The serum protease network-one key to understand complex regional pain syndrome pathophysiology.

Complex regional pain syndrome (CRPS) develops after fracture. The acute CRPS phenotype resembles exaggerated inflammation, which is explained by local and systemic activation of a proinflammatory network including peptides and cytokines. Epidemiologic data suggest that inactivation of the peptidase angiotensin-converting enzyme in patients treated for hypertension increases the odds to develop CRPS. This hint leads us to investigate the serum protease network activity in patients with CRPS vs respective controls. For this purpose, we developed a dabsyl-bradykinin (DBK)-based assay and used it to investigate patients with CRPS, as well as healthy and pain (painful diabetic neuropathy [dPNP]) controls. The major result is that the degradation of DBK to fragments 1-8 and 1-5 in healthy control and dPNP is shifted to higher values for DBK1-8 and lower values for DBK1-5 at 1 hour of incubation in patients with CRPS. Using this novel reporter peptide assay, we have been able to show that the resolving protease network for mediators such as BK might be different in patients with CRPS; having a look at the clinical signs, which resemble inflammation, this resolving protease network is probably less effective in CRPS.

[Reliability of venous blood gas analysis and radionuclide angiography in post-traumatic dystrophy]. / Reliabilität der venösen Blutgasanalyse und Radionuklidangiographie bei Posttraumatischer Dystrophie.

BACKGROUND: The diagnosis "post-traumatic dystrophy" (PTD) was first defined with clinical and paraclinical criteria by Scola et al. in 2013. OBJECTIVES: The objectivity and reliability of the paraclinical criteria (venous blood gas analysis [vBGA], radionuclide angiography [RNA]), and recommendations for therapy should be assessed in a prospective study. MATERIALS AND METHODS: In five patients with clinical signs of post-traumatic nonbacterial inflammation of the hand, both diagnosis and a 3­week hospital treatment were carried out in accordance with the publication mentioned above. The primary traumata (four fractures and one soft-tissue injury) were located in either the hand or the forearm. Unsuccessful outpatient treatment always led to hospital admission. One patient with severe osteopenia in the hand skeleton was treated with bisphosphonates for 6 months. RESULTS: All patients fulfilled the clinical and paraclinical criteria for the diagnosis of PTD. On admission, an elevated venous partial pressure of oxygen was found by vBGA in the affected hand (∆pO2 mean 22 ± 3 mm Hg) and a hyperperfusion due to arteriovenous shunts was measured using RNA (mean 75 ± 47%). The symptomatic treatment was extremely well tolerated; by the time of discharge, all patients achieved full functioning of the hand with minor loss of strength (venous ∆pO2 mean 5 ± 3 mm Hg). The osteopenia in the one patient treated with bisphosphonates showed recalcification after 6 months. CONCLUSION: The reliability of clinical and paraclinical criteria for PTD were confirmed. vBGA and RNA seem to be good parameters for confirming the diagnosis of PTD. "Rubor," a symptom traditionally interpreted as "hyperemia," contradicts the paraclinical findings and leads to the assumption that the cause of this post-traumatic syndrome is microvascular dysfunction.

Endocrine disorders in women with complex regional pain syndrome type I.

BACKGROUND: The question of hormonal dysregulation in patients with CRPS I in whole was investigated very scantily. There are only a few studies concerning catecholamines, oestrogens and endorphins independently. Other hormones were studied in patients with different other chronic pain conditions. Considering the accumulation of sufficient knowledge about the role of disadaptation processes in CRPS I pathogenesis and the role of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-ovarian systems in the process of adaptation it was logical and consistent to define the role of hormonal dysregulation of these systems in patients with CRPS I. OBJECTIVES: Our objective was to determine the role of hypothalamic-pituitary-adrenal and hypothalamic-pituitary-ovarian systems in pathogenesis of complex regional pain syndrome type I (CRPS I) in women. METHODS: We investigated the pituitary gonadotropic function and the function of sex glands in women with CRPS I and healthy volunteers by measuring the plasma levels of estradiol (E2 ), follicle-stimulating hormone, luteinizing hormone, prolactin, adrenocorticotropic hormone, and cortisol, and urinary excretion of 17-ketosteroids, 17-oxycocorticosteroids, epinephrine and norepinephrine. RESULTS: Women with CRPS I were characterized by the decreased content of oestrogens in the blood plasma and increased pituitary gonadotrophic function. The disturbed ratio of anabolic and catabolic steroids in women with CRPS I was detected due to lower adrenal cortex function. CONCLUSIONS: In patients with CRPS I endocrine status is characterized by hormonal imbalances of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal systems. The changes in reproductive and adaptation homeostasis characterize CRPS I as a form of the disease of disadaptation. SIGNIFICANCE: This study determined the role of hypothalamic-pituitary-adrenal and hypothalamic-pituitary-ovarian systems in pathogenesis of CRPS I.

