Elevated Plasma Levels of sIL-2R in Complex Regional Pain Syndrome: A Pathogenic Role for T-Lymphocytes?

The efficacy of oral corticoids in treating complex regional pain syndrome: A retrospective cohort study

OBJECTIVES

There is growing evidence supporting the role of inflammatory mechanisms in complex regional pain syndrome (CRPS). Corticoids, as most effective anti-inflammatory drugs, are widely used in treating inflammation. The aim of this study was to retrospectively assess the efficacy of oral corticoid treatment in CRPS patients.

METHODS

Patients treated at the center of pain medicine in the Erasmus University Medical Centre between January 2015 and January 2020 were approached to partake in this study. Medical records were screened for age, gender, medical history, duration of CRPS, and CRPS severity score. Also, treatment effect, dose and duration, pain scores (NRS), and side effects were extracted from medical records. In addition, global perceived effect was completed in patients treated with corticoids.

RESULTS

Between January 2015 and January 2020, twenty-nine CRPS patients received corticoids and met the inclusion criteria. One extreme outlier was excluded and treatment effect was unknown for one patient. Average daily dose was 28.9 mg (range 10-30 mg) and the mean treatment duration was 10.5 days (7-21 days). Fourteen patients (51.9%) responded positively to treatment and thirteen (48.1%) did not respond. Side effects were reported in five patients (17.9%).

CONCLUSIONS

Corticoid treatment was effective in more than half of the patients. With only mild side effects reported the treatment also appears to be relatively safe. Further research is needed to investigate the efficacy of corticoids in treating (early) CRPS, preferably in an intervention study.

Different Types of Pain in Complex Regional Pain Syndrome Require a Personalized Treatment Strategy

Complex regional pain syndrome (CRPS) is a debilitating painful state of an extremity that can develop after trauma. CRPS is diagnosed by the new International Association for the Study of Pain (IASP) diagnostic criteria for CRPS. The syndrome is characterized by continuing regional pain with abnormal sensory, motor, sudomotor, vasomotor, edema, and/or trophic signs. The clinical presentation of CRPS can be very heterogeneous because CRPS is a multi-mechanism syndrome. Therefore, mechanism-based subgroups have been suggested to personalize treatment for CRPS. Additionally, the presentation of symptom pain may also be able to identify different subgroups of CRPS. In this review, the types of pain recognized by the IASP-nociceptive, neuropathic, and nociplastic pain-will be discussed as possible subgroups for CRPS. Each pain type should be identified in CRPS patients, with a thorough history taking, physical examination, and diagnostic tests or (novel) biomarkers to optimize treatment effectiveness. Over the course of the syndrome, patients with CRPS probably experience more than one distinct pain type. Therefore, pain specialists should be alert to not only adjust their treatment if underlying pathophysiologic mechanisms tend to change but also to personalize the treatment of the associated type of pain in the CRPS patient.

Is there an association between serum soluble interleukin-2 receptor levels and syndrome severity in persistent Complex Regional Pain Syndrome?

OBJECTIVE

A potentially useful biomarker for Complex Regional Pain Syndrome (CRPS) is the serum soluble interleukin-2 receptor (sIL-2R) level, which is a marker for T-cell activation. Elevated serum sIL-2R levels have been described in CRPS patients compared to healthy controls. In T-cell mediated inflammatory diseases such as sarcoidosis and rheumatoid arthritis, the serum sIL-2R levels correlate with disease severity. In this study, we investigate whether an association exists between serum sIL-2R levels in CRPS patients and CRPS severity.

METHODS

A cross-sectional cohort study was conducted in a tertiary pain referral center in the Netherlands. Adult CRPS patients diagnosed by the IASP criteria were included between October 2018 until October 2022. The main study parameters were serum sIL-2R levels and the CRPS severity score.

RESULTS

Fifty-three CRPS patients were included with a mean syndrome duration of 84 months (Q3 - Q1:180 - 48). The majority had persistent CRPS with a syndrome duration >1 year (n = 52, 98%). The median pain Numerical Rating Score (NRS) was 7 (Q3 - Q1: 8 - 5) and the mean CRPS severity score was 11 (SD ± 2.3). The median serum sIL-2R level was 330 U/mL (Q3 - Q1:451 - 256). No statistically significant correlation was observed between serum sIL-2R levels and the CRPS severity score (rs = 0.15, P = .28).

