Adult Complex Regional Pain Syndrome Type I: A Narrative Review

An Emerging Perspective on the Role of Fascia in Complex Regional Pain Syndrome: A Narrative Review

Complex Regional Pain Syndrome (CRPS) is a debilitating pain disorder involving chronic inflammation, neural sensitization and autonomic dysfunction. Fascia, a highly innervated connective tissue, is increasingly recognized for its role in pain modulation, yet its contribution to CRPS remains underexplored. This narrative review synthesizes the current evidence on fascia's involvement in CRPS pathophysiology and potential therapeutic strategies. A literature search was conducted in PubMed, Scopus and Web of Science, selecting studies on fascia, CRPS, inflammation, oxidative stress and autonomic dysfunction, with emphasis on recent experimental, anatomical and clinical research. Fascia contributes to CRPS through neuroinflammation, fibrosis and autonomic dysregulation. Its rich innervation facilitates peripheral and central sensitization, while inflammatory mediators drive fibrosis, reducing elasticity and exacerbating pain. Autonomic dysfunction worsens hypoxia and oxidative stress, fueling chronic dysfunction. Advances in sonoelastography provide new insights, while fascial manipulation and targeted therapies show promise in early studies. Fascia plays a key role in CRPS pathophysiology, yet its clinical relevance remains underexplored. Future research integrating imaging, molecular profiling and clinical trials is needed to develop evidence-based fascia-targeted interventions, potentially improving CRPS diagnosis and treatment.

Effect of Prednisolone on Clinical and Cytokine mRNA Profiling in Complex Regional Pain Syndrome

The cardinal clinical features of complex regional pain syndrome type I (CRPS-I) are pain, edema, autonomic changes, and limitation of motoric movement, which may indicate the role of inflammation and cytokines. We report the effect of prednisolone on the clinical severity and mRNA profiling of proinflammatory (tumor necrosis factor (TNF)-α and interleukin (IL)-2) and anti-inflammatory cytokines (IL-10 and transforming growth factor (TGF)-β) in the patient with CRPS-I. Thirty-nine patients with CRPS-I of shoulder joint were enrolled. Their CRPS, Visual Analog Scale (VAS) and Daily Sleep Interference Scale (DSIS) scores were recorded. TNF-α, IL-2, IL-10, and TGF-β gene expressions at mRNA of whole blood were measured by reverse transcriptase polymerase chain reaction. Patients were randomized to prednisolone 20 mg or 40 mg using 1: 1 randomization. The primary outcome was change in VAS score, and secondary outcomes were change in CRPS and DSIS scores at 1 month. Side effects were noted. The patients had increased expressions of TNF-α (p < 0.001) and IL-2 (p < 0.001) and reduced IL-10 (p < 0.01) mRNA compared to the healthy controls. The baseline characteristics were matched between the two treatment arms. At 1 month, CRPS, VAS, and DSIS scores improved significantly compared to baseline, which paralleled with improvement in IL-10 (p < 0.032) and reduction in TNF-α (p = 0.046). The improvement in clinical and biomarkers was similar in prednisolone 20 mg and 40 mg arms. None had to be withdrawn due to severe side effects. Future study in larger cohort may validate these findings.

Complex regional pain syndrome type II localized to the index finger. A case report translating scientific evidence into clinical practice

BACKGROUND

Complex regional pain syndrome type II (CRPS-II) is a rare condition associated with peripheral nervous system lesions. Its localized distribution in the fingers is unique, and its treatment is unclear.

CASE DESCRIPTION

A 56-year-old male presented to the emergency department with a saw-cut index finger injury with associated tendon and nerve injuries. After surgery, he was admitted to physical therapy (PT) with persistent pain, joint stiffness, allodynia, and trophic changes compatible with CRPS-II localized in the index finger. The diagnosis was confirmed after applying the Budapest Criteria, and PT was progressive and individualized according to the patient's needs, including graded motor imagery, mobilizations, exercises, and education.

OUTCOMES

After 12 weeks of PT, a clinically significant decrease in pain intensity and improvements in mobility and index finger and upper limb functionality was observed, reducing CRPS symptomatology.

