Medical history and the onset of complex regional pain syndrome (CRPS)

Bone Turnover Markers and Wnt Signaling Modulators in Early Complex Regional Pain Syndrome. A Pre-specified Observational Study

To explore serum levels of some bone turnover markers and the involvement of the Wnt signaling in CRPS-1. Query ID="Q1" Text="Please check and confirm whether the edit made to the article title is in order." We conducted an observational study on patients with early CRPS-1 recruited before any treatment. Clinical measures were assessed together with biochemical evaluation. Values of sclerostin, DKK1, CTX-I, and P1NP were compared with sex-age-matched healthy controls (HCs). We enrolled 34 patients diagnosed with CRPS-1 (mean age 59.3 ± 10.6 years, Male/Female 10/24), median disease duration = 2 weeks (IQR 1-5); median VAS score = 76 (IQR 68-80). Foot localization was slightly more frequent than hand localization (18/16). No statistically significant difference was found between CRPS-1 patients and HCs for CTX-I (0.3 ± 0.1 ng/ml vs 0.3 ± 0.1, p = 0.140), while mean serum values of P1NP were significantly higher in CRPS-1 patients compared to HCs (70.0 ± 38.8 ng/ml vs 50.1 ± 13.6, p = 0.005). Mean levels of sclerostin and DKK1 were lower in CRPS-1 patients vs HCs (sclerostin 28.4 ± 10.8 pmol/l vs 34.1 ± 11.6, p = 0.004; DKK1 12.9 ± 10.8 pmol/l vs 24.1 ± 11.9, p = 0.001). No statistically significant difference was found for all biochemical assessments in a subgroup of fracture-induced CRPS-1. No statistically significant differences were observed according to disease localization, disease duration, presence of hyperalgesia, allodynia, sudomotor alterations, and mild or moderate/severe swelling. No significant correlation emerged between sclerostin, DKK1 levels, baseline VAS score, or McGill Pain Questionnaire score. Bone involvement in early CRPS-1 does not seem to rely on increased osteoclast activity. Conversely, a serum marker of bone formation resulted increased. Both Sclerostin and DKK1 showed decreased values, probably suggesting a widespread osteocyte loss of function.Trial registration number: Eudract Number: 2014-001156-28.

Association of dietary vitamin C consumption with severe headache or migraine among adults: a cross-sectional study of NHANES 1999-2004

Background

An antioxidant-rich diet has been shown to protect against migraines in previous research. However, little has been discovered regarding the association between migraines and vitamin C (an essential dietary antioxidant). This study assessed the dietary vitamin C intake among adult migraineurs in the United States to determine if there is a correlation between migraine incidence and vitamin C consumption in adults.

Methods

This cross-sectional research encompassed adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004, providing detailed information on their dietary vitamin C intake as well as their history of severe headaches or migraines. The study used weighted multivariable and logistic regression analyses to find an independent connection between vitamin C consumption and severe headache or migraine. Tests of interactions and subgroup analysis were conducted.

Results

Among the 13,445 individuals in the sample, 20.42% had a severe headache or migraine. In fully adjusted models, dietary vitamin C consumption was substantially linked negatively with severe headache or migraine (odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.91-0.98, p = 0.0007). Compared to quartile 1, quartile 4 had 22% fewer odds of having a severe headache or migraine (OR = 0.78, 95% CI = 0.69-0.89, p = 0.0002). Subgroup analyses showed a significant difference between vitamin C intake and severe headaches or migraines by gender (p for interaction < 0.01).

Conclusion

Reduced risk of severe headaches or migraines may be associated with increased consumption of vitamin C.

Complex regional pain syndrome: advances in epidemiology, pathophysiology, diagnosis, and treatment

Complex regional pain syndrome (CRPS) is a rare pain disorder that usually occurs in a limb after trauma. The features of this disorder include severe pain and sensory, autonomic, motor, and trophic abnormalities. Research from the past decade has offered new insights into CRPS epidemiology, pathophysiology, diagnosis, and treatment. Early identification of individuals at high risk of CRPS is improving, with several risk factors established and some others identified in prospective studies during the past 5 years. Better understanding of the pathophysiological mechanisms of CRPS has led to its classification as a chronic primary pain disorder, and subtypes of CRPS have been updated. Procedures for diagnosis have also been clarified. Although effective treatment of CRPS remains a challenge, evidence-based integrated management approaches provide new opportunities to improve patient care. Further advances in diagnosis and treatment of CRPS will require coordinated, international multicentre initiatives.

Complex Regional Pain Syndrome (CRPS) and the Value of Early Detection

PURPOSE OF REVIEW

The goal of this narrative review is to describe the current understanding of the pathology of Complex Regional Pain Syndrome (CRPS), as well as diagnostic standards and therapeutic options. We will then make the case for early recognition and management.

RECENT FINDINGS

CRPS remains an enigmatic pain syndrome, comprising several subtypes. Recent recommendations clarify diagnostic ambiguities and emphasize the importance of standardized assessment and therapy. Awareness of CRPS should be raised to promote prevention, early detection, and rapid escalation of therapy in refractory cases. Comorbidities and health costs (i.e., the socioeconomic impact) must also be addressed early to prevent negative consequences for patients.

Interventions for treating pain and disability in adults with complex regional pain syndrome- an overview of systematic reviews

BACKGROUND

Complex regional pain syndrome (CRPS) is a chronic pain condition that usually occurs in a limb following trauma or surgery. It is characterised by persisting pain that is disproportionate in magnitude or duration to the typical course of pain after similar injury. There is currently no consensus regarding the optimal management of CRPS, although a broad range of interventions have been described and are commonly used. This is the first update of the original Cochrane review published in Issue 4, 2013.

OBJECTIVES

To summarise the evidence from Cochrane and non-Cochrane systematic reviews of the efficacy, effectiveness, and safety of any intervention used to reduce pain, disability, or both, in adults with CRPS.

METHODS

We identified Cochrane reviews and non-Cochrane reviews through a systematic search of Ovid MEDLINE, Ovid Embase, Cochrane Database of Systematic Reviews, CINAHL, PEDro, LILACS and Epistemonikos from inception to October 2022, with no language restrictions. We included systematic reviews of randomised controlled trials that included adults (≥18 years) diagnosed with CRPS, using any diagnostic criteria.  Two overview authors independently assessed eligibility, extracted data, and assessed the quality of the reviews and certainty of the evidence using the AMSTAR 2 and GRADE tools respectively. We extracted data for the primary outcomes pain, disability and adverse events, and the secondary outcomes quality of life, emotional well-being, and participants' ratings of satisfaction or improvement with treatment.  MAIN RESULTS: We included six Cochrane and 13 non-Cochrane systematic reviews in the previous version of this overview and five Cochrane and 12 non-Cochrane reviews in the current version. Using the AMSTAR 2 tool, we judged Cochrane reviews to have higher methodological quality than non-Cochrane reviews. The studies in the included reviews were typically small and mostly at high risk of bias or of low methodological quality. We found no high-certainty evidence for any comparison.  There was low-certainty evidence that bisphosphonates may reduce pain intensity post-intervention (standardised mean difference (SMD) -2.6, 95% confidence interval (CI) -1.8 to -3.4, P = 0.001; I2 = 81%; 4 trials, n = 181) and moderate-certainty evidence that they are probably associated with increased adverse events of any nature (risk ratio (RR) 2.10, 95% CI 1.27 to 3.47; number needed to treat for an additional harmful outcome (NNTH) 4.6, 95% CI 2.4 to 168.0; 4 trials, n = 181).  There was moderate-certainty evidence that lidocaine local anaesthetic sympathetic blockade probably does not reduce pain intensity compared with placebo, and low-certainty evidence that it may not reduce pain intensity compared with ultrasound of the stellate ganglion. No effect size was reported for either comparison. There was low-certainty evidence that topical dimethyl sulfoxide may not reduce pain intensity compared with oral N-acetylcysteine, but no effect size was reported. There was low-certainty evidence that continuous bupivacaine brachial plexus block may reduce pain intensity compared with continuous bupivacaine stellate ganglion block, but no effect size was reported. For a wide range of other commonly used interventions, the certainty in the evidence was very low and provides insufficient evidence to either support or refute their use. Comparisons with low- and very low-certainty evidence should be treated with substantial caution. We did not identify any RCT evidence for routinely used pharmacological interventions for CRPS such as tricyclic antidepressants or opioids.

AUTHORS' CONCLUSIONS

Despite a considerable increase in included evidence compared with the previous version of this overview, we identified no high-certainty evidence for the effectiveness of any therapy for CRPS. Until larger, high-quality trials are undertaken, formulating an evidence-based approach to managing CRPS will remain difficult. Current non-Cochrane systematic reviews of interventions for CRPS are of low methodological quality and should not be relied upon to provide an accurate and comprehensive summary of the evidence.

Dorsal root ganglion stimulation for treatment of chronic postsurgical pain secondary to triple neurectomy

Triple neurectomy (resection of Ilioinguinal, Iliohypogastric, and Genitofemoral nerves) is performed in cases of inguinal neuralgia, refractory to conservative management. However, this procedure comes with several adverse effects, including but not limited to ectopic afferent firing and tactile allodynia. In such a scenario, the inguinal pain can become chronic and debilitating and can be classified as chronic post-surgical pain. Spinal neuromodulation techniques have been employed for treating such refractory, intractable chronic groin, pelvic and abdominal pain. One such technique is dorsal root ganglion stimulation which is designed to manage difficult-to-treat chronic pain in specific areas of the lower body, such as the foot, knee, hip, or groin. The authors present a case in which the patient underwent a laparoscopic neurectomy of ilioinguinal, Iliohypogastric, and genitofemoral nerves that failed to resolve her pain-related symptoms. The patient presented to the authors' pain clinic with severe inguinal pain and allodynia, refractory to multiple analgesic agents. The patient underwent a successful trial and subsequent implant with ipsilateral dorsal root ganglion stimulation at L1& L2. At six months post-implant, the patient continues to report 80-90% improvement in her pain and physical function.

Modern Principles of Diagnosis and Treatment in Complex Regional Pain Syndrome

BACKGROUND

Background: Complex regional pain syndrome (CRPS) is a relatively common complication, occurring in 5% of cases after injury or surgery, particularly in the limbs. The incidence of CPRS is around 5-26/100 000. The latest revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) now categorizes CRPS as a primary pain condition of multifactorial origin, rather than a disease of the skeletal system or the autonomic nervous system.

METHODS

Method: Based on a selective search of the literature, we summarize current principles for the diagnosis and treatment of CRPS.

RESULTS

Results: Regional findings in CRPS are accompanied by systemic symptoms, especially by neurocognitive disorders of body perception and of symptom processing. The therapeutic focus is shifting from predominantly passive peripheral measures to early active treatments acting both centrally and peripherally. The treatment is centered on physiotherapy and occupational therapy to improve sensory perception, strength, (fine) motor skills, and sensorimotor integration/ body perception. This is supported by stepped psychological interventions to reduce anxiety and avoidance behavior, medication to decrease inflammation and pain, passive physical measures for reduction of edema and of pain, and medical aids to improve functioning in daily life. Interventional procedures should be limited to exceptional cases and only be performed in specialized centers. Spinal cord and dorsal root ganglion stimulation, respectively, are the interventions with the best evidence.

CONCLUSION

Conclusion: The modern principles for the diagnosis and treatment of CRPS consider both, physiological and psychological mechanisms, with the primary goal of restoring function and participation. More research is needed to strengthen the evidence base in this field.

Korean Medicine Treatment for Managing Complex Regional Pain Syndrome: Case Report

A 53-year-old male who had received surgery on his right ankle joint 10 years previously was diagnosed with Complex Regional Pain Syndrome the following year. Despite various treatments (sympathetic nerve-block medication, pain relievers, corticosteroids, nerve blocks, and transcutaneous electrical nerve stimulation) over the years there was no improvement in his symptoms. Recently the patient was admitted to a Korean medicine hospital where he received treatment (acupuncture, pharmacopuncture, and herbal treatment) and his symptoms gradually showed improvement. The patient was concurrently on psychiatric medicine, antihistamine medication, and opioids for pain (when necessary). A decrease in numeric rating scale, Oswestry disability index scores, and an increase in the Korean version of the 5-level EuroQol-5 dimension score showed symptom improvement within 36 days. This study suggests complex Korean medicine treatment for Complex Regional Pain Syndrome may result in a reduction in pain and improved quality of life.

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.

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.

Determinants of Diagnostic Delay in Complex Regional Pain Syndrome Type 1: An Observational Study of 180 Consecutive New Cases

BACKGROUND/OBJECTIVE

Complex regional pain syndrome type 1 (CRPS-1) is a disabling painful disease, with variable outcomes in terms of chronic pain and disability. A long time between onset and diagnosis seems predictive for late recovery and progression toward a chronic disease. This study aims to investigate demographic and clinical variables associated with delayed CRPS-1 diagnosis.

METHODS

From March 2013 to January 2018, consecutive patients newly diagnosed according to International Association for the Study of Pain diagnostic criteria for CRPS-1 were recruited. Demographic and clinical variables were collected at diagnosis. Student t test and Mann-Whitney U test were used for comparisons; Cox proportional hazards model was applied to evaluate the variables associated with delayed CRPS-1 diagnosis.

RESULTS

One hundred eighty patients entered the study. At diagnosis, women were older, and foot was more often involved than hand. The triggering event was more commonly a trauma without fracture for foot disease and a fracture for hand localization. No differences between hand and foot disease were found by the International Association for the Study of Pain diagnostic categories (clinical vs research) or pain measures. Variables significantly associated with a longer time between disease onset and diagnosis were foot localization, general practitioner referral, higher number of visits before CRPS diagnosis, and prior physiotherapy prescribed for symptoms later diagnosed as CRPS. An overt clinical manifestation (research CRPS-1) predicted a shorter delay.

CONCLUSIONS

Foot localization, prior physiotherapy prescribed for symptoms later diagnosed as CRPS, and a disease without overt clinical manifestations were independent predictive factors for a delayed diagnosis. Clinicians should pay attention to these issues to ensure a timely diagnosis and possibly avoid progression toward a chronic disease.

Denying the Truth Does Not Change the Facts: A Systematic Analysis of Pseudoscientific Denial of Complex Regional Pain Syndrome

Purpose

Several articles have claimed that complex regional pain syndrome (CRPS) does not exist. Although a minority view, it is important to understand the arguments presented in these articles. We conducted a systematic literature search to evaluate the methodological quality of articles that claim CRPS does not exist. We then examined and refuted the arguments supporting this claim using up-to-date scientific literature on CRPS.

Methods

A systematic search was conducted in MEDLINE, EMBASE and Cochrane CENTRAL databases. Inclusion criteria for articles were (a) a claim made that CRPS does not exist or that CRPS is not a distinct diagnostic entity and (b) support of these claims with subsequent argument(s). The methodological quality of articles was assessed if possible.

Results

Nine articles were included for analysis: 4 narrative reviews, 2 personal views, 1 letter, 1 editorial and 1 case report. Seven points of controversy were used in these articles to argue that CRPS does not exist: 1) disagreement with the label “CRPS”; 2) the “unclear” pathophysiology; 3) the validity of the diagnostic criteria; 4) CRPS as a normal consequence of immobilization; 5) the role of psychological factors; 6) other identifiable causes for CRPS symptoms; and 7) the methodological quality of CRPS research.

Conclusion

The level of evidence for the claim that CRPS does not exist is very weak. Published accounts concluding that CRPS does not exist, in the absence of primary evidence to underpin them, can harm patients by encouraging dismissal of patients’ signs and symptoms.

Complex Regional Pain Syndrome. A Comprehensive Review on Neuroplastic Changes Supporting the Use of Non-invasive Neurostimulation in Clinical Settings

Background: Complex regional pain syndrome (CRPS) is a rare debilitating disorder characterized by severe pain affecting one or more limbs. CRPS presents a complex multifactorial physiopathology. The peripheral and sensorimotor abnormalities reflect maladaptive changes of the central nervous system. These changes of volume, connectivity, activation, metabolism, etc., could be the keys to understand chronicization, refractoriness to conventional treatment, and developing more efficient treatments. Objective: This review discusses the use of non-pharmacological, non-invasive neurostimulation techniques in CRPS, with regard to the CRPS physiopathology, brain changes underlying chronicization, conventional approaches to treat CRPS, current evidence, and mechanisms of action of peripheral and brain stimulation. Conclusion: Future work is warranted to foster the evidence of the efficacy of non-invasive neurostimulation in CRPS. It seems that the approach has to be individualized owing to the integrity of the brain and corticospinal function. Non-invasive neurostimulation of the brain or of nerve/muscles/spinal roots, alone or in combination with conventional therapy, represents a fertile ground to develop more efficient approaches for pain management in CRPS.

Photophobia in complex regional pain syndrome: visual discomfort is greater on the affected than unaffected side

ABSTRACT

In complex regional pain syndrome (CRPS), hyperalgesia encompasses uninjured sites on the ipsilateral side of the body and may also include the special senses because auditory discomfort often is greater on the CRPS-affected side. To determine whether this hemilateral hyperalgesia involves the visual system, the discomfort threshold to a light-source that increased in intensity at 100 lux/second from 500 to 3600 lux was investigated for each eye, and the nasal and temporal half of each visual field, in 33 patients with CRPS and 21 pain-free controls. Recent headache history was reviewed and, in patients with CRPS, sensitivity to mechanical and thermal stimuli was assessed in all 4 limbs and on each side of the forehead. In addition, the pupils were photographed in dim and bright light. The visual discomfort threshold was lower in patients than controls and was lower on the CRPS-affected than unaffected side (P < 0.001), indicating photophobia. Visual discomfort was unrelated to pupil diameter. Headache frequency was greater in CRPS patients than controls, and unilateral headaches were more likely to be on the CRPS-affected than contralateral side. Similarly, mechanical and thermal hyperalgesia was greater in the CRPS-affected than contralateral limb and was greater ipsilateral than contralateral to CRPS in the forehead and nonsymptomatic limbs. Ipsilateral photophobia was associated with mechanical and thermal hyperalgesia in the ipsilateral forehead but not the CRPS-affected limb. Together, these findings suggest that aberrant processing of nociceptive input in the ipsilateral trigeminal-medullary region of the brainstem contributes to visual discomfort in CRPS.

The challenge of recognizing severe pain and autonomic abnormalities for early diagnosis of CRPS

OBJECTIVES

Complex regional pain syndrome (CRPS) is a disabling usually post-traumatic pain condition. International guidelines emphasize early diagnosis for treatment and improved outcome. Early intense and persistent pain along with features of autonomic dysfunction in the first week's post-injury are early warning signs for development of CRPS. We have previously reported a delayed diagnosis of CRPS. The main purpose of the present study was to investigate possible causes of a delayed diagnosis, with a special focus of recognition of risk factors.

METHODS

A total of 52 CRPS 1 (without detectable nerve damage) and CRPS 2 (with evidence of nerve lesion) patients were included in the study. When examined at OUS-Rikshospitalet, we retrospectively asked the patients on the development of pain and autonomic abnormalities from the time of the eliciting injury, performed a thorough clinical investigation with an emphasis on signs of autonomic failure and compared symptoms and clinical findings with such information in previous medical records. We also evaluated symptoms and signs according to the type of injury they had suffered.

RESULTS

Of a total of 52 patients (30 women and 22 men, mean age 39.0 years at the time of injury), 34 patients had CRPS type 1 (65.4%) and 18 CRPS type 2 (34.6%), 25 patients with pain in the upper and 27 in the lower extremity. A total of 35 patients (67.3%) were diagnosed with CRPS (following mean 2.1 years) prior to the investigation at OUS-Rikshospitalet (mean 4.86 years following injury). Mean time from injury to diagnosis was 33.5 months (SD 30.6) (2.8 years) for all patients. In retrospect, all 17 patients first diagnosed at OUS met the CRPS diagnosis at an earlier stage. All patients retrospectively reported intense pain (numeric rating scale > 7) from the time of injury with a large discrepancy to previous medical records which only stated intense pain in 29.4% of patients with CRPS type 1 and 44.4% of patients with CRPS type 2 within the first four months. While the patients reported an early onset of autonomic dysfunction, present in 67.3 and 94.2% of the patients within one week and one month, respectively, reports of autonomic abnormalities within the first four months was far less (maximum in 51.7% of patients with CRPS type 1 and in 60% in CRPS 2). In 10 patients with CRPS type 1, no symptom nor sign of autonomic abnormalities was reported.

CONCLUSIONS

We still find a significant delay in the diagnosis of CRPS. There is a large discrepancy between both self-reporting of intense, disproportionate pain, as well as symptoms of autonomic abnormalities from the time of injury, and documentation in previous medical records. Our findings suggest a lack of awareness of risk factors for the development of CRPS, such as early intense pain and autonomic abnormalities without recovery, contributing to delayed diagnosis. The present results suggest causes of delayed CRPS-diagnosis. An increased attention to early warning signs/risk factors may improve diagnosis of CRPS.

Prism adaptation treatment for upper-limb complex regional pain syndrome: a double-blind randomized controlled trial

ABSTRACT

Initial evidence suggested that people with complex regional pain syndrome (CRPS) have reduced attention to the affected side of their body and the surrounding space, which might be related to pain and other clinical symptoms. Three previous unblinded, uncontrolled studies showed pain relief after treatment with prism adaptation, an intervention that has been used to counter lateralised attention bias in brain-lesioned patients. To provide a robust test of its effectiveness for CRPS, we conducted a double-blind randomized controlled trial of prism adaptation for unilateral upper-limb CRPS-I. Forty-nine eligible adults with CRPS were randomized to undergo 2 weeks of twice-daily home-based prism adaptation treatment (n = 23) or sham treatment (n = 26). Outcomes were assessed in person 4 weeks before and immediately before treatment, and immediately after and 4 weeks after treatment. Long-term postal follow-ups were conducted 3 and 6 months after treatment. We examined the effects of prism adaptation vs sham treatment on current pain intensity and the CRPS symptom severity score (primary outcomes), as well as sensory, motor, and autonomic functions, self-reported psychological functioning, and experimentally tested neuropsychological functions (secondary outcomes). We found no evidence that primary or secondary outcomes differed between the prism adaptation and sham treatment groups when tested at either time point after treatment. Overall, CRPS severity significantly decreased over time for both groups, but we found no benefits of prism adaptation beyond sham treatment. Our findings do not support the efficacy of prism adaptation treatment for relieving upper-limb CRPS-I. This trial was prospectively registered (ISRCTN46828292).

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.

Psychiatric Comorbidity and Complex Regional Pain Syndrome Through the Lens of the Biopsychosocial Model: A Comparative Study

PURPOSE

To compare the prevalence of psychiatric comorbidity between patients with complex regional pain syndrome (CRPS) of the hand and non-CRPS patients and to assess the association between biopsychosocial (BPS) complexity profiles and psychiatric comorbidity in a comparative study.

PATIENTS AND METHODS

We included a total of 103 patients with CRPS of the hand and 290 patients with chronic hand impairments but without CRPS. Psychiatric comorbidities were diagnosed by a psychiatrist, and BPS complexity was measured by means of the INTERMED. The odds ratios (OR) of having psychiatric comorbidities according to BPS complexity were calculated with multiple logistic regression (adjusted for age, sex, and pain).

RESULTS

Prevalence of psychiatric comorbidity was 29% in CRPS patients, which was not significantly higher than in non-CRPS patients (21%, relative risk=1.38, 95% CI: 0.95 to 2.01 p=0.10). The median total scores of the INTERMED were the same in both groups (23 points). INTERMED total scores (0-60 points) were related to an increased risk of having psychiatric comorbidity in CRPS patients (OR=1.46; 95% CI: 1.23-1.73) and in non-CRPS patients (OR=1.21; 95% CI: 1.13-1.30). The four INTERMED subscales (biological, psychological, social, and health care) were correlated with a higher risk of having psychiatric comorbidity in both groups. The differences in the OR of having psychiatric comorbidity in relation to INTERMED total and subscale scores were not statistically different between the two groups.

CONCLUSION

The total scores, as well as all four dimensions of BPS complexity measured by the INTERMED, were associated with psychiatric comorbidity, with comparable magnitudes of association between the CRPS and non-CRPS groups. The INTERMED was useful in screening for psychological vulnerability in the two groups.

Modifiable Factors Associated With Chronic Pain 1 Year After Operative Management of Distal Radius Fractures: A Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

Despite appropriate treatment, many patients who sustain distal radius fractures (DRFs) report persistent wrist pain. Chronic musculoskeletal pain is among the leading health problems in the elderly population associated with significant personal and societal burden.

OBJECTIVE

To identify modifiable preoperative factors that are significantly associated with developing chronic pain.

DESIGN, SETTING, AND PARTICIPANTS

This is a secondary analysis of the Wrist and Radius Injury Surgical Trial (WRIST), a randomized multicenter clinical trial of 24 study sites in the United States, Canada, and Singapore that enrolled patients from April 10, 2012, to December 31, 2016. Adults older than 60 years who sustained closed extra-articular DRFs, were treated operatively, and completed 12-month Michigan Hand Outcomes Questionnaires (MHQs) were included in this study. Analysis was conducted from September to December 2019.

INTERVENTIONS

Volar locking plate internal fixation, external fixation, or percutaneous pinning.

MAIN OUTCOMES AND MEASURES

12-month MHQ pain domain score. Inverse probability weighted logistic regression was used to identify factors associated with of chronic pain.

RESULTS

A total of 146 patients with DRF who were treated operatively and had 12-month MHQ scores met inclusion criteria. The mean (SD) patient age was 68.9 (7.2) years, 128 (87.6%) were women, and 93 (63.7%) were retired. Chronic pain was present in 87 patients (59.6%) and absent in 59 patients (40.4%) at 1-year follow-up. A 1-week delay in surgery was associated with more than triple the odds of developing chronic pain (odds ratio [OR], 3.65; 95% CI, 1.48-9.00), and each 10-point increase in preoperative pain was associated with a 17% increase in the odds of experiencing chronic pain (OR, 1.17; 95% CI, 1.02-1.34). Internal fixation was associated with decreased odds of developing chronic pain compared with the other 2 procedures (OR, 0.29; 95% CI, 0.10-0.90).

CONCLUSIONS AND RELEVANCE

In this study, preoperative pain, time to surgery, and procedure type were modifiable factors associated with chronic pain 1 year after DRF treated with surgery. Adequate pain control in patients with acute DRFs even before definitive surgical management and earlier fixation for patients requiring surgery may decrease the risk of developing chronic pain. Internal fixation may decrease the risk of chronic pain after DRF surgery, compared with percutaneous pinning or external fixation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01589692.

Complex regional pain syndrome: an evolving perspective

BACKGROUND

Complex regional pain syndrome (CRPS) is a heterogenous and poorly understood condition that can be provoked by quite minor injuries. The symptoms and signs of CRPS persist, long after the patient has recovered from the inciting event. In some cases, there is a clear association with a peripheral nerve injury. The degree of disability produced by CRPS is often out of proportion to the scale of the original insult and the condition is associated with protracted recovery times and frequent litigation.

METHODS

We have performed a PubMed literature search, referenced landmark papers in the field and included a national expert in peripheral nerve injury and repair in our team of authors.

RESULTS AND CONCLUSIONS

The diagnostic criteria for CRPS have changed repeatedly over the last two centuries and much of the historical literature is difficult to compare with more recent research. In this review article, we consider how our understanding of the condition has evolved and discuss its pathogenesis, its apparent heterogenicity and the various investigations and treatments available to the clinician.

Reduction in Migraine and Headache Frequency and Intensity With Combined Antioxidant Prophylaxis (N-acetylcysteine, Vitamin E, and Vitamin C): A Randomized Sham-Controlled Pilot Study

OBJECTIVE

To investigate the preventive effects of a combined antioxidant drug (N-acetylcysteine, vitamin E, and vitamin C [NEC]) on migraine outcomes. Migraine is characterized by increased oxidative stress and neurogenic inflammation in the brain; therefore, antioxidants may have a migraine preventive effect.

DESIGN

Randomized, double-blind, sham-controlled pilot study.

SETTING

Australian community.

SUBJECTS

Adults reporting 2 to 8 migraines per month for at least a year.

METHODS

After a 1-month baseline period, 35 subjects completed 3 months of treatment with NEC (n = 19) or sham (n = 16) capsules. The primary outcome was the difference in mean number of headaches per month between baseline and final month of the trial for NEC and sham groups; secondary outcomes are listed below.

RESULTS

For NEC there was a significant decrease in mean number of headaches by 3.0 per month (P = 0.004) compared with 1.4 for sham (P = 0.073); there was no significant difference in these changes between the 2 groups (P = 0.052). Average monthly headache (P = 0.041) and migraine frequency (P = 0.018) were significantly less for NEC vs. sham. In NEC subjects, there was a significant decrease in average monthly migraine days (-3.1), moderate/severe headache days (-3.2), migraine duration, headache pain scores, and acute headache medication use.

CONCLUSIONS

This is the first randomized controlled trial to find that combined antioxidant therapy with NEC reduces headaches and migraines in adult migraineurs. Given the limitations of this pilot study, an adequately powered randomized controlled trial is planned to further investigate antioxidant prophylaxis in migraine.

Molecular Aspects of Regional Pain Syndrome

The purpose of this review is to summarize the pathophysiology of complex regional pain syndrome (CRPS), the underlying molecular mechanisms, and potential treatment options for its management. CRPS is a multifactorial pain condition. CRPS is characterized by prolonged or excessive pain and changes in skin color and temperature, and/or swelling in the affected area, and is generally caused by stimuli that lead to tissue damage. An inflammatory response involving various cytokines and autoantibodies is generated in response to acute trauma/stress. Chronic phase pathophysiology is more complex, involving the central and peripheral nervous systems. Various genetic factors involved in the chronicity of pain have been identified in CRPS patients. As with other diseases of complex pathology, CRPS is difficult to treat and no single treatment regimen is the same for two patients. Stimulation of the vagus nerve is a promising technique being tested for different gastrointestinal and inflammatory diseases. CRPS is more frequent in individuals of 61–70 years of age with a female to male ratio of 3 : 1. Menopause, migraine, osteoporosis, and asthma all represent risk factors for CRPS and in smokers the prognosis appears to be more severe. The pathophysiological mechanisms underlying CRPS involve both inflammatory and neurological pathways. Understanding the molecular basis of CRPS is important for its diagnosis, management, and treatment. For instance, vagal nerve stimulation might have the potential for treating CRPS through the cholinergic anti-inflammatory pathway.

A randomized controlled trial on Aspirin and complex regional pain syndrome after radius fractures

Complex regional pain syndrome (CRPS) is often diagnosed in patients who are recovered with surgery or injury. CRPS is usually diagnosed in patients recovering from distal radius fractures. The aim of study was the effects of aspirin in prevention of the complex regional pain syndrome (CRPS) following a fracture of distal radius. In a double-blind, randomized controlled trial, 91 patients with unilateral extra-articular distal radius fractures were randomly allocated to receive either placebo (PLA) or 500 mg of aspirin (ASA) daily for 7 days. The effect of aspirin on the occurrence of CRPS was evaluated. The patients were assessed clinically and radiographically in the second, fourth and twelfth weeks by a physician who was unaware of the treatment allocation. Ninety-one patients (ASA, n=44; PLA, n=47) were enrolled in the study. The prevalence of CRPS in all patients was 16.5%. The prevalence of CRPS in the aspirin group was lower (13.6%) than the placebo group (19.1%), but this difference was not statistically significant. The only significant difference was the lower rate of regional osteoporosis seen in the radiographs of aspirin group. Mean age was significantly higher in the patients with CRPS. Also, comminuted distal radius fractures (A3-type) were significantly more common in the patients with CRPS. Administration of aspirin in patients with a distal radius fracture was associated with a lower incidence of CRPS, but, not statistically significant. Further investigations needs to be done with a larger sample size, longer follow-up period and multi-center design.

Complex regional pain syndrome: A rare but potentially disabling complication of transradial cardiac catheterization

BACKGROUND

Chronic Regional Pain Syndrome (CRPS) is a rare complication following transradial cardiac catheterization.

AIMS

To discuss the clinical features, pathophysiology, diagnosis and management of CRPS.

METHODS

Literature review performed.

RESULTS

CRPS is seen rarely in the literature following upper limb arterial access for coronary procedures, which may be due to a low incidence of the syndrome as well as limited recognition and underreporting.

DISCUSSION

The diagnosis and management of CRPS are discussed in detail.

CONCLUSION

If CRPS is a potential diagnosis then prompt early referral to a center with a specialist interest in CRPS is recommended. Prompt diagnosis and early commencement on the correct patient treatment pathway are essential, to avoid potentially life changing disability and the psychological consequences of living with intractable chronic undiagnosed pain.

Persons with Complex Regional Pain Syndrome Renegotiate Social Roles and Intimacy: A Qualitative Study

Objective

Persons with complex regional pain syndrome often experience allodynia, where touch is painful. Allodynia is associated with poor prognosis, but the impacts on roles, activities, social relationships, and intimacy remain unclear. There is a need to examine intimacy in complex regional pain syndrome from a lived experience perspective.

Methods

We conducted a secondary analysis of cognitive debriefing interview data from 44 persons with complex regional pain syndrome who completed a patient-reported questionnaire. Using interpretive description and thematic analysis, we analyzed items and responses addressing allodynia, relationships, and intimacy.

Results

Two themes were developed to understand intimacy related to the pain experience: a renegotiated social identity and participation and a reinvented intimate self. These themes included elements of a) loss of control, b) loss of shared experiences, c) feeling that their condition was misunderstood, d) a need for self-preservation, e) altered self-concept, and e) the concept of intimacy is broader than sexuality. Our findings suggest that complex regional pain syndrome has pervasive impacts on relationships and intimacy that merit discussion with their health care team.

Conclusions

Persons with persistent pain need to be supported in roles and activities that allow them to express intimacy in their everyday lives.

Complex regional pain syndrome and functional neurological disorders - time for reconciliation

There have been many articles highlighting differences and similarities between complex regional pain syndrome (CRPS) and functional neurological disorders (FND) but until now the discussions have often been adversarial with an erroneous focus on malingering and a view of FND as 'all in the mind'. However, understanding of the nature, frequency and treatment of FND has changed dramatically in the last 10-15 years. FND is no longer assumed to be only the result of 'conversion' of psychological conflict but is understood as a complex interplay between physiological stimulus, expectation, learning and attention mediated through a Bayesian framework, with biopsychosocial predisposing, triggering and perpetuating inputs. Building on this new 'whole brain' perspective of FND, we reframe the debate about the 'psychological versus physical' basis of CRPS. We recognise how CRPS research may inform mechanistic understanding of FND and conversely, how advances in FND, especially treatment, have implications for improving understanding and management of CRPS.

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).

Comparison of complex regional pain syndrome and fibromyalgia: Differences in beta and gamma bands on quantitative electroencephalography

Complex regional pain syndrome (CRPS) and fibromyalgia (FM) share many features. Both can cause severe pain and are considered to have a mechanism of action, including dysfunction of the sympathetic nervous system. However, they have clinical differences in pain range and degree. The present study aimed to find neurophysiologic differences between CRPS and FM using quantitative electroencephalography (QEEG). Thirty-eight patients with CRPS and 33 patients with FM were included in the analysis. Resting-state QEEG data were grouped into frontal, central, and posterior regions to analyze for regional differences. General linear models were utilized to test for group differences in absolute and relative powers. As a result, the CRPS group relative to FM group showed lower total absolute powers in the beta band (F = 5.159, P < .05), high beta (F = 14.120, P < .05), and gamma band (F = 15.034, P < .05). There were no significant differences between 2 groups in the delta, theta, and alpha bands. The present findings show that the CRPS and FM groups differ mainly in the high frequency, which may reflect their distinct pathophysiology and symptomatology. Our study suggests that the QEEG differences can be clinically useful in assessing brain function in patients with CRPS and FM.

AAPT Diagnostic Criteria for Peripheral Neuropathic Pain: Focal and Segmental Disorders

Peripheral neuropathic pain is among the most prevalent types of neuropathic pain. No comprehensive peripheral neuropathic pain classification system that incorporates contemporary clinical, diagnostic, biological, and psychological information exists. To address this need, this article covers the taxonomy for 4 focal or segmental peripheral neuropathic pain disorders, as part of the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership and the American Pain Society (APS) collaborative to develop a standardized, evidence-based taxonomy initiative: the ACTTION-APS Pain Taxonomy (AAPT). The disorders-postherpetic neuralgia, persistent posttraumatic neuropathic pain, complex regional pain disorder, and trigeminal neuralgia-were selected because of their clinical and clinical research relevance. The multidimensional features of the taxonomy are suitable for clinical trials and can also facilitate hypothesis-driven case-control and cohort epidemiologic studies. PERSPECTIVE: The AAPT peripheral neuropathic pain taxonomy subdivides the peripheral neuropathic pain disorders into those that are generalized and symmetric and those that are focal or segmental and asymmetric. In this article, we cover the focal and segmental disorders: postherpetic neuralgia, persistent posttraumatic neuropathic pain, complex regional pain disorder, and trigeminal neuralgia. The taxonomy is evidence-based and multidimensional, with the following dimensions: 1) core diagnostic criteria; 2) common features; 3) common medical and psychiatric comorbidities; 4) neurobiological, psychosocial, and functional consequences; and 5) putative neurobiological and psychosocial mechanisms, risk factors, and protective factors.

Sensory modulation dysfunction is associated with Complex Regional Pain Syndrome

OBJECTIVE

Complex Regional Pain Syndrome (CRPS), a chronic pain condition, develops mainly after limb trauma and severely inhibits function. While early diagnosis is essential, factors for CRPS onset are elusive. Therefore, identifying those at risk is crucial. Sensory modulation dysfunction (SMD), affects the capacity to regulate responses to sensory input in a graded and adaptive manner and was found associated with hyperalgesia in otherwise healthy individuals, suggestive of altered pain processing.

AIM

To test SMD as a potential risk factor for CRPS.

METHODS

In this cross-sectional study, forty-four individuals with CRPS (29.9±11 years, 27 men) and 204 healthy controls (27.4±3.7 years, 105 men) completed the Sensory Responsiveness Questionnaire-Intensity Scale (SRQ-IS). A physician conducted the CRPS Severity Score (CSS), testing individuals with CRPS.

RESULTS

Thirty-four percent of the individuals with CRPS and twelve percent of the healthy individuals were identified to have SMD (χ2 (1) = 11.95; p<0.001). Logistic regression modeling revealed that the risk of CRPS is 2.68 and 8.21 times higher in individuals with sensory over- and sensory under-responsiveness, respectively, compared to non-SMD individuals (p = 0.03 and p = 0.01, respectively).

CONCLUSIONS

SMD, particularly sensory under-responsiveness, might serve as a potential risk factor for CRPS and therefore screening for SMD is recommended. This study provides the risk index probability clinical tool a simple evaluation to be applied by clinicians in order to identify those at risk for CRPS immediately after injury. Further research is needed.

Passive transfer autoimmunity in a mouse model of complex regional pain syndrome

It has been proposed that complex regional pain syndrome (CRPS) is a posttraumatic autoimmune disease, and we previously observed that B cells are required for the full expression of CRPS-like changes in a mouse tibia fracture CRPS model. The current study used the mouse model to evaluate the progression of postfracture CRPS-like changes in wild-type (WT) and muMT fracture mice lacking B cells and antibodies. The pronociceptive effects of injecting WT fracture mouse serum antibodies into muMT fracture mice were also evaluated. Postfracture pain behaviors transitioned from being initially dependent on both innate and autoimmune inflammatory mechanisms at 3 weeks after fracture to being entirely mediated by antibody responses at 12 weeks after fracture and spontaneously resolving by 21 weeks after fracture. Furthermore, serum IgM antibodies from WT fracture mice had pronociceptive effects in the fracture limb when injected into muMT fracture mice. IgM antibody levels gradually increased in the fracture limb hind paw skin, sciatic nerve, and corresponding lumbar cord, peaking at 12 to 18 weeks after fracture and then declining. Immunohistochemistry localized postfracture IgM antibody binding to antigens in the fracture limb hind paw dermal cell nuclei. We postulate that fracture induces expression of neoantigens in the fracture limb skin, sciatic nerve, and cord, which trigger B cells to secret IgM antibodies that bind those antigens and initiate a pronociceptive antibody response. Autoimmunity plays a key role in the progression of nociceptive and vascular changes in the mouse fracture model and potentially contributes to the CRPS disease process.

Bisphosphonates in the treatment of complex regional pain syndrome: is bone the main player at early stage of the disease?

Complex Regional Pain Syndrome type 1 (CRPS-1) is a disabling painful disease whose hallmark is pain disproportionate to inciting event. CRPS is also characterized by symptoms and signs, such as vasomotor, sudomotor, trophic and motor changes. Therapeutic approach of CRPS-1 still remains a challenge for clinicians treating a disease with potential heavy consequences on patient prognosis. In the past years, the treatment with bisphosphonates (BPs) has gained some success as confirmed by the results of a number of meta-analyses. The aim of this paper is to point out the pivotal role of bone in CRPS pathogenesis. The efficacy of BPs is likely to be related to bone tissue involvement in the early pathophysiological steps of the disease, as demonstrated by evidences highlighting the central role of bone in the initial phases. Bone can become a source of inflammatory cytokines when triggered by a direct injury. Moreover, peptidergic fibers that innervate both mineralized bone and bone marrow can play a role in triggering or maintaining the microvascular disturbance at bone level. Indeed, bone involvement is consistent with the mineralization disturbance as well as the results of instrumental investigations (e.g., MRI, bone scan). In this regard, an intriguing issue relies on the excellent therapeutic response to BPs treatment of other diseases (e.g., Transient Osteoporosis of the Hip and Regional Migratory Osteoporosis) that share with CRPS-1 some clinical and instrumental features.

Complex regional pain syndrome type 1 in the medico-legal setting: High rates of somatoform disorders, opiate use and diagnostic uncertainty

Objective The aim of this study was to review demographic and clinical characteristics of patients with complex regional pain syndrome type 1 (CRPS) seen in a UK medico-legal setting - particularly the relationship between CRPS and somatoform disorders. Methods Fifty consecutive cases of CRPS (interviewed 2005-2016) undergoing psychiatric assessment were reviewed. A systematic assessment of mental states was conducted via interview and examination of medical/psychiatric records. Thirty patients also completed the Brief Illness Perception Questionnaire (BIPQ). Results Sixty per cent of patients ( n = 30) were female, and the mean age was 43 years. Twenty-two per cent ( n = 11) were employed, and 60% ( n = 30) received disability benefits. Symptoms were reported in the upper limb (62%; n = 31), lower limb (30%; n = 15), both (6%; n = 3) or elsewhere (2%; n = 1). Eighty-four per cent ( n = 42) satisfied DSM-5 criteria for current somatoform disorder. A history of more than two pain-related functional somatic syndromes (e.g. non-cardiac chest pain) was found in 42% ( n = 21) and functional neurological symptoms (e.g. 'claw-hand') in 42% ( n = 21). BIPQ scores resembled those associated with somatoform disorders and disorders mediated by psychological factors (e.g. irritable bowel syndrome). In 38% ( n = 19), the CRPS diagnosis was disputed among experts. A history of depression was noted in 60% ( n = 30), panic attacks in 20% ( n = 10) and alcohol/substance misuse in 18% ( n = 9). Opiates were prescribed to 64% ( n = 32). Conclusions Patients diagnosed with CRPS involved in litigation have high rates of prior psychopathology (mainly somatoform disorders) and pain-related disability for which opiate use is common. They risk an adverse reaction to limb pain 'shaped' by maladaptive illness beliefs. The CRPS diagnosis lacks reliability in medico-legal settings and may cause iatrogenic harm.

The experiences and beliefs of patients with complex regional pain syndrome: An exploratory survey study

Objectives To determine the beliefs and describe the health care experiences of patients with complex regional pain syndrome. Methods A survey tool for patients with complex regional pain syndrome was designed for this study. The survey tool collected self-reported measures associated with pain, disability, health care experiences, education, beliefs, and treatments. Results Thirty-one patients attending physical therapy for complex regional pain syndrome (mean age 40.48; female n = 20) completed the survey. Patients with presented with high levels of pain and disability and reported various changes associated with altered neuroplasticity such as confused body part recognition, left/right discrimination, neglect, and spreading pain. The patients' experiences with diagnostic testing and interventions are not in line with the current pain science research and/or evidence-based practice. Overall, patients are ill-informed, confused, and receive conflicting information. Discussion The suffering associated with complex regional pain syndrome is real, as told by patients. This suffering coincides with a lack of consensus by health care providers and conflicting information on complex regional pain syndrome. Overall, patient experiences show health care providers are not up to date with the current best-evidence regarding complex regional pain syndrome.

Redox Mechanisms in Migraine: Novel Therapeutics and Dietary Interventions

SIGNIFICANCE

Migraine represents the third most prevalent and the seventh most disabling human disorder. Approximately 30% of migraine patients experience transient, fully reversible, focal neurological symptoms (aura) preceding the attack. Recent Advances: Awareness of the hypothesis that migraine actually embodies a spectrum of illnesses-ranging from episodic to chronic forms-is progressively increasing and poses novel challenges for clarifying the underlying pathophysiological mechanisms of migraine as well as for the development of novel therapeutic interventions. Several theories have evolved to the current concept that a combination of genetic, epigenetic, and environmental factors may play a role in migraine pathogenesis, although their relative importance is still being debated.

CRITICAL ISSUES

One critical issue that deserves a particular attention is the role of oxidative stress in migraine. Indeed, potentially harmful oxidative events occur during the migraine attack and long-lasting or frequent migraine episodes may increase brain exposure to oxidative events that can lead to chronic transformation. Moreover, a wide variety of dietary, environmental, physiological, behavioral, and pharmacological migraine triggers may act through oxidative stress, with clear implications for migraine treatment and prophylaxis. Interestingly, almost all current prophylactic migraine agents exert antioxidant effects.

FUTURE DIRECTIONS

Increasing awareness of the role of oxidative stress and/or decreased antioxidant defenses in migraine pathogenesis and progression to a chronic condition lays the foundations for the design of novel prophylactic approaches, which, by reducing brain oxidative phenomena, could favorably modify the clinical course of migraine. Antioxid. Redox Signal. 28, 1144-1183.

Migraine and Complex Regional Pain Syndrome: A Case-Referent Clinical Study

We studied clinical phenotype differences between migraineurs with CRPS (Mig + CRPS) and those without (Mig − CRPS). Mig + CRPS cases and Mig − CRPS referents aged ≥18 years were enrolled. Diagnosis was made in accordance with International Classification of Headache Disorders-3 beta (ICHD-3 beta) for migraine and Budapest Criteria for CRPS. Migraines both with and without aura were included. A total of 70 Mig + CRPS cases (13% males, mean age 48 years) and 80 Mig − CRPS referents (17% males, mean age 51 years) were included. 33% of Mig + CRPS and 38% of Mig − CRPS exhibited episodic migraine (EM) while 66% of Mig + CRPS and 62% of Mig − CRPS had chronic migraine (CM) (OR = 0.98, CI 0.36, 2.67). Median duration of CRPS was 3 years among EM + CRPS and 6 years among CM + CRPS cohort (p < 0.02). Mig + CRPS (57%) carried higher psychological and medical comorbidities compared to Mig − CRPS (6%) (OR 16.7, CI 10.2, 23.6). Higher migraine frequency was associated with longer CRPS duration. Migraineurs who developed CRPS had higher prevalence of psychological and medical disorders. Alleviating migraineurs' psychological and medical comorbidities may help lower CRPS occurrence.

Autonomic components of Complex Regional Pain Syndrome (CRPS) are favourably affected by Electrical Twitch-Obtaining Intramuscular Stimulation (ETOIMS): effects on blood pressure and heart rate

INTRODUCTION

Favourable pain relief results on evoking autonomous twitches at myofascial trigger points with Electrical Twitch Obtaining Intramuscular Stimulation (ETOIMS).

AIM

To document autonomic nervous system (ANS) dysfunction in Complex Regional Pain Syndrome (CRPS) from blood pressure (BP) and pulse/heart rate changes with ETOIMS.

METHODS AND MATERIALS

A patient with persistent pain regularly received serial ETOIMS sessions of 60, 90, 120 or ≥150 min over 24 months. Outcome measures include BP: systolic, diastolic, pulse pressure and pulse/heart rate, pre-session/immediate-post-session summed differences (SDPPP index), and pain reduction. His results were compared with that of two other patients and one normal control. Each individual represented the following maximal elicitable twitch forces (TWF) graded 1-5: maximum TWF2: control subject; maximum TWF3: CRPS patient with suspected ANS dysfunction; and maximum TWF4 and TWF5: two patients with respective slow-fatigue and fast-fatigue twitches who during ETOIMS had autonomous twitching at local and remote myotomes simultaneously from denervation supersensitivity. ETOIMS results between TWFs were compared using one-way analysis of variance test.

RESULTS

The patients showed immediate significant pain reduction, BP and pulse/heart rate changes/reduction(s) except for diastolic BP in the TWF5 patient. TWF2 control subject had diastolic BP reduction with ETOIMS but not with rest. Linear regression showed TWF grade to be the most significant variable in pain reduction, more so than the number of treatments, session duration and treatment interval. TWF grade was the most important variable in significantly reducing outcome measures, especially pulse/heart rate. Unlike others, the TWF3 patient had distinctive reductions in SDPPP index.

CONCLUSIONS

Measuring BP and pulse/heart rate is clinically practical for alerting ANS dysfunction maintained CRPS. SDPPP index (≥26) and pulse/heart rate (≥8) reductions with almost every ETOIMS treatment, plus inability to evoke autonomous twitches due to pain-induced muscle hypertonicity, are pathognomonic of this problem.

Complex regional pain syndrome: a recent update

Complex regional pain syndrome (CRPS) is a debilitating condition affecting the limbs that can be induced by surgery or trauma. This condition can complicate recovery and impair one’s functional and psychological well-being. The wide variety of terminology loosely used to describe CRPS in the past has led to misdiagnosis of this condition, resulting in poor evidence-base regarding the treatment modalities available and their impact. The aim of this review is to report on the recent progress in the understanding of the epidemiology, pathophysiology and treatment of CRPS and to discuss novel approaches in treating this condition.

The Treatment of Longstanding Complex Regional Pain Syndrome with Oral Steroids

OBJECTIVE

Evaluate the effectiveness of oral steroids in relieving pain in patients with Complex Regional Pain Syndrome (CRPS) of more than 3 months duration.

DESIGN

Service evaluation/Open label uncontrolled trial.

SETTING

Two pain outpatient clinics specialized in CRPS diagnosis and treatment in the period 2009-2012.

SUBJECTS

Thirty-one patients diagnosed with CRPS with the Budapest criteria in two specialized centers, with a disease duration of more than 3 months and not responsive to standard treatment were included.

METHODS

Patients were treated with oral prednisolone in both centers [100 mg daily tapered by 25 mg every 4 days to zero (Σ1g) at center 1 (C1) and 60 mg daily for 2 weeks lowered 20 mg every 4 days to zero (Σ1.06g) at center 2 (C2)]. The average pain intensity was recorded by patients using a numeric rating scale before the treatment start, and 6 weeks after treatment onset (treatment duration was respectively 16 days and 22 days at the two centers).

RESULTS

Overall the authors observed no significant reduction in the average pain intensity (P = 0.059), but 2 patients had a consistent reduction in pain intensity with return to baseline pain levels 9 weeks after treatment onset, and 1 patient had ongoing stable pain relief of >50%.

CONCLUSIONS

This study provides indications that the efficacy of oral corticosteroids is limited in treating CRPS of more than 3 months duration who did not respond to previous treatment. Randomized controlled studies (with enriched designs), or single subject designs would be required to identify the possible existence of a patient subgroup with a specific disease profile that may benefit from a steroid treatment.

[Complex regional pain syndrome: A review]

BACKGROUND

Complex regional pain syndrome is characterized by spontaneous or induced pain disproportionate in relation to the initial event and is accompanied by a variety of regional and motor disturbances, leading to a variety of clinical presentations. It is often associated with surgery and minor trauma.

PATHOPHYSIOLOGY

Three mechanisms are postulated: changes secondary to post traumatic inflammation, peripheral vasomotor dysfunction and structural and functional changes of the central nervous system as a result of maladaptation.

DIAGNOSIS

made based on the criteria of Budapest. The patient must have one symptom and sign of each criterion at diagnosis: Continuing pain, disproportionate to any inciting event. A sensory, vasomotor, oedema and motor/trophic change sign and symptoms that are not explained by another diagnosis or cause.

TREATMENT

Multimodal treatment is suggested. There is no gold standard. In early stage NSAIDs or steroids can be used. Drugs used for neuropathic pain treatment have been suggested, but there is not enough evidence for any of these. There is low evidence that bisphosphonates, calcitonin, ketamine and mirror therapy are effective compared to placebo. Interventional treatment should be stepped from epidural block, neurostimulation, intrathecal pump to experimental therapies in case of intractable pain.

DISCUSSION

Although complex regional pain syndrome has been a recognized entity for over 100 years, no clear evidence exists for first-line treatments; however, new technologies that are applicable in complex regional pain syndrome treatment have been developed.

Adult Complex Regional Pain Syndrome Type I: A Narrative Review

Complex regional pain syndrome type I (CRPS I) is a multifactorial painful disorder with a complex pathogenesis. Both peripheral and central mechanisms are involved. Acute CRPS I is considered to be an exaggerated inflammatory disorder; however, over time, because of altered function of the sympathetic nervous system and maladaptive neuroplasticity, CRPS I evolves into a neurological disorder. This review thoroughly describes the pathophysiological aspects of CRPS I and summarizes the potential therapeutic options. The mechanisms and targets of the treatment are different in the early and late stages of the disease. This current review builds on a previous review by this author group by deepening the role of the peripheral classic and neuronal inflammatory component in the acute stage of this painful disorder.

LEVEL OF EVIDENCE

Not applicable.

Local anaesthetic sympathetic blockade for complex regional pain syndrome

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews, 2005, Issue 4 (and last updated in the Cochrane Database of Systematic Reviews, 2013 issue 8), on local anaesthetic blockade (LASB) of the sympathetic chain to treat people with complex regional pain syndrome (CRPS).

OBJECTIVES

To assess the efficacy of LASB for the treatment of pain in CRPS and to evaluate the incidence of adverse effects of the procedure.

SEARCH METHODS

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 9), MEDLINE (Ovid), EMBASE (Ovid), LILACS (Birme), conference abstracts of the World Congresses of the International Association for the Study of Pain, and various clinical trial registers up to September 2015. We also searched bibliographies from retrieved articles for additional studies.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) that evaluated the effect of sympathetic blockade with local anaesthetics in children or adults with CRPS compared to placebo, no treatment, or alternative treatments.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The outcomes of interest were reduction in pain intensity, the proportion who achieved moderate or substantial pain relief, the duration of pain relief, and the presence of adverse effects in each treatment arm. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table.

MAIN RESULTS

We included an additional four studies (N = 154) in this update. For this update, we excluded studies that did not follow up patients for more than 48 hours. As a result, we excluded four studies from the previous review in this update. Overall we included 12 studies (N = 461), all of which we judged to be at high or unclear risk of bias. Overall, the quality of evidence was low to very low, downgraded due to limitations, inconsistency, imprecision, indirectness, or a combination of these.Two small studies compared LASB to placebo/sham (N = 32). They did not demonstrate significant short-term benefit for LASB for pain intensity (moderate quality evidence).One small study (N = 36) at high risk of bias compared thoracic sympathetic block with corticosteroid and local anaesthetic versus injection of the same agents into the subcutaneous space, reporting statistically significant and clinically important differences in pain intensity at one-year follow-up but not at short term follow-up (very low quality evidence).Of two studies that investigated LASB as an addition to rehabilitation treatment, the only study that reported pain outcomes demonstrated no additional benefit from LASB (very low quality evidence).Eight small randomised studies compared sympathetic blockade to various other active interventions. Most studies found no difference in pain outcomes between sympathetic block versus other active treatments (low to very low quality evidence).One small study compared ultrasound-guided LASB with non-guided LASB and found no clinically important difference in pain outcomes (very low quality evidence).Six studies reported adverse events, all with minor effects reported.

AUTHORS' CONCLUSIONS

This update's results are similar to the previous versions of this systematic review, and the main conclusions are unchanged. There remains a scarcity of published evidence and a lack of high quality evidence to support or refute the use of local anaesthetic sympathetic blockade for CRPS. From the existing evidence, it is not possible to draw firm conclusions regarding the efficacy or safety of this intervention, but the limited data available do not suggest that LASB is effective for reducing pain in CRPS.

Immunotherapy Prospects for Painful Small-fiber Sensory Neuropathies and Ganglionopathies

The best-known peripheral neuropathies are those affecting the large, myelinated motor and sensory fibers. These have well-established immunological causes and therapies. Far less is known about the somatic and autonomic "small fibers"; the unmyelinated C-fibers, thinly myelinated A-deltas, and postganglionic sympathetics. The small fibers sense pain and itch, innervate internal organs and tissues, and modulate the inflammatory and immune responses. Symptoms of small-fiber neuropathy include chronic pain and itch, sensory impairment, edema, and skin color, temperature, and sweating changes. Small-fiber polyneuropathy (SFPN) also causes cardiovascular, gastrointestinal, and urological symptoms, the neurologic origin of which often remains unrecognized. Routine electrodiagnostic study does not detect SFPN, so skin biopsies immunolabeled to reveal axons are recommended for diagnostic confirmation. Preliminary evidence suggests that dysimmunity causes some cases of small-fiber neuropathy. Several autoimmune diseases, including Sjögren and celiac, are associated with painful small-fiber ganglionopathy and distal axonopathy, and some patients with "idiopathic" SFPN have evidence of organ-specific dysimmunity, including serological markers. Dysimmune SFPN first came into focus in children and teenagers as they lack other risk factors, for example diabetes or toxic exposures. In them, the rudimentary evidence suggests humoral rather than cellular mechanisms and complement consumption. Preliminary evidence supports efficacy of corticosteroids and immunoglobulins in carefully selected children and adult patients. This paper reviews the evidence of immune causality and the limited data regarding immunotherapy for small-fiber-predominant ganglionitis, regional neuropathy (complex regional pain syndrome), and distal SFPN. These demonstrate the need to develop case definitions and outcome metrics to improve diagnosis, enable prospective trials, and dissect the mechanisms of small-fiber neuropathy.

Neurogenic neuroinflammation in fibromyalgia and complex regional pain syndrome

Although fibromyalgia and complex regional pain syndrome (CRPS) have distinct clinical phenotypes, they do share many other features. Pain, allodynia and dysaesthesia occur in each condition and seem to exist on a similar spectrum. Fibromyalgia and CRPS can both be triggered by specific traumatic events, although fibromyalgia is most commonly associated with psychological trauma and CRPS is most often associated with physical trauma, which is frequently deemed routine or minor by the patient. Fibromyalgia and CRPS also seem to share many pathophysiological mechanisms, among which the most important are those involving central effects. Nonetheless, peripheral effects, such as neurogenic neuroinflammation, are also important contributors to the clinical features of each of these disorders. This Review highlights the differing degrees to which neurogenic neuroinflammation might contribute to the multifactorial pathogenesis of both fibromyalgia and CRPS, and discusses the evidence suggesting that this mechanism is an important link between the two disorders, and could offer novel therapeutic targets.

Complex regional pain syndrome type I: a comprehensive review

BACKGROUND

Complex regional pain syndrome type I (CRPS I), formerly known as reflex sympathetic dystrophy (RSD), is a chronic painful disorder that usually develops after a minor injury to a limb. This topical review gives a synopsis of CRPS I and discusses the current concepts of our understanding of CRPS I in adults, the diagnosis, and treatment options based on the limited evidence found in medical literature. CRPS I is a multifactorial disorder. Possible pathophysiological mechanisms of CRPS I are classic and neurogenic inflammation, and maladaptive neuroplasticity. At the level of the central nervous system, it has been suggested that an increased input from peripheral nociceptors alters the central processing mechanisms.

METHODS

A literature search was conducted using, as electronic bibliographic database, Medline from 1980 until 2014.

RESULTS

An early diagnosis and multidisciplinary treatment are necessary to prevent permanent disability.

CONCLUSIONS

The pharmacological treatment of CRPS I is empirical and insufficiently effective. Further research is needed regarding the therapeutic modalities discussed in the guidelines. Physical therapy is widely recommended as a first-line treatment. The efficacy of local anesthetic sympathetic blockade as treatment for CRPS I is questionable.

Brain alterations and neurocognitive dysfunction in patients with complex regional pain syndrome

Few studies have examined the involvement of specific subregions of the prefrontal cortex in complex regional pain syndrome (CRPS). We analyzed cortical thickness to identify morphologic differences in local brain structures between patients with CRPS and healthy control subjects (HCs). Furthermore, we evaluated the correlation between cortical thickness and neurocognitive function. Cortical thickness was measured in 25 patients with CRPS and 25 HCs using the FreeSurfer method. Pain severity and psychiatric symptoms were assessed using the Short Form McGill Pain Questionnaire and the Beck Depression and Anxiety Inventories, respectively. Neurocognitive function was assessed via the Wisconsin Card Sorting Test and the stop-signal task. The right dorsolateral prefrontal cortex and left ventromedial prefrontal cortex were significantly thinner in CRPS patients than in HCs. CRPS patients made more perseveration errors on the Wisconsin Card Sorting Test and had longer stop-signal task reaction times than HCs. Although the Beck Depression Inventory and the Beck Anxiety Inventory differ significantly between the groups, they were not correlated with cortical thickness. Our study suggests that the pathophysiology of CRPS may be related to reduced cortical thickness in the dorsolateral prefrontal cortex and the ventromedial prefrontal cortex. The structural alterations in dorsolateral prefrontal cortex may explain executive dysfunction and disinhibited pain perception in CRPS.

PERSPECTIVE

The present study reports decreased cortical thickness in the prefrontal cortex and neurocognitive dysfunctions in patients with CRPS. These findings may contribute to the understanding of pain-related impairments in cognitive function and could help explain the symptoms or progression of CRPS.

Vitamin supplementation as possible prophylactic treatment against migraine with aura and menstrual migraine

Migraine is the most common form of headache disorder globally. The etiology of migraine is multifactorial, with genetic components and environmental interactions considered to be the main causal factors. Some researchers postulate that deficits in mitochondrial energy reserves can cause migraine or an increase in homocysteine levels can lead to migraine attacks; therefore, vitamins could play a vital role in migraine prevention. For instance, riboflavin influences mitochondrial dysfunction and prevents migraine. Genes such as flavoenzyme 5,10-methylenetetrahydrofolate reductase (MTHFR), especially the C677T variant, have been associated with elevated plasma levels of homocysteine and migraine with aura. Homocysteine catalyzation requires the presence of vitamins B₆, B₁₂, and folic acid, which can decrease the severity of migraine with aura, making these vitamins potentially useful prophylactic agents for treating migraine with aura. Menstrual migraine, on the other hand, is associated with increased prostaglandin (PG) levels in the endometrium, indicating a role for vitamin E, which is an anti-PG. Vitamin C can also be used as a scavenger of reactive oxygen species for treating neurogenic inflammation in migraine patients. This paper reviews possible therapies based on vitamin supplementation for migraine prophylaxis, focusing on migraine with aura and menstrual migraine.