[Pain inhibition by opioids-new concepts]

BACKGROUND

Opioids are the oldest and most potent drugs for the treatment of severe pain but they are burdened by detrimental side effects, such as respiratory depression, addiction potential, sedation, nausea and constipation. Their clinical application is undisputed in the treatment of acute (e.g. perioperative) and cancer pain but their long-term use in chronic pain has met increasing criticism and has contributed to the current "opioid crisis".

OBJECTIVES

This article reviews the pharmacological principles and new research strategies aiming at novel opioids with reduced side effects. The basic mechanisms underlying pain and opioid analgesia and other effects of opioids are outlined. To illustrate the clinical situation and medical problems, the plasticity of opioid receptors, intracellular signaling pathways, endogenous and exogenous opioid receptor ligands, central and peripheral sites of analgesic and side effects are discussed.

CONCLUSION

The epidemic of opioid misuse has shown that there is a lack of fundamental knowledge about the characteristics and management of chronic pain, that conflicts of interest and validity of models must be more intensively considered in the context of drug development and that novel analgesics with less addictive potential are urgently needed. Currently, the most promising perspectives appear to be augmenting endogenous opioid actions and the selective activation of peripheral opioid receptors.

Effects of Transcutaneous Electrical Nerve Stimulation in Autonomic Nervous System of Hypertensive Patients: A Randomized Controlled Trial

BACKGROUND

Patients with hypertension have altered autonomic nervous system function, which are increased sympathetic activity. Transcutaneous Electrical Nerve Stimulation (TENS) is a useful modality for pain control and has also been shown to be effective in the reduction of sympathetic activity in healthy subjects and individuals with cardiovascular diseases.

OBJECTIVE

The aim of this study was to verify the effects of transcutaneous electrical nerve stimulation by the evaluation of heart rate variability (HRV) in patients with essential hypertension.

METHOD

Twenty-eight patients received an application of low-frequency TENS(4 Hz) n=8, highfrequency TENS (100 Hz) n=10 or placebo TENS n=10 in paravertebral ganglionar region during thirty minutes.

RESULTS

After 4 Hz TENS, there was a decrease in the low-frequency (LFn.u.) component (57.71±9.46 vs 45.58±13.51, p<0.026) and an increase in the high-frequency (HFn.u.) component (33.03±13.83 vs 45.83±20.19, p <0.05) of HRV. After 100 Hz TENS and placebo, there were no changes in the LF and HF components. No significant differences were found in systolic blood pressure with low-frequency TENS (129.37± 15.48 vs 126.69 ± 15.21, p<0.490). There was an increase, although not significant, with high-frequency TENS (131.00 ± 15.97 vs 138.75 ± 25.79, p<0.121) and placebo (133.80 ± 29.85 vs 134.80 ± 29.72, p< 0.800). No differences were found in the diastolic blood pressure with low-frequency TENS and placebo, but there was a significant increase in high-frequency TENS (81.00 ± 11.78 vs 85.65 ± 13.68, p< 0.018).

CONCLUSION

Low-frequency TENS decreases sympathetic nervous system activity and increases parasympathetic nervous system activity and high-frequency TENS increases diastolic blood pressure, when applied on the paravertebral ganglionar region in the hypertensive patients.

Noninvasive brain stimulation combined with other therapies improves gait speed after stroke: a systematic review and meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are noninvasive brain stimulation (NIBS) techniques able to modulate cortical excitability.

OBJECTIVE

To determine the effects of NIBS combined with other therapies on gait speed after stroke.

METHODS

Electronic databases searched were PUBMED, EMBASE, COCHRANE, SCOPUS, SCIELO and PEDro. Eligibility criteria were randomized controlled trials that reported the effects of tDCS and rTMS combined with other therapies for improving gait speed, walking cadence, functional ambulation category (FAC) and motricity index (MI-LE) after stroke. Risk of bias was assessed by Cochrane risk of bias assessment tool. Mean differences (MD) and 95% confidence intervals were calculated. Quality of evidence was assessed by Grades of Researches, Assessment, Development and Evaluation approach.

RESULTS

Ten studies (226 subjects) were included in the meta-analysis. NIBS combined with other therapies was effective for improving gait speed (MD 0.09 m/s [95% CI, 0.05 to 0.13; I² 0%, p < 0.0001]). Gait speed improved in both acute/subacute (MD 0.08 m/s [95% CI, 0.02 to 0.14]) and chronic phases (MD 0.08 m/s [95% CI, 0.03 to 0.13]). Furthermore, inhibitory (MD 0.09 m/s [95% CI, 0.04 to 0.14]) and excitatory (MD 0.07 m/s [95% CI, 0.02 to 0.12]) protocols were effective to improve gait speed. NIBS was also effective to improve walking cadence but was unable to modify other outcomes (FAC and MI-LE).

