Small fibre pathology, small fibre symptoms and pain in fibromyalgia syndrome.

A proportion of people with fibromyalgia demonstrate small fibre pathology (SFP). However, it is unclear how SFP directly relates to pain phenomenology. Thirty-three individuals with FMS and ten healthy volunteers underwent assessment of SFP and sensory phenotyping using corneal confocal microscopy, validated questionnaires and quantitative sensory testing (QST). Corneal nerve fibre length was used to stratify participants with fibromyalgia into with SFP [SFP+] and without SFP [SFP-]. SFP was detected in 50% of the fibromyalgia cohort. Current pain score and QST parameters did not differ between SFP+ and SFP-. Mechanical pain sensitivity (MPS) demonstrated a significant gain-of-function in the SFP- cohort compared to healthy-volunteers (p = 0.014, F = 4.806, η2 = 0.22). Further stratification revealed a cohort without structural SFP but with symptoms compatible with small fibre neuropathy symptoms and a significant gain in function in MPS (p = 0.020 Chi-square). Additionally, this cohort reported higher scores for both depression (p = 0.039, H = 8.483, η2 = 0.312) and anxiety (p = 0.022, F = 3.587, η2 = 0.293). This study confirms that SFP is present in a proportion of people with fibromyalgia. We also show that in a proportion of people with fibromyalgia, small fibre neuropathy symptoms are present in the absence of structural SFP. Greater mechanical pain sensitivity, depression and anxiety are seen in these individuals.

Results from an expedited spinal nerve root block clinic at a UK tertiary neurosurgical centre.

STUDY DESIGN: Retrospective Observational Study. INTRODUCTION: Lumbar radicular pain has a prevalence of 3-5%. Level 1 evidence has demonstrated equivalence between surgical and injection treatment. We assess the outcomes from a transforaminal epidural steroid injection clinic in a tertiary neuroscience referral centre. METHODS: We performed an analysis of data from consecutive patients entered into a new internal referral database between August 2018 to May 2021. Radicular pain was classified as one of "first presentation" or "recurrence". Outcomes were obtained from follow up clinic letters and recorded in a binary manner of "positive result" or "negative result". Spinal pathology was documented from radiology reports and MRI images. RESULTS: We analysed 208 patients referred to the clinic. Excluding those who improved to a point of not requiring treatment, and those who underwent surgical intervention, 119 patients undergoing injection were included, of which 14 were lost to follow-up. 68 % of patients had a positive result from injection. Subgroup analysis demonstrated good outcomes for both hyperacute (<6 weeks) and chronic (>12 months). Contained disk pathologies had better outcomes than uncontained. There was no difference in outcomes across grades of compression, but previous same level surgery was associated with poorer response rates. CONCLUSIONS: There is a high rate of natural resolution of symptoms in patients with LSRP. In those where pain persists, TFESI is a valuable first line treatment modality. This study suggests the efficacy of TFESI is potentially independent of grade of stenosis and chronicity of symptoms. Contained disc pathologies respond better than uncontained.

Study protocol for a randomised controlled trial to investigate the effectiveness of thoracic epidural and paravertebral blockade in reducing chronic post-thoracotomy pain: 2 (TOPIC 2).

BACKGROUND: Thoracotomy is considered one of the most painful surgical procedures and can cause debilitating chronic post-surgical pain lasting months or years postoperatively. Aggressive management of acute pain resulting from thoracotomy may reduce the likelihood of developing chronic pain. This trial compares the two most commonly used modes of acute analgesia provision at the time of thoracotomy (thoracic epidural blockade (TEB) and paravertebral blockade (PVB)) in terms of their clinical and cost-effectiveness in preventing chronic post-thoracotomy pain. METHODS: TOPIC 2 is a multi-centre, open-label, parallel group, superiority, randomised controlled trial, with an internal pilot investigating the use of TEB and PVB in 1026 adult (≥ 18 years old) patients undergoing thoracotomy in up to 20 thoracic centres throughout the UK. Patients (N = 1026) will be randomised in a 1:1 ratio to receive either TEB or PVB. During the first year, the trial will include an integrated QuinteT (Qualitative Research Integrated into Trials) Recruitment Intervention (QRI) with the aim of optimising recruitment and informed consent. The primary outcome is the incidence of chronic post-surgical pain at 6 months post-randomisation defined as 'worst chest pain over the last week' equating to a visual analogue score greater than or equal to 40 mm indicating at least a moderate level of pain. Secondary outcomes include acute pain, complications of regional analgesia and surgery, health-related quality of life, mortality and a health economic analysis. DISCUSSION: Both TEB and PVB have been demonstrated to be effective in the prevention of acute pain following thoracotomy and nationally practice is divided. Identification of which mode of analgesia is both clinically and cost-effective in preventing chronic post-thoracotomy pain could ameliorate the debilitating effects of chronic pain, improving health-related quality of life, facilitating return to work and caring responsibilities and resulting in a cost saving to the NHS. TRIAL REGISTRATION: NCT03677856 [ClinicalTrials.gov] registered September 19, 2018. https://clinicaltrials.gov/ct2/show/NCT03677856 . First patient recruited 8 January 2019.