CONCLUSIONS

Our findings suggest that serum sIL-2R levels cannot be used as a biomarker for syndrome severity in persistent CRPS (syndrome duration >1 year). Serial measurements of serum sIL-2R from early CRPS to persistent CRPS are needed to investigate whether serum sIL-2R levels can be used to monitor T-cell mediated inflammatory syndrome activity.

The Role of Neuroinflammation in Complex Regional Pain Syndrome: A Comprehensive Review

Complex Regional Pain Syndrome (CRPS) is an excess and/or prolonged pain and inflammation condition that follows an injury to a limb. The pathogenesis of CRPS is multifaceted that remains incompletely understood. Neuroinflammation is an inflammatory response in the peripheral and central nervous systems. Dysregulated neuroinflammation plays a crucial role in the initiation and maintenance of pain and nociceptive neuronal sensitization, which may contribute to the transition from acute to chronic pain and the perpetuation of chronic pain in CRPS. The key features of neuroinflammation encompass infiltration and activation of inflammatory cells and the production of inflammatory mediators in both the central and peripheral nervous systems. This article reviews the role of neuroinflammation in the onset and progression of CRPS from six perspectives: neurogenic inflammation, neuropeptides, glial cells, immune cells, cytokines, and keratinocytes. The objective is to provide insights that can inform future research and development of therapeutic targets for CRPS.

Effectiveness of Infliximab in Patients with Complex Regional Pain Syndrome: A Case Series

Purpose

Complex regional pain syndrome (CRPS) is a multi-mechanism disease, with an exaggerated inflammatory response as an important underlying mechanism. Auto-inflammation can theoretically be combated by anti-inflammatories, such as TNF-α inhibitors. This study's aim was to assess the effectiveness of intravenous infliximab, a TNF-α inhibitor, in patients with CRPS.

Patients and Methods

CRPS patients treated with infliximab between January 2015 and January 2022 were approached to participate in this retrospective study. Medical records were screened for age, gender, medical history, CRPS duration, and CRPS severity score. Additionally, treatment effect, dose and duration, and side effects were extracted from medical records. Patients who still receive infliximab completed a short global perceived effect survey.

Results

Eighteen patients received infliximab, and all but two gave consent. Trial treatment with three sessions of 5 mg/kg intravenous infliximab was completed in 15 patients (93.7%). Eleven patients (73.3%) were categorized as responders with a positive treatment effect. Treatment was continued in nine patients, and seven patients are currently treated. Infliximab dose is 5 mg/kg, and frequency is every four to six weeks. Seven patients completed a global perceived effect survey. All patients reported improvement (median 2, IQR 1-2) and treatment satisfaction (median 1, IQR 1-2). One patient described side effects such as itching and rash.

Conclusion

Infliximab proved effective in 11 out of 15 CRPS patients. Seven patients are still being treated. Further research is needed on the role of infliximab in the treatment of CRPS and possible predictors of response to treatment.

Intermittent versus continuous esketamine infusions for long-term pain modulation in complex regional pain syndrome: protocol of a randomized controlled non-inferiority study (KetCRPS-2)

BACKGROUND

Complex regional pain syndrome (CRPS) is a chronic pain condition of an extremity. While achieving pain relief in CRPS is challenging, esketamine infusions can accomplish pain relief for several weeks post-infusion in a subgroup of CRPS patients. Unfortunately, CRPS esketamine protocols are very heterogeneous in advice on dosage, administration and treatment setting. Currently, no trials are available that study differences between intermittent and continuous esketamine infusions for CRPS. With the current situation of bed shortages, it is difficult to admit patients for several consecutive days for inpatient esketamine treatments. In this study, we investigate whether 6 intermittent outpatient esketamine treatments are not inferior to a continuous 6-day inpatient esketamine treatment in establishing pain relief. In addition, several secondary study parameters will be assessed in order to investigate mechanisms responsible for pain relief by esketamine infusions. Furthermore, the cost-effectiveness will be analyzed.

METHODS

In this RCT, the primary objective is to demonstrate that an intermittent esketamine dosing regimen is non-inferior to a continuous esketamine dosing regimen at 3 months follow-up. We will include 60 adult CRPS patients. The inpatient treatment group receives a continuous intravenous esketamine infusion for 6 consecutive days. The outpatient treatment group receives a 6-hour intravenous esketamine infusion every 2 weeks for 3 months. Esketamine dose will be individually tailored and is started at 0.05 mg/kg/h and can be increased to a maximum of 0.2 mg/kg/h. Each patient will be followed for 6 months. The primary study parameter is perceived pain intensity, measured by an 11-point Numerical Rating Scale. Secondary study parameters are conditioned pain modulation, quantitative sensory testing, adverse events, thermography, blood inflammatory parameter, questionnaires about functionality, quality of life and mood and costs per patient.