CONCLUSIONS

This systematic review with meta-analysis synthesizes moderate-quality evidence that NIBS combined with other therapies are effective to improve gait speed after stroke. Systematic Review registration number: PROSPERO registration number CDR42015024237.

[Pain inhibition by opioids-new concepts]

BACKGROUND

Opioids are the oldest and most potent drugs for the treatment of severe pain but they are burdened by detrimental side effects, such as respiratory depression, addiction potential, sedation, nausea and constipation. Their clinical application is undisputed in the treatment of acute (e.g. perioperative) and cancer pain but their long-term use in chronic pain has met increasing criticism and has contributed to the current "opioid crisis".

OBJECTIVES

This article reviews the pharmacological principles and new research strategies aiming at novel opioids with reduced side effects. The basic mechanisms underlying pain and opioid analgesia and other effects of opioids are outlined. To illustrate the clinical situation and medical problems, the plasticity of opioid receptors, intracellular signaling pathways, endogenous and exogenous opioid receptor ligands, central and peripheral sites of analgesic and side effects are discussed.

CONCLUSION

The epidemic of opioid misuse has shown that there is a lack of fundamental knowledge about the characteristics and management of chronic pain, that conflicts of interest and validity of models must be more intensively considered in the context of drug development and that novel analgesics with less addictive potential are urgently needed. Currently, the most promising perspectives appear to be augmenting endogenous opioid actions and the selective activation of peripheral opioid receptors.

Comparison of Cardiac and Vascular Parameters in Powerlifters and Long-Distance Runners: Comparative Cross-Sectional Study

BACKGROUND

Cardiac remodeling is a specific response to exercise training and time exposure. We hypothesized that athletes engaging for long periods in high-intensity strength training show heart and/or vascular damage.

OBJECTIVE

To compare cardiac characteristics (structure and function) and vascular function (flow-mediated dilation [FMD] and peripheral vascular resistance [PVR]) in powerlifters and long-distance runners.

METHODS

We evaluated 40 high-performance athletes (powerlifters [PG], n = 16; runners [RG], n = 24) and assessed heart structure and function (echocardiography), systolic and diastolic blood pressure (SBP/DBP), FMD, PVR, maximum force (squat, bench press, and deadlift), and maximal oxygen uptake (spirometry). A Student's t Test for independent samples and Pearson's linear correlation were used (p < 0.05).

RESULTS

PG showed higher SBP/DBP (p < 0.001); greater interventricular septum thickness (p < 0.001), posterior wall thickness (p < 0.001) and LV mass (p < 0.001). After adjusting LV mass by body surface area (BSA), no difference was observed. As for diastolic function, LV diastolic volume, wave E, wave e', and E/e' ratio were similar for both groups. However, LA volume (p = 0.016) and BSA-adjusted LA volume were lower in PG (p < 0.001). Systolic function (end-systolic volume and ejection fraction), and FMD were similar in both groups. However, higher PVR in PG was observed (p = 0.014). We found a correlation between the main cardiovascular changes and total weight lifted in PG.

CONCLUSIONS

Cardiovascular adaptations are dependent on training modality and the borderline structural cardiac changes are not accompanied by impaired function in powerlifters. However, a mild increase in blood pressure seems to be related to PVR rather than endothelial function.

Effects of transcutaneous electrical nerve stimulation alone or as additional therapy on chronic post-stroke spasticity: systematic review and meta-analysis of randomized controlled trials

Purpose: To evaluate the effects and to compare transcutaneous electrical nerve stimulation protocols, alone or as additional therapy in chronic post-stroke spasticity through a systematic review and meta-analysis of randomized clinical trials.Methods: Search was conducted in MEDLINE, Cochrane Library, EMBASE and Physiotherapy Evidence Database through November 2017 (CRD42015020146). Two independent reviewers performed articles selection, data extraction and methodological quality assessment using the Cochrane Collaboration's risk of bias tool. The main outcome was spasticity assessed with Modified Ashworth Scale or other valid scale. Meta-analysis was conducted using random effects method, and pooled-effect results are mean difference with 95% confidence interval.Results: Of 6506 articles identified, 10 studies with 360 subjects were included in the review. Transcutaneous electrical nerve stimulation alone or as additional therapy is superior to placebo TENS to reduce post-stroke spasticity assessed with Modified Ashworth Scale (-0.52 [-0.74 to -0.30] p < 0.0001, 6 studies), especially in lower limbs (-0.58 [-0.82 to -0.34] p < 0.0001, 5 studies), which is in accordance with the studies that used other scales. Low frequency TENS showed a slightly larger improvement than high-frequency, but without significant difference between subgroups. Most studies present low or unclear risk of bias.Conclusion: Transcutaneous electrical nerve stimulation can provide additional reduction in chronic post-stroke spasticity, mainly as additional therapy to physical interventions. Studies with better methodological quality and larger sample are needed to increase evidence power.Implications for RehabilitationTranscutaneous electrical nerve stimulation as additional treatment to physical interventions can lead to additional reduction in chronic post-stroke spasticity.High and low frequency transcutaneous electrical nerve stimulation showed similar results, with a smaller numerical superiority of low frequency TENS.More studies are needed to substantiate the best protocol of transcutaneous electrical nerve stimulation to the treatment of spasticity.