DISCUSSION

This report provides information about a unique case of a localized form of CRPS-II. After reviewing the literature on clinical cases of both CRPS-II and localized forms of CRPS, we highlight that the clinical features of this patient and his positive therapeutic response support the importance of translating the scientific evidence on CRPS into clinical practice.

Complex Regional Pain Syndrome Type I: Evidence for the CB1 and CB2 Receptors Immunocontent and Beneficial Effect of Local Administration of Cannabidiol in Mice

Introduction: Complex regional pain syndrome type I (CRPS-I) is a debilitating neuropathic painful condition associated with allodynia, hyperalgesia, sudomotor and/or vasomotor dysfunctions, turning investigation of its pathophysiology and new therapeutic strategies into an essential topic. We aim to investigate the impact of ischemia/reperfusion injury on the immunocontent of CB1 and CB2 cannabinoid receptor isoforms in the paws of mice submitted to a chronic postischemia pain (CPIP) model and the effects of local administration of cannabidiol (CBD) on mechanical hyperalgesia. Methods: Female Swiss mice, 30-35 g, were submitted to the CPIP model on the right hind paw. Skin and muscle samples were removed at different periods for western blot analysis. Results: No changes in the immunocontent of CB1 and CB2 receptors in paw muscle tissues after ischemia-reperfusion were observed. CBD promoted an antihyperalgesic effect in both phases. AM281 reversed the effect of CBD, whereas ruthenium red abolished the late phase. Conclusion: Our results point to the possible beneficial effects of local administration of CBD in modulating CRPS-I in humans. As possible targets for CBD antihyperalgesia in this model, the contribution of cannabinoid receptor CB1, in addition to TRPM8 is suggested.

Effects of mirror therapy in post-traumatic complex regional pain syndrome type-1: a randomized controlled study

OBJECTIVE

To investigate the effects of mirror therapy applied in addition to routine rehabilitation on clinical outcomes in post-traumatic complex regional pain syndrome type 1.

DESIGN

Single-blind randomized controlled trial.

SUBJECTS

Patients with trauma-induced complex regional pain syndrome type 1 of the hand receiving outpatient rehabilitation.

METHODS

Patients were randomized into mirror therapy and control groups. All patients received routine physical therapy and rehabilitation for 20 sessions (5 sessions/week, for 4 weeks). The mirror group received additional mirror therapy at each session. The primary outcome was pain intensity by numeric rating scale. Secondary outcomes were grip/pinch strength, hand/wrist circumference, dexterity, hand activities, and health-related quality of life. All assessments were performed before and immediately after the treatment, and 4 weeks later at follow-up.

RESULTS

Forty patients were enrolled, 20 in each group. Both groups revealed statistically significant improvements from therapy regarding pain, grip/pinch strength, wrist circumference, dexterity, and hand activities (p <  0.05). When groups were compared regarding the improvements in assessment parameters, no statistically significant difference was found between the 2 groups in any of the outcomes (p > 0.05).

CONCLUSION

Mirror therapy applied in addition to routine therapy in post-traumatic complex regional pain syndrome type 1 did not provide extra benefit to the improvement of pain, function, and other clinical outcomes.

Breaking the Cycle of Pain: The Role of Graded Motor Imagery and Mirror Therapy in Complex Regional Pain Syndrome

Background: Complex Regional Pain Syndrome (CRPS) is a chronic condition characterized by severe pain and functional impairment. Graded Motor Imagery (GMI) and Mirror Therapy (MT) have emerged as potential non-invasive treatments; this review evaluates the effectiveness of these therapies in reducing pain, improving function, and managing swelling in CRPS patients. Methods: A systematic review was conducted including randomized controlled trials (RCTs) that investigated GMI and MT in CRPS patients. This review was registered in PROSPERO (CRD42024535972) to ensure transparency and adherence to protocols. This review included searches of PubMed, Cochrane, SCOPUS, and Web of Science databases. Out of 81 studies initially screened, 6 were included in the final review. Studies were assessed for quality using the PEDro and RoB-2 scales. The primary outcomes were pain reduction, functional improvement, and swelling reduction. Results: Graded Motor Imagery (GMI) and Mirror Therapy (MT) reduced pain by an average of 20 points on the Neuropathic Pain Scale (NPS) and resulted in functional improvements as measured by the Task-Specific Numeric Rating Scale (NRS). GMI also contributed to some reduction in swelling. MT, particularly in post-stroke CRPS patients, showed significant pain reduction and functional improvements, with additional benefits in reducing swelling in certain studies. However, the included studies had small sample sizes and mixed designs, which limit the generalizability of the findings. The studies varied in sample size and design, with some risk of bias noted. Conclusions: Graded Motor Imagery (GMI) and Mirror Therapy (MT) have proven to be effective interventions for managing Complex Regional Pain Syndrome (CRPS), with significant improvements in pain reduction and functional recovery. These non-invasive treatments hold potential for integration into standard rehabilitation protocols. However, the small sample sizes and variability in study designs limit the generalizability of these findings. Future research should focus on larger, more homogeneous trials to validate the long-term effectiveness of GMI and MT, ensuring more robust clinical application.

Mechanisms of complex regional pain syndrome

Complex Regional Pain Syndrome (CRPS) is a chronic pain disorder characterized by a diverse array of symptoms, including pain that is disproportionate to the initial triggering event, accompanied by autonomic, sensory, motor, and sudomotor disturbances. The primary pathology of both types of CRPS (Type I, also known as reflex sympathetic dystrophy, RSD; Type II, also known as causalgia) is featured by allodynia, edema, changes in skin color and temperature, and dystrophy, predominantly affecting extremities. Recent studies started to unravel the complex pathogenic mechanisms of CRPS, particularly from an autoimmune and neuroimmune interaction perspective. CRPS is now recognized as a systemic disease that stems from a complex interplay of inflammatory, immunologic, neurogenic, genetic, and psychologic factors. The relative contributions of these factors may vary among patients and even within a single patient over time. Key mechanisms underlying clinical manifestations include peripheral and central sensitization, sympathetic dysregulation, and alterations in somatosensory processing. Enhanced understanding of the mechanisms of CRPS is crucial for the development of effective therapeutic interventions. While our mechanistic understanding of CRPS remains incomplete, this article updates recent research advancements and sheds light on the etiology, pathogenesis, and molecular underpinnings of CRPS.

Mirror visual feedback as therapeutic modality in unilateral upper extremity complex regional pain syndrome type I: randomized controlled trial

BACKGROUND

There is growing evidence for the effectiveness of mirror therapy (MT) on pain reduction in patients with type I complex regional pain syndrome (CRPS I).

AIM

To evaluate the efficacy of MT on pain reduction and hand function in subjects with unilateral upper extremity CRPS I.

DESIGN

Randomized controlled trial with control group cross-over (half cross-over design).

SETTING

Subjects with CRPS I were outpatients of a university hospital and cooperating centers. All patients carried out the daily exercise at home.

POPULATION

Subjects with unilateral upper extremity CRPS I meeting the Budapest diagnostic criteria.

METHODS

Subjects were randomly divided into two groups. Group A (N.=13) carried out a ten-minute MT exercise daily, for a total duration of six weeks. Group B (N.=14) acted as a control group for six weeks followed by six weeks of MT with the same characteristics as Group A. Upper extremity active range of motion, strength, dexterity, limb volume, affected-to-unaffected hand temperature difference, and health-related quality of life were evaluated before and after each period. Daily records on the visual analogue scale were used for pain evaluation. Effectiveness was calculated using mixed-effects modelling for between-group comparisons and within-group variability, and identification of significant predictors.

RESULTS

Twenty-three females and four males with an average age of 56.1±9.6 years completed the study. Except for the affected-to-unaffected hand temperature difference, both groups consistently demonstrated significant or near-significant improvements in measured parameters after MT period. The improvements were evident upon an intergroup comparison of Group A and the control period of Group B as well as longitudinally within Group B. No significant improvement was found during the control period.

CONCLUSIONS

Principles focused on mirror visual feedback to the central nervous system can sustain promising therapeutic potential as part of the treatment for pain reduction and hand function in CRPS I patients.

CLINICAL REHABILITATION IMPACT

MT can be considered as part of the therapeutic regimen employed for the treatment of CRPS I.

Complex Regional Pain Syndrome: Evidence-Based Advances in Concepts and Treatments

PURPOSE OF REVIEW

This review presents the most current information about the epidemiology of complex regional pain syndrome (CRPS), classification and diagnostic criteria, childhood CRPS, subtypes, pathophysiology, conventional and less conventional treatments, and preventive strategies.

RECENT FINDINGS

CRPS is a painful disorder with multifactorial pathophysiology. The data describe sensitization of the central and peripheral nervous systems, inflammation, possible genetic factors, sympatho-afferent coupling, autoimmunity, and mental health factors as contributors to the syndrome. In addition to conventional subtypes (type I and type II), cluster analyses have uncovered other proposed subtypes. Prevalence of CRPS is approximately 1.2%, female gender is consistently associated with a higher risk of development, and substantial physical, emotional, and financial costs can result from the syndrome. Children with CRPS seem to benefit from multifaceted physical therapy leading to a high percentage of symptom-free patients. The best available evidence along with standard clinical practice supports pharmacological agents, physical and occupational therapy, sympathetic blocks for engaging physical restoration, steroids for acute CRPS, neuromodulation, ketamine, and intrathecal baclofen as therapeutic approaches. There are many emerging treatments that can be considered as a part of individualized, patient-centered care. Vitamin C may be preventive. CRPS can lead to progressively painful sensory and vascular changes, edema, limb weakness, and trophic disturbances, all of which substantially erode healthy living. Despite some progress in research, more comprehensive basic science investigation is needed to clarify the molecular mechanisms of the disease so that targeted treatments can be developed for better outcomes. Incorporating a variety of standard therapies with different modes of action may offer the most effective analgesia. Introducing less conventional approaches may also be helpful when traditional treatments fail to provide sufficient improvement.

Senso-Immunologic Prospects for Complex Regional Pain Syndrome Treatment

Complex regional pain syndrome (CRPS) is a chronic pain syndrome that occurs in tissue injuries as the result of surgery, trauma, or ischemia. The clinical features of this severely painful condition include redness and swelling of the affected skin. Intriguingly, it was recently suggested that transient receptor potential ankyrin 1 (TRPA1) is involved in chronic post-ischemia pain, a CRPS model. TRPA1 is a non-selective cation channel expressed in calcitonin gene-related peptide (CGRP)-positive primary nociceptors that becomes highly activated in ischemic conditions, leading to the generation of pain. In this review, we summarize the history of TRPA1 and its involvement in pain sensation, inflammation, and CRPS. Furthermore, bone atrophy is also thought to be a characteristic clinical sign of CRPS. The altered bone microstructure of CRPS patients is thought to be caused by aggravated bone resorption via enhanced osteoclast differentiation and activation. Although TRPA1 could be a target for pain treatment in CRPS patients, we also discuss the paradoxical situation in this review. Nociceptor activation decreases the risk of bone destruction via CGRP secretion from free nerve endings. Thus, TRPA1 inhibition could cause severe bone atrophy. However, the suitable therapeutic strategy is controversial because the pathologic mechanisms of bone atrophy in CRPS are unclear. Therefore, we propose focusing on the remission of abnormal bone turnover observed in CRPS using a recently developed concept: senso-immunology.

Vitamin C Could Prevent Complex Regional Pain Syndrome Type I in Trauma and Orthopedic Care? A Systematic Review of the Literature and Current Findings

The aim of this systematic review is to evaluate the efficacy of Vitamin C (VC) in preventing Complex Regional Pain Syndrome type I (CRPS-I) in fractures or surgery of the upper and lower extremities. During December 2020, Scopus and PubMed search was performed to analyze VC supplementation in preventing CRPS-I after trauma and orthopedic care, according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guideline. Patient, Intervention, Comparison, Outcomes, Study Design model, and a modified version of the Coleman Methodology Score were used to analyze the included studies. The research was limited from 1990 to December 2020. Initial screening results identified 649 studies. After reviewing each study, six clinical studies were included in the study. A total of 2026 patients of whom 632 male and 1394 female were collected in our systematic review. During the entire follow-up period, the occurrence of CRPS-I was evaluated in 1939 patients. Five of the six analyzed studies were favoring prophylactic use of the 500-1000 mg daily dose of VC for 45-50 days after orthopedic or trauma care for prevention of CRPS-I. Only one study found no benefit in VC supplementation compared with placebo to prevent CRPS-I. Analysis of the literature suggests that a daily 500-1000 mg VC supplementation may reduce the onset of CRPS-I in trauma of upper/lower extremities and in orthopedic surgery.

Complex regional pain syndrome - Autoimmune or functional neurologic syndrome

Complex regional pain syndrome (CRPS) purports to explain extremity pain accompanied by a variety of subjective complaints, including sensitivity to touch, fatigue, burning sensations, allodynia and signs consistent with voluntary immobilization, including skin changes, edema and trophic changes. By its own definition, CRPS pain is disproportionate to any inciting event or underlying pathology, which means that the syndrome describes non-anatomic and exaggerated symptoms. Although CRPS was coined in the early 1990s, physicians have described unexplained exaggerated pain for centuries. Before a small group of researchers assigned this historical phenomenon with the name CRPS, other physicians in various subspecialties investigated the existence of a common pathophysiologic mechanism but found none. The literature was searched for evidence of a reproducible pathologic mechanism for CRPS. Although some have suggested that CRPS is an autoimmune disease, there is a paucity of evidence to support this. While cytokines such as IL-1β, IL-6 and TNF-α have been detected during the early phases of CRPS, this cannot lead to the conclusion that CRPS is an autoimmune disease, nor that it is an autoinflammatory disorder. Moreover, intravenous immunoglobulin has showed inconsistent results in the treatment of CRPS. On the other hand, CRPS has been found to meet at least three out of four criteria of malingering, which was previously a DSM-IV diagnosis; and its diagnostic criteria are virtually identical to current DSM-5 Functional Neurological Disorder ("FND"), and proposed ICD-11 classification, which includes FND as a distinct neurological diagnosis apart from any psychiatric condition. Unfortunately, the creation of CPRS is not merely misguided brand marketing. It has serious social and health issues. At least in part, the existence of CRPS has led to the labeling of many patients with a diagnosis that allows the inappropriate use of invasive surgery, addictive opioids, and ketamine. The CRPS hypothesis also ignores the nature and purpose of pain, as a symptom of some organic or psychological process. Physicians have long encountered patients who voice symptoms that cannot be biologically explained. Terminology historically used to describe this phenomenon have been medically unexplained symptoms ("MUS"), hysterical, somatic, non-organic, psychogenic, conversion disorder, or dissociative symptoms. The more recent trend describes disorders where there is a functional, rather than structural cause of the symptoms, as "functional disorders." Physicians report high success treating functional neurological symptoms with reassurance, physiotherapy, and cognitive behavior therapy measured in terms of functional improvement. The CRPS label, however, neither leads to functional improvement in these patients nor resolution of symptoms. Under principles of evidence-based medicine, the CRPS label should be abandoned and the syndrome should simply be considered a subset of FNDs, specifically Functional Pain Disorder; and treated appropriately.

Understanding the Rehabilitation Needs of Korean Patients With Complex Regional Pain Syndrome

OBJECTIVE

To evaluate the current status of pain severity and quality of life (QoL) in patients with complex regional pain syndrome (CRPS), and to assess both their perceived needs and any unmet needs of current rehabilitation services.

METHODS

A single-center questionnaire-based survey was conducted on 47 patients with CRPS who were diagnosed based on Budapest's criteria. It collected demographic and clinical data, and the structured questionnaire included the Brief Pain Inventory (BPI), the Korean version of the World Health Organization Disability Assessment Schedule II (WHODAS-K II), as well as the 5-Level EuroQol-5D (EQ-5D-5L) for measuring the QoL.

RESULTS

The average value of BPI and WHODAS-K II were 7.69%±2.26% and 70.49%±19.22%, respectively. In the evaluation of their perceived needs and unmet needs for rehabilitation, patients had the highest rehabilitation needs in terms of pain (95.74%), followed by bodyaches (80.85%). Regarding their unmet needs, patients had the highest unmet needs in terms of memory impairment (83.33%), followed by weight management (72.00%). According to the regression analysis, only the overall BPI was significantly associated with QoL (p=0.01), and a higher BPI value led to poorer results for QoL.

CONCLUSION

In Korea, patients with CRPS do not receive adequate rehabilitation, and they are not satisfied with current received treatments. A more structured and individualized rehabilitation treatment plan is required to manage every aspect related to chronic pain, and provision should be made for improved care guidelines for future CRPS management.

Complex regional pain syndrome: a narrative review for the practising clinician

Complex regional pain syndrome (CRPS) is a life-altering condition that usually affects the extremities after a trauma or nerve injury. The physiologic changes that occur as a result of the inciting injury are complex, as the name of the syndrome implies. The pain and disability associated with CRPS often lead to psychological co-morbidities that create a vicious cycle of pain, isolation, and depression. We review recent developments in the understanding of CRPS and advancements in management of this syndrome. Further research in targeting specific mechanisms involved in the pathophysiology of CRPS should lead to prevention of this condition.

Physical therapy in patients with complex regional pain syndrome type I after distal radius fracture: a case series

[Purpose] To describe the effect of a physical therapy program in function improvement and pain reduction in patients older than 60 years with complex regional pain syndrome (CRPS) type I after distal radius fracture (DRF) treated conservatively. [Participants and Methods] Fifty-four patients received a 6 weeks physical therapy program that included in hydrotherapy, manual therapy, and exercises based on motor skill training. Two evaluations were performed, the wrist/hand function was assessed with Patient-Rated Wrist Evaluation (PRWE) questionnaire, the upper extremity function with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, grip strength with Jamar Dynamometer, and pain intensity with the Visual Analog Scale (VAS). [Results] At the end of the treatment, PRWE showed a decrease of 30.9 points, DASH 34.7 points, and the VAS, 3.4 cm. The grip strength showed an increase of 14.4%. [Conclusion] A physical therapy program based on hydrotherapy, manual therapy, and exercises in a short term improves the function and reduces the pain in patients older than 60 years with CRPS I after DRF treated conservatively.

The Efficacy of Vitamin C in the Prevention of Complex Regional Pain Syndrome After Distal Radius Fractures: A Synthesis

The current recommendation is to use daily doses of vitamin C to prevent the occurrence of the complex regional pain syndrome (CRPS) following a distal radius fracture. The study is a synthesis of the four primary studies that examine this issue. These studies have been previously examined in the meta-analysis literature. The incidence of CRPS is lower in patients treated with the vitamin C protocol compared with the control. The significance of the difference varies from P = .02 to P = .13. Our analysis points to the fact that the relative efficacy of vitamin C has decreased over the past 15 years (P < .001). In 2014, the incidence of CRPS in the vitamin C cohort is not statistically different from the incidence in the control group (P = .76). Vitamin C has lost its relative efficacy.

Complex Regional Pain Syndrome: An update

Complex regional pain syndrome (CRPS) is a perplexing painful syndrome of the extremities usually following a harmful event. It is distinguished in two types, mainly depending on the presence of nerve injury. Although its prevalence may vary depending on social and ethnic factors, middle-aged women seem to suffer most often and the upper limb is the most commonly affected extremity. Apart from pain, which is the dominating feature, the clinical picture unfolds across several domains: sensory, motor, autonomic and trophic. This syndrome develops in two phases, the acute (warm) phase, with the classic symptoms of inflammation, and the chronic (cold) phase, often characterized by trophic changes of the soft tissues and even bones. Although the syndrome has been studied for over two decades, no imaging or laboratory test has been established for the diagnosis and recently proposed diagnostic criteria have not yet been validated and are only occasionally applied. Its pathophysiology is still quite obscure, although the most likely mechanisms involve the classic and neurogenic paths of inflammation mediated by cytokines and neuropeptides, intertwined with changes of the autonomic and central nervous system, psychological mechanisms and, perhaps, autoimmunity. Although plenty of treatment modalities have been tried, none has been proven unequivocally efficacious. Apart from information and education, which should be offered to all patients, the most effective pharmacological treatments seem to be bisphosphonates, glucocorticoids and vasoactive mediators, while physical therapy and rehabilitation therapy also make part of the treatment.

Neurometabolite changes in patients with complex regional pain syndrome using magnetic resonance spectroscopy: a pilot study

The aim of this study was to investigate distinct neurometabolites in the right and left thalamus and insula of patients with complex regional pain syndrome (CRPS) compared with healthy controls using proton magnetic resonance spectroscopy. Levels of N-acetylaspartate (NAA), N-acetylaspartylglutamate (NAAG), myo-inositol (ml), glutamine (Gln), glycerophosphocholine (GPC), glutathione (GSH), and alanine (Ala) relative to total creatine (tCr) levels, including creatine and phosphocreatine, were determined in the right and left thalamus and insula in 12 patients with CRPS compared with 11 healthy controls using magnetic resonance spectroscopy. Levels of NAAG/tCr and Ala/tCr were higher in patients with CRPS than in controls in the left thalamus. NAAG/tCr, ml/tCr, and Gln/tCr levels were higher but NAA/tCr levels were lower in the right insula of patients with CRPS compared with controls. There were negative correlations between GSH/tCr and pain score (McGill Pain Questionnaire) in the left thalamus. These findings are paramount to understand and determine all aspects of the complex pathophysiological mechanisms that underlie CRPS, including involvement of the central and parasympathetic nervous systems as well as oxidative stress and antioxidants. Thus, the distinct metabolites presented herein may be essential to understand a strong diagnostic and prognostic potential for CRPS and to develop effective medical treatments.

Aberrant interactions of peripheral measures and neurometabolites with lipids in complex regional pain syndrome using magnetic resonance spectroscopy: A pilot study

Background The aim of this study was to assess peripheral measures and central metabolites associated with lipids using magnetic resonance spectroscopy. Results Twelve patients with complex regional pain syndrome (CRPS) and 11 healthy controls participated. Using magnetic resonance spectroscopy, we measured the levels of lipid 13a (Lip13a) and lipid 09 (Lip09) relative to total creatine (tCr) levels in the right and left thalamus. We found negative correlations of Lip13a/tCr in the right thalamus with red blood cells or neutrophils, but a positive correlation between Lip13a/tCr and lymphocytes in the controls. We found negative correlations between Lip09/tCr and peripheral pH or platelets in the controls. There were positive correlations between Lip09a/tCr and myo-inositol/tCr, between Lip13a/tCr and N-acetylaspartate (NAA)/tCr, and between Lip09/tCr and NAA/tCr in healthy controls. On the other hand, there were positive correlations between Lip13a/tCr and Lip09/tCr and urine pH in CRPS patients. There were significant correlations between Lip13a/tCr or Lip09/tCr and different peripheral measures depending on the side of the thalamus (right or left) in CRPS patients. Conclusion This is the first report indicating that abnormal interactions of Lip13a and Lip09 in the thalamus with peripheral measures and central metabolites may mediate the complex pathophysiological mechanisms underlying CRPS.

Peripheral and Central Metabolites Affecting Depression, Anxiety, Suicidal Ideation, and Anger in Complex Regional Pain Syndrome Patients Using a Magnetic Resonance Spectroscopy: A Pilot Study

OBJECTIVE

This study investigated peripheral and central metabolites affecting depression, anxiety, suicidal ideation, and anger in complex regional pain syndrome (CRPS) patients.

METHODS

Metabolite levels were determined in the right and left thalamus and insula, in 12 CRPS patients using magnetic resonance spectroscopy (MRS).

RESULTS

There were positive correlations between valine (Val)/tNAA (N-acetylaspartate+N-acetylaspartylglutamate) and the anxiety, and a negative correlation between glutamine (Gln)/NAA and the depression. There were positive correlations between alanine (Ala)/Gln and the depression and suicidal ideation, between glutamate (Glu)/Gln and the depression and suicidal ideation, between N-acetylaspartylglutamate (NAAG)/Gln and the depression. There was a positive correlation between Ala/NAAG and the trait anger and a negative correlation between creatine (Cr)/N-acetylaspartate (NAA) and the trait anger. There was a negative correlation between Cr/Glx (Glu+Gln) and the trait anger. High hemoglobin and alkaline phosphatase were associated with low pain levels, but CO2 and chloride showed positive correlations with pain levels in CRPS patients. Peripheral glucose, CO2 and chloride were associated with depression, anxiety, anger and suicidal ideation.

CONCLUSION

The specific central and peripheral metabolites were associated with psychological disorders including depression, anxiety, suicidal ideation and anger in CRPS patients, showing pathological interactions between a painful body and mind.