DISCUSSION

If our study reveals non-inferiority between intermittent and continuous esketamine infusions, these findings can be beneficial to increase the availability and flexibility of esketamine infusions through outpatient treatments. Furthermore, the costs of outpatient esketamine infusions could be lower than inpatient esketamine infusions. In addition, secondary parameters may predict response to esketamine treatment.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT05212571 , date of registration 01-28-2022.

PROTOCOL VERSION

Version 3, February 2022.

Glucocorticoid treatment in patients with complex regional pain syndrome: A systematic review

BACKGROUND AND OBJECTIVE

The pathophysiology of complex regional pain syndrome (CRPS) is multifactorial, with an exaggerated inflammatory response being the most prominent. Treatment for CRPS is carried out according to the presenting pathophysiological mechanism. Anti-inflammatory treatment with glucocorticoids is therefore an option. The aim of this study was to systematically review the efficacy of glucocorticoids in CRPS.

DATABASES AND DATA TREATMENT

Embase, Medline, Web of Science and Google Scholar were systematically searched for articles focusing on glucocorticoid treatment and CRPS. Screening based on title and abstract was followed by full-text reading (including reference lists) to determine the final set of relevant articles. Bias was assessed using the revised Cochrane risk-of-bias-tool for randomized trials (Rob2).

RESULTS

Forty-one studies were included, which reported on 1208 CRPS patients. A wide variety of glucocorticoid administration strategies were applied, with oral being the most frequently chosen. Additionally, researchers found great heterogeneity in outcome parameters, including clinical symptoms, pain relief and range of motion. The use of glucocorticoids caused an improvement of parameters in all but two studies. In particular, improvement in pain relief and range of motion were reported. Using glucocorticoids in CRPS of longer duration (i.e. more than 3 months) appears to be less effective.

CONCLUSION

Based on the present review, there is evidence to support glucocorticoid treatment in CRPS. However, the ideal administration route and dose remain unclear. We therefore recommend future research via an intervention study, as well as studies on the aetiological mechanisms and corresponding optimal treatment because CRPS pathogenesis is only partially understood.

SIGNIFICANCE

Several studies point towards CRPS being an inflammatory response after tissue or nerve damage, with higher levels of pro-inflammatory cytokines in serum, plasma, cerebrospinal fluid and artificial skin blisters. Inflammation provides a possible role for glucocorticoids in treating CRPS. This systematic review provides a structured overview of glucocorticoid treatment in patients with CRPS. Improvement in pain and range of motion is shown. Systematic review registration number: PROSPERO-CRD42020144671.

[Complex regional pain syndrome-An update]

Complex regional pain syndrome (CRPS) is a pain disorder that develops in the hands or feet after injury. Currently, two types are differentiated, CRPS I without and CRPS II with nerve lesions as well as with either an initially warm or an initially cold subtype, depending on the clinical symptoms. After trauma a certain amount of inflammatory reaction is considered physiological. In acute CRPS this inflammation persists for months and is maintained by diverse inflammatory mediators in peripheral tissue and in blood. This persisting inflammation leads to a sensitization of the nociceptive system, causes somatic cells to proliferate and gives rise to a disrupted endothelial function. The treatment concept aims to antagonize the pathophysiologic components and includes anti-inflammatory and analgetic treatment, mobilization and restoration of the sensorimotor function of the affected limb.

From a Symptom-Based to a Mechanism-Based Pharmacotherapeutic Treatment in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a debilitating painful condition of a distal extremity that can develop after tissue damage. CRPS is thought to be a multimechanism syndrome and ideally the most prominent mechanism(s) should be targeted by drugs in an individually tailored manner. This review gives an overview of the action and evidence of current and future pharmacotherapeutic options for CRPS. The available options are grouped in four categories by their therapeutic actions on the CRPS mechanisms, i.e. inflammation, central sensitisation, vasomotor disturbances and motor disturbances. More knowledge about the underlying mechanisms of CRPS helps to specifically target important CRPS mechanisms. In the future, objective biomarkers could potentially aid in selecting appropriate mechanism-based drugs in order to increase the effectiveness of CRPS treatment. Using this approach, current and future pharmacotherapeutic options for CRPS should be studied in multicentre trials to prove their efficacy. The ultimate goal is to shift the symptom-based selection of therapy into a mechanism-based selection of therapy in CRPS.