Effects of High-Intensity Inspiratory Muscle Training Associated with Aerobic Exercise in Patients Undergoing CABG: Randomized Clinical Trial

OBJECTIVE

Evaluate the interaction between high-intensity inspiratory muscle training (IMT) and aerobic exercise on physical capacity, respiratory muscle strength, peripheral muscle strength, and quality of life of patients who underwent coronary artery bypass grafting (CABG).

METHODS

Twenty-four patients underwent CABG were randomized into two groups. During 36 sessions, one group received IMT associated with aerobic exercise and the other group received only aerobic exercise. Primary outcome was the distance in the six-minute walk distance (6MWD) test. Secondary outcomes included respiratory muscle strength, peripheral muscle strength, and quality of life. Measures were taken at the baseline, at the 12th session, the 24th session, and 36th session.

RESULTS

Baseline characteristics were similar between the groups. There was no statistically significant difference between the two groups in any outcome [6MWD - P=0.935; peak oxygen consumption (PeakVO2) - P=0.853; maximal inspiratory pressure (MIP) - P=0.243; maximal expiratory pressure (MEP) - P=0.268; sitting-rising test (SRT) - P=0.212], but there was interaction in MIP (P=0.000) and all outcomes improved in the two groups (6MWD - P=0.000; PeakVO2 - P=0.000; MIP - P=0.000; MEP - P=0.000; SRT - P=0.000).

CONCLUSION

There was an improvement of all outcomes in both groups, but IMT was not able to provide additional benefits. The use of this combination should be used with caution to not generate higher costs in the rehabilitation process of these patients.

Isosorbide and nifedipine for Chagas' megaesophagus: A systematic review and meta-analysis

BACKGROUND

Chagas disease is a neglected tropical disease. About 6 to 8 million people are chronically infected and 10% to 15% develop irreversible gastrointestinal disorders, including megaesophagus. Treatment focuses on improving symptoms, and isosorbide and nifedipine may be used for this purpose.

METHODOLOGY

We conducted a systematic review to evaluate the effectiveness of pharmacological treatment for Chagas' megaesophagus. We searched MEDLINE, Embase and LILACS databases up to January 2018. We included both observational studies and RCTs evaluating the effects of isosorbide or nifedipine in adult patients with Chagas' megaesophagus. Two reviewers screened titles and abstracts, selected eligible studies and extracted data. We assessed the risk of bias using NIH 'Quality Assessment Tool for Before-After (Pre-Post) Studies with No Control Group' and RoB 2.0 tool. Overall quality of evidence was assessed using GRADE.

PRINCIPAL FINDINGS

We included eight studies (four crossover RCTs, four before-after studies). Three studies evaluated the effect of isosorbide on lower esophageal sphincter pressure (LESP), showing a significant reduction (mean difference -10.52mmHg, 95%CI -13.57 to-7.47, very low quality of evidence). Three studies reported the effect of isosorbide on esophageal emptying, showing a decrease in esophageal retention rates (mean difference -22.16%, 95%CI -29.94 to -14.38, low quality of evidence). In one study, patients on isosorbide reported improvement in the frequency and severity of dysphagia (moderate quality of evidence). Studies evaluating nifedipine observed a decrease in LESP but no effect on esophageal emptying (very low and low quality of evidence, respectively). Isosorbide had a higher incidence of headache as a side effect than nifedipine.

CONCLUSIONS

Although limited, available evidence shows that both isosorbide and nifedipine are effective in reducing esophageal symptoms. Isosorbide appears to be more effective, and its use is supported by a larger number of studies; nifedipine, however, appears to have a better tolerability profile.

TRIAL REGISTRATION

PROSPERO CRD42017055143. ClinicalTrials.gov CRD42017055143.

