Complex Regional Pain Syndrome Type 1: Diagnosis and Management

Complex Regional Pain Syndrome in Cancer Cases: Current Knowledge and Perspectives

Background

Complex regional pain syndrome (CRPS) is a disabling painful disorder caused by many different and poorly understood mechanisms. It often affects the distal limbs and usually happens as consequence of a trauma. Its severity can remarkably affect patients' quality of life. When this painful complication happens in a cancer patient, the impact may be exponential. To date, there is limited knowledge of the surrounding circumstances of CRPS cases in this population.

Methods

We present two clinical cases of patients diagnosed with cancer-related pain presenting with symptoms and signs compatible with CRPS. In one case, CRPS was attributed to direct tumor nerve compression, and it responded successfully to an interventional pain procedure. The second case was associated with a Zoster infection in an immunocompromised cancer patient. Patient responded to multidisciplinary pain management strategies. Additionally, we conducted a literature review to investigate the coexistence of cancer pain and CRPS and suggest some pathophysiology mechanisms of action.

Results and Discussion

Literature reviewed and potential pathophysiology mechanisms are simultaneously explored in terms of classification, etiopathology, evidence, challenges, and future scientific directions.

Conclusion

Comorbid CRPS can impact negatively in cases of cancer pain by affecting their diagnosis and treatment. Further studies are necessary to elucidate how these two conditions present together and how they can be better addressed.

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

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

The Effectiveness of Rehabilitation Interventions on Pain and Disability for Complex Regional Pain Syndrome: A Systematic Review and Meta-analysis

OBJECTIVES

To summarize and critically appraise the body of evidence on conservative management of complex regional pain syndrome (CRPS), we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

We conducted a literature search from inception to November 2021 in the following databases: Embase, Medline, CINAHL, Google Scholar, PEDRO, and Psychinfo. Two independent reviewers conducted risk of bias and quality assessment. Qualitative synthesis and meta-analysis were the methods for summarizing the findings of the RCTs. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to rate the overall quality and certainty of the evidence on each treatment outcome.

RESULT

Through a database search, 751 records were found, and 33 RCTs were eligible for inclusion. Studies were published between 1995 and 2021. The overall risk of bias for 2 studies was low, 8 studies were unclear, and 23 studies were high.Low-quality evidence suggests that mirror therapy (as an addition to conventional stroke rehabilitation interventions) and graded motor imagery program (compared with routine rehabilitation interventions) may result in a large improvement in pain and disability up to 6-month follow-up in poststroke CRPS-1 patients. Low-quality evidence suggests that pain exposure therapy and aerobic exercises as an additive treatment to physical therapy interventions may result in a large improvement in pain up to a 6-month follow-up. The evidence is very uncertain about the effect of all other targeted interventions over conventional physical therapy or sham treatments on pain and disability.

DISCUSSION

There is an ongoing need for high-quality studies to inform conservative management choices in CRPS.

Relative Prevalence and Associated Factors of Complex Regional Pain Syndrome Type I in Patients with Radial Head Fractures Treated with Open Reduction and Internal Fixation: A Cross-Sectional Study

Objective

This cross-sectional study aimed to examine the incidence and associated factors of complex regional pain syndrome type I (CRPS I) in patients who underwent open reduction and internal fixation (ORIF) for radial head fractures.

Methods

The study enrolled 601 radial head fracture patients treated with ORIF, 523 of which completed the 1-year follow-up. The incidence of CRPS I in those patients was assessed using the Budapest criteria. Patients were then divided into 2 groups: patients with CRPS I (n = 28) and patients without CRPS I (n = 495). The patients' demographic and clinical data before the operation were prospectively collected by our team. Independent t-tests and χ² tests were used as univariate analyses to compare the demographic and clinical data between the two groups. Meanwhile, multivariate regression analysis was conducted to identify the associated risk factors for CRPS I.

Results

The incidence of CRPS I in patients with radial head fractures treated with ORIF was 5.5% during the first year following surgery. Significant differences were observed in age, gender, type of trauma, modified Mason Classification, and depressive personality disorders. The logistic regression analysis revealed that the female gender, modified Mason type III fractures, and depressive patients were significantly more likely to develop CRPS I (p=0.021, 0.023, and 0.025, respectively).

Conclusions

The incidence of CRPS I among radial head fracture patients undergoing ORIF was 5.5%. In addition, early detection of CRPS I and providing adequate intervention will likely result in greater benefits for those patients.

Preventive Supplementation of Omega-3 Reduces Pain and Pro-inflammatory Cytokines in a Mouse Model of Complex Regional Pain Syndrome Type I

Complex regional pain syndrome type I (CRPS-I) is a condition that responds poorly to treatments. The role of omega-3 fatty acids in the treatment of inflammatory disorders is well described in the literature; however, few studies have evaluated its therapeutic benefits in different types of pain. We evaluated the potential antihyperalgesic and anti-inflammatory effects of preventive omega-3 supplementation in an animal model of CRPS-I. In experiment 1, Swiss female mice were supplemented for 30 days with omega-3 before the induction of the CRPS-I model and 14 days after. Mechanical hyperalgesia was evaluated at baseline and from the 4th to the 14th day after CPRS-I induction along with open field locomotor activity after 30 days of supplementation. In experiment 2, Swiss female mice were supplemented for 30 days with omega-3 and then subjected to the CRPS-I model. Twenty-four hours later the animals were euthanized, and tissue samples of the spinal cord and right posterior paw muscle were taken to measure pro-inflammatory cytokine TNF and IL-1β concentrations. Omega-3 supplementation produced antihyperalgesic and anti-inflammatory effects, as well as reducing pro-inflammatory cytokine concentrations, without altering the animals’ locomotion. No open field locomotor changes were found. The 30-day supplementation at the tested dose was effective in the CRPS-I model.

[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.

Successful treatment of complex regional pain syndrome type 1 of upper limb with cryoneurolysis of the stellate ganglion: A rare case report

Complex regional pain syndrome type I (CRPS I) is a multifactorial condition that is related to neural damage, and leads to chronic neuropathic pain. Due to its multifactorial nature, there are many methods that have been recruited for its management. Most of them limit the symptoms to some degree, but the most effective of them so far seems to be blockade of the sympathetic innervation of the region. We present the case of a 71-year-old woman, with an upper limb fracture which was treated conservatively, and later on developed CRPS type I. Analgesic medications and pregabalin were ineffective in controlling her symptoms. Blockade of the stellate ganglion was performed with local anesthetic and dexamethasone. After the stellate ganglion blockade was marked as successful in relieving her symptoms, cryoneurolysis was performed which was very effective. There are not many cases that have been treated with cryoneurolysis, and this is what makes this case interesting.

Is adhesive capsulitis of the shoulder a form of complex regional pain syndrome type I?

[No Abstract Available].

Bradykinin Receptors Play a Critical Role in the Chronic Post-ischaemia Pain Model

Complex regional pain syndrome type-I (CRPS-I) is a chronic painful condition resulting from trauma. Bradykinin (BK) is an important inflammatory mediator required in acute and chronic pain response. The objective of this study was to evaluate the association between BK receptors (B₁ and B₂) and chronic post-ischaemia pain (CPIP) development in mice, a widely accepted CRPS-I model. We assessed mechanical and cold allodynia, and paw oedema in male and female Swiss mice exposed to the CPIP model. Upon induction, the animals were treated with BKR antagonists (HOE-140 and DALBK); BKR agonists (Tyr-BK and DABK); antisense oligonucleotides targeting B₁ and B₂ and captopril by different routes in the model (7, 14 and 21 days post-induction). Here, we demonstrated that treatment with BKR antagonists, by intraperitoneal (i.p.), intraplantar (i.pl.), and intrathecal (i.t.) routes, mitigated CPIP-induced mechanical allodynia and oedematogenic response, but not cold allodynia. On the other hand, i.pl. administration of BKR agonists exacerbated pain response. Moreover, a single treatment with captopril significantly reversed the anti-allodynic effect of BKR antagonists. In turn, the inhibition of BKRs gene expression in the spinal cord inhibited the nociceptive behaviour in the 14th post-induction. The results of the present study suggest the participation of BKRs in the development and maintenance of chronic pain associated with the CPIP model, possibly linking them to CRPS-I pathogenesis.