Antioxidant profile in patients with complex regional pain syndrome type I.

OBJECTIVE: Complex regional pain syndrome (CRPS) type I is one of the most important problems with regard to physical medicine and rehabilitation. CRPS may cause not only higher therapeutic costs but also greater work time loss. The mechanism and pathogenesis of CRPS still remains unknown. Some findings indicating oxidative stress have been reported. This study was carried out to determine the role of oxidative stress in patients with CRPS. MATERIALS AND METHODS: Twenty patients (13 women and seven men) with CRPS and 20 age- and sex-matched healthy controls were enrolled in this study. Complex regional pain syndrome was diagnosed according to the modified International Association for the Study of Pain (IASP) criteria. We evaluated demographic, clinical and laboratory characteristics of the patients. Antioxidant enzymatic activities consisting of serum superoxide dismutase (SOD), glutathion peroxidase (GPX) and glutathione S-transferase (GST) activities were measured using appropriate methods and compared with healthy controls. RESULTS: The mean age of the patients was 39.5 years and the mean duration of symptoms was 5.5 months. Complex regional pain syndrome devoleped after a traumatic event in 90% of patients. In 10% of patients there were no traumatic events. SOD, GPX and GST levels were significantly higher in patients with CRPS than healthy controls (P = 0.012, P = 0.036 and P = 0.016, respectively). CONCLUSION: Our findings suggest a possible role of oxidative stress in the pathogenesis of CRPS.

Local cytokine changes in complex regional pain syndrome type I (CRPS I) resolve after 6 months.

There is evidence that inflammatory processes are involved in at least the early phase of complex regional pain syndrome (CRPS). We compared a panel of pro- and antiinflammatory cytokines in skin blister fluids and serum from patients with CRPS and patients with upper-limb pain of other origin (non-CRPS) in the early stage (< 1 year) and after 6 months of pain treatment. Blister fluid was collected from the affected and contralateral nonaffected side. We used a multiplex-10 bead array cytokine assay and Luminex technology to measure protein concentrations of the cytokines interleukin-1 receptor antagonist (IL-1RA), IL-2, IL-6, IL-8, IL-10, IL-12p40, and tumor necrosis factor-alpha (TNF-α) and the chemokines eotaxin, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1ß (MIP-1ß). We found bilaterally increased proinflammatory TNF-α and MIP-1ß and decreased antiinflammatory IL-1RA protein levels in CRPS patients compared to non-CRPS patients. Neither group showed side differences. After 6 months under analgesic treatment, protein levels of all measured cytokines in CRPS patients, except for IL-6, significantly changed bilaterally to the level of non-CRPS patients. These changes were not related to treatment outcome. In serum, only IL-8, TNF-α, eotaxin, MCP-1, and MIP-1ß were detectable without intergroup differences. Blister fluid of CRPS patients showed a bilateral proinflammatory cytokine profile. This profile seems to be relevant only at the early stage of CRPS. Almost all measured cytokine levels were comparable to those of non-CRPS patients after 6 months of analgesic treatment and were not related to treatment outcome.

Oxidative stress in Complex Regional Pain Syndrome (CRPS): no systemically elevated levels of malondialdehyde, F2-isoprostanes and 8OHdG in a selected sample of patients.

Exaggerated inflammation and oxidative stress are involved in the pathogenesis of Complex Regional Pain Syndrome (CRPS). However, studies assessing markers for oxidative stress in CRPS patients are limited. In this study, markers for lipid peroxidation (malondialdehyde and F2-isoprostanes) and DNA damage (8-hydroxy-2-deoxyguanosine) were measured in nine patients (mean age 50.1 ± 17.1 years) with short term CRPS-1 (median 3 months) and nine age and sex matched healthy volunteers (mean age 49.3 ± 16.8 years) to assess and compare the level of oxidative stress. No differences were found in plasma between CRPS patients and healthy volunteers for malondialdehyde (5.2 ± 0.9 µmol/L vs. 5.4 ± 0.5 µmol/L) F2-isoprostanes (83.9 ± 18.7 pg/mL vs. 80.5 ± 12.3 pg/mL) and 8-hydroxy-2-deoxyguanosine (92.6 ± 25.5 pmol/L vs. 86.9 ± 19.0 pmol/L). Likewise, in urine, no differences were observed between CRPS patients and healthy volunteers for F2-isoprostanes (117 ng/mmol, IQR 54.5-124.3 vs. 85 ng/mmol, IQR 55.5-110) and 8-hydroxy-2-deoxyguanosine (1.4 ± 0.7 nmol/mmol vs. 1.4 ± 0.5 nmol/mmol). Our data show no elevation of systemic markers of oxidative stress in CRPS patients compared to matched healthy volunteers. Future research should focus on local sampling methods of oxidative stress with adequate patient selection based on CRPS phenotype and lifestyle.

The first scintigraphic detection of tumor necrosis factor-alpha in patients with complex regional pain syndrome type 1.

Tumor necrosis factor (TNF)-alpha has been identified as a pathogenic factor in many immunologically based diseases and complex regional pain syndrome (CRPS). In this case series, we used radiolabeled technetium anti-TNF-alpha antibody to scintigraphically image TNF-alpha in 3 patients with type 1 CRPS. The results show that TNF-alpha was localized only in affected hands of patients with early-stage CRPS. No uptake was seen in clinically unaffected hands and late-stage CRPS. Our findings support the growing evidence for neuroimmune disturbance in patients with CRPS and may have important further implications for specific anticytokine treatment in patients with CRPS.

Enhanced anandamide plasma levels in patients with complex regional pain syndrome following traumatic injury: a preliminary report.

The complex regional pain syndrome (CRPS) is a disabling neuropathic pain condition that may develop following injuries of the extremities. The pathogenesis of this syndrome is not clear; however, it includes complex interactions between the nervous and the immune system resulting in chronic inflammation, pain and trophic changes. This interaction may be mediated by chronic stress which is thought to activate the endogenous cannabinoid (endocannabinoid) system (ECS). We conducted an open, prospective, comparative clinical study to determine plasma level of the endocannabinoid anandamide by high-performance liquid chromatography and a tandem mass spectrometry system in 10 patients with CRPS type I versus 10 age- and sex-matched healthy controls. As compared to healthy controls, CRPS patients showed significantly higher plasma concentrations of anandamide. These results indicate that the peripheral ECS is activated in CRPS. Further studies are warranted to evaluate the role of the ECS in the limitation of inflammation and pain.

Systemic inflammatory mediators in post-traumatic complex regional pain syndrome (CRPS I) - longitudinal investigations and differences to control groups.

OBJECTIVES: The Complex Regional Pain Syndrome I (CRPS I) is a disease that might affect an extremity after trauma or operation. The pathogenesis remains yet unclear. It has clinical signs of severe local inflammation as a result of an exaggerated inflammatory response but neurogenic dysregulation also contributes to it. Some studies investigated the role inflammatory mediators and cytokines; however, few longitudinal studies exist and control groups except healthy controls were not investigated yet. METHODS: To get further insights into the role of systemic inflammatory mediators in CRPS I, we investigated a variety of pro-, anti-, or neuro-inflammatory mediators such as C-Reactive Protein (CRP), White Blood Cell Count (WBC), Interleukins 4, 6, 8, 10, 11, 12 (p70), Interferon gamma, Tumor-Necrosis-Factor alpha (TNF-a) and its soluble Receptors I/II, soluble Selectins (E,L,P), Substance-P (SP), and Calcitonin Gene-Related Peptide (CGRP) at different time points in venous blood from patients with acute (AC) and chronic (CC) CRPS I, patients with forearm fractures (FR), with neuralgia (NE), and from healthy volunteers (C). RESULTS: No significant changes for serum parameters investigated in CRPS compared to control groups were found except for CC/C (CGRP p = 0.007), FR/C (CGRP p = 0.048) and AC/CC (IL-12 p = 0.02; TNFRI/II p = 0.01; SP p = 0.049). High interindividual variations were observed. No intra- or interindividual correlation of parameters with clinical course (e.g. chronification) or outcome was detectable. CONCLUSION: Although clinically appearing as inflammation in acute stages, local rather than systemic inflammatory responses seem to be relevant in CRPS. Variable results from different studies might be explained by unpredictable intermittent release of mediators from local inflammatory processes into the blood combined with high interindividual variabilities. A clinically relevant difference to various control groups was not notable in this pilot study. Determination of systemic inflammatory parameters is not yet helpful in diagnostic and follow-up of CRPS I.

Increased plasma serotonin in complex regional pain syndrome type 1.

BACKGROUND: In patients with complex regional pain syndrome type 1 (CRPS1), some improvement can be achieved by the administration of ketanserin, a 5-HT(2A) receptor antagonist. We measured plasma levels of serotonin (5-HT) during CRPS1 and correlated these levels with disease characteristics. METHODS: Plasma 5-HT was measured in 35 patients who had CRPS1 for 3 yr and compared with 35 age-matched healthy controls. RESULTS: The plasma 5-HT levels were 411 +/- 263 nmol/L and 29 +/- 18 nmol/L, respectively (P < 0.001). No correlations with disease characteristics were observed. CONCLUSIONS: The markedly elevated levels of plasma 5-HT in CRPS1 patients suggest a role for 5-HT during the course of this disease. However, because of the lack of correlations with distinct disease characteristics, 5-HT is probably one of a number of mediators in CRPS1.

Increased plasma glutamate, glycine, and arginine levels in complex regional pain syndrome type 1.

BACKGROUND: Various inflammatory mediators have been identified as potential contributors to complex regional pain syndrome type 1 (CRPS1), but these mediators do not entirely explain certain manifestations of the syndrome, such as pain. The objective of this study was to investigate the role of amino acids in the pathogenesis of CRPS1. METHODS: We used HPLC to determine plasma concentrations of 16 amino acids, especially those related to the NMDA receptor (e.g., glutamate and glycine) and nitric oxide (NO) synthesis (e.g., arginine and citrulline) in patients with CRPS1 (n=64) and age- and sex-matched healthy controls (n=51). Patients rated pain intensity (visual analog scale) and the subjective experience of pain intensity (McGill Pain Questionnaire). Psychological dysfunction was assessed using the SCL-90. RESULTS: Relative to controls, in CRPS1 patients, plasma levels of glutamate, arginine, taurine, and glycine were increased, and plasma levels of glutamine and the ratio of citrulline to arginine were decreased. Remarkably, in CRPS1 patients there was a highly significant inverse correlation between glutamine and glutamate, although the sum of molar concentrations of glutamate and glutamine remains unchanged. Subjective measures of pain and indicators of psychoneuroticism and emotional instability did not correlate with amino acid levels. CONCLUSION: This study shows for the first time a pronounced increase in amino acid levels in this chronic pain syndrome. The marked differences in glutamate, glutamine, glycine, taurine and arginine levels between patients and controls suggest the involvement of both the NDMA receptor and the endothelium-dependent arginine-NO system in CRPS1.

Dysautonomia, fibromyalgia and reflex dystrophy.

Autonomic nervous system dysfunction observed in fibromyalgia, characterized without exception by a sympathetic hyperactivity and hyporeactivity, has been reported. However, several studies demonstrated reduced levels of norepinephrine and neuropeptide Y at rest and after tilt table in some patients, which was improved by beta-stimulating agents. These findings support heterogeneity in fibromyalgia-associated dysautonomia. Fibromyalgia could be a generalized sympathetic dystrophy since both conditions are activated by trauma and partly linked to sympathetic mechanisms. Yet they differ on several points: hormonal and neurochemical abnormalities are observed in fibromyalgia whereas activation by peripheral trauma and hyperosteolysis are observed in reflex sympathetic dystrophy.

Multiplex bead array assay for detection of 25 soluble cytokines in blister fluid of patients with complex regional pain syndrome type 1.

Inflammatory processes are known to be involved at least in the early phase of complex regional pain syndrome type 1 (CRPS1). Blister fluid obtained from the involved extremities displayed increased amounts of proinflammatory cytokines IL-6 and TNFalpha compared with the noninvolved extremities. The aim of this paper is to investigate the involvement of mediators by measurement of several other cytokines using new detection techniques that enable multiple cytokine measurement in small samples. The use of a multiplex-25 bead array cytokine assay and Luminex technology enabled simultaneous measurement of representative (1) proinflammatory cytokines such as GM-CSF, IL-1beta, IL-1RA, IL-6, IL-8, and TNF-alpha; (2) Th1/Th2 distinguishing cytokines IFN-gamma, IL-2, IL-2R, IL-4, IL-5, and IL-10; (3) nonspecific acting cytokines IFN-alpha, IL-7, IL-12p40/p70, IL-13, IL-15, and IL-17; and (4) chemokines eotaxin, IP-10, MCP-1, MIP-1alpha, MIP-1beta, MIG, and RANTES. Although minimal detection levels are significantly higher in the bead array system than those in common ELISA assays, in blister fluid, IL-1RA, IL-6, IL-8, TNF-alpha, IL-12p40/p70, MCP-1, and MIP-1beta were detectable and increased in CRPS1 affected extremities. Levels of IL-6 and TNF-alpha simultaneously measured by ELISA (Sanquin Compact kit) and by multiplex-25 bead array assay (Biosource) were highly correlated (r = 0.85, P < .001 for IL-6 and r = 0.88, P < .001 for TNF-alpha). Furthermore, IP-10 and eotaxin were detectable but diminished in CRPS1, whereas detectable amounts of IL-10 were similar in involved and noninvolved extremities. Multiplex bead array assays are useful systems to establish the involvement of cytokines in inflammatory processes by measurements in blister fluids of CRPS1. Ten representative cytokines were detectable. However, detection levels and amounts measured are at least 3 times higher in the multiplex-25 array assay than in the ELISA assays used simultaneously for the measurement of cytokines.

Inflammatory mediators are altered in the acute phase of posttraumatic complex regional pain syndrome.

OBJECTIVES: Complex regional pain syndrome type 1 (CRPS 1) is a disorder that can affect an extremity after minor trauma or surgery. The pathogenesis of this syndrome is unclear. It has clinical signs of severe local inflammation as a result of an exaggerated inflammatory response, but neurogenic dysregulation also may contribute to it. METHODS: For further insights into the pathogenesis of CRPS 1, the authors investigated inflammatory and neurogenic mediators-C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-8 (IL-8), soluble tumor necrosis factor receptor I/II (sTNFR I/II), sE-selectin, sL-selectin, sP-selectin, substance P, neuropeptide Y, and calcitonin gene-related peptide-in venous blood from both the healthy arm and the arm with acute CRPS I from 25 patients and from 30 healthy volunteers. RESULTS: Levels of IL-8 and sTNFR I/II were significantly elevated in patients, whereas all soluble forms of selectins were significantly suppressed. There was no significant difference in white blood cell count (WBC), CRP, and IL-6. Substance P was significantly elevated in patients. The other two neuropeptides were unchanged. None of the parameters studied showed any differences between the CRPS I-affected arm and the normal arm. CONCLUSIONS: Elevated IL-8 and sTNFR I/II levels indicate an association between CRPS I and an inflammatory process. Normal WBC, CRP, and IL-6 give evidence for localized inflammation. The hypothesis of neurogenic-induced inflammation mediated by neuropeptides is supported by elevated substance P levels.

Reliability of transcutaneous oxygen tension measurement on the back of the hand and complex regional pain syndrome after stroke.

OBJECTIVE: To verify the reproducibility of measurement of transcutaneous oxygen tension (TcPo(2)) on the back of the hand in control subjects and stroke patients in the assessment of the complex regional pain syndrome type I (CRPS I). DESIGN: Case series study. SETTING: Physical medicine and rehabilitation department at a university hospital. PARTICIPANTS: Eighteen control subjects, 30 stroke patients without CRPS I, and 12 stroke patients with CRPS I. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: TcPo(2) was measured on the back of hands on 2 consecutive days using a polarographic technique. The reproducibility was evaluated by using the intraclass correlation coefficient (ICC) and the coefficient of variation. RESULTS: In the controls, the values of TcPo(2) were not reproducible, with an ICC of.51 (95% confidence interval [CI],.23-.72). Similarly, in the hemiplegics with and without CRPS I, TcPo(2) was not reproducible, with an ICC of.43 (95% CI, -.15 to.74) and.69 (95% CI,.45-.84), respectively. The differences between the 2 upper limbs were even less reproducible in each population. CONCLUSIONS: Measurement of TcPo(2) on the hand using our procedure did not seem to be sufficiently reproducible for application to a pathology such as CRPS I.

Normal sympathetic nervous system response in reflex sympathetic dystrophy.

We evaluated sympathetic nervous system activity by sympathetic skin response (SSR) recording and we further investigated sympathetic and opioid outflow indirectly in patients with features of reflex sympathetic dystrophy by measuring concentrations of plasma catecholamines (CAs) and their metabolites and plasma metenkephalin (ME), before and after corticoid treatment. Six patients were studied. Basal SSR latencies, morphologies and amplitudes were normal in five patients. In one woman, latency and amplitude were also normal but the morphology was disturbed. Basal plasma ME, CA and metabolite levels were similar in the affected and non-affected limbs and a significant increase in plasma ME concentrations was observed in both affected and non-affected limbs after two weeks of steroid treatment. Altogether these results point to an adaptive supersensitivity rather than a sympathetic hyperactivity in this syndrome; also, they indicate that the therapeutic effect of steroids adds, to their known anti-inflammatory action, a stimulatory action on the endogenous opioid system.

Screening of patients with complex regional pain syndrome for antecedent infections.

OBJECTIVE: This study was designed to investigate whether Complex Regional Pain Syndrome type I (CRPS I) could be linked to any previous infection. PATIENTS: Fifty-two patients with CRPS I of one extremity were screened for the presence of antibodies against mostly neurotropic microorganisms. RESULTS: Of these 52 patients, none had antibodies against Treponema pallidum, Borrelia burgdorferi, or HTLV-1. Only four patients were positive for Campylobacter jejuni. For cytomegalovirus, Epstein-Barr virus, herpes simplex virus, and Toxoplasma gondii, seroprevalences were similar to control values. The total seroprevalence of Parvovirus B 19 in our CRPS population was 77%, which was significantly higher than in an independent Dutch population group (59%). Seroprevalence in lower extremity CRPS 1 (94%) was significantly higher than in upper extremity CRPS I patients (68%). In this study all patients were seropositive for varicella zoster virus (VZV) antibodies, but a high prevalence of VZV antibodies is similar to its prevalence in a normal population (>90%). CONCLUSIONS: In this study we found a significantly higher seroprevalence of Parvovirus B19 in CRPS I and this is most striking in lower extremity CRPS I patients. Further serologic research in other geographic areas is needed to provide additional information about a potential role of Parvovirus B 19 or other microorganisms in the etiopathogenesis of CRPS I.