Amiodarone for arrhythmia in patients with Chagas disease: A systematic review and individual patient data meta-analysis

Background

Chagas disease is a neglected chronic condition caused by Trypanosoma cruzi, with high prevalence and burden in Latin America. Ventricular arrhythmias are common in patients with Chagas cardiomyopathy, and amiodarone has been widely used for this purpose. The aim of our study was to assess the effect of amiodarone in patients with Chagas cardiomyopathy.

Methodology

We searched MEDLINE, Embase and LILACS up to January 2018. Data from randomized and observational studies evaluating amiodarone use in Chagas cardiomyopathy were included. Two reviewers selected the studies, extracted data and assessed risk of bias. Overall quality of evidence was accessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Principal findings

We included 9 studies (3 before-after studies, 5 case series and 1 randomized controlled trial). Two studies with a total of 38 patients had the full dataset, allowing individual patient data (IPD) analysis. In 24-hour Holter, amiodarone reduced the number of ventricular tachycardia episodes in 99.9% (95%CI 99.8%-100%), ventricular premature beats in 93.1% (95%CI 82%-97.4%) and the incidence of ventricular couplets in 79% (RR 0.21, 95%CI 0.11–0.39). Studies not included in the IPD analysis showed a reduction of ventricular premature beats (5 studies), ventricular tachycardia (6 studies) and ventricular couplets (1 study). We pooled the incidence of adverse side effects with random effects meta-analysis; amiodarone was associated with corneal microdeposits (61.1%, 95%CI 19.0–91.3, 5 studies), gastrointestinal events (16.1%, 95%CI 6.61–34.2, 3 studies), sinus bradycardia (12.7%, 95%CI 3.71–35.5, 6 studies), dermatological events (10.6%, 95%CI 4.77–21.9, 3 studies) and drug discontinuation (7.68%, 95%CI 4.17–13.7, 5 studies). Quality of evidence ranged from moderate to very low.

Conclusions

Amiodarone is effective in reducing ventricular arrhythmias, but there is no evidence for hard endpoints (sudden death, hospitalization). Although our findings support the use of amiodarone, it is important to balance the potential benefits and harms at the individual level for decision-making.

Chagas disease is a chronic neglected tropical disease, with high prevalence and burden in Latin America. About 30% of chronically infected patients develop Chagas cardiomyopathy. Ventricular arrhythmias are common in patients with Chagas cardiomyopathy and treatment approaches include medications, resynchronization therapy, and implantable cardioverter defibrillator. Studies published from 1980 to 1990 have evaluated the effect of amiodarone. According to our systematic review and individual patient meta-analysis, amiodarone reduced ventricular tachycardia, ventricular premature beats and incidence of ventricular couplets. Although the strong evidence of clinical benefit with arrhythmia reduction, this information should be interpreted with caution, since arrhythmia is a surrogate outcome and since its clinical impact on death and hospitalization reduction over time is not clear. Little information was identified related to hard endpoints. Regarding side effects, our systematic review observed that amiodarone was associated with corneal microdeposits, gastrointestinal events, sinus bradycardia, dermatological events, pneumonitis, hypothyroidism and drug discontinuation. The currently available evidence shows that amiodarone seems to be an effective antiarrhythmic drug for patients with Chagas disease, especially in settings where an implantable cardioverter defibrillator is not available or affordable, but that a balance between potential benefits and harms at the individual level is needed.

[Research consortium Neuroimmunology and pain in the research network musculoskeletal diseases]

BACKGROUND

The research consortium Neuroimmunology and Pain (Neuroimpa) explores the importance of the relationships between the immune system and the nervous system in musculoskeletal diseases for the generation of pain and for the course of fracture healing and arthritis.

MATERIAL AND METHODS

The spectrum of methods includes analyses at the single cell level, in vivo models of arthritis and fracture healing, imaging studies on brain function in animals and humans and analysis of data from patients.

RESULTS

Proinflammatory cytokines significantly contribute to the generation of joint pain through neuronal cytokine receptors. Immune cells release opioid peptides which activate opioid receptors at peripheral nociceptors and thereby evoke hypoalgesia. The formation of new bone after fractures is significantly supported by the nervous system. The sympathetic nervous system promotes the development of immune-mediated arthritis. The studies show a significant analgesic potential of the neutralization of proinflammatory cytokines and of opioids which selectively inhibit peripheral neurons. Furthermore, they show that the modulation of neuronal mechanisms can beneficially influence the course of musculoskeletal diseases.

DISCUSSION

Interventions in the interactions between the immune system and the nervous system hold a great therapeutic potential for the treatment of musculoskeletal diseases and pain.

Acute Effects of Low-Level Laser Therapy on Patients' Functional Capacity in the Postoperative Period of Coronary Artery Bypass Graft Surgery: A Randomized, Crossover, Placebo-Controlled Trial

OBJECTIVE

The aim of this study was to evaluