Intravenous Therapies for Complex Regional Pain Syndrome: A Systematic Review

Current and Evolving Concepts in the Management of Complex Regional Pain Syndrome: A Narrative Review

Background/Objectives: Complex regional pain syndrome (CRPS) is characterized by severe pain and reduced functionality, which can significantly affect an individual's quality of life. The current treatment of CRPS is challenging. However, recent advances in diagnostic and treatment methods show promise for improving patient outcomes. This review aims to place the question of CRPS in a broader context and highlight the objectives of the research for future directions in the management of CRPS. Methods: This study involved a comprehensive literature review. Results: Research has identified three primary pathophysiological pathways that may explain the clinical variability observed in CRPS: inflammatory mechanisms, vasomotor dysfunction, and maladaptive neuroplasticity. Investigations into these pathways have spurred the development of novel diagnostic and treatment strategies focused on N-Methyl-D-aspartate Receptor Antagonists (NMDA), Toll-like receptor 4 (TLR-4), α1 and α2 adrenoreceptors, as well as the identification of microRNA (miRNA) biomarkers. Treatment methods being explored include immune and glial-modulating agents, intravenous immunoglobulin (IVIG) therapy, plasma exchange therapy, and neuromodulation techniques. Additionally, there is ongoing debate regarding the efficacy of other treatments, such as free radical scavengers, alpha-lipoic acid (ALA), dimethyl fumarate (DMF), adenosine monophosphate-activated protein kinase (AMPK) activators such as metformin, and phosphodiesterase-5 inhibitors such as tadalafil. Conclusions: The controversies surrounding the mechanisms, diagnosis, and treatment of CRPS have prompted researchers to investigate new approaches aimed at enhancing understanding and management of the condition, with the goal of alleviating symptoms and reducing associated disabilities.

The Impact of Ketamine on Outcomes in Acute Pain Management: An Umbrella Review

Background/Objectives: Ketamine offers effective pain relief with fewer side effects than traditional analgesics, making it a promising alternative for acute pain treatment. However, further research is needed to fully assess its role in perioperative care. This umbrella review aimed to compile the highest-quality evidence available regarding the application of ketamine in managing acute pain. Methods: A thorough search of the literature was carried out in PubMed, Scopus, and the Cochrane Library, including systematic reviews that focused on the application of ketamine in managing acute pain. The data extraction included the research type, analgesics used, number of studies and patients per review, pain types, scoring methods, ketamine doses, administration routes, and reporting guidelines. Results: Of the 807 records identified, 20 studies met the inclusion criteria. In accordance with the AMSTAR-2 evaluation, most of the systematic reviews were rated as critically low quality. Intravenous ketamine administered during the perioperative period was found to reduce the pain intensity of acute pain within 15-30 and 60 min following treatment, and decrease postoperative opioid consumption by 14-50% at both 24 and 48 h after surgery. Conclusions: Evidence shows that intravenous ketamine reduces the pain intensity, postoperative opioid use, and the risk of vomiting and nausea while improving analgesia, making it a valuable adjunct in perioperative pain management.

Efficacy and Safety of Pharmacological Treatment in Patients with Complex Regional Pain Syndrome: A Systematic Review and Meta-Analysis

Complex regional pain syndrome (CRPS) is a disabling condition that usually affects the extremities after trauma or surgery. At present, there is no FDA-approved pharmacological treatment for patients with CRPS. We performed this systematic review and meta-analysis to evaluate the efficacy and safety of pharmacological therapies and determine the best strategy for CRPS. We searched the databases, including PubMed, Embase, Cochrane, Web of Science, Scopus, and ClinicalTrials.gov, for published eligible randomized controlled trials (RCTs) comparing pharmacological treatment with placebo in CRPS patients. Target patients were diagnosed with CRPS according to Budapest Criteria in 2012 or the 1994 consensus-based IASP CRPS criteria. Finally, 23 RCTs comprising 1029 patients were included. We used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach to rate certainty (confidence in evidence and quality of evidence). Direct meta-analysis showed that using bisphosphonates (BPs) (mean difference [MD] -2.21, 95% CI -4.36--0.06, p = 0.04, moderate certainty) or ketamine (mean difference [MD] -0.78, 95% CI -1.51--0.05, p = 0.04, low certainty) could provide long-term (beyond one month) pain relief. However, there was no statistically significant difference in the efficacy of short-term pain relief. Ketamine (rank p = 0.55) and BPs (rank p = 0.61) appeared to be the best strategies for CRPS pain relief. Additionally, BPs (risk ratio [RR] = 1.86, 95% CI 1.34-2.57, p < 0.01, moderate certainty) and ketamine (risk ratio [RR] = 3.45, 95% CI 1.79-6.65, p < 0.01, moderate certainty) caused more adverse events, which were mild, and no special intervention was required. In summary, among pharmacological interventions, ketamine and bisphosphonate injection seemed to be the best treatment for CRPS without severe adverse events.

Mechanisms of complex regional pain syndrome

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

An update on the pharmacotherapeutic options for complex regional pain syndrome

INTRODUCTION

Complex regional pain syndrome (CRPS) is a rare and painful condition that has a wide range of triggering factors, often traumatic, and can present various clinical manifestations. The lack of knowledge about the underlying mechanisms has led to numerous treatment approaches, both conservative and surgical, which work through different mechanisms of action.

AREAS COVERED

In this review, the authors explore the key aspects of CRPS, including definition, diagnostic criteria, pitfalls, pathogenic hypotheses, and treatment strategies with a focus on pharmacotherapy. The review was based on a comprehensive search of the literature using PubMed, while also considering international guidelines for managing CRPS.

EXPERT OPINION

Based on the available evidence, pharmacological interventions appear to be effective in treating CRPS, especially when they target peripheral mechanisms, specifically nociceptive inflammatory pain, and when administered early in the course of the disease. However, there is still a lack of reliable evidence regarding the effects of drugs on central mechanisms of chronic pain in CRPS. In our expert opinion, drug therapy should be initiated as soon as possible, particularly in warm CRPS patient clusters, to prevent significant functional limitations, psychological distress, and negative impacts on individuals' social and economic well-being.

Experience from a single-center study on multimodal medication therapy for patients with complex regional pain syndrome

BACKGROUND

Despite the application of various therapeutic methods, pain caused by complex regional pain syndrome (CRPS) is not sufficiently managed and often progresses to a chronic stage. For the systematic and effective treatment of CRPS, we developed an algorithm for multimodal medication therapy based on the established pathophysiology of CRPS to control CRPS-related pain.

OBJECTIVE

In this study, we present the outcomes of our novel algorithm for multimodal medication therapy for patients with CRPS, consisting of three major components: multimodal oral medication, intravenous ketamine, and intravenous lidocaine therapy.

METHODS

We retrospectively investigated patients with CRPS who received multimodal therapy. Pain severity scores were evaluated using a numerical rating scale at four time points (P1, pain at initial consultation; P2, pain after oral medication; P3, pain after ketamine treatment; and P4, pain after lidocaine treatment). The effect of the multimodal medication therapy algorithm on pain management was evaluated at each time point.

RESULTS

In patients with CRPS, multimodal oral medication, intravenous ketamine, and intravenous lidocaine therapies led to significantly improved pain control (p< 0.05). Additionally, the combination of these three therapies (through the multimodal medication therapy algorithm) resulted in significant pain relief in patients with CRPS (p< 0.05).

CONCLUSIONS

Our multimodal medication therapy algorithm effectively controlled pain in patients with CRPS. However, further prospective studies with large sample sizes and randomized controlled trials are needed for more accurate generalization.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

AUTHORS' CONCLUSIONS

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

Perioperative Breast Analgesia: a Systematic Review of the Evidence for Perioperative Analgesic Medications

PURPOSE OF REVIEW

Breast surgery is common and may result in significant acute as well as chronic pain. A wide range of pharmacologic interventions is available including opioids, non-steroidal anti-inflammatory drugs (NSAIDs), N-methyl-D-aspartate (NMDA) receptor antagonists, anticonvulsants, and other non-opioids with analgesic properties. We present a review of the evidence for these pharmacologic interventions. A literature search of the MEDLINE database was performed via PubMed with combined terms related to breast surgery, anesthesia, and analgesia. Articles were limited to randomized controlled trial (RCT) design, adult patients undergoing elective surgery on the breast (not including biopsy), and pharmacologic interventions only. Article titles and abstracts were screened, and risk of bias assessments were performed.

RECENT FINDINGS

The search strategy initially captured 7254 articles of which 60 articles met the full inclusion criteria. Articles were organized according to intervention: 6 opioid agonists, 14 NSAIDs and acetaminophen, 4 alpha-2 agonists, 7 NMDA receptor antagonists, 6 local anesthetics, 7 steroids, 15 anticonvulsants (one of which also discussed an NMDA antagonist), 1 antiarrhythmic, and 2 serotonin reuptake inhibitors (one of which also studied an anticonvulsant). A wide variety of medications is effective for perioperative breast analgesia, but results vary by agent and dose. The most efficacious are likely NSAIDs and anticonvulsants. Some agents may also decrease the incidence of chronic postoperative pain, including flurbiprofen, gabapentin, venlafaxine, and memantine. While many individual agents are well studied, optimal combinations of analgesic medications remain unclear.

Advances in Interventional Therapies for Painful Diabetic Neuropathy: A Systematic Review

BACKGROUND

Painful diabetic neuropathy (PDN) is one of the major complications of diabetes mellitus. It is often debilitating and refractory to pharmaceutical therapies. Our goal was to systematically review and evaluate the strength of evidence of interventional management options for PDN and make evidence-based recommendations for clinical practice.

METHODS

We searched PubMed, Scopus, Google Scholar, and Cochrane Llibrary and systematically reviewed all types of clinical studies on interventional management modalities for PDN.

RESULTS

We identified and analyzed 10 relevant randomized clinical trials (RCTs), 8 systematic reviews/meta-analyses, and 5 observational studies of interventional modalities for PDN using pain as primary outcome. We assessed the risk of bias in grading of evidence and found that there is moderate to strong evidence to support the use of dorsal column spinal cord stimulation (SCS) in treating PDN in the lower extremities (evidence level: 1B+), while studies investigating its efficacy in the upper extremities are lacking. Evidence exists that acupuncture and injection of botulinum toxin-A provide relief in pain or muscle cramps due to PDN with minimal side effects (2B+/1B+). Similar level of evidence supports surgical decompression of lower limb peripheral nerves in patients with intractable PDN and superimposed nerve compression (2B±/1B+). Evidence for sympathetic blocks or neurolysis and dorsal root ganglion (DRG) stimulation is limited to case series (2C+).

CONCLUSIONS

Moderate to strong evidence exists to support the use of SCS in managing lower extremity pain in patients who have failed conventional medical management for PDN. Acupuncture or injection of botulinum toxin-A can be considered as an adjunctive therapy for PDN. Surgical decompression of peripheral nerves may be considered in patients with PDN superimposed with nerve compression. High-quality studies are warranted to further evaluate the safety, efficacy, and cost-effectiveness of interventional therapies for PDN.

Complex Regional Pain Syndrome: A Comprehensive Review

Complex regional pain syndrome (CRPS) is a chronic pain condition often involving hyperalgesia and allodynia of the extremities. CRPS is divided into CRPS-I and CRPS-II. Type I occurs when there is no confirmed nerve injury. Type II is when there is known associated nerve injury. Female gender is a risk factor for developing CRPS. Other risk factors include fibromyalgia and rheumatoid arthritis. Unfortunately, the pathogenesis of CRPS is not yet clarified. Some studies have demonstrated different potential pathways. Neuropathic inflammation, specifically activation of peripheral nociceptors of C-fibers, has been shown to play a critical role in developing CRPS. The autonomic nervous system (ANS) is involved. Depending on whether it is acute or chronic CRPS, norepinephrine levels are either decreased or increased, respectively. Some studies have suggested the importance of genetics in developing CRPS. More consideration is being given to the role of psychological factors. Some association between a history of depression and/or post-traumatic stress disorder (PTSD) and the diagnosis of CRPS has been demonstrated. Treatment modalities available range from physical therapy, pharmacotherapy, and interventional techniques. Physical and occupational therapies include mirror therapy and graded motor imagery. Medical management with non-steroidal anti-inflammatory drugs (NSAIDs) has not shown significant improvement. There have been supporting findings in the use of short-course steroids, bisphosphonates, gabapentin, and ketamine. Antioxidant treatment has also shown some promise. Other pharmacotherapies include low-dose naltrexone and Botulinum toxin A (BTX-A). Sympathetic blocks are routinely used, even if their short- and long-term effects are not clear. Finally, spinal cord stimulation (SCS) has been used for decades. In conclusion, CRPS is a multifactorial condition that still requires further studying to better understand its pathogenesis, epidemiology, genetic involvement, psychological implications, and treatment options. Future studies are warranted to better understand this syndrome. This will provide an opportunity for better prevention, diagnosis, and treatment of CRPS.

A randomised placebo-controlled clinical trial on the efficacy of local lidocaine injections and oral citalopram for the treatment of complex regional pain syndrome

BACKGROUND

Complex regional pain syndrome (CRPS) is a neuropathic pain condition with no universally recognised treatment. The study evaluates the efficacy of a therapeutic protocol consisting of oral citalopram and lidocaine injections in patients affected by CRPS.

METHODS

Between January 2010 and December 2014, 150 consecutive patients with CRPS were enrolled in the study and randomly assigned into three groups: group one - lidocaine injection and oral citalopram; group two - lidocaine injection and oral placebo; and group three - injective and oral placebo. The Impairment Sum Score (ISS) was used to assess the severity of CRPS before, as well as at regular intervals after treatment commenced. Statistical significance (p < 0.05) was determined by paired t-tests.

RESULTS

The combined treatment proved to be more effective (ISS 47.6 to 12.6) than local anaesthetic alone (ISS 47.5 to 21.5) and to placebo (ISS 47.2 to 29.9).

CONCLUSION

This study indicates that CRPS may be managed with well-tolerated association of oral citalopram and lidocaine injections.

Use of bisphosphonates in a retrospective case series of children and adolescents with complex regional pain syndrome

BACKGROUND

There is increasing evidence for the use of bisphosphonates to treat Complex Regional Pain Syndrome in adults. However, there are scarce data for their use in children with Complex Regional Pain Syndrome.

AIM

This retrospective case series aimed to analyze the effects of intravenous bisphosphonate use in children and adolescents with Complex Regional Pain Syndrome enrolled in a multidimensional pain treatment program.

METHODS

We analyzed the data of 16 patients (15 females and 1 male, mean age 14 ± 3 years) who received infusions of zoledronic acid (0.015 ± 0.0044mg/kg), pamidronate (0.72 ± 0.17mg/kg), or both depending on their initial response between October 2014 and December 2019. The primary endpoint of the study was the patient's global impression of change. Secondary outcomes included pain intensity, physical function, role function (school attendance), need for pain medications, and adverse effects.

RESULTS

Nine of 16 patients reported meaningful improvements (global impressions of change of 84% or higher) at a median follow-up time of 16 (8-21) months after their last infusion of bisphosphonates. There were also meaningful reductions in pain intensity and the need for pain medications. There was an increase in the proportion of patients with minimal or without physical disability, and almost all patients normalized their school activities. Thirteen patients (81%) reported adverse effects, mostly flu-like symptoms, for a few days after the infusion.

CONCLUSION

The use of bisphosphonate infusions may represent an effective treatment option for children with Complex Regional Pain Syndrome, not responding to multidisciplinary pain treatment programs.

Team Approach: Complex Regional Pain Syndrome in Children and Adolescents

Children and adolescents with chronic pain are best managed by an interdisciplinary team. In cases of complex regional pain syndrome (CRPS), the interdisciplinary team consists of a pain management specialist, such as an anesthesiologist or physiatrist, a physical therapist, an occupational therapist, a pain psychologist, and an orthopaedist. It may also include other professions, such as a gastroenterologist, psychiatrist, nurse practitioner, nutritionist, endocrinologist, acupuncturist, or social worker. Key factors include rapid recognition of CRPS and the initiation of appropriate treatment, both for the pain syndrome as well as for the orthopaedic injury. Intensive therapies have been shown to be effective in treating CRPS in children. Children often are more responsive to noninvasive treatments than adults.

Treatment of Complex Regional Pain Syndrome in Children and Adolescents: A Structured Literature Scoping Review

BACKGROUND

Complex regional pain syndrome (CRPS) is characterized by chronic, spontaneous and provoked pain of the distal extremities whose severity is disproportionate to the triggering event. Diagnosis and treatment are still debated and multidisciplinary. The purpose of this systematic review is to analyze the available literature to provide an update on the latest evidence related to the treatment of CRPS in growing age.

METHODS

Data extraction was performed independently by three reviewers based on predefined criteria and the methodologic quality of included studies was quantified by the Newcastle-Ottawa Quality Assessment Scale Cohort Studies.

RESULTS

At the end of the first screening, following the previously described selection criteria, we selected n = 103 articles eligible for full-text reading. Ultimately, after full-text reading and a reference list check, we selected n = 6. The articles focused on physical (PT), associated with cognitive behavioral (CBT) and pharmacological (PhT) treatments. The combination of PT + CBT shows the most efficacy as suggested, but a commonly accepted protocol has not been developed.

CONCLUSIONS

Physical therapy in association with occupational and cognitive behavioral treatment is the recommended option in the management of pediatric CPRS. Pharmacological therapy should be reserved for refractory and selected patients. The design and development of a standard protocol are strongly suggested.

Intravenous Ketamine Infusion for Complex Regional Pain Syndrome: Survey, Consensus, and a Reference Protocol

OBJECTIVE

To find and reach a consensus on the usage of ketamine in the treatment of complex regional pain syndrome and to determine a reference protocol for future studies.

DESIGN

Three hundred fifty-one medical professionals participated in our survey on practice procedures, with 104 respondents providing information on their usage of ketamine for treating the pain associated with complex regional pain syndrome. Respondents answered questions about inpatient treatment, outpatient treatment, children vs adults, safety, and basic demographic information. An expert group then met to reach a consensus for a reference protocol.

RESULTS

There is a difference in how inpatients are treated compared with outpatients, making it necessary to have two different reference protocols. The duration of pain relief varied from one to 10 days to one to six months, with a correlation between the duration of pain relief and total infusion hours per round.

CONCLUSIONS

The consensus reference protocols are made up of nine recommended topics. Reference protocols need to be validated by extensive research before guidelines can be created.

Pharmacotherapeutic options for complex regional pain syndrome

INTRODUCTION

Complex regional pain syndromes (CRPS) are rare painful conditions characterized by considerable variability in possible triggering factors, usually traumatic, and in the clinical scenario. The limited knowledge of the pathophysiological mechanisms has led to countless treatment attempts with multiple conservative and surgical options that act by different mechanisms of action.

AREAS COVERED

In this narrative review, the authors discuss key points about CRPS definitions, diagnostic criteria and pitfalls, pathophysiological hypotheses, and treatment strategies with particular reference to pharmacotherapy. The article was based on a literature search using PubMed while the available guidelines for the management of CRPS were also examined.

EXPERT OPINION

According to the quality of evidence, pharmacological interventions for CRPS seem to be more effective all the more so when they act on peripheral mechanisms, particularly on nociceptive pain, and when applied early in the disease, while reliable evidence about central mechanisms of chronic pain in CRPS is lacking. In our opinion, drug therapy should be preferred as early as possible, particularly in warm forms of CRPS to prevent significant functional limitation, psychological distress, and social and economic fallout.

A Systematic Review of Growth Hormone in Pain Medicine: From Rodents to Humans

Objective

Growth hormone (GH) and GH-related signaling molecules play an important role in nociception and development of chronic pain. This review aims to examine the potential molecular mechanisms through which GH-related signaling modulates sensory hypersensitivity in rodents, the clinical pharmacology of GH, and the clinical evidence of GH treatment for several common pain syndromes.

Methods

A search was conducted using the PUBMED/MEDLINE database, Scopus, and the Cochrane library for all reports published in English on GH in pain management from inception through May 2018. A critical review was performed on the mechanisms of GH-related signaling and the pharmacology of GH. The levels of clinical evidence and implications for recommendations of all of the included studies were graded.

Results

The search yielded 379 articles, of which 201 articles were deemed irrelevant by reading the titles. There were 53 reports deemed relevant after reading abstracts. All of these 53 articles were retrieved for the analysis and discussion.

Conclusions

Dysfunction of the GH/insulin-like growth factor 1 (IGF-1)/ghrelin axis was linked to hyperalgesia and several common clinical pain syndromes. Low levels of GH and IGF-1 were linked to pain hypersensitivity, whereas ghrelin appeared to provide analgesic effects. Pretreatment of GH reversed mechanical and thermal hypersensitivity in an animal model of inflammatory pain. Clinical trials support GH treatment in a subgroup of patients with fibromyalgia syndrome (level of evidence: 1B+) or chronic lower back pain syndrome (level of evidence: 2C+).

Changes in the Skin Conductance Monitor as an End Point for Sympathetic Nerve Blocks

Objective

There is a lack of objective methods for determining the achievement of sympathetic block. This study validates the skin conductance monitor (SCM) as an end point indicator of successful sympathetic blockade as compared with traditional monitors.

Methods

This interventional study included 13 patients undergoing 25 lumbar sympathetic blocks to compare time to indication of successful blockade between the SCM indices and traditional measures, clinically visible hyperemia, clinically visible engorgement of veins, subjective skin temperature difference, unilateral thermometry monitoring, bilateral comparative thermometry monitoring, and change in waveform amplitude in pulse oximetry plethysmography, within a 30-minute observation period. Differences in the SCM indices were studied pre- and postblock to validate the SCM.

Results

SCM showed substantially greater odds of indicating achievement of sympathetic block in the next moment (i.e., hazard rate) compared with all traditional measures (clinically visible hyperemia, clinically visible engorgement of veins, subjective temperature difference, unilateral thermometry monitoring, bilateral comparative thermometry monitoring, and change in waveform amplitude in pulse oximetry plethysmography; P ≤ 0.011). SCM indicated successful block for all (100%) procedures, while the traditional measures failed to indicate successful blocks in 16-84% of procedures. The SCM indices were significantly higher in preblock compared with postblock measurements (P < 0.005).

Conclusions

This preliminary study suggests that SCM is a more reliable and rapid response indicator of a successful sympathetic blockade when compared with traditional monitors.

Conservative Management of Neuropathic Pain in a Patient With Pancoast-Tobias Syndrome: A Case Report

Pancoast-Tobias syndrome characterizes the signs and symptoms of a superior pulmonary sulcus tumor, and includes arm and shoulder pain, atrophy of intrinsic hand muscles, and ipsilateral Horner syndrome. The rarity and overall poor prognosis of patients with superior pulmonary sulcus tumors associated with Pancoast-Tobias syndrome has led to few reports detailing pain management strategies with adjunctive therapies, such as continuous infusions of ketamine and lidocaine, chemotherapy, radiation, and multimodal oral medication regimens. This case highlights the diagnosis and treatment of pain in a patient with Pancoast-Tobias syndrome.

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

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

Anti-tumor activity of phenoxybenzamine and its inhibition of histone deacetylases

The principal finding from this study was the recognition that the α-adrenergic antagonist, phenoxybenzamine, possesses histone deacetylase inhibitory activity. Phenoxybenzamine is approved by the United States Food and Drug Administration for the treatment of hypertensive crises associated with tumors of the adrenal medulla, pheochromocytomas. It has several "off label" indications relative to its capacity to relax vascular smooth muscle and smooth muscle of the urogenital tract. The drug also has a long history of apparent efficacy in ameliorating, and perhaps reversing, the severe symptoms of neuropathic pain syndromes. Our interest in this feature of the drug relates to the fact that certain types of neuropathic pain, in particular complex regional pain syndrome, demonstrate a proliferative nature, with the capacity to spread from an injured limb, for example, to a non-injured limb and perhaps to essentially the entire body. Sensory neuronal sprouting in the spinal cord has been observed under conditions where there is a high sensory input from painful stimuli. Searches of gene expression signatures in the BroadBuild02 Molecular Signature Database using their connectivity map software suggested that phenoxybenzamine may have histone deacetylase inhibitory activity. Studies by others have reported inhibitory effects of phenoxybenzamine on growth, invasion and migration of human tumor cell cultures and, in one study, inhibition of tumor expansion in animal experiments. Inhibitory effects on human tumor cell cultures are also reported in the present study. Phenoxybenzamine was also found to have histone deacetylase inhibitory activity; histone deacetylase isoforms 5, 6, and 9 were the most sensitive to inhibition by phenoxybenzamine. The importance of elevated levels of these isoforms as biomarkers of poor prognosis in human malignant disease, and the recognized suppression of tumor growth that may accrue from their inhibition, opens consideration of possible translation of phenoxybenzamine to new clinical applications. This might be facilitated by the fact that phenoxybenzamine is already an approved drug entity. There appears to be no previous report of the activity of phenoxybenzamine as a histone deacetylase inhibitor.

The Pharmacological Management of Complex Regional Pain Syndrome in Pediatric Patients

The awareness of complex regional pain syndrome (CRPS) in the pediatric population is increasing. The condition involves regional pain that is out of proportion to any initiating event (if there is one) and is associated with sensory, functional, autonomic, and inflammatory changes in the region of the pain. The signs and symptoms of CRPS can vary between patients and stage of the disease process. Like many chronic pain conditions, it is often associated with significant disability and a detrimental effect on quality of life. It has a complex pathophysiology that remains poorly understood but provides many potential targets for treatments. Management involves a biopsychosocial formulation that encompasses physical and psychological interventions alongside pharmacological strategies. We review the current evidence for the treatment of this condition in children, with particular reference to pharmacological management.