Understanding, diagnosing, and treating Myalgic encephalomyelitis/chronic fatigue syndrome - State of the art: Report of the 2nd international meeting at the Charité Fatigue Center.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a devastating disease affecting millions of people worldwide. Due to the 2019 pandemic of coronavirus disease (COVID-19), we are facing a significant increase of ME/CFS prevalence. On May 11th to 12th, 2023, the second international ME/CFS conference of the Charité Fatigue Center was held in Berlin, Germany, focusing on pathomechanisms, diagnosis, and treatment. During the two-day conference, more than 100 researchers from various research fields met on-site and over 700 attendees participated online to discuss the state of the art and novel findings in this field. Key topics from the conference included: the role of the immune system, dysfunction of endothelial and autonomic nervous system, and viral reactivation. Furthermore, there were presentations on innovative diagnostic measures and assessments for this complex disease, cutting-edge treatment approaches, and clinical studies. Despite the increased public attention due to the COVID-19 pandemic, the subsequent rise of Long COVID-19 cases, and the rise of funding opportunities to unravel the pathomechanisms underlying ME/CFS, this severe disease remains highly underresearched. Future adequately funded research efforts are needed to further explore the disease etiology and to identify diagnostic markers and targeted therapies.

The biology of symptom-based disorders - time to act.

Symptom-based disorders are conditions that are characterised mostly by somatic symptoms rather than objectively identifiable signs. They are very common, including pain and fatigue disorders, functional gastrointestinal and respiratory disorders, and others, and they cause far greater disability than diseases where signs are prominent. Such conditions may sometimes be triggered by infection, as in Post Covid Syndrome (Cabral-Marques et al., 2022; Baiocchi et al., 2022) or physical or psychological trauma. By employing passive immunoglobulin transfer experimental approaches, recent research in several 'unexplained' chronic pain conditions has demonstrated that pathogenic IgG autoantibodies can explain several of these conditions' core symptoms and are ubiquitous in patients with severe phenotypes. The promise from placing positive resources into exploring the role of 'invisible', functional, non-inflammatory autoantibodies in symptom-based disorders across additional areas of Medicine includes patient empowerment and the development of new diagnostic tests and therapies.

The diagnosis of fibromyalgia syndrome.

Fibromyalgia syndrome (FMS) is a common widespread primary pain condition, with a worldwide prevalence of 2%-4%. Recent research has revealed important evidence for changes in central and peripheral nervous system functions and immunological activity. The diagnosis of FMS can be challenging with no known clinical laboratory investigations to confirm or refute its presence. Symptoms are commonly multiple, fluctuant and may not easily align with established medical diagnostic categories. It can be difficult for patients to articulate their array of symptoms, and for both patients and healthcare professionals to fully make sense of the complexities of the condition. As such, patients may be diagnosed inaccurately with alternative conditions, delaying diagnosis by years. The recent publication of the Royal College of Physicians' guidance aims to support clinicians in the diagnosis of FMS. Its purpose is to provide succinct, relevant information for patients and clinicians about FMS and its diagnosis.

Discovery of novel targets in a complex regional pain syndrome mouse model by transcriptomics: TNF and JAK-STAT pathways.