A Critical Review on the Standardization and Quality Assessment of Nonfunctional Laboratory Tests Frequently Used to Identify Inborn Errors of Immunity

Inborn errors of immunity (IEI), which were previously termed primary immunodeficiency diseases, represent a large and growing heterogeneous group of diseases that are mostly monogenic. In addition to increased susceptibility to infections, other clinical phenotypes have recently been associated with IEI, such as autoimmune disorders, severe allergies, autoinflammatory disorders, benign lymphoproliferative diseases, and malignant manifestations. The IUIS 2019 classification comprises 430 distinct defects that, although rare individually, represent a group affecting a significant number of patients, with an overall prevalence of 1:1,200-2,000 in the general population. Early IEI diagnosis is critical for appropriate therapy and genetic counseling, however, this process is deeply dependent on accurate laboratory tests. Despite the striking importance of laboratory data for clinical immunologists, several IEI-relevant immunoassays still lack standardization, including standardized protocols, reference materials, and external quality assessment programs. Moreover, well-established reference values mostly remain to be determined, especially for early ages, when the most severe conditions manifest and diagnosis is critical for patient survival. In this article, we intend to approach the issue of standardization and quality control of the nonfunctional diagnostic tests used for IEI, focusing on those frequently utilized in clinical practice. Herein, we will focus on discussing the issues of nonfunctional immunoassays (flow cytometry, enzyme-linked immunosorbent assays, and turbidimetry/nephelometry, among others), as defined by the pure quantification of proteins or cell subsets without cell activation or cell culture-based methods.

[Complex regional pain syndrome-An update]

Complex regional pain syndrome (CRPS) is a pain disorder that develops in the hands or feet after injury. Currently, two types are differentiated, CRPS I without and CRPS II with nerve lesions as well as with either an initially warm or an initially cold subtype, depending on the clinical symptoms. After trauma a certain amount of inflammatory reaction is considered physiological. In acute CRPS this inflammation persists for months and is maintained by diverse inflammatory mediators in peripheral tissue and in blood. This persisting inflammation leads to a sensitization of the nociceptive system, causes somatic cells to proliferate and gives rise to a disrupted endothelial function. The treatment concept aims to antagonize the pathophysiologic components and includes anti-inflammatory and analgetic treatment, mobilization and restoration of the sensorimotor function of the affected limb.

Serum sCD25 Protein as a Predictor of Lack of Long-Term Benefits from Immunotherapy in Non-Small Cell Lung Cancer: A Pilot Study

Prognosis of advanced non-small cell lung carcinoma (NSCLC) is poor. Even though it can improve with anti-PD-1/PD-L1 agents, most patients do not respond to treatment. We hypothesized that the serum soluble form of the unit α of the interleukin-2 receptor (sCD25) could be used as a biomarker of successful immunotherapy in NSCLC. We recruited patients dosed with atezolizumab (n = 42) or pembrolizumab (n = 20) and collected samples at baseline and during the treatment. Levels of sCD25 were quantified with the ELISA kits. Patients with a high sCD25 at baseline (sCD25.0 ≥ 5.99 ng/mL) or/and at the end of the fourth treatment cycle (sCD25.4 ≥ 7.73 ng/mL) progressed faster and lived shorter without the disease progression and serious toxicity. None of the patients with high sCD25 at both time points continued therapy longer than 9.3 months, while almost 40% of patients with low sCD25 were treated for ≥12.3 months. There was a 6.3-times higher incidence of treatment failure (HR = 6.33, 95% CI: 2.10-19.06, p = 0.001) and a 6.5-times higher incidence of progression (HR = 6.50, 95% CI: 2.04-20.73, p = 0.002) in patients with high compared with low sCD25.0 and sCD25.4. Serum levels of sCD25 may serve as a non-invasive biomarker of long-term benefits from the anti-PD-1/PD-L1s in NSCLC.

Review of complex regional pain syndrome and the role of the neuroimmune axis

Background

Complex regional pain syndrome (CRPS) is a progressive and painful disease of the extremities that is characterized by continuous pain inconsistent with the initial trauma. CRPS is caused by a multi-mechanism process that involves both the peripheral and central nervous system, with a prominent role of inflammation in CRPS pathophysiology. This review examines what is currently known about the CRPS inflammatory and pain mechanisms, as well as the possible impact of neurostimulation therapies on the neuroimmune axis of CRPS.

Study design

A narrative review of preclinical and clinical studies provided an overview of the pain and inflammatory mechanisms in CRPS and addressed the effect of neurostimulation on immunomodulation.

Methods

A systematic literature search was conducted based on the PRISMA guidelines between September 2015 to September 2020. Data sources included relevant literature identified through searches of PubMed, Embase and the Cochrane Database of Systematic Reviews.

Results

Sixteen preclinical and eight clinical studies were reviewed. Preclinical studies identified different mechanisms of pain development in the acute and chronic CRPS phases. Several preclinical and clinical studies investigating inflammatory mechanisms, autoimmunity, and genetic profiles in CRPS, supported a role of neuroinflammation in the pathophysiology of CRPS. The immunomodulatory effects of neurostimulation therapy is still unclear, despite clinical improvement in the CRPS patients.

Conclusions

Increasing evidence supports a role for inflammation and neuroinflammation in CRPS pathophysiology. Preliminary neurostimulation findings, together with the role of (neuro)inflammation in CRPS, seems to provide a compelling rationale for its use in CRPS pain treatment. The possible immunomodulatory effects of neurostimulation opens new therapeutic possibilities, however further research is needed to gain a better understanding of the working mechanisms.

Sex differences in neuro(auto)immunity and chronic sciatic nerve pain

Chronic pain occurs with greater frequency in women, with a parallel sexually dimorphic trend reported in sufferers of many autoimmune diseases. There is a need to continue examining neuro-immune-endocrine crosstalk in the context of sexual dimorphisms in chronic pain. Several phenomena in particular need to be further explored. In patients, autoantibodies to neural antigens have been associated with sensory pathway hyper-excitability, and the role of self-antigens released by damaged nerves remains to be defined. In addition, specific immune cells release pro-nociceptive cytokines that directly influence neural firing, while T lymphocytes activated by specific antigens secrete factors that either support nerve repair or exacerbate the damage. Modulating specific immune cell populations could therefore be a means to promote nerve recovery, with sex-specific outcomes. Understanding biological sex differences that maintain, or fail to maintain, neuroimmune homeostasis may inform the selection of sex-specific treatment regimens, improving chronic pain management by rebalancing neuroimmune feedback. Given the significance of interactions between nerves and immune cells in the generation and maintenance of neuropathic pain, this review focuses on sex differences and possible links with persistent autoimmune activity using sciatica as an example.

The Tourniquet Ischemia Test in the Diagnosis of Complex Regional Pain Syndrome

BACKGROUND

The tourniquet ischemia test (IT) is a hitherto rarely used tool for the diagnostic work-up of patients with suspected complex regional pain syndrome (CRPS). This analysis aims to determine the sensitivity and specificity of this test, and elucidate factors that can influence the test result.

METHODS

Consecutive data on clinical presentation, results of the IT and other diagnostic tests, and clinical characteristics were analyzed from patients presenting at our autonomic laboratory between 2000 and 2011. IT results were compared with the final clinical diagnosis at discharge, and statistical analysis was performed to determine specificity, sensitivity, and positive and negative predictive values of the IT.

RESULTS

A total of 78 patients were assessed. IT results were positive (≥50% reduction in pain during ischemia) in 26 cases and negative in 52 cases. CRPS was the final diagnosis in 45 cases, and in 33 cases, a different diagnosis was made. This results in a test sensitivity of 49% and a specificity of 88%, with a positive predictive value of 85% and a negative predictive value of 56%. Age, sex, the type and stage of CRPS, and the affected extremity did not influence the test result in a statistically significant manner. Specificity worsened to 76% if any pain reduction was rated as a positive test result.

CONCLUSIONS

A positive tourniquet IT has a high positive predictive value for the diagnosis of CRPS. It is thus useful as a confirmatory assay in patients with suspected CRPS. Low sensitivity rules out its use as a screening test.

SIGNIFICANCE

This study retrospectively analyzed the clinical significance of the tourniquet IT that was routinely used in patients with suspected CRPS. It showed that a positive IT result is useful as a confirmatory assay in patients fulfilling the clinical criteria.

Serum Soluble Interleukin-2 Receptor Does Not Differentiate Complex Regional Pain Syndrome from Other Pain Conditions in a Tertiary Referral Setting

Previously, we showed that serum soluble interleukin-2 receptor (sIL-2R) levels, a marker for T-cell activation, were higher in complex regional pain syndrome (CRPS) patients than in healthy controls, suggesting pathogenic T-cell activation in CRPS. Additionally, sIL-2R levels discriminated well between CRPS and healthy controls with a high sensitivity (90%) and specificity (89.5%), suggesting a possible role for sIL-2R in the diagnosis of CRPS. In order to further validate this marker in the diagnostic workup of CRPS, we conducted this prospective cohort study in which we determined sIL-2R levels in patients that were referred to our tertiary referral center with a suspicion of CRPS in a limb, and subsequently compared sIL-2R levels between the patients that were diagnosed with CRPS (CRPS group) and those who were not (no CRPS group). A group of anonymous blood bank donors were used as a healthy control group. Furthermore, we explored the relationship between sIL-2R and CRPS disease severity using the CRPS severity score. Median sIL-2R levels of both the CRPS group (2809.0 pg/ml; Q3-Q1: 3913.0-1589.0) and no CRPS group (3654.0 pg/ml; Q3-Q1: 4429.0-2095.5) were significantly higher than that of the control group (1515.0 pg/ml; Q3-Q1: 1880.0-1150.0): CRPS vs. controls, p < .001; no CRPS vs. controls, p < 0.001. Serum sIL-2R levels did not differ significantly between the CRPS and no CRPS group. A statistically significant negative correlation was observed between sIL-2R levels and the CRPS severity score (r_s = −0.468, p = 0.024). Our results confirm our previous findings of higher sIL-2R levels in CRPS patients than in healthy controls. We further showed that serum sIL-2R cannot differentiate between CRPS and other pain conditions of a limb in a tertiary referral setting. Interestingly, a negative correlation was found between sIL-2R and CRPS disease severity; this finding warrants further research into the relationship between sIL-2R and CRPS disease severity.

Novel immune biomarkers in complex regional pain syndrome

We investigated serum levels of 29 cytokines and immune-activated kynurenine and tetrahydrobiopterin pathway metabolites in 15 complex regional pain syndrome (CRPS) subjects and 14 healthy controls. Significant reductions in interleukin-37 and tryptophan were found in CRPS subjects, along with positive correlations between kynurenine/tryptophan ratio and TNF-α levels with kinesiophobia, tetrahydrobiopterin levels with McGill pain score, sRAGE, and xanthurenic acid and neopterin levels with depression, anxiety and stress scores. Using machine learning, we identified a set of binary variables, including IL-37 and GM-CSF, capable of distinguishing controls from established CRPS subjects. These results suggest possible involvement of various inflammatory markers in CRPS pathogenesis.

Highlighting the Role of Biomarkers of Inflammation in the Diagnosis and Management of Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is characterized by continuous pain that is often accompanied by sensory, motor, vasomotor, sudomotor, and trophic disturbances. If left untreated, it can have a significant impact on the quality of life of patients. The diagnosis of CRPS is currently based on a set of relatively subjective clinical criteria: the New International Association for the Study of Pain clinical diagnostic criteria for CRPS. There are still no objective laboratory tests to diagnose CRPS and there is a great need for simple, objective, and easily measurable biomarkers in the diagnosis and management of this disease. In this review, we discuss the role of inflammation in the multi-mechanism pathophysiology of CRPS and highlight the application of potential biomarkers of inflammation in the diagnosis and management of this disease.

Management of long-term complex regional pain syndrome with allodynia: A case report

STUDY DESIGN

Case report.

INTRODUCTION

Conventional rehabilitation alone may not be effective in reducing symptoms in some patients with complex regional pain syndrome.

PURPOSE OF THE STUDY

This case report portrays the benefits of a new tailored rehabilitation program for a 39-year-old patient suffering from upper limb complex regional pain syndrome with severe touch-evoked pain (static mechanical allodynia).

METHODS

This patient had previously received conventional rehabilitation for a year and a half including physical and nonsurgical medical interventions that did not improve symptoms or function. In the search for an alternative, this patient was referred to occupational therapy to try a tailored rehabilitation program, drawing on multiple strategies used sequentially according to the patient's tolerance and symptom evolution. During this 22-month program, the following methods were added (listed chronologically): somatosensory rehabilitation of pain method, graded motor imagery, pain management modalities, active mobilizations, strengthening exercises, and task simulation. The patient successively showed resolution of mechanical allodynia, decreased pain, reduction of tactile hypesthesia and improvement in active range of motion, strength, and function. These improvements allowed him to return to work.

DISCUSSION

This suggests that a tailored rehabilitation program combining somatosensory rehabilitation of pain method, graded motor imagery and more conventional approaches could improve symptoms and functional status in patients with upper limb complex regional pain syndrome, even with persistent refractory symptoms.

CONCLUSION

The addition of the somatosensory rehabilitation of pain method and the graded motor imagery approach to conventional therapy could be considered in cases of complex regional pain syndrome that do not respond to conventional rehabilitation alone.

Biomarkers in IgG4-related disease: A systematic review

OBJECTIVE

ImmunoglobulinG4-related disease (IgG4-RD) is a recently recognized disease and, as such, there is a pressing need to identify biomarkers for diagnosis, monitoring disease activity, and predicting prognosis and response to therapy. Here, we review the recent development and identification of biomarkers for IgG4-RD.

METHODS

Through extensive literature review and analysis, we updated the biomarkers for IgG4-RD and further put forward our own viewpoints.

RESULTS

In addition to traditional biomarkers, such as serum IgG4 concentration and typical histological characteristics, several novel indicators, including IgG2, serum soluble IL-2 receptor (sIL2R), and cc-chemokine ligand 18 (CCL18), indicate inflammation and fibrosis and can be used to accurately diagnose and predict treatment response. Studies to identify target autoantigens in IgG4-RD have shed light on the unmet need for biomarkers that can identify this disorder. Additionally, both serological and histopathologic immune cells involved in antigen-induced responses, innate immune cells (macrophages, mast cells, and the I-IFN/ IL-33 pathway), as well as subsequent acquired immune cells (T and B cell subsets), may also serve as new biomarkers for IgG4-RD. Since IgG4-RD often clinically manifests with multiple organs involvement, non-invasive PET-CT can improve diagnosis and antidiastole levels.

CONCLUSION

These novel biomarkers provide information to help diagnose IgG4-RD, monitor disease activity, as well as predict prognosis and response to therapy.

Diagnosing complex regional pain syndrome using an electronic nose, a pilot study

OBJECTIVE

Complex regional pain syndrome (CRPS) is a complication after surgery or trauma and is characterized by a continuing regional pain in a distal extremity. The pain is disproportionate in severity and duration in relation to the preceding trauma. Currently, the diagnosis is based on the patients' signs and symptoms. There is no objective clinically applicable test available to confirm the diagnosis of CRPS, however this could contribute to a more reliable and valid diagnosis. Since the treatment of CRPS differs from that of other types of pain this could thereby lead to earlier and (more) appropriate treatment and possibly to lower medical costs. The Aeonose™ is a diagnostic test device which detects volatile organic profiles in exhaled air. Exhaled breath analysis using an electronic nose has been successfully applied to differentiate between sick and healthy persons for various indications. This study was a feasibility study in which we investigated whether the Aeonose™ is able to measure a difference in the volatome of CRPS patients compared to the volatome of healthy controls.

DESIGN

Prospective observational study.

SETTING

University Center for Pain Medicine.

SUBJECTS

Adult patients diagnosed with CRPS according to the latest IASP criteria (n = 36) and matched healthy controls (n = 36).

METHODS

Breath profiles were sampled by breathing in and out through the Aeonose™. Data were compressed using a Tucker3-like solution and subsequently used for training an artificial neural network together with the classification 'CRPS: Yes' or 'CRPS: No'. Cross-validation was applied using the leave-10%-out method.

RESULTS

Data of the 72 participants were analyzed, resulting in a sensitivity of 83% (95% CI 67%-93%), specificity of 78% (95% CI 60%-89%), and an overall accuracy of 81%.

CONCLUSIONS

This study suggests that the Aeonose™ can possibly distinguish patients with CRPS from healthy controls based on analysis of their volatome (MEC-2014-149).

Expansion and activation of distinct central memory T lymphocyte subsets in complex regional pain syndrome

BACKGROUND

Complex regional pain syndrome (CRPS) is a debilitating condition where trauma to a limb results in devastating persistent pain that is disproportionate to the initial injury. The pathophysiology of CRPS remains unknown; however, accumulating evidence suggests it is an immunoneurological disorder, especially in light of evidence of auto-antibodies in ~ 30% of patients. Despite this, a systematic assessment of all circulating leukocyte populations in CRPS has never been performed.

METHODS

We characterised 14 participants as meeting the Budapest clinical criteria for CRPS and assessed their pain ratings and psychological state using a series of questionnaires. Next, we performed immunophenotyping on blood samples from the 14 CRPS participants as well as 14 healthy pain-free controls using mass cytometry. Using a panel of 38 phenotypic and activation markers, we characterised the numbers and intracellular activation status of all major leukocyte populations using manual gating strategies and unsupervised cluster analysis.

RESULTS

We have shown expansion and activation of several distinct populations of central memory T lymphocytes in CRPS. The number of central memory CD8+ T cells was increased 2.15-fold; furthermore, this cell group had increased phosphorylation of NFkB and STAT1 compared to controls. Regarding central memory CD4+ T lymphocytes, the number of Th1 and Treg cells was increased 4.98-fold and 2.18-fold respectively, with increased phosphorylation of NFkB in both populations. We also found decreased numbers of CD1c+ myeloid dendritic cells, although with increased p38 phosphorylation. These changes could indicate dendritic cell tissue trafficking, as well as their involvement in lymphocyte activation.

CONCLUSIONS

These findings represent the first mass cytometry immunophenotyping study in any chronic pain state and provide preliminary evidence of an antigen-mediated T lymphocyte response in CRPS. In particular, the presence of increased numbers of long-lived central memory CD4+ and CD8+ T lymphocytes with increased activation of pro-inflammatory signalling pathways may indicate ongoing inflammation and cellular damage in CRPS.

Altered regulation of the T-cell system in patients with CRPS

The aim of this study was to investigate T-cell subsets and immunomodulatory factors in patients with complex regional pain syndrome (CRPS). We found decreased numbers of pro-inflammatory Th17 cells in patients with CRPS as compared to healthy volunteers. The expression of Th17 related RORγT mRNA was also significantly decreased. Patients with CRPS showed an increased proportion of CD39⁺ Tregs. CD39 is a known inhibitor of Th17 cell differentiation. Systemic cytokine levels were almost unchanged in patients with CRPS. These findings suggest that the decrease in Th17 cells in CRPS is regulated by an increase in CD39⁺ Tregs and that this anti-inflammatory T-cell shift may be a mechanism to control inflammation in CRPS. GERMAN CLINICAL TRIAL REGISTER: Registration Trial DRKS00005954.

How a Simple Ankle Sprain Turned Into Neuropathic Pain: Complex Reflex Sympathetic Dystrophy Versus Erythromelalgia

A 36-year-old woman sustained a Grade 2 ankle sprain at work. Two days after the injury, the ankle and foot became red and she complained of “intense burning pain.” First diagnosed with complex reflex sympathetic dystrophy, the employee was prescribed medications that provided some pain relief; a subsequent temporary nerve block provided additional relief. However, the symptoms returned and she was treated unsuccessfully with surgical sympathectomy. The employee was referred to a neurologist and diagnosed with primary erythromelalgia, a rare pain disorder that can be mistaken as complex reflex sympathetic dystrophy.

Soluble Interleukin-2 Receptor: A Potential Marker for Monitoring Disease Activity in IgG4-Related Disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a fibroinflammatory condition. T-cells play a crucial role in the pathogenesis, and therefore, serum soluble interleukin-2 receptor (sIL-2R) may be a potential biomarker.

METHOD

We studied the levels of sIL-2R in 26 histologically proven IgG4-RD patients with available serum sIL-2R and compared them to those in newly diagnosed and untreated sarcoidosis patients (n = 78) and controls (n = 101) and the serum sIL-2R levels in patients after treatment of IgG4-RD (n = 15). The disease activity was measured using the IgG4-Related Disease Responder Index (IgG4-RD RI).

RESULTS

Median serum sIL-2R in IgG4-RD patients was 4667 pg/ml compared to 1515 pg/ml in controls (P < 0.001) and 6050 pg/ml in sarcoidosis patients (P = 0.004 compared to IgG4-RD). All IgG4-RD patients had elevated serum sIL-2R levels compared to the reference value of <2500 pg/ml in controls and 85% elevated serum IgG4; however, these did not correlate with each other. Both serum sIL-2R and IgG4 levels declined significantly after treatment (P = 0.001 and P = 0.01, resp.). Before treatment, serum sIL-2R level and IgG4-RD RI did not correlate with each other. However, the decrease in serum sIL-2R upon treatment did correlate significantly (P = 0.04) with the decrease in disease activity assessed by IgG-RD RI.

CONCLUSION

Serum sIL-2R is elevated in IgG4-RD reflecting the inflammatory process with enhanced T-cell activation. Furthermore, serum sIL-2R might serve as a potential marker of response to treatment in IgG4-RD.