Complex regional pain syndrome: An optimistic perspective

Painful Raynaud's mimics

Raynaud's syndrome is a common finding in many autoimmune conditions. Accurately diagnosing Raynaud's, and differentiating it from mimicking conditions, is imperative in rheumatologic diseases. Raynaud's syndrome and Raynaud's mimickers, especially painful Raynaud's mimickers, can prove a diagnostic challenge for the practicing rheumatologist. Painful Raynaud's mimickers can lead to increased patient stress and unnecessary medical work up; Healthcare providers need to be aware of Raynaud's mimickers when evaluating patient concerns of skin color changes and pain. The present narrative review aims to highlight Raynaud's syndrome, important painful mimickers that may be seen, diagnosis, and updated management recommendations.

Early versus persistent Complex Regional Pain Syndrome: Is there a difference in patient reported outcomes following rehabilitation?

BACKGROUND

Expert consensus asserts that early treatment of Complex Regional Pain Syndrome (CRPS) leads to better outcomes. Yet no evidence supports this assumption regarding the recognized gold standard of multidisciplinary functional rehabilitation. To address this, we aimed to establish if there is a difference in outcomes between early CRPS (<1 year symptom duration) and persistent CRPS (= >1 year symptom duration) following rehabilitation and whether any gains are maintained at three months.

METHOD

Secondary analysis was conducted on previously collected clinical Patient Reported Outcome Measures (PROMS) data from 218 patients attending a residential multidisciplinary rehabilitation programme. Datasets were categorized into early CRPS (n = 40) or persistent CRPS (n = 178) dependent on symptom duration. Function, pain, self-efficacy, kinesiophobia and psychological health domains were compared using repeated measures analysis of covariance for a two group design for group difference post rehabilitation and at three month follow-up.

RESULTS

Post-rehabilitation, both groups improved in pain, function, kinesiophobia, psychological health and self-efficacy. At three months, the persistent CRPS group maintained improvements in pain and function. This was not achieved in early CRPS.

CONCLUSION

This exploratory study is the first to empirically test the assumption that those with early CRPS have better outcomes following rehabilitation. Our clinical data challenges this, as both early and persistent CRPS groups improved following rehabilitation. Findings indicate that rehabilitation benefits those with CRPS, regardless of symptom duration. However, unlike early CRPS, those with persistent CRPS sustain gains at follow-up. Further prospective exploration is warranted.

SIGNIFICANCE

Expert consensus recommends early treatment for Complex Regional Pain Syndrome, yet there is little empirical evidence to support this. Our findings are the first to challenge this assumption by revealing no difference in outcomes between early and persistent CRPS post-rehabilitation. However, those with persistent CRPS maintain gains after three months, unlike people with early CRPS (symptoms < one year). These findings are relevant to clinical practice as they challenge established assumptions, suggesting a focus on improving early CRPS follow-up outcomes.

Resting-state Electroencephalography Microstates Correlate with Pain Intensity in Patients with Complex Regional Pain Syndrome

Objective: Severe pain and other symptoms in complex regional pain syndrome (CRPS), such as allodynia and hyperalgesia, are associated with abnormal resting-state brain network activity. No studies to date have examined resting-state brain networks in CRPS patients using electroencephalography (EEG), which can clarify the temporal dynamics of brain networks. Methods: We conducted microstate analysis using resting-state EEG signals to prospectively reveal direct correlations with pain intensity in CRPS patients (n = 17). Five microstate topographies were fitted back to individual CRPS patients' EEG data, and temporal microstate measures were subsequently calculated. Results: Our results revealed five distinct microstates, termed microstates A to E, from resting EEG data in patients with CRPS. Microstates C, D and E were significantly correlated with pain intensity before pain treatment. Particularly, microstates D and E were significantly improved together with pain alleviation after pain treatment. As microstates D and E in the present study have previously been related to attentional networks and the default mode network, improvement in these networks might be related to pain relief in CRPS patients. Conclusions: The functional alterations of these brain networks affected the pain intensity of CRPS patients. Therefore, EEG microstate analyses may be used to identify surrogate markers for pain intensity.

Against cortical reorganisation

Neurological insults, such as congenital blindness, deafness, amputation, and stroke, often result in surprising and impressive behavioural changes. Cortical reorganisation, which refers to preserved brain tissue taking on a new functional role, is often invoked to account for these behavioural changes. Here, we revisit many of the classical animal and patient cortical remapping studies that spawned this notion of reorganisation. We highlight empirical, methodological, and conceptual problems that call this notion into doubt. We argue that appeal to the idea of reorganisation is attributable in part to the way that cortical maps are empirically derived. Specifically, cortical maps are often defined based on oversimplified assumptions of 'winner-takes-all', which in turn leads to an erroneous interpretation of what it means when these maps appear to change. Conceptually, remapping is interpreted as a circuit receiving novel input and processing it in a way unrelated to its original function. This implies that neurons are either pluripotent enough to change what they are tuned to or that a circuit can change what it computes. Instead of reorganisation, we argue that remapping is more likely to occur due to potentiation of pre-existing architecture that already has the requisite representational and computational capacity pre-injury. This architecture can be facilitated via Hebbian and homeostatic plasticity mechanisms. Crucially, our revised framework proposes that opportunities for functional change are constrained throughout the lifespan by the underlying structural 'blueprint'. At no period, including early in development, does the cortex offer structural opportunities for functional pluripotency. We conclude that reorganisation as a distinct form of cortical plasticity, ubiquitously evoked with words such as 'take-over'' and 'rewiring', does not exist.

A retrospective review of the management and outcomes of patients diagnosed with complex regional pain syndrome type II using electrodiagnostic findings

Objectives

The objective of this study was to assess the outcomes of the use of electrodiagnosis in the diagnosis and management of discrete nerve injuries in patients with complex regional pain syndrome (CRPS).

Design

This study is a secondary retrospective cohort analysis of patients diagnosed with CRPS from a single outpatient physical medicine and rehabilitation clinic and included all patients who had abnormal electrodiagnostic findings, in addition to CRPS.

Results

Sixty patients of 248 diagnosed with CRPS underwent electrodiagnosis, 41 of whom had abnormal electrodiagnostic findings indicating a discrete nerve injury. Only 51% of the 41 referrals had indicated the suspicion of a nerve injury. Nearly all patients had undergone physiotherapy. Forty-one percent responded to treatment with oral prednisone alone, 54% had a functional improvement after a combination of treatments including corticosteroids, and 5% improved with treatments that did not involve corticosteroids. Surgical interventions for nerve injuries were required for 34% of patients in the cohort. All surgeries involved the median or ulnar nerve, with the exception of one fibular nerve. After treatment, 39 of 41 patients had functional recoveries or better.

Conclusions

Electrodiagnosis can inform diagnosis of nerve injury and direct intervention including the need for surgical intervention. Electrodiagnosis should be considered for patients with initial signs of concomitant discrete nerve injury or with CRPS who are not responding to treatments because a nerve injury may be underlying.

What is Known Complex Regional Pain Syndrome (CRPS) is a poorly understood pain condition. CRPS has been divided into two subtypes, the second subtype involves a discrete nerve injury with pain that extends beyond the territory of the nerve injury.

What is New We observed that nerve injuries that may require surgical intervention are diagnosed just over half of the time upon initial assessment in patients with suspected CRPS. We observed that nerve injuries frequently required specifically directed interventions in place of or in conjunction with CRPS treatments. We suggest that electrodiagnosis is an important part of the triage protocol for CRPS II to reveal discrete nerve injuries that may be hidden. We recommend that electrodiagnosis be considered for patients with initial signs of concomitant discrete nerve injury or for CRPS patients who do not improve with medical therapies.

Prescription Trends in Complex Regional Pain Syndrome: A Retrospective Case-Control Study

OBJECTIVE

The objective of this study was to evaluate discrepancies in prescription trends for analgesic medications in complex regional pain syndrome (CRPS) patients based on recommendations in the literature.

DESIGN

We conducted a retrospective case-control study.

SUBJECTS

A total of 2510 CRPS patients and 2510 demographic-matched controls participated in this study.

METHODS

The SlicerDicer feature in Epic was used to find patients diagnosed with CRPS I or II between January 2010 and November 2022. An equal number of age-, gender-, and race-matched controls without a CRPS diagnosis were retracted from Epic. General and CRPS-associated prescription frequencies for the following classes were retrieved for both cases and controls: benzodiazepines, bisphosphonates, calcitonin, capsaicin, neuropathic pain medications, NSAIDs, opioids, and steroids.

RESULTS

A total of 740 (29%) CRPS patients and 425 (17%) controls were prescribed benzodiazepines (95% CI 0.1-0.15), 154 (6.1%) CRPS patients and 52 (2.1%) controls were prescribed capsaicin (95% CI 0.03-0.05), 1837 (73%) CRPS patients and 927 (37%) controls were prescribed neuropathic pain medications (95% CI 0.05-0.34), 1769 (70%) CRPS patients and 1217 (48%) controls were prescribed opioids (95% CI 0.19-0.25), 1095 (44%) CRPS patients and 1217 (48%) controls were prescribed steroids (95% CI 0.08-0.14), and 1638 (65%) CRPS patients and 1765 (70%) controls were prescribed NSAIDs (95% CI -0.08-0.02), p < 0.001 for all classes. With CRPS-associated prescriptions, (95% CI 0.05-0.16, p < 0.001) more CRPS patients were prescribed opioids (N = 398, 59%) than controls (N = 327, 49%).

CONCLUSIONS

CRPS is difficult to treat with significant variance in suggested treatment modalities. Based on the results of our study, there is a divergence between some published recommendations and actual practice.

Complex regional pain syndrome: diagnosis and management

Complex regional pain syndrome is a rare and not well understood chronic pain condition that can affect anyone, irrespective of age and sex. It is important that nurses and the wider healthcare team are aware of the symptoms and recommended management of this condition, with timely diagnosis and appropriate rehabilitation being particularly important. This article provides an overview of complex regional pain syndrome and explains what is involved in the diagnosis and treatment of this condition. Understanding the complexity of the condition and the relevant management guidelines will enable nurses to provide effective care and support for patients.

Hand Allodynia, Lack of Finger Flexion, and the Need for Carpal Tunnel Release

PURPOSE

The clinical features of classic carpal tunnel syndrome are well known. However, some patients who may respond equally well to carpal tunnel release (CTR) display atypical signs and symptoms. The chief differential features are allodynia (painful dysesthesias), lack of finger flexion, and, on examination, pain on passive finger flexion. The goal of the study was to present the clinical features, increase awareness, facilitate accurate diagnosis, and report the outcomes after surgery.

METHODS

Thirty-five hands, from 22 patients with the main features of allodynia and lack of full finger flexion, were gathered in the period 2014-2021. The other common complaints included sleeping disturbances (20 patients), hand swelling (31 hands), and shoulder pain on the same side as the hand problem with limited range of motion (30 sides). The Tinel or Phalen signs were obscured by the pain. However, pain with passive flexion of the fingers was universally present. All the patients were treated with carpal tunnel release through a mini-incision approach: four patients had a trigger finger, which was treated concomitantly in six hands, and one patient underwent contralateral CTR for carpal tunnel syndrome with a more standard presentation.

RESULTS

At a minimum of 6 months of follow-up (mean, 22 months; range, 6-60 months), the pain decreased by 7.5 ± 1.9 points on the Numerical Rating Scale, which ranges from 0 to 10. The pulp-to-palm distance improved from 3.7 to 0.3 cm. The mean Disabilities of the Arm, Shoulder, and Hand score decreased from 67 to 20. The mean Single-Assessment Numeric Evaluation score for the whole group was 9.7 ± 0.6.

CONCLUSIONS

Hand allodynia and lack of finger flexion may be indications of median neuropathy in the carpal canal, which responds to CTR. Awareness of this condition is important because the uncharacteristic clinical presentation may not be considered an indication for surgery that can be beneficial.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Usefulness of the perfusion index for monitoring the response to intravenous ketamine infusion therapy in patients with complex regional pain syndrome

BACKGROUND

This study was performed to compare the perfusion index (PI) between affected and unaffected limbs in patients with complex regional pain syndrome (CRPS); it also evaluated the usefulness of the PI for monitoring the response to intravenous ketamine infusion therapy in such patients.

METHODS

In total, 46 patients with CRPS in one arm or leg were enrolled in this study. The PIs of the unaffected (PI_Control ) and affected (PI_CRPS ) limbs were simultaneously evaluated before and after treatment.

RESULTS

PI_CRPS was significantly lower than PI_Control at all time points. The change in PI from immediately before to 30 min after intravenous ketamine infusion therapy (T_Before and T_{30 min} , respectively) in the affected limb was significantly correlated with the change in visual analog pain scale (VAS) between the two time points (r = 0.646, p < 0.001). The area under the curve for the changes in VAS and PI_CRPS between T_Before and T_{30 min} was 0.928. The optimal threshold value for the change in PI_CRPS between T_Before and T_{30 min} , to distinguish responders with a ≥ 50-point reduction in VAS score from nonresponders, was 22.60% with a sensitivity of 0.811 (95% CI: 0.774-0.848) and a specificity of 0.889 (95% CI: 0.848-0.930). Thirty-one patients showed a ≥ 50-point reduction in VAS score [67% (95% CI: 54%-80%)] and 15 patients showed a < 50-point reduction in VAS score [33% (95% CI: 20%-46%)]. Thirty patients showed an increased PI ≥ 22.60% [65% (95% CI: 50%-78%)] and 16 patients showed an increased PI < 22.60% [35% (95% CI: 22%-50%)]. Twenty-seven patients had a ≥ 50-point reduction in VAS score and an increased PI ≥ 22.60% [59% (95% CI: 44%-74%)]. Eleven patients had shown a < 50-point pain reduction in VAS score and increased PI < 22.60% [24% (95% CI: 13%-37%)].

CONCLUSION

The PI significantly differed between affected and unaffected limbs in patients with CRPS. The PI may be useful for monitoring the response to intravenous ketamine therapy in patients with CRPS.

Effect and mechanisms of exercise for complex regional pain syndrome

Complex regional pain syndrome characterized by severe pain and dysfunction seriously affects patients' quality of life. Exercise therapy is gaining attention because it can effectively relieve pain and improve physical function. Based on the previous studies, this article summarized the effectiveness and underlying mechanisms of exercise interventions for complex regional pain syndrome, and described the gradual multistage exercise program. Exercises suitable for patients with complex regional pain syndrome mainly include graded motor imagery, mirror therapy, progressive stress loading training, and progressive aerobic training. In general, exercise training for patients with complex regional pain syndrome not only alleviates pain but also improves physical function and positive mental status. The underlying mechanisms of exercise interventions for complex regional pain syndrome include the remodeling of abnormal central and peripheral nervous system, the regulation of vasodilation and adrenaline levels, the release of endogenous opioids, and the increased anti-inflammatory cytokines. This article provided a clear explanation and summary of the research on exercise for complex regional pain syndrome. In the future, more high-quality studies with sufficient sample sizes may provide more exercise regimens and better evidence of efficacy.

Harmful or safe? Exposure and pain provocation during physiotherapy of complex regional pain syndrome I: a narrative review

BACKGROUND

Complex regional pain syndrome (CRPS) is a clinical diagnosis and an umbrella term for a heterogeneous group of states associated with pain disproportionate to any inciting event, together with a number of signs and symptoms that are manifested mainly in the limbs. There are often concerns among clinicians and patients about the potential harms caused by pain provocation during physiotherapy of CRPS, even though clinical guidelines de-emphasize pain-contingency.

OBJECTIVE

The objective of this narrative review is to summarize current evidence regarding potential harms due to pain provocation during so-called exposure-based therapies in individuals with CRPS.

METHODS

Six studies evaluating exposure-based approach were included (n= 6).

RESULTS

Although only one included study focused primarily on safety and in the rest of the included studies the reporting of harms was insufficient and therefore our certainty in evidence is very low, taken together with outcome measures, available data does not point to any long-term deterioration in symptoms or function, or any major harms associated with pain provocation during physiotherapy of CRPS.

CONCLUSION

There is a great need for higher-quality studies to determine which therapeutic approach is the most appropriate for whom and to evaluate the risks and benefits of different approaches in more detail.

Post-fracture serum cytokine levels are not associated with a later diagnosis of complex regional pain syndrome: a case-control study nested in a prospective cohort study

Background

Complex Regional Pain Syndrome (CRPS) is a disabling pain disorder that is most common after a distal limb fracture. While the acute systemic immune response to the injury is thought to play a role in the development of CRPS, this hypothesis has never been tested directly. Thus, we evaluated whether elevated levels of circulating pro-inflammatory cytokines early after a fracture were associated with the development of CRPS.

Methods

We conducted a case-control study nested within a prospective cohort study. Individuals with wrist and/or hand fractures were recruited from specialist hand units. Baseline clinical data were obtained from participants within 28 days of fracture. CRPS status was determined 16 weeks after the fracture using a two-stage diagnostic process. Cytokine assays were obtained from all cases (defined using the Budapest criteria) and a random sample of those who did not have CRPS at 16 weeks. We calculated odds ratios with 95% confidence intervals to determine the risk of CRPS associated with the expression of each of 25 cytokines.

Results

Baseline data were collected for 702 consenting participants, of whom 535 provided blood samples. Follow-up at 16 weeks was 97.2%. 15 (2.2% of the cohort) met the Budapest CRPS criteria and 69 (including those who met the Budapest criteria; 9.8%) met the International Association for the Study of Pain (IASP) CRPS criteria. In all of the primary analyses (using Budapest criteria) and 49/50 secondary analyses (using IASP criteria), 95% confidence intervals for the association between cytokine levels and the risk of subsequently developing CRPS included the null value (OR = 1). However, the confidence intervals were wide.

Conclusion

There was no evidence that early post-injury expression of systemic cytokines was associated with a CRPS diagnosis 16 weeks after injury. This study does not provide support for the hypothesis that innate immune activation has a determinative role in the development of CRPS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02910-z.

Clinical practice guidelines for the management of patients with chronic regional pain syndrome: a systematic appraisal using the AGREE II instrument

Aim: Chronic regional pain syndrome (CRPS) is a debilitating, painful condition of limbs that often arises after an injury and is associated with significant morbidity. Materials & methods: The Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument, used to assess the quality of clinical practice guidelines (CPGs), was used to evaluate seven CRPS management guideline. Results: Out of the seven CPGs evaluated using the AGREE II instrument, only one from Royal College of Physicians was found to have high-quality consensus guidelines for diagnosis and management of CRPS. Conclusion: Future CPGs should be backed by systematic literature searches, focus on guidelines clinical translation into clinical practice and applicability to the desired patient population.

Outcomes of Carpal Tunnel Release in Complex Regional Pain Syndrome/Reflex Sympathetic Dystrophy/Sudeck Disease Patients

BACKGROUND

The clinical features of classic carpal tunnel syndrome are well known. However, some patients who display atypical symptoms and signs of pain and dysesthesias in the hand, worsening of symptoms at night, and above all, inability to make a full fist, respond equally well to carpal tunnel release. This same clinical picture was shared by some patients labeled as having complex regional pain syndrome. Because of the poor outcome of complex regional pain syndrome patients with current regimens, the authors tested the hypothesis that carpal tunnel release could be effective on them. The purpose of this article is to report the outcome of carpal tunnel release in complex regional pain syndrome patients who presented the above signs and symptoms.

METHODS

Fifty-three patients with an average age of 55 years presenting the above cluster of symptoms were operated on. All were unilateral cases, had sustained trauma, and were treated for complex regional pain syndrome before referral for an average of 16 months. All patients underwent carpal tunnel release.

RESULTS

At a minimum of 6 months' follow-up, pain dropped 7.5 points on a numerical rating scale of 0 to 10 ( p < 0.001). Disabilities of the Arm, Shoulder and Hand scoring fell from 82 to 17 ( p < 0.001). Six patients had an unsatisfactory result.

CONCLUSIONS

Some patients with complex regional pain syndrome may respond successfully to a carpal tunnel release operation. Recognition of this possibility is crucial, as the symptoms and signs might lead the clinician away from the proper diagnosis and treatment.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Successful treatment of acute worsening complex regional pain syndrome in affected dominant right-hand from secondary pathology of new onset third and fourth digit trigger finger

65 year old male with preexisting Complex Regional Pain Syndrome (CRPS) in right dominant hand with sudden onset of right third and fourth digit trigger finger successfully treated with flexor tendon sheath corticosteroid and lidocaine injection resulting in long-term resolution of symptoms without causing widely believed aggravation of CRPS.

Deep Learning-Based Medical Information System in First Aid of Surgical Trauma

The aim of this study was to explore the application of process reengineering integration in trauma first aid based on deep learning and medical information system. According to the principles and methods of process reengineering, based on the analysis of the problems and causes of the original trauma first aid process, a new set of trauma first aid integration process is established. The Deep Belief Network (DBN) in deep learning is used to optimize the travel path of emergency vehicles, and the accuracy of travel path prediction of emergency vehicles under different environmental conditions is analyzed. DBN is applied to the surgical clinic of the hospital to verify the applicability of this method. The results showed that in the analysis of sample abscission, the abscission rates of the two groups were 2.23% and 0.78%, respectively. In the analysis of the trauma severity (TI) score between the two groups, more than 60% of the patients were slightly injured, and there was no significant difference (P > 0.05). In the comparative analysis of treatment effect and family satisfaction between the two groups, the proportion of rehabilitation patients in the experimental group (55.91%) was significantly better than that in the control group, and the satisfaction of the experimental group (7.93 ± 0.59) was significantly higher than that of the control group (5.87 ± 0.43) (P < 0.05). Therefore, integrating Wireless Sensor Network (WSN) measurement and process reengineering under the medical information system provides feasible suggestions and scientific methods for the standardized trauma first aid.

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.

[Complex regional pain syndrome-An interdisciplinary view from the surgical consultation]

Chronic pain disorders are common and have a substantial impact on the patients' daily life. The specific syndrome of complex regional pain syndrome (CRPS, Sudeck's disease) is comparatively rare and characterized by additional sensorimotor, vascular and trophic dysfunctions. The diagnosis is made based on the Budapest criteria and according to clinical symptoms. According to the German national guidelines, multimodal therapy includes drug, rehabilitative and psychosomatic approaches for the reduction of pain and restoration of functionality. Bisphosphonates, steroids and antiepileptic drugs are well-established as medicinal treatment but should always be used in combination with functional therapy. Interventional treatment options are reserved for patients with complicated and enduring symptoms and should be carried out in specialized centers. The course of the disease is highly individual and frequently requires a long-term interdisciplinary treatment.

The Utility of Dynamic Movement Orthoses in the Management of Complex Regional Pain Syndrome-A Case Series

Complex regional pain syndrome (CRPS) is a relatively rare, but debilitating condition that may occur after limb or peripheral nerve trauma. Typical symptoms of CRPS include swelling, allodynia, hyperalgesia, and skin temperature changes. Although a variety of pharmacological and non-pharmacological approaches are commonly used in caring for individuals with CRPS, they are frequently ineffective and often associated with side effects and/or additional risks. Previously, elastomeric orthotic garments have been shown to decrease neuropathic pain, reduce edema, and increase proprioception, but no previous reports have described their use in treating CRPS. Accordingly, this case series describes our experiences using a Lycra-based, custom-fabricated Dynamic Movement Orthosis (DMO) as a novel treatment to reduce the symptoms of CRPS and promote function. Four patients were included in this case series, all of whom had very different causes for their CRPS, including a combat-related gunshot injury resulting in multiple foot fractures with a partial nerve injury, a post-metatarsophalangeal fusion, an L5 radiculopathy, and a case of post-lower leg fasciotomies. These four patients all reported subjective improvement in their pain, function, and exercise tolerance in association with their DMO use. All patients demonstrated reduced use of analgesic medications. The pre- and post-DMO lower extremity functional scale showed clinically significant improvement in the two patients for which it was obtained.

Complex Regional Pain Syndrome Type I Following Non-Orthopedic Surgery: Case Report and Narrative Review

Complex regional pain syndrome type I (CRPS I)-or algodystrophy-is a rare disease that usually occurs after a traumatic event. It is characterized by typical clinical findings such as severe and disabling pain disproportionate to the injury, functional limitations, as well as sensory and vasomotor alterations. However, some people do not report any injury associated with algodystrophy onset in personal history. We describe the management of an unusual case of CRPS I which occurred during the long-term follow-up of percutaneous transluminal coronary angioplasty (PTCA) and performed a narrative review of algodystrophy in non-orthopedic surgery. A clinical case of a 44-year-old man with a spontaneous onset of CRPS I of the right ankle is presented. He did not refer to history of any memorable significant trigger event. Approximately 5 months before the onset of clinical manifestations, he received a PTCA via the right femoral approach. We suppose an association between CRPS and this procedure and propose a possible pathophysiologic mechanism. The patient was treated with intramuscular neridronate, which resulted in significant pain relief and improved his quality of life. A comprehensive clinical and instrumental evaluation in patients with CRPS is challenging but mandatory for a correct diagnosis. An extensive analysis of patient history is important for identifying any potential trigger event, including non-orthopedic procedures. Bone scan could have a pivotal role for improving diagnostic sensitivity and specificity in CRPS I. Neridronate was a safe and effective therapeutic approach for this patient, confirming the results of the high-quality evidence available.

Multicenter survey of symptoms, work life, economic status, and quality of life of complex regional pain syndrome patients

Background

Complex regional pain syndrome (CRPS) is an intractable pain disease with various symptoms. Here, we investigated the disease status, work life, sleep problems, medical insurance, economic status, psychological problems, and quality of life (QOL) of CRPS patients.

Methods

CRPS patients from 37 university hospitals in South Korea were surveyed. The survey questionnaire consisted of 24 questions on the following aspects of CRPS patients sex, age, occupation, cause of injury, activities of daily living (ADL), pain severity, sleep disturbance, level of education, economic status, therapeutic effect, and suicidal ideation. Additionally, the abbreviated World Health Organization Quality of Life (WHOQOL-BREF) questionnaire, consisting of 26 questions, was used to identify the status of QOL.

Results

A total of 251 patients completed the questionnaire. According to the survey, 54.2% patients could not perform ADL on their own. Over the previous week, the mean pain score was 7.15 ± 1.78 (out of a total of 10 points); 92.1% of patients had sleep disorders and 80.5% had suicidal ideation, with most patients suffering from psychological problems. The average for each domain of WHOQOL-BREF was as follows 21.74 ± 14.77 for physical, 25.22 ± 17.66 for psychological, 32.02 ± 22.36 for social relationship, and 30.69 ± 15.83 for environmental (out of a total of 100 points each). Occupation, ADL, sleep time, therapeutic effect, and suicidal ideation were statistically correlated with multiple domains.

Conclusions

Most patients had moderate to severe pain, economic problems, limitations of their ADL, sleep problems, psychological problems, and a low QOL score.

Effects of photobiomodulation on different application points and different phases of complex regional pain syndrome type I in the experimental model

Background

Complex regional pain syndrome type I (CRPS-I) consists of disorders caused by spontaneous pain or induced by some stimulus. The objective was to verify the effects of photobiomodulation (PBM) using 830 nm wavelength light at the affected paw and involved spinal cord segments during the warm or acute phase.

Methods

Fifty-six mice were randomized into seven groups. Group (G) 1 was the placebo group; G2 and G3 were treated with PBM on the paw in the warm and acute phase, respectively; G4 and G5 treated with PBM on involved spinal cord segments in the warm and acute phase, respectively; G6 and G7 treated with PBM on paw and involved spinal cord segments in the warm and acute phase, respectively. Edema degree, thermal and mechanical hyperalgesia, skin temperature, and functional quality of gait (Sciatic Static Index [SSI] and Sciatic Functional Index [SFI]) were evaluated.

Results

Edema was lower in G3 and G7, and these were the only groups to return to baseline values at the end of treatment. For thermal hyperalgesia only G3 and G5 returned to baseline values. Regarding mechanical hyperalgesia, the groups did not show significant differences. Thermography showed increased temperature in all groups on the seventh day. In SSI and SFI assessment, G3 and G7 showed lower values when compared to G1, respectively.

Conclusions

PBM irradiation in the acute phase and in the affected paw showed better results in reducing edema, thermal and mechanical hyperalgesia, and in improving gait quality, demonstrating efficacy in treatment of CRPS-I symptoms.

[Effectiveness of inpatient interdisciplinary multimodal pain therapy (IMPT) in patients with complex regional pain syndrome (CRPS) : A retrospective study]

BACKGROUND

The primary symptom of complex regional pain syndrome (CRPS) is pain. Interdisciplinary multimodal pain therapy (IMPT) is the gold standard of treatment. The purpose of this study was to identify the beneficial effect of inpatient IMPT on pain level, sensation, perception and impairment in patients with CRPS.

QUESTION

The aim of the present study was to examine the effect of full-term IMPT on pain intensity, pain perception, pain processing, and pain impairment in patients with CRPS.

METHODS

In 265 patients with CRPS, pain level was retrospectively assessed by the numeric rating scale for pain (NRS), the Pain Perception Scale (SES) and the Pain Management Questionnaire (FESV) at the beginning and end of IMPT.

RESULTS

There was a significant reduction in the average and highest pain level on the NRS, a significant improvement in the affective experience of pain and cognitive pain management, as well as pain-related mental impairment. All patients improved significantly in resting and relaxation techniques. With regard to pain-related helplessness and depression, patients with mental comorbidity benefitted most. Patients undergoing invasive procedures in the form of peripheral nerve blockage showed no significantly improved outcome with regard to the tested parameters.

DISCUSSION

The current study demonstrated that IMPT has a highly beneficial effect on the level, experience and processing of pain in patients with CRPS.

Hsa-miR-605 regulates the proinflammatory chemokine CXCL5 in complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by inflammation and debilitating pain. CRPS patients with pain refractory to more conventional analgesics can be treated with subanesthetic doses of ketamine. Our previous studies found that poor responders to ketamine had a 22-fold downregulation of the miRNA hsa-miR-605 in blood prior to ketamine treatment. Hence, we sought to investigate the functional significance of miR-605 downregulation and its impact on target gene expression, as investigating target mRNAs of differentially expressed miRNAs can provide important insights on aberrant gene expression that may contribute to disease etiology. Using a bioinformatics prediction, we identified that miR-605 can target the proinflammatory chemokine CXCL5, which plays a role in leukocyte recruitment and activation. We hypothesized that downregulation of miR-605 in poor responders to ketamine could increase CXCL5 expression and thereby contribute to inflammation in these patients. We confirmed that miR-605 regulates CXCL5 by using a miRNA mimic and inhibitor in human primary endothelial cells. Inhibition of miR-605 increased CXCL5 secretion and migration of human monocytic cells, thereby demonstrating a functional impact of miR-605 on chemotaxis. Additionally, CXCL5 mRNA was upregulated in whole blood from poor responders to ketamine, and CXCL5 protein was increased in plasma from CRPS patients. Thus, our studies suggest that miR-605 regulation of CXCL5 can regulate inflammation.

Intact tactile anisotropy despite altered hand perception in complex regional pain syndrome: rethinking the role of the primary sensory cortex in tactile and perceptual dysfunction

Complex Regional Pain Syndrome (CRPS) is characterised by pain, autonomic, sensory and motor abnormalities. It is associated with changes in the primary somatosensory cortex (S1 representation), reductions in tactile sensitivity (tested by two-point discrimination), and alterations in perceived hand size or shape (hand perception). The frequent co-occurrence of these three phenomena has led to the assumption that S1 changes underlie tactile sensitivity and perceptual disturbances. However, studies underpinning such a presumed relationship use tactile sensitivity paradigms that involve the processing of both non-spatial and spatial cues. Here, we used a task that evaluates anisotropy (i.e., orientation-dependency; a feature of peripheral and S1 representation) to interrogate spatial processing of tactile input in CRPS and its relation to hand perception. People with upper limb CRPS (n = 14) and controls with (n = 15) or without pain (n = 19) judged tactile distances between stimuli-pairs applied across and along the back of either hand to provide measures of tactile anisotropy. Hand perception was evaluated using a visual scaling task and questionnaires. Data were analysed with generalised estimating equations. Contrary to our hypotheses, tactile anisotropy was bilaterally preserved in CRPS, and the magnitude of anisotropic perception bias was comparable between groups. Hand perception was distorted in CRPS but not related to the magnitude of anisotropy or bias. Our results suggest against impairments in spatial processing of tactile input, and by implication S1 representation, as the cause of distorted hand perception in CRPS. Further work is warranted to elucidate the mechanisms of somatosensory dysfunction and distorted hand perception 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.

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

Background

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

Study design

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

Methods

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

Results

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

Conclusions

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

Pain Phenotypes in Rare Musculoskeletal and Neuromuscular Diseases

For patients diagnosed with a rare musculoskeletal or neuromuscular disease, pain may transition from acute to chronic; the latter yielding additional challenges for both patients and care providers. We assessed the present understanding of pain across a set of ten rare, noninfectious, noncancerous disorders; Osteogenesis Imperfecta, Ehlers-Danlos Syndrome, Achondroplasia, Fibrodysplasia Ossificans Progressiva, Fibrous Dysplasia/McCune-Albright Syndrome, Complex Regional Pain Syndrome, Duchenne Muscular Dystrophy, Infantile- and Late-Onset Pompe disease, Charcot-Marie-Tooth Disease, and Amyotrophic Lateral Sclerosis. Through the integration of natural history, cross-sectional, retrospective, clinical trials, & case studies we described pathologic and genetic factors, pain sources, phenotypes, and lastly, existing therapeutic approaches. We highlight that while rare diseases possess distinct core pathologic features, there are a number of shared pain phenotypes and mechanisms that may be prospectively examined and therapeutically targeted in a parallel manner. Finally, we describe clinical and research approaches that may facilitate more accurate diagnosis, monitoring, and treatment of pain as well as elucidation of the evolving nature of pain phenotypes in rare musculoskeletal or neuromuscular illnesses.

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.

Applying the Power of the Mind in Acupuncture Treatment of Pain

Background: Healing is a complicated process that can have several components including the self-healing properties of the body, the nonspecific effects of treatment (e.g., the power of the mind), and the specific effects of an intervention. This article first discusses the brain imaging studies on placebo acupuncture analgesia and the modulation effects of expectancy on real acupuncture in healthy subjects. Then, it introduces some attempts to translate findings from healthy subjects to patient population using power of the mind as a way to enhance acupuncture's treatment effects on chronic pain. After that, a new alternative method which merges acupuncture and imagery, while also drawing on power of the mind, is presented. Finally, the specific effects of acupuncture are discussed. Conclusions: Elucidating the mechanism underlying power of the mind would provide new opportunities for boosting the therapeutic effect of acupuncture treatment and furthering the development of new alternative interventions.

Complex Regional Pain Syndrome Following Snakebite: A Putatively Rare Complication of Envenomation and Review of the Literature

Background

Complex regional pain syndrome (CRPS) following snakebite is considered rare. Only four cases have been reported in the world literature. The present case is the first in the United States. We felt the need to report this case to bring attention to health-care providers that CRPS is probably an under-recognized complication of snakebite.

Case Presentation

A 44-year-old right-handed man developed signs and symptoms of complex regional pain syndrome (CRPS) in the left upper extremity following a bite by a cat-eyed snake (genus Leptodeira), a slightly venomous snake that belongs to the Colubridae (colubrids) family. The man did not develop muscle weakness or hematologic complications at that time. However, in subsequent years, he developed sporadic jerking of the upper extremities without alteration in consciousness or electroencephalographic abnormalities. These movements tended to occur during emotional tension and exacerbation of pain, and decreased in frequency when the subject was distracted. This is the fifth case of snakebite-induced CRPS described in the world literature (Nepal, Turkey, Korea, and Norway), the first reported in the United States, and the first induced by a slightly venomous snake.

Conclusion

With closer attention to the presence of indicators of sympathetic nerve dysfunction in association with allodynia, it is probable that cases of persistent pain following snakebite might have been instances of CRPS.

Prognostic Factors in Complex Regional Pain Syndrome Type 1 Occurring in the Korean Army

OBJECTIVES

In Korea, patients diagnosed with complex regional pain syndrome (CRPS) in the army are typically discharged from the army; however, the course of the disease after discharge is not known. The purpose of this study was to investigate the course of CRPS that occurred in the army and to identify the influences of various clinical and psychosocial factors immediately before discharge on the disease course.

METHODS

Clinical profiles and psychosocial status were collected from the medical records of 16 patients with CRPS type 1 who were discharged during the period between March 2017 and April 2018. The degree of improvement after discharge was assessed by follow-up evaluation through telephone contact. Cox proportional hazards regression was performed to identify clinical and psychosocial predictors for the rate of recovery.

RESULTS

The median time to recovery after discharge was 39 weeks (95% confidence interval [CI] = 8.8-69.2 weeks). The sole predictor for time to recovery after discharge was the time period from the onset of pain to discharge. Each one-week increase in the duration of pain experienced in the military was associated with a 18.2% (95% CI = 5.3%-29.5%) reduction in the rate of recovery after discharge (P = 0.007).

CONCLUSIONS

Patients who experienced a short period of pain in the military demonstrated a relatively good prognosis after discharge. This may show how prolonged pain in the army could affect the experience of pain from a social point of view, in that it shows the disease course after a change in the social environment.

A role for the microbiota in complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is a debilitating neuroinflammatory condition of unknown etiology. Symptoms include excruciating pain and trophic changes in the limbs as defined by the Budapest criteria. The severity and functional recovery of CRPS, unlike most pain conditions, is quantifiable using a variation of the Budapest criteria known as the CRPS severity score. Like many chronic pain conditions, CRPS is difficult to treat once pain has been present for more than 12 months. However, previous work has demonstrated that a subset of patients with new-onset CRPS (~50%) improve if treated within one year, while the rest have minimal to no symptom improvement. Unfortunately, this leads to permanent disability and often requires invasive and costly treatments such as spinal cord stimulation or long-term opioid therapy. Because the etiology is unknown, treatment is multimodal, and often supportive. Biomarkers that predict severity or resolution of symptoms would significantly change treatment but have not yet been identified. Interestingly, there are case reports of remission or resolution of CRPS symptoms with the use of antibiotics known to affect the gut flora. Mouse studies have demonstrated that modulation of the gut microbiome is anti-nociceptive in visceral, inflammatory and neuropathic pain models. We hypothesize that the variable clinical potential for recovery and response to therapy in CRPS may be secondary to or reflected in changes in the gut microbiota. We suggest that the microbiota may mediate or reflect clinical status via the metabolome, activation of the immune system and/or microglial activation. We hypothesize that the gut microbiome is a potential mediator in development and persistence of CRPS symptoms and propose that the clinical condition of CRPS could provide a unique opportunity to identify biomarkers of the microbiota and potential therapies to prevent pain chronification.

The Role of Nonmedical Therapeutic Approaches in the Rehabilitation of Complex Regional Pain Syndrome

Purpose of the Review

Nonmedical therapeutic approaches are fundamental to the management of of Complex Regional Pain Syndrome (CRPS) in order to promote the best outcome for patients. This review focuses on three key approaches underpinning CRPS rehabilitation, namely, physiotherapy and occupational therapy, psychological approaches and education and self-management.

Recent Findings

Recently published European standards outline the quality of therapeutic care that people with CRPS must receive. Early initiated therapy is essential to optimise outcomes, underpinned by patient education. Therapists should promote early movement of the affected limb and encourage re-engagement with usual activities as immobilisation is known to have negative outcomes. There is evidence to support the possible long-term benefit of graded motor imagery and mirror therapy. Psychological assessment should include identification of depression and post-traumatic stress disorder, as treatment of these conditions may improve the trajectory of CRPS. Novel therapies include neurocognitive approaches and those addressing spatial bias, both of which should provide a focus for future research.

Summary

There exists a broad range of nonmedical therapeutic approaches to rehabilitation for CPRS that are thought to be important. However, the evidence for their efficacy is limited. Further research using standardised outcomes would be helpful in developing targeted therapies for the future.

Neuromodulation of the Dorsal Root Ganglion for Chronic Postsurgical Pain

Objective

The objective of this study is to review the available evidence for dorsal root ganglion (DRG) stimulation for the treatment of complex regional pain syndrome type II (CRPS II; peripheral causalgia) associated with chronic neuropathic postsurgical pain (NPP).

Design

Available literature was identified through a search of the US National Library of Medicine’s Medline database, PubMed.gov. References from published articles also were reviewed for relevant citations.

Results

The data published to date support the use of DRG stimulation to treat chronic NPP of the groin, knee, and foot. NPP following procedures such as thoracotomy, hernia surgery, and knee replacement surgery were identified as some of the conditions for which DRG stimulation is likely to be effective.

Conclusion

DRG stimulation is known to be an effective treatment for focal neuropathic pain. Currently, NPP of the foot, groin, and knee all appear to be the conditions with the most clinical experience, backed by a limited but growing body of evidence. However, prospective studies lag behind real-world clinical experience and are needed to confirm these findings.

Photobiomodulation Decreases Hyperalgesia in Complex Regional Pain Syndrome: An Experimental Mouse Model Subjected to Nicotine

BACKGROUND AND OBJECTIVES

Complex regional pain syndrome (CRPS) is defined as an extreme and chronic pain condition, and photobiomodulation has relevance as a complementary treatment for CRPS. The objective of this study was to verify the effects of photobiomodulation (PBMT) therapy protocols at two wavelengths 660 and 830 nm, associated or not to nicotine in complex regional pain syndrome type I (CRPS-I).

STUDY DESIGN/MATERIALS AND METHODS

Sixty-four Swiss mice were divided into the following groups: (i) Naive, (ii) Sham, (iii) Control, (iv) 660 nm, (v) 830 nm, (vii) Nicotine, (vii) Nicotine/660 nm, and (viii) Nicotine/830 nm. CRPS-I was induced in an experimental ischemia/reperfusion model by affixing an elastic ring, proximal to the ankle joint of the right hind mouse paw, for 3 hours. Nicotine, in the respective groups was administered for 28 days prior to the induction of CRPS-I. PBMT was applied immediately after the procedure and for 20 consecutive days. The animals were evaluated for mechanical hyperalgesia, thermal hyperalgesia, paw edema at baseline and for 7, 14, and 21 days. Statistical analyses comprised a mixed-effects model, using the Tukey post hoc test (P < 0.05).

RESULTS

The PBMT wavelengths in 660 and 830 nm groups had beneficial effects (P < 0.05) in reducing mechanical and thermal hyperalgesia, but the effects at 660 nm were significantly better than 830 nm. At reducing edema, both wavelengths had significant effects statistically, absolutely no difference between them.

CONCLUSIONS

The use of PBMT (660 and 830 nm) was effective in reducing mechanical hyperalgesia and thermal hyperalgesia; however, PBMT at 660 nm generated significant results. In reducing edema, both wavelengths had similar effects, which were significant statistically. The deleterious effects of nicotine were evident statistically and were softened when treated with PBMT (P < 0.05). Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Combining Transcranial Direct Current Stimulation and Transcutaneous Electrical Nerve Stimulation to Relieve Persistent Pain in a Patient Suffering from Complex Regional Pain Syndrome: A Case Report

PURPOSE

Complex regional pain syndrome (CRPS) is a rare neuropathic pain condition characterized by sensory, motor and autonomic alterations. Previous investigations have shown that transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) can alleviate pain in various populations, and that a combination of these treatments could provide greater hypoalgesic effects. In the present case report, we describe the effect of tDCS and TENS treatment on pain intensity and unpleasantness in a patient suffering from chronic CRPS.

RESULTS

The patient was a 37-year-old woman, suffering from left lower limb CRPS (type I) for more than 5 years. Despite medication (pregabalin, tapentadol, duloxetine), rehabilitation treatments (sensorimotor retraining, graded motor imagery) and spinal cord stimulation (SCS), the participant reported moderate to severe pain. Treatments of tDCS alone (performed with SCS turned off during tDCS application, 1 session/day, for 5 consecutive days) did not significantly decrease pain. Combining tDCS with TENS (SCS temporarily turned off during tDCS, 1 session/day, for 5 consecutive days) slightly reduced pain intensity and unpleasantness.

DISCUSSION

Our results suggest that combining tDCS and TENS could be a therapeutic strategy worth investigating further to relieve pain in chronic CRPS patients. Future studies should examine the efficacy of combined tDCS and TENS treatments in CRPS patients, and other chronic pain conditions, with special attention to the cumulative and long-term effects and its effect on function and quality of life.

Prednisone for Acute Complex Regional Pain Syndrome: A Retrospective Cohort Study

Objective

The objective of this study was to evaluate prednisone effectiveness on complex regional pain syndrome (CRPS) features in a community-based outpatient rehabilitation setting.

Design

A single-centre, retrospective inception cohort design was used. Inclusion criteria were CRPS diagnosis according to the Budapest criteria, involvement of multiple joints, treatment with prednisone, and duration of symptoms less than one year. Typical prednisone treatment was 28-day taper regimen with 60 mg. Patient symptoms and signs were compared before and after treatment.

Results

There were 39 patients who met inclusion criteria for analysis. Duration of symptoms before treatment was 80.8 ± 67.7 days. Following treatment, 19 (48.7%) patients reported complete pain resolution, 19 (48.7%) patients reported decreased pain permitting functional use, and 1 (2.6%) patient reported no improvement. All symptoms and signs decreased significantly following oral prednisone treatment (p < 0.001). Range of motion (ROM) deficits persisted in 19 (49%) patients. However, 17 of these patients reported functional ROM recovery. Degree of ROM recovery and time-to-treatment had low positive correlation (r = 0.354, p < 0.001). Range of motion (ROM) deficits persisted in 19 (49%) patients. However, 17 of these patients reported functional ROM recovery. Degree of ROM recovery and time-to-treatment had low positive correlation (.

Conclusions

These data support short-course prednisone treatment for acute and subacute CRPS with multijoint involvement in a community rehabilitation setting. The association between time-to-treatment and ROM recovery suggests earlier treatment may result in improved ROM outcomes.

Spinal cord stimulation for the treatment of complex regional pain syndrome leads to improvement of quality of life, reduction of pain and psychological distress: a retrospective case series with 24 months follow up

Background and aims

Complex regional pain syndrome (CRPS) is a common pain condition which is characterized by pain, functional impairment, and trophic changes. Neurosurgical treatment is not widely offered. In this study the treatment with spinal cord stimulation (SCS) was evaluated over 24 months follow up.

Methods

A retrospective case analysis of six patients with severe CRPS was performed. Pain chronicity was recorded with the Mainz Pain Staging System (MPSS). Pain intensity (NRS), activity level and health-related quality of life (EQ-5D-5L), the actual mood state (ASTS), and treatment satisfaction (CSQ-8) were assessed. All patients received conventional pharmacological treatments including multimodal pain therapy through their local pain therapist or in specialized centers as well as physical therapy. A SCS electrode was implanted for trial stimulation. After successful trial a neurostimulator was implanted and connected to the electrode. Patients were retrospectively analyzed before implantation and 6, 12 and 24 months postoperatively. Statistical analysis was performed using Mann–Whitney U and Wilcoxon rank-sum test.

Results

Patients median age was 43 years (IQR25−75 37–43 years). The median MPSS Score was 3 of 3 indicating a high pain chronicity. Median NRS before implantation of the neurostimulator was 8.8 (IQR25−75 7.6–9.3). A reduction to 7.8 (IQR25−75 4.8–8.1; p = 0.14) after 6 months, 6.5 (IQR25−75 3.8–8.1; p = 0.08) after 1 year, and 6.8 (IQR25−75 3.8–8.5; p = 0.15) after 2 years was achieved. Median EQ-5D-5L index value before treatment was 0.27 (IQR25−75 0.25–0.41) indicating a severely lowered quality of life. A significant improvement to 0.53 (IQR25−75 0.26–0.65; p = 0.03) after 6 months, 0.58 (IQR25−75 0.26–0.84; p = 0.03) after 1 year as well as after 2 years was seen. ASTS scale showed an increase of values for positive mood, and a reduction in values for sorrow, fatigue, anger and desperation during the whole follow up period. The treatment satisfaction in the whole cohort with a median CSQ-8 value of 29.5 of 32 was very high.

Conclusion

The results of this small case series showed a significant improvement of the EQ-5D-5L after implantation of a neurostimulator. NRS reduction was not significant but a clear tendency towards reduced values was observed. We therefore conclude that SCS is an alternative option to relieve chronic pain and psychological distress originating from CRPS if non-invasive managements of severe CRPS failed. The preoperative selection plays a crucial role for good results.

Implications

CRPS is difficult to treat. SCS is an alternative option to improve the quality of life and relieve chronic pain originating from severe CRPS if conservative treatment modalities fail. Further psychological distress is reduced in long-term follow up. SCS should be kept in mind for therapy refractory cases.

Mechanism-specific rehabilitation management of complex regional pain syndrome: Proposed recommendations from evidence synthesis

STUDY DESIGN

Narrative review.

INTRODUCTION

There are a variety of treatments with demonstrated effectiveness for the management of complex regional pain syndrome (CRPS). However given the variability in symptom presentation in this population, therapists may be unsure what treatments would be most effective for individual clients.

PURPOSE OF THE STUDY

To present a brief synthesis of the literature and propose a rehabilitation version of a mechanism-specific management algorithm to guide personalized treatment of CRPS.

METHODS

A systematic search of the literature was conducted to identify all randomized controlled trials, systematic reviews, and clinical practice guidelines addressing rehabilitation of CRPS. Results were reviewed independently by 2 reviewers and final selection of articles was reached by consensus, Data was extracted using standardized forms, and a single rater gave quality ratings. Both reviewers then used the extracted data to present a synthesis of the evidence categorized by the proposed mechanisms of effect.

RESULTS

A total of 111 articles were retrieved and reviewed for inclusion; 49 were selected for data extraction. A synthesis of the key recommendations was compiled into a rehabilitation-specific version of the mechanism-based management algorithm proposed by Gierthmühlen et al (2014).

CONCLUSIONS

Consideration of mechanism-appropriate rehabilitation interventions may assist therapists to select the most appropriate and effective treatments from the body of evidence supporting rehabilitation of CRPS.

Evaluation of pain in pediatric upper extremity conditions

STUDY DESIGN

Narrative Review.

INTRODUCTION

Hand surgeons and therapists play an important role in the early identification of children at risk of developing chronic or recurrent pain after an upper extremity injury. Early identification of children at risk of developing a pain syndrome is critical because their physical, psychological, and/or social functioning may decline quickly without proper management due to the multidimensional nature of pain.

PURPOSE OF THE STUDY

This article outlines one approach to evaluating upper extremity pain in children to help identify those with, or at risk of, chronic pain.

METHODS

An assessment framework that recognizes the biological, sensory, emotional, and psychosocial components of pain is described.

RESULTS

The key components of a screening evaluation include obtaining a detailed history and a thorough physical examination that involves: systematic upper extremity mapping of sensory thresholds, mapping of sensory disturbances, and screening of self-reported pain intensity, location, descriptors, and interference.

DISCUSSION AND CONCLUSION

The evaluation approach described will enable hand therapists to identify children with upper extremity pain that are at risk of developing a chronic pain and make an early referral to a multidisciplinary pain team that provides education, pharmacological pain management, physical rehabilitation, and psychological treatments.

Measurement Properties of the SF-MPQ-2 Neuropathic Qualities Subscale in Persons with CRPS: Validity, Responsiveness, and Rasch Analysis

OBJECTIVES

The purpose of this study was to conduct classical psychometric evaluation and Rasch analysis on the Neuropathic Qualities subscale of the Short-Form McGill Pain Questionnaire-2 utilizing scores from persons with complex regional pain syndrome to consider reliability and person separation, validity (including unidimensionality), and responsiveness in this population.

METHODS

Secondary analysis of longitudinal data from persons with acute complex regional pain syndrome was utilized for analysis of the psychometric properties and fit to the Rasch model of the Neuropathic Qualities subscale. We followed an iterative process of Rasch analysis to evaluate and address data fitting challenges.

RESULTS

Repeated measures from 59 persons meeting the Budapest criteria were used for analysis. Both item-total correlations and unidimensionality analyses supported theoretical construct validity; all convergent construct validity hypotheses were also supported. Responsiveness was demonstrated comparing baseline and one-year data at d = 0.92, with a standardized response mean of 0.97. Data were able to fit the Rasch model, but all Neuropathic Qualities items had disordered thresholds that required rescoring. Additionally, local dependency and differential item function were addressed by "bundling," suggesting that no further item reduction would be possible.

CONCLUSIONS

This study provided preliminary support for the validity and responsiveness of the Neuropathic Qualities subscale in persons with complex regional pain syndrome. Rasch analysis further endorses use of the Neuropathic Qualities subscale as a "stand-alone" measure for neuropathic features, but with substantial background data transformations. Replication with larger samples is recommended to increase confidence in these findings.

Reflex Sympathetic Dystrophy of the Right Hand following an Acute Traumatic Injury

Complex regional pain syndrome (CRPS), formerly known as reflex sympathetic dystrophy, is a chronic neuropathic pain disorder with significant autonomic features. Recently, it has been recognized that CRPS is not simply a sympathetically mediated peripheral pain condition but rather a disease of the central nervous system as well. Herein, we present a case of a patient who presented with complaints of severe pain following a traumatic event, severing his extensor tendon of his right fifth finger. 

National Trends in the Diagnosis of CRPS after Open and Endoscopic Carpal Tunnel Release

Background  Complex regional pain syndrome (CRPS) occurs in 2 to 8% of patients that receive open or endoscopic carpal tunnel release (CTR). Because CRPS is difficult to treat after onset, identifying risk factors can inform prevention. We determined the incidence of CRPS following open and endoscopic CTR using a national claims database. We also examined whether psychosocial conditions were associated with CRPS after CTR. Methods  We accessed insurance claims using diagnostic and procedural codes. We calculated the incidence of CRPS following open carpal tunnel release and endoscopic carpal tunnel release within 1 year. The response variable was the presence of CRPS after CTR. Explanatory variables included procedure type, age, gender, and preoperative diagnosis of anxiety or depression. Results  The number of open CTRs (85% of total) outweighs the number of endoscopic procedures. In younger patients, the percentage of endoscopic CTRs is increasing. Rates of CRPS are nearly identical between surgery types for both privately insured (0.3%) and Medicare patients (0.1%). Middle aged (range: 40-64 years) and female patients had significantly higher rates of CRPS than did the general population. Preoperative psychosocial conditions did not correlate with the presence of CRPS in surgical patients. Clinical Relevance  The decision between endoscopic and open CTR should not be made out of concern for development of CRPS postsurgery, as rates are low and similar for both procedures. Rates of CRPS found in this study are much lower than rates found in previous studies, indicating inconsistency in diagnosis and reporting or generalizability of prior work. Preoperative psychosocial disorders and CRPS are unrelated.

The Effectiveness of Transcranial Direct Current Stimulation as an Add-on Modality to Graded Motor Imagery for Treatment of Complex Regional Pain Syndrome: A Randomized Proof of Concept Study

BACKGROUND

The efficacy of Graded Motor Imagery (GMI) for the management of Complex Regional Pain Syndrome (CRPS) is supported by evidence, but its treatment effect remains generally modest. Transcranial Direct Current Stimulation (tDCS) has been advocated as an adjunct intervention to enhance the effect of motor imagery approaches in pain populations.

OBJECTIVE

The purpose of this study was to investigate the effectiveness of GMI+active tDCS compared with the GMI+sham tDCS in the treatment of CRPS type I.

METHODS

A total of 22 patients (n=11/group) were randomly assigned to the experimental (GMI+tDCS) or placebo (GMI+sham tDCS) group. GMI treatments lasted 6 weeks; anodal tDCS was applied over the motor cortex for 5 consecutive days during the first 2 weeks and once a week thereafter. Changes in pain perception, quality of life, kinesiophobia, pain catastrophizing, anxiety and mood were monitored after 6 weeks of treatment (T1) and 1-month posttreatment (T2).

RESULTS

GMI+tDCS induced no statistically significant reduction in pain compared with GMI+sham tDCS. Although we observed significant group differences in kinesiophobia (P=0.012), pain catastrophizing (P=0.049), and anxiety (P=0.046) at T1, these improvements were not maintained at T2 and did not reached a clinically significant difference.

DISCUSSION

We found no added value of tDCS combined with GMI treatments for reducing pain in patients with chronic CRPS. However, given that GMI+sham tDCS induced no significant change, further studies comparing GMI+tDCS and tDCS alone are needed to further document tDCS's effect in CRPS.