomatic sistress scale (PDS) and the fibromyalgia impact questionnaire (FIQ) (range 0-100).

MATERIALS AND METHODS

Participants were recruited from referrals to a rheumatology outpatient clinic and the fibromyalgia diagnosis was verified by a rheumatologist. They completed the PDS and FIQ and underwent QST of pressure pain threshold (PPT) at five sites, temporal summation (TS), and conditioned pain modulation (CPM) estimated as post-stimuli/pre-stimuli PPT. The associations between QST and disease burden were analysed in linear regression models adjusted for age, sex, and body mass index.

RESULTS

A total of 78 individuals with clinically verified fibromyalgia (90% women, mean age 40.9 years (SD 7.3)) were recruited. Overall mean PPT was associated with the FIQ total score (β-2.1, 95% CI-4.3, -0.0) and the function component (β-2.1, (-4.3, -0.0)). When examining the associations between PPT at individual sites and fibromyalgia disease severity, PPTs at the distal interphalangeal joint and tibialis anterior muscle were associated with both FIQ total score and the FIQ fatigue component. All associations were weak and insignificant after Bonferroni corrections.

CONCLUSION

In this cohort of individuals with fibromyalgia, sensitization was not significantly associated with self-reported disease burden. Our results point to the multifactorial nature of fibromyalgia disease severity.

SIGNIFICANCE

In patients with fibromyalgia, commonly used measures of sensitization do not explain the symptom burden or the functional impact.

Application of the grading system for "nociplastic pain" in chronic primary and chronic secondary pain conditions: a field study

ABSTRACT

The concept "nociplastic pain" has been developed for patients with features of nociceptive system sensitization that are not explained as nociceptive or neuropathic. Here, we tested how well the recently published grading system differentiates between chronic primary and secondary pain conditions. We recruited patients with fibromyalgia (FMS, n = 41), complex regional pain syndrome (CRPS, n = 11), osteoarthritis (OA, n = 21), or peripheral nerve injury (PNI, n = 8). We used clinical history, pain drawings, quantitative sensory testing (QST), and questionnaires to classify their pains as possibly or probably "nociplastic." All patients with chronic primary pain exhibited widespread/regional pain not explainable by either nociceptive or neuropathic mechanisms. Widespread pain occurred in 12 patients with OA but was identified as nociceptive in 11 of 12. Regional pain occurred in 4 patients with PNI but was identified as neuropathic in 3 of 4. At this step, the grading system had 100% sensitivity and 93% specificity. Clinical evidence for pain hypersensitivity by QST, and history of hypersensitivity and mental comorbidities did not differentiate between chronic primary pain (QST: 36/52 = 69%, history: 43/52 = 83%) and secondary pain conditions (QST: 20/29 = 69%, history: 24/29 83%). Based on these data, specificity remained excellent (93%), but sensitivity dropped substantially (60%) due to lacking evidence for pain hypersensitivity in many patients with FMS. This low sensitivity suggests that the published grading system is not suitable for screening purposes. We suggest structural and content modifications to improve sensitivity, including placement of patient history before clinical examination and addition of a high tender point count as evidence for widespread pain hypersensitivity.

Efficiency of Lidocaine Intramuscular and Intraosseous Trigger Point Injections in the Treatment of Residual Chronic Pain after Degenerative Lumbar Spinal Stenosis Decompression Surgery

Introduction: Despite the long-term use of intramuscular and intraosseous lidocaine trigger point injections (LTPI) in the treatment of patients with low back pain, there have been no studies examining their efficiency in treatment of residual pain after degenerative lumbar spinal stenosis (DLSS) decompression surgery. The purpose of our research is to examine the LTPI efficiency in the treatment of residual lumbar pain after DLSS decompression surgery and to compare the analgesic and recovery effects of intramuscular and intraosseous LTPI administered in the L4-S1 region and in the posterior superior iliac spine (PSIS) after treatment and during four months of follow-up. Materials and Methods: We observed 99 patients (F:50, M:49) aged 42 to 59 years with residual neurological disorders after DLSS decompression surgery. In all patients, the pain syndrome exceeded 6 points on the VAS and averaged 7.2 ± 0.11 points. The control group (n = 21) underwent only pharmacotherapy. In addition to pharmacotherapy, the LTPI group underwent intramuscular LTPI in L4-S1 (n = 20), intramuscular LTPI in the PSIS (n = 19), intraosseous LTPI in L5, S1 (n = 20), and intraosseous LTPI in the PSIS (n = 19). A neurological examination was carried out before treatment, 7 days after completion of treatment, and at the end of the second and fourth months of the follow-up period. Results: In the control group, intramuscular LTPI in L4-S1 subgroup, intramuscular LTPI in PSIS subgroup, intraosseous LTPI in L5, S1 subgroup, and intraosseous LTPI in PSIS subgroup, the severity of pain decreased after treatment by 27.1% (p ≤ 0.05), 41.7% (p ≤ 0.01), 50.7% (p ≤ 0.01), 69% (p ≤ 0.01), and 84.7% (p ≤ 0.01), respectively, and at the end of the second month of follow-up, by 14.3% (p > 1), 29.2% (p ≤ 0.05), 38% (p ≤ 0.01), 53.5% (p ≤ 0.01), and 72.2% (p ≤ 0.01), respectively. Reduction of neurogenic claudication, regression of sensory deficit, increase of daily step activity, and improvement of quality of life after treatment were noted in intramuscular LTPI subgroups by 19.6% (p ≤ 0.05), 36.4 (p ≤ 0.05), 40.3% (p ≤ 0.01), and 21.0% (p ≤ 0.05), respectively, and in interosseous LTPI subgroups by 48.6% (p ≤ 0.01), 67.4% (p ≤ 0.01), 68.3% (p ≤ 0.01), and 46% (p ≤ 0.01), respectively. Conclusions: LTPI is highly effective in the treatment of patients with residual pain after DLSS decompression surgery. High analgesic effect, significant regression of sensory deficits and gait disorders, and remarkable improvement of daily step activity and quality of life are noted not only after the end of LTPI treatment but also continue for at least 2 months after treatment. Intraosseous LTPI is more effective than intramuscular LTPI by 92%, and LTPI in PSIS is more effective than LTPI in L4-S1 by 28.6%.

Clinical Characterization of New-Onset Chronic Musculoskeletal Pain in Long COVID: A Cross-Sectional Study

Purpose

New-onset chronic musculoskeletal (MSK) pain is one of the common persistent symptoms in Long COVID (LC). This study investigated its clinical characteristics, underlying mechanisms, and impact on function, psychological health, and quality of life.

Patients and Methods

Thirty adults (19 female, 11 male) with LC and new-onset chronic MSK pain underwent clinical examination, Quantitative Sensory Testing (QST), and blood tests for inflammatory markers and completed the following outcome measures: Timed Up and Go test (TUG), handgrip strength test, COVID-19 Yorkshire Rehabilitation Scale (C19-YRS), Brief Pain Inventory (BPI), Pain Self-Efficacy Questionnaire (PSEQ), Pain Catastrophizing Scale (PCS), International Physical Activity Questionnaire-short form (IPAQ-sf), Generalized Anxiety Disorder (GAD-7), Patient Health Questionnaire (PHQ-9), and EuroQol Five Dimensions health-related quality of life (EQ-5D-5L).

Results

New-onset chronic MSK pain was widespread and continuous in nature, and worse in the joints. When compared to normative values reported in the literature: a) QST revealed mechanical hyperalgesia, heightened temporal summation of pain, and hypoesthesia to vibration stimuli, which is strongly suggestive of central sensitization; b) Plasma cytokine assays indicated distinct pro-inflammatory profiles; c) TUG time indicated reduced balance and mobility; d) handgrip strength revealed general weakness; e) physical activity was lower; and f) there were moderate levels of depression and anxiety with lower self-efficacy scores and lower levels of pain catastrophizing. LC symptoms were of moderate severity (44.8/100), moderate functional disability (22.8/50) and severely compromised overall health (2.6/10) when compared to pre-COVID scores.

Conclusion

New-onset chronic MSK pain in LC tends to be widespread, constant, and associated with weakness, reduced function, depression, anxiety, and reduced quality of life. There is associated central sensitization and proinflammatory state in the condition. Further research is essential to explore the longitudinal progression and natural evolution of the new-onset chronic MSK pain in LC.

Fibromyalgia: A Review of the Pathophysiological Mechanisms and Multidisciplinary Treatment Strategies

Fibromyalgia is a syndrome characterized by chronic widespread musculoskeletal pain, which may or may not be associated with muscle or joint stiffness, accompanied by other symptoms such as fatigue, sleep disturbances, anxiety, and depression. It is a highly prevalent condition globally, being considered the third most common musculoskeletal disorder, following lower back pain and osteoarthritis. It is more prevalent in women than in men, and although it can occur at any age, it is more common between the ages of thirty and thirty-five. Although the pathophysiology and etiopathogenesis remain largely unknown, three underlying processes in fibromyalgia have been investigated. These include central sensitization, associated with an increase in the release of both excitatory and inhibitory neurotransmitters; peripheral sensitization, involving alterations in peripheral nociceptor signaling; and inflammatory and immune mechanisms that develop concurrently with the aforementioned processes. Furthermore, it has been determined that genetic, endocrine, psychological, and sleep disorders may influence the development of this pathology. The accurate diagnosis of fibromyalgia remains challenging as it lacks specific diagnostic biomarkers, which are still under investigation. Nonetheless, diagnostic approaches to the condition have evolved based on the use of scales and questionnaires for pain identification. The complexity associated with this pathology makes it difficult to establish a single effective treatment. Therefore, treatment is multidisciplinary, involving both pharmacological and non-pharmacological interventions aimed at alleviating symptoms. The non-pharmacological treatments outlined in this review are primarily related to physiotherapy interventions. The effectiveness of physical exercise, both on land and in water, as well as the application of electrotherapy combined with transcranial therapy and manual therapy has been highlighted. All of these interventions aim to improve the quality of life of patients highly affected by fibromyalgia.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Surveying the International Prevalence and Nature of Eating, Drinking and Swallowing Difficulties in Adults Presenting with Fibromyalgia

Fibromyalgia is a centralized pain syndrome characterized by widespread pain, fatigue, sleep and sensory issues. Fibromyalgia is present in up to 8% of the global population, disproportionally affecting females. Research acknowledges that patients with similar rheumatic/neurological disorders experience eating, drinking and swallowing difficulties. There are also anecdotal reports regarding dysphagia among the fibromyalgia community. However, there is limited research exploring these issues, with potential impact on care delivery and patient outcomes. This study investigated the nature and prevalence of dysphagia in an international sample of adults with fibromyalgia. An online cross-sectional survey design was used to gather data. Questions were adapted from a criterion-based assessment and available evidence. The survey focused on demographics, dysphagia symptoms, and symptom experiences. Results were analyzed using descriptives and correlational analysis. 1983 individuals participated (age range: 18-94), located: Australia (n = 18), Ireland (n = 63), Canada (n = 174), New Zealand (n = 253), the UK (n = 434) and the USA (n = 1024). Many eating, drinking and swallowing symptoms were reported, including food sticking in the throat during swallowing (89%), and pills taking extra effort to swallow (88%), and dry mouth (85%). This study identified previously under-explored eating, drinking and swallowing difficulties among adults with fibromyalgia. These difficulties were self-reported across age, gender, and location, highlighting the potential prevalence of these concerns among a wide range of people, despite having not been explored in depth in previous studies. Timely and accurate dysphagia identification is vital given the its' potential impact on nutrition, prognosis and quality of life. This study highlighted the importance of honoring patient experiences in fibromyalgia management while also recommending input from allied health professionals such as SLTs and dietitians to improve therapeutic relationships and clinical outcomes. As such, continued research into the cause, implications, and management of these issues beyond is required to inform and optimise future patient-centred service delivery and care provision.

Atrophy patterns in hippocampal subregions and their relationship with cognitive function in fibromyalgia patients with mild cognitive impairment

Objectives

Fibromyalgia (FM) has been associated with decreased hippocampal volume; however, the atrophy patterns of hippocampal subregions have not yet been identified. We therefore aimed to evaluate the volumes of hippocampal subregions in FM patients with mild cognitive impairment (MCI), and to explore the relationship between different subregional alterations and cognitive function.

Methods

The study included 35 FM patients (21 with MCI and 14 without MCI) and 35 healthy subjects. All subjects performed the Montreal Cognitive Assessment (MoCA) to assess cognitive function. FreeSurfer V.7.3.2 was used to calculate hippocampal subregion volumes. We then compared hippocampal subregion volumes between the groups, and analyzed the relationship between hippocampal subregion volume and cognitive function using a partial correlation analysis method.

Results

Compared with the healthy subjects, FM patients with MCI had smaller hippocampal volumes in the left and right CA1 head, Molecular layer head, GC-DG head, and CA4 head, and in the left Presubiculum head. Poorer executive function, naming ability, and attention were associated with left CA1 head and left Molecular layer head atrophy. By contrast, hippocampal subregion volumes in the FM patients without MCI were slightly larger than or similar to those in the healthy subjects, and were not significantly correlated with cognitive function.

Conclusion

Smaller volumes of left CA1 head and left Molecular layer head were associated with poorer executive function, naming ability, and attention in FM patients with MCI. However, these results were not observed in the FM patients without MCI. These findings suggest that the hippocampal subregions of FM patients might present compensatory mechanisms before cognitive decline occurs.

Cold-evoked potentials in Fabry disease and polyneuropathy

Background

Fabry disease (FD) causes cold-evoked pain and impaired cold perception through small fiber damage, which also occurs in polyneuropathies (PNP) of other origins. The integrity of thinly myelinated fibers and the spinothalamic tract is assessable by cold-evoked potentials (CEPs). In this study, we aimed to assess the clinical value of CEP by investigating its associations with pain, autonomic measures, sensory loss, and neuropathic signs.

Methods

CEPs were examined at the hand and foot dorsum of patients with FD (n = 16) and PNP (n = 21) and healthy controls (n = 23). Sensory phenotyping was performed using quantitative sensory testing (QST). The painDETECT questionnaire (PDQ), FabryScan, and measures for the autonomic nervous system were applied. Group comparisons and correlation analyses were performed.

Results

CEPs of 87.5% of the FD and 85.7% of the PNP patients were eligible for statistical analysis. In all patients combined, CEP data correlated significantly with cold detection loss, PDQ items, pain, and autonomic measures. Abnormal CEP latency in FD patients was associated with an abnormal heart frequency variability item (r = -0.684; adjusted p = 0.04). In PNP patients, CEP latency correlated significantly with PDQ items, and CEP amplitude correlated with autonomic measures (r = 0.688, adjusted p = 0.008; r = 0.619, adjusted p = 0.024). Furthermore, mechanical pain thresholds differed significantly between FD (gain range) and PNP patients (loss range) (p = 0.01).

Conclusions

Abnormal CEPs were associated with current pain, neuropathic signs and symptoms, and an abnormal function of the autonomic nervous system. The latter has not been mirrored by QST parameters. Therefore, CEPs appear to deliver a wider spectrum of information on the sensory nervous system than QST alone.

Mechanisms of transcranial direct current stimulation (tDCS) for pain in patients with fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a recurrent pain condition that can be challenging to treat. Transcranial direct current stimulation (tDCS) has become a promising non-invasive therapeutic option in alleviating FMS pain, but the mechanisms underlying its effectiveness are not yet fully understood. In this article, we discuss the most current research investigating the analgesic effects of tDCS on FMS and discuss the potential mechanisms. TDCS may exert its analgesic effects by influencing neuronal activity in the brain, altering cortical excitability, changing regional cerebral blood flow, modulating neurotransmission and neuroinflammation, and inducing neuroplasticity. Overall, evidence points to tDCS as a potentially safe and efficient pain relief choice for FMS by multiple underlying mechanisms. This article provides a thorough overview of our ongoing knowledge regarding the mechanisms underlying tDCS and emphasizes the possibility of further studies to improve the clinical utility of tDCS as a pain management tool.

Bodily maps of emotions and pain: tactile and hedonic sensitivity in healthy controls and patients experiencing chronic pain

ABSTRACT

Pain is an unpleasant sensory and emotional experience. Both pain and emotions are warning signals against outside harm. Interoception, bodily sensations of emotions can be assessed with the emBODY tool where participants colour the body parts where they feel different emotions. Bodily maps of emotions (BMoE) have been shown to be similar between healthy individuals independent of age, sex, cultural background, and language. We used this tool to analyze how these body maps may differ between healthy controls and patients with persistent pain. We recruited 118 patients with chronic pain. An algorithm-selected matched controls from 2348 individuals who were recruited through social media, message boards, and student mailing lists. After providing background information, the participants completed the bodily topography colouring tasks with the emBODY tool using tablets (patients) and online using their own devices (controls), for pain, sensitivity for tactile, nociceptive and hedonic stimuli, and for the 6 basic emotions and a neutral state. Patients with pain coloured significantly larger areas for pain and more negative emotions. On the whole, their BMoEs were dampened compared with healthy controls. They also coloured more areas for nociceptive but not for tactile or hedonic sensitivity. Patients and controls marked different body areas as sensitive to nociceptive and tactile stimulation, but there was no difference in sensitivity to hedonic touch. Our findings suggest that emotional processing changes when pain persists, and this can be assessed with these colouring tasks. BMoEs may offer a new approach to assessing pain.

Strong and aversive cold processing and pain facilitation in fibromyalgia patients relates to augmented thermal grill illusion

The thermal grill illusion (TGI) is assumed to result from crosstalk between the thermoreceptive and nociceptive pathways. To elucidate this further, we compared 40 female fibromyalgia patients to 20 healthy women in an exploratory cross-sectional study. Sensations (cold, warm/heat, unpleasantness, pain and burning) evoked by 20 °C, 40 °C and alternating 20 °C/40 °C (TGI) and somatosensory profiles according to standardized quantitative sensory testing (QST) were assessed on the palm of the dominant hand. Compared to healthy controls, fibromyalgia patients reported stronger thermal grill-evoked cold, warm, unpleasantness and pain as well as stronger and more aversive 20 °C- and 40 °C-evoked sensations. They showed a loss in warm, mechanical and vibration detection, a gain in thermal pain thresholds and higher temporal summation (TS). Among QST parameters higher TS in fibromyalgia patients was most consistently associated with an augmented TGI. Independently, an increased TGI was linked to cold (20 °C) but less to warm (40 °C) perception. In fibromyalgia patients all thermal grill-evoked sensations were positively related to a higher 20 °C-evoked cold sensation and/or 20 °C-evoked unpleasantness. In conclusion, the TGI appears to be driven mainly by the cold-input. Aversive cold processing and central pain facilitation in fibromyalgia patients seem to independently augment the activation of the pain pathway.

Long-lasting mood deterioration following transcranial direct current stimulation treatment for fibromyalgia: A case report

Key Clinical Message

While tDCS has been studied as a safe and effective tool for managing pain in fibromyalgia, there is a possibility of triggered long-lasting mood changes. TDCS may potentially negatively affect mood in specific individuals with fibromyalgia.

Abstract

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulator that showed promising results in pain reduction among individuals with fibromyalgia (FM). Despite the potential benefits, it may have some adverse events that are mainly transient. However, long-lasting effects can also occur. We presented a 31-year-old man whose symptoms and signs were consistent with fibromyalgia, and he received tDCS over C3 to reduce diffuse pain. Although, immediately after fulfilling the session, he became restless, agitated, and aggressive, and his symptoms lasted approximately 2 months later.

Clinical criteria and diagnostic assessment of fibromyalgia: position statement of the Italian Society of Neurology-Neuropathic Pain Study Group

BACKGROUND

The role of central and/or peripheral nervous system dysfunction is basically fundamental in fibromyalgia.

AIM

The aim of this position statement on behalf of the Neuropathic Pain Study Group of the Italian Society of Neurology is to give practical guidelines for the clinical and instrumental assessment of fibromyalgia (FM) in the neurological clinical practice, taking into consideration recent studies.

METHODS

Criteria for study selection and consideration were original studies, case-controls design, use of standardized methodologies for clinical practice, and FM diagnosis with ACR criteria (2010, 2011, 2016).

RESULTS

ACR criteria were revised. For diagnostic procedure of small-fiber pathology, 47 studies were totally considered. Recent diagnostic criteria should be applied (ACR, 2016). A rheumatologic visit seems mandatory. The involvement of small fibers should request at least 2 among HRV + SSR and/or laser-evoked responses and/or skin biopsy and/or corneal confocal microscopy, eventually followed by monitoring of metabolic and/or immunological/ and or/paraneoplastic basis, to be repeated at 1-year follow-up.

CONCLUSIONS

The correct diagnostic approach to FM could promote the exclusion of the known causes of small-fiber impairment. The research toward common genetic factors would be useful to promote a more specific therapeutic approach.

Small-fibre damage is associated with distinct sensory phenotypes in patients with fibromyalgia and small-fibre neuropathy

BACKGROUND

In this clinical and psychophysical study, we aimed to verify whether patients with fibromyalgia with and without small-fibre pathology and patients with pure small-fibre neuropathy share common sensory phenotypes.

METHODS

Using an algorithm based on quantitative sensory testing variables, we grouped 64 consecutive patients with fibromyalgia (20 with small-fibre pathology, 44 without) and 30 patients with pure small-fibre neuropathy into different sensory phenotypes: sensory loss, thermal hyperalgesia, mechanical hyperalgesia and healthy phenotypes.

RESULTS

We found that the frequency of the different sensory phenotypes differed markedly between patients with fibromyalgia and patients with small-fibre neuropathy. In patients with fibromyalgia, with and without small-fibre pathology, healthy and hyperalgesia phenotypes (both thermal and mechanical) were similarly represented, whilst sensory loss and mechanical hyperalgesia phenotypes were the most frequent phenotypes in patients with small-fibre neuropathy.

CONCLUSIONS

Our findings indicate that small-fibre damage is associated with distinct sensory phenotypes in patients with fibromyalgia and in patients with small-fibre neuropathy. The lack of phenotype differences between patients with fibromyalgia with and without small-fibre pathology and the relatively high frequency of the healthy phenotype in these patients highlight a complex relationship between small-fibre pathology and pain in patients with fibromyalgia.

Central Sensitization and Small-fiber Neuropathy Are Associated in Patients With Fibromyalgia

OBJECTIVE

To study the prevalence of small-fiber neuropathy (SFN) in a large cohort of patients with fibromyalgia (FM) and to better characterize the subset of patients with both FM and SFN.

METHODS

This 1-year, retrospective, observational cohort study included 265 patients with FM. They all performed electrochemical skin conductance (ESC) using the Sudoscan device, 1 of the simplest and most reliable technique to assess the distal autonomic nerve fibers. They completed 4 self-assessment questionnaires: (1) the Central Sensitization Inventory (CSI), (2) the Neuropathic Pain Symptom Inventory (NPSI), and (3) the Hospital Anxiety and Depression Scale (HADS), the Fibromyalgia Impact Questionnaire (FIQ).

RESULTS

Fifty-three patients (20%) had reduced ESC values. These patients had higher CSI and HADS scores, and a larger intake of analgesic drugs compared with patients with no ESC abnormalities. Central sensitization, which was extreme in 69% of the patients (CSI score ≥60), was 1 of the main determinants of ESC abnormalities and was associated with a higher NPSI score, even though these 2 factors were not correlated.

CONCLUSION

Over the past 10 years, studies have shown that a significant proportion of patients with FM have signs of small nerve fiber impairment. The possible involvement of SFN, in the occurrence and presentation of clinical symptoms in FM patients, remains however unclear. This is the first study that showed an association between central sensitization and both small nerve fiber impairment and neuropathic pain features in FM patients, rather than a direct association between SFN and neuropathic pain.

Algometry for the assessment of central sensitisation to pain in fibromyalgia patients: a systematic review

INTRODUCTION

The pathophysiology of fibromyalgia (FM) is related to central sensitisation (CS) to pain. Algometry allows assessing CS based on dynamic evoked pain. However, current algometrýs protocols require optimising, unifying and updating.

OBJECTIVES

1) identify the dynamic pain measures used most frequently to effectively assess CS processes in FM, and 2) consider the future of the algometry assessing CS in these patients.

METHODS

Cochrane Collaboration guidelines and PRISMA statements were followed. The protocol was registered in PROSPERO database (ID: CRD42021270135). The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched.

RESULTS

Thirty-four studies were selected, including measures such as temporal summation of pain (TSP), aftersensations (AS), spatial summation of pain (SSP), the noxious flexion reflex (NFR) threshold, conditioned pain modulation (CPM), cutaneous silent period (CuSP), and slowly repeated evoked pain (SREP); and evoked pain combined with neuroimaging. Each measure offered various advantages and limitations. According to ROB, 28 studies were of low quality, 3 of moderate quality, and 3 of high quality.

CONCLUSIONS

Several pain indicators have been demonstrated to successfully examine CS involvement in FM in the last years. Algometry, especially when it involves diverse body sites and tissues, might provide further insight into (1) the evaluation of psychological factors known to influence pain experience, (2) new dynamic pain indicators, and (3) the simultaneous use of certain neuroimaging techniques. Further research clarifying the mechanisms underlying some of these measures, and homogenisation and optimisation of the algometrýs protocols, are needed. KEY MESSAGESAlgometry allows for assessing Central Sensitisation by applying dynamic evoked pain.The future of algometry could relapse in its combination with neuroimaging.Recently-emerged pain indicators should be considered for algometrýs new protocols.

Managing fibromyalgia with complementary and alternative medical exercise: a systematic review and meta-analysis of clinical trials

Fibromyalgia is a chronic medical condition of unclear etiopathology that diminished patients' quality of life; chronic pain is the main symptom, yet patients with fibromyalgia struggle also with depression, anxiety, and insomnia. For many years, pharmaceutical management of pain was the mainstay of treatment. In the latest decade, conventional low-impact aerobic exercise and complementary and alternative medical (CAM) exercise have become important when structuring a personalized therapeutic plan, since side effects are practically inexistent. Heterogenous studies with different methodological approaches have failed to display a clear clinical effect. We conducted a systematic review with meta-analysis of clinical trials putting emphasis on standardized measurable outcomes (Fibromyalgia Impact Questionnaire, FIQ) in our effort to draw a safe conclusion on CAM exercise's effect. After analyzing 14 studies, including 886 patients, meta analysis showed CAM exercise had a beneficial effect on patients' FIQ score reports: standardized mean difference (SMD) 1.330 (95% CI 0.733-1.928). Among them, dance and Tai chi, had a more profound effect: SMD 1.969 (95% CI 0.575-3.364) and SMD 1.852 (95% CI 0.119-3.584), respectively. However, the risk of bias was overall medium to high and statistical heterogeneity was very high. Our meta-regression analysis failed to identify any variable that could account for high heterogeneity. Even though more experimental studies should be done on this subject, CAM exercise seems beneficial for patients with Fibromyalgia.

Sensory Perception Quotient Reveals Visual, Scent and Touch Sensory Hypersensitivity in People With Fibromyalgia Syndrome

Background

Environmental sensitivity is commonly reported by people with fibromyalgia syndrome. People living with fibromyalgia syndrome frequently report hypersensitivity to noxious and non-noxious sensations. To date, there has been little empirical validation of sensory disturbance to non-noxious triggers. Environmental sensitivity is used as a diagnostic feature only in Bennet's alternative criteria for diagnosis of fibromyalgia, where it was ranked the second most important of the components for diagnosis, after number of pain sites. The aim of this study was to use a validated sensory measure to determine if people with fibromyalgia have greater sensory disturbances compared to people with other chronic pain conditions.

Methods

This study used the Sensory Perception Quotient (SPQ) 92 question survey in adults with chronic pain conditions. A fibromyalgia group (n = 135) and a non-fibromyalgia chronic pain control group (n = 45) were recruited. All participants completed the SPQ as a self-report measure of sensory processing. In addition to the original SPQ scoring method, the Revised Scoring of the Sensory Perception Quotient (SPQ-RS) method was used to investigate self-reported hypersensitivity and hyposensitivity and the vision, hearing, taste, touch, and smell subscales. Chi-squared tests were used for categorical variables and Mann Whitney U, or Kruskal-Wallis H test were used to compare groups.

Results

The fibromyalgia group reported significantly more sensitivity compared to the control group (p = 0.030). The fibromyalgia group reported significantly greater hypersensitivity (p = 0.038), but not more hyposensitivity (p = 0.723) compared to controls. The average fibromyalgia SPQ score (92.64 ± 23.33) was similar to that previously reported for adults with autism (92.95 ± 26.61). However, whereas adults with autism had broad range hypersensitivity, the fibromyalgia group reported significantly more hypersensitivity compared to the control group, but the range was restricted to vision (p = 0.033), smell (p = 0.049) and touch (0.040).

Conclusions

These findings demonstrate greater sensory hypersensitivity in people with fibromyalgia compared to people with other chronic pain disorders. Greater hypersensitivity was restricted to touch, vision, and smell, all of which have previously been demonstrated to crosstalk with nociception.

Therapeutic Approaches to Nociplastic Pain Based on Findings in the Reserpine-Induced Fibromyalgia-Like Animal Model

Nociplastic pain, the third category of chronic pain, has emerged as a serious medical issue. Due to its significant negative influences on patients and society, high prevalence, and lack of sufficiently effective treatments, more efficacious therapies are required. This review highlights the potential therapeutic approaches identified in studies that used reserpine-induced myalgia (RIM) animal model that exhibits nociplastic pain-associated phenotypes. These studies have revealed that biological processes including the chronic reduction of monoamines, increase of oxidative/nitrosative stresses and inflammatory mediators, upregulation of pronociceptive neurotransmitters and their receptors, increase of trophic factors, enhancement of the apoptotic pathway, sensory nerve sensitization, and activation of immune cells in central and/or peripheral regions, underly the nociplastic pain-associated phenotypes in RIM animal model. Potential therapeutic approaches to nociplastic pain, i.e., 1) functional modification of specific molecules which expression is distinctly altered following monoamine reduction, 2) targeting the molecules which are responsible for other major categories of chronic pain (i.e., chronic inflammatory pain and neuropathic pain), 3) supplementation of nutrition to correct the disrupted nutritional balance, 4) improvement of physical constitution by natural substances, and 5) nonpharmacological interventions, have been identified. Significance Statement Studies in RIM animal model have revealed the pathologies that occur after the chronic reduction of monoamines and identified potential therapeutic approaches to nociplastic pain. Translation of their analgesic efficacy from RIM animal model to patients remains an issue to be addressed. Successful translation would lead to better therapies for nociplastic pain.

Virtual Reality-Based Therapy Reduces the Disabling Impact of Fibromyalgia Syndrome in Women: Systematic Review with Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Virtual reality-based therapy (VRBT) is a novel therapeutic approach to be used in women with fibromyalgia syndrome (FMS). The aim of our study is to assess the effect of VRBT to reduce the impact of FMS in outcomes such as pain, dynamic balance, aerobic capacity, fatigue, quality of life (QoL), anxiety and depression.

METHODS

Systematic review with meta-analysis was conducted from a bibliographic search in PubMed, Scopus, PEDro, Web of Science and CINAHL until April 2021 in accordance with PRISMA guidelines. We included randomized controlled trials (RCTs) that compare VRBT versus others to assess the mentioned outcomes in women with FMS. Effect size was calculated with standardized mean difference (SMD) and its 95% confidence interval (95% CI).

RESULTS

Eleven RCTs involving 535 women with FMS were included. Using the PEDro scale, the mean methodological quality of the included studies was moderate (6.63 ± 0.51). Our findings showed an effect of VRBT on the impact of FMS (SMD -0.62, 95% CI -0.93 to -0.31); pain (SMD -0.45, 95% CI -0.69 to -0.21); dynamic balance (SMD -0.76, 95% CI -1.12 to -0.39); aerobic capacity (SMD 0.32, 95% CI 0.004 to 0.63); fatigue (SMD -0.58, 95% CI -1.02 to -0.14); QoL (SMD 0.55, 95% CI 0.3 to 0.81); anxiety (SMD -0.47, 95% CI -0.91 to -0.03) and depression (SMD -0.46, 95% CI -0.76 to -0.16).

CONCLUSIONS

VRBT is an effective therapy that reduces the impact of FMS, pain, fatigue, anxiety and depression and increases dynamic balance, aerobic capacity and quality of life in women with FMS. In addition, VRBT in combination with CTBTE showed a large effect in reducing the impact of FMS and fatigue and increasing QoL in these women.

Thermal Pain Thresholds Are Significantly Associated with Plasma Proteins of the Immune System in Chronic Widespread Pain-An Exploratory Pilot Study Using Multivariate and Network Analyses

Chronic widespread pain (CWP), including fibromyalgia (FM), is characterized by generalized musculoskeletal pain. An important clinical feature is widespread increased pain sensitivity such as lowered pain thresholds for different stimuli such as heat (HPT) and cold (CPT). There is a growing interest in investigating the activated neurobiological mechanisms in CWP. This explorative proteomic study investigates the multivariate correlation pattern between plasma and muscle proteins and thermal pain thresholds in CWP and in healthy controls (CON). In addition, we analysed whether the important proteins and their networks for CPT and HPT differed between CWP and CON. We used a proteomic approach and analysed plasma and muscle proteins from women with CWP (n = 15) and CON (n = 23). The associations between the proteins and CPT/HPT were analysed using orthogonal partial least square (OPLS). The protein-protein association networks for the important proteins for the two thermal pain thresholds were analysed using STRING database. CWP had lowered pain thresholds for thermal stimulus. These levels were generally not related to the included clinical variables except in CWP for HPT. Highly interacting proteins mainly from plasma showed strong significant associations with CPT and HPT both in CWP and in CON. Marked differences in the important proteins for the two thermal pain thresholds were noted between CWP and CON; more complex patterns emerged in CWP. The important proteins were part of the immune system (acute phase proteins, complement factors, and immunoglobulin factors) or known to interact with the immune system. As expected, CWP had lowered pain thresholds for thermal stimulus. Although different proteins were important in the two groups, there were similarities. For example, proteins related to the host defence/immunity such as acute phase proteins, complement factors, immunoglobulin factors, and cytokines/chemokines (although not in CON for CPT) were important habitual/tonic factors for thermal pain thresholds. The fact that peripheral proteins contribute to thermal pain thresholds does not exclude that central factors also contribute and that complex interactions between peripheral and central factors determine the registered pain thresholds in CWP.