Complex Regional Pain Syndrome (CRPS) represents severe chronic pain, hypersensitivity, and inflammation induced by sensory-immune-vascular interactions after a small injury. Since the therapy is unsatisfactory, there is a great need to identify novel drug targets. Unbiased transcriptomic analysis of the dorsal root ganglia (DRG) was performed in a passive transfer-trauma mouse model, and the predicted pathways were confirmed by pharmacological interventions. In the unilateral L3-5 DRGs 125 genes were differentially expressed in response to plantar incision and injecting IgG of CRPS patients. These are related to inflammatory and immune responses, cytokines, chemokines and neuropeptides. Pathway analysis revealed the involvement of Tumor Necrosis Factor (TNF) and Janus kinase (JAK-STAT) signaling. The relevance of these pathways was proven by abolished CRPS IgG-induced hyperalgesia and reduced microglia and astrocyte markers in pain-associated central nervous system regions after treatment with the soluble TNF alpha receptor etanercept or JAK inhibitor tofacitinib. These results provide the first evidence for CRPS-related neuroinflammation and abnormal cytokine signaling at the level of the primary sensory neurons in a translational mouse model and suggest that etanercept and tofacitinib might have drug repositioning potentials for CRPS-related pain.

Aftersensations and Lingering Pain After Examination in Patients with Fibromyalgia Syndrome.

BACKGROUND: Fibromyalgia syndrome (FMS) is a chronic widespread pain condition with mixed peripheral and central contributions. Patients display hypersensitivities to a spectrum of stimuli. Patients' blunt pressure pain thresholds are typically reduced, and sometimes (∼15%) gentle brushstroke induces allodynia. However, aftersensations after these stimuli have not, to our knowledge, been reported. METHODS: We examined the perception of blunt pressure and "pleasant touch" in FMS. Patients were first interviewed and completed standard psychometric questionnaires. We then measured their sensitivity to blunt pressure and perception of pleasant touch, including aftersensations; patients were followed up for 5 days to evaluate lingering pain from blunt pressure. RESULTS: We recruited 51 patients with FMS and 16 pain-free healthy controls (HCs) at a UK Pain Management Centre. Forty-four patients completed the aftersensation protocol. Most patients reported pain after the application of less mechanical pressure than the level of pressure at which HCs reported pain; median arm and leg thresholds for the patients with FMS were 167 kPa and 233 kPa, respectively. Eighty-four percent (31/37) of patients reported ongoing pain at the site of pressure application 1 day after testing, and 49% (18/37) still perceived pain at 5 days. Aftersensations after brushstroke were common in the FMS group, reported by 77% (34/44) of patients with FMS vs 25% (4/16) of HCs; 34% (15/44) of patients, but no HCs, perceived these aftersensations as uncomfortable. For patients with FMS who experienced aftersensations, brushstroke pleasantness ratings were reduced, and the skin was often an important site of pain. CONCLUSION: Pain after blunt pressure assessment typically lingers for several days. Aftersensations after brushstroke stimulation are a previously unreported FMS phenomenon. They are associated with tactile anhedonia and might identify a clinically distinct subgroup.

Percutaneous cervical cordotomy for cancer-related pain: prospective multimodal outcomes evaluation.

BACKGROUND: Percutaneous cervical cordotomy (PCC) offers pain relief to patients with unilateral treatment-refractory cancer-related pain. There is insufficient evidence about any effects of this intervention on patients' quality of life. METHOD: Comprehensive multimodal assessment to determine how PCC affects pain, analgesic intake and quality of life of patients with medically refractory, unilateral cancer-related pain.This study was set in a multidisciplinary, tertiary cancer pain service. Patient outcomes immediately following PCC were prospectively recorded. Patients were also followed up at 4 weeks. RESULTS: Outcome variables collected included: background and breakthrough pain numerical rating scores before PCC, at discharge and 4 weeks postprocedure; oral morphine equivalent opioid dose changes, Patient's Global Impression of Change, Eastern Cooperative oncology group performance status and health related quality of life score, that is, EuroQol-5 dimension-5 level (EQ-5D). CONCLUSIONS: Despite significant improvement in pain and other standard outcomes sustained at 4 weeks, there was little evidence of improvement in EQ-5D scores. In patients with terminal cancer, improved pain levels following cordotomy for cancer-related pain does not appear to translate into improvements in overall quality of life as assessed with the generic EQ-5D measure.

Research Recommendations Following the Discovery of Pain Sensitizing IgG Autoantibodies in Fibromyalgia Syndrome.

BACKGROUND: Fibromyalgia syndrome (FMS) is the most common chronic widespread pain condition in rheumatology. Until recently, no clear pathophysiological mechanism for fibromyalgia had been established, resulting in management challenges. Recent research has indicated that serum immunoglobulin Gs (IgGs) may play a role in FMS. We undertook a research prioritisation exercise to identify the most pertinent research approaches that may lead to clinically implementable outputs. METHODS: Research priority setting was conducted in five phases: situation analysis; design; expert group consultation; interim recommendations; consultation and revision. A dialogue model was used, and an international multi-stakeholder expert group was invited. Clinical, patient, industry, funder, and scientific expertise was represented throughout. Recommendation-consensus was determined via a voluntary closed eSurvey. Reporting guideline for priority setting of health research were employed to support implementation and maximise impact. RESULTS: Arising from the expert group consultation (n = 29 participants), 39 interim recommendations were defined. A response rate of 81.5% was achieved in the consensus survey. Six recommendations were identified as high priority- and 15 as medium level priority. The recommendations range from aspects of fibromyalgia features that should be considered in future autoantibody research, to specific immunological investigations, suggestions for trial design in FMS, and therapeutic interventions that should be assessed in trials. CONCLUSIONS: By applying the principles of strategic priority setting we directed research towards that which is implementable, thereby expediating the benefit to the FMS patient population. These recommendations are intended for patients, international professionals and grant-giving bodies concerned with research into causes and management of patients with fibromyalgia syndrome.

The autoimmune aetiology of unexplained chronic pain.

Chronic pain is the leading cause of life years lived with disability worldwide. The aetiology of most chronic pain conditions has remained poorly understood and there is a dearth of effective therapies. The WHO ICD-11 has categorised unexplained chronic pain states as 'chronic primary pains' (CPP), which are further defined by their association with significant distress and/or dysfunction. The new mechanistic term, 'nociplasticic pain' has been developed to illustrate their presumed generation by a structurally intact, but abnormally functioning nociceptive system. Recently, researchers have unravelled the surprising, ubiquitous presence of pain-sensitising autoantibodies in four investigated CPP indicating autoimmune causation. In persistent complex regional pain syndrome, fibromyalgia syndrome, chronic post-traumatic limb pain, and non-inflammatory joint pain associated with rheumatoid arthritis, passive transfer experiments have shown that either IgG or IgM antibodies from patient-donors cause symptoms upon injection to rodents that closely resemble those of the clinical disorders. Targets of antibody-binding and downstream effects vary between conditions, and more research is needed to elucidate the molecular and cellular details. The central nervous system appears largely unaffected by antibody binding, suggesting that the clinically evident CNS symptoms associated with CPP might arise downstream of peripheral processes. In this narrative review pertinent findings are described, and it is suggested that additional symptom-based disorders might be examined for the contribution of antibody-mediated autoimmune mechanisms.

Passive transfer of fibromyalgia symptoms from patients to mice.

Fibromyalgia syndrome (FMS) is characterized by widespread pain and tenderness, and patients typically experience fatigue and emotional distress. The etiology and pathophysiology of fibromyalgia are not fully explained and there are no effective drug treatments. Here we show that IgG from FMS patients produced sensory hypersensitivity by sensitizing nociceptive neurons. Mice treated with IgG from FMS patients displayed increased sensitivity to noxious mechanical and cold stimulation, and nociceptive fibers in skin-nerve preparations from mice treated with FMS IgG displayed an increased responsiveness to cold and mechanical stimulation. These mice also displayed reduced locomotor activity, reduced paw grip strength, and a loss of intraepidermal innervation. In contrast, transfer of IgG-depleted serum from FMS patients or IgG from healthy control subjects had no effect. Patient IgG did not activate naive sensory neurons directly. IgG from FMS patients labeled satellite glial cells and neurons in vivo and in vitro, as well as myelinated fiber tracts and a small number of macrophages and endothelial cells in mouse dorsal root ganglia (DRG), but no cells in the spinal cord. Furthermore, FMS IgG bound to human DRG. Our results demonstrate that IgG from FMS patients produces painful sensory hypersensitivities by sensitizing peripheral nociceptive afferents and suggest that therapies reducing patient IgG titers may be effective for fibromyalgia.

A Systematic Review Into the Influence of Temperature on Fibromyalgia Pain: Meteorological Studies and Quantitative Sensory Testing.

Fibromyalgia syndrome (FMS) is a chronic widespread pain condition of unknown aetiology. The role of temperature in FMS pain has not been reviewed systematically. The goal of this study was to review the influences of temperature on pain in FMS, from meteorological and quantitative sensory testing (QST) studies. The review was registered with Prospero: ID-CRD42020167687, and followed PRISMA guidance. Databases interrogated were: MEDLINE (via OVID), EMBASE, PubMed, Web of Science, ScienceDirect, CINAHL, and ProQuest (Feb'20). Exclusion criteria were: age <18, animal studies, non-English, and noncontrolled articles. Thirteen studies pertaining to ambient temperature and FMS pain were identified; 9 of these found no uniform relationship. Thirty-five QST studies were identified, 17 of which assessed cold pain thresholds (CPTs). All studies showed numerically reduced CPTs in patients, ranging from 10.9°C to 26.3°C versus 5.9°C to 13.5°C in controls; this was statistically significant in 14/17. Other thermal thresholds were often abnormal. We conclude that the literature provides consistent evidence for an abnormal sensitization of FMS patients' temperature-sensation systems. Additional work is required to elucidate the factors that determine why a subgroup of patients perceive low ambient temperatures as painful, and to characterize that group. PERSPECTIVE: Patients often report increased pain with changes in ambient temperature; even disabling, extreme temperature sensitivity in winter. Understanding this phenomenon may help clinicians provide reassurance and advice to patients and may guide research into the everyday impact of such hypersensitivity, whilst directing future work into the pathophysiology of FMS.

Bodily changes and sensory sensitivity in complex regional pain syndrome and fibromyalgia.

Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions of unexplained origins. In addition to symptoms in the diagnostic criteria, patients can report changes to vision and other sensations or bodily functions. It is unclear whether these are greater than would be expected due to normal ageing, living with chronic pain generally, or common comorbidities of chronic pain such as depression or anxiety. We administered an on-line survey evaluating the frequencies and types of self-reported somatic symptoms, bodily changes, and sensory sensitivity in respondents with CRPS (n = 390), fibromyalgia (n = 425), and both CRPS and fibromyalgia ("CRPS+fibromyalgia"; n = 88) compared to respondents with other chronic pain conditions (n = 331) and pain-free controls (n = 441). The survey assessed somatic symptoms (Patient Health Questionnaire-15), bodily changes, pain/discomfort/distress triggers, and pain intensifiers. We conducted analysis of covariance's with age, sex, Patient Health Questionnaire-9 (measuring depression), Generalized Anxiety Disorder-7, pain duration in years, hours of pain per day, and number of pain-related medical diagnoses as covariates. After controlling for covariates, respondents with CRPS and/or fibromyalgia reported more somatic symptoms, changes in movement and biological responses, pain/discomfort/distress triggers, and pain intensifiers than pain(-free) control groups. Fibromyalgia specifically related to changes in vision and hearing, urinary/intestinal function, and drinking and eating. Complex regional pain syndrome related to changes in hair, skin, and nails; and infection and healing. The CRPS+fibromyalgia group presented with features of both disorders with minimal additional stressors or symptoms over and above these. Our findings suggest that CRPS and fibromyalgia share underlying pathophysiologies, although specific mechanisms might be different.

Complex regional pain syndrome patient immunoglobulin M has pronociceptive effects in the skin and spinal cord of tibia fracture mice.

It has been proposed that complex regional pain syndrome (CRPS) is a post-traumatic autoimmune disease. Previously, we observed that B cells are required for the full expression of CRPS-like changes in a mouse tibia fracture model and that serum immunoglobulin M (IgM) antibodies from fracture mice have pronociceptive effects in muMT fracture mice lacking B cells. The current study evaluated the pronociceptive effects of injecting CRPS patient serum or antibodies into muMT fracture mice by measuring hind paw allodynia and unweighting changes. Complex regional pain syndrome serum binding was measured against autoantigens previously identified in the fracture mouse model. Both CRPS patient serum or IgM antibodies had pronociceptive effects in the fracture limb when injected systemically in muMT fracture mice, but normal subject serum and CRPS patient IgG antibodies had no effect. Furthermore, CRPS serum IgM antibodies had pronociceptive effects when injected into the fracture limb hind paw skin or intrathecally in the muMT fracture mice. Early (1-12 months after injury) CRPS patient (n = 20) sera were always pronociceptive after systemic injection, and chronic (>12 months after injury) CRPS sera were rarely pronociceptive (2/20 patients), while sera from normal subjects (n = 20) and from patients with uncomplicated recoveries from orthopedic surgery and/or fracture (n = 15) were never pronociceptive. Increased CRPS serum IgM binding was observed for keratin 16, histone 3.2, gamma actin, and alpha enolase autoantigens. We postulate that CRPS patient IgM antibodies bind to neoantigens in the fracture mouse skin and spinal cord to initiate a regionally restricted pronociceptive complement response potentially contributing to the CRPS disease process.

Randomised controlled trial to investigate the effectiveness of thoracic epidural and paravertebral blockade in reducing chronic post-thoracotomy pain (TOPIC): a pilot study to assess feasibility of a large multicentre trial.

OBJECTIVES: Thoracotomy is considered one of the most painful surgical procedures. The incidence of chronic post-thoracotomy pain (CPTP) is up to 50%. Paravertebral blockade (PVB) may be superior to thoracic epidural blockade (TEB) in preventing CPTP. The specific objective of this pilot study was to assess the feasibility of conducting a larger trial to determine whether PVB at thoracotomy is more effective in reducing CPTP compared with TEB. DESIGN: A randomised, parallel, external pilot study was conducted to assess whether a large randomised trial of TEB and PVB with CPTP as the primary outcome is feasible. SETTING: Two adult thoracic centres in the UK. PARTICIPANTS: All adult patients admitted for elective open thoracotomy. Participants were excluded if they were American Society of Anesthesiologists physical status IV or V; or if there is contraindication to local anaesthetics; infection near the proposed puncture site; coagulation/thoracic spine disorders; required chest wall resection or emergency thoracic surgery or had a previous thoracotomy. RESULTS: All patients presenting for thoracotomy were screened over a 12-month period with 194 found to be eligible. Of these, 69 (36%) were randomised (95% CI 29% to 42%). Discounting five participants who died, 54 of 64 participants (84%) returned questionnaire booklets at 6 months. The number of participants indicating at least a moderate level of chest pain at 6 months was lower with PVB but with high levels of uncertainty (RR: 0.7; 95% CI 0.3 to 1.7 for worst pain; RR: 0.3; 95% CI 0.0 to 2.8 for average pain). There were no safety concerns. CONCLUSIONS: A large, multicentre randomised controlled trial of PVB versus TEB is feasible as it is possible to randomise and follow up participants with high fidelity. Pain scores were lower on average with PVB compared with TEB but a much larger trial is required to confirm this reliably. TRIAL REGISTRATION NUMBER: ISRCTN45041624.

Standards for the diagnosis and management of complex regional pain syndrome: Results of a European Pain Federation task force.

BACKGROUND: Complex regional pain syndrome is a painful and disabling post-traumatic primary pain disorder. Acute and chronic complex regional pain syndrome (CRPS) are major clinical challenges. In Europe, progress is hampered by significant heterogeneity in clinical practice. We sought to establish standards for the diagnosis and management of CRPS. METHODS: The European Pain Federation established a pan-European task force of experts in CRPS who followed a four-stage consensus challenge process to produce mandatory quality standards worded as grammatically imperative (must-do) statements. RESULTS: We developed 17 standards in 8 areas of care. There are 2 standards in diagnosis, 1 in multidisciplinary care, 1 in assessment, 3 for care pathways, 1 in information and education, 4 in pain management, 3 in physical rehabilitation and 2 on distress management. The standards are presented and summarized, and their generation and consequences were discussed. Also presented are domains of practice for which no agreement on a standard could be reached. Areas of research needed to improve the validity and uptake of these standards are discussed. CONCLUSION: The European Pain Federation task force present 17 standards of the diagnosis and management of CRPS for use in Europe. These are considered achievable for most countries and aspirational for a minority of countries depending on their healthcare resource and structures. SIGNIFICANCE: This position statement summarizes expert opinion on acceptable standards for CRPS care in Europe.

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.

Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome (CRPS) Recurrence after Amputation for CRPS, and Failure of Conventional Spinal Cord Stimulation.

BACKGROUND: Limb amputation is sometimes being performed in long-standing complex regional pain syndrome (CRPS), although little evidence is available guiding management decisions, including how CRPS recurrence should be managed. METHODS: This report details the management of a young soldier with CRPS recurrence 2 years after midtibial amputation for CRPS. RESULTS: Conventional spinal cord stimulation did not achieve paraesthetic coverage, or pain relief in the stump, whereas L4 dorsal root ganglion stimulation achieved both coverage and initially modest pain relief, and over time, substantial pain relief. CONCLUSIONS: Current evidence does not support the use of amputation to improve either pain or function in CRPS. Before a decision is made, in exceptional cases, about referral for amputation, dorsal root ganglion stimulation should be considered as a potentially effective treatment, even where conventional spinal cord stimulator treatment has failed to achieve reliable paraesthetic cover. Furthermore, this treatment may provide pain relief in those patients with CRPS recurrence in the stump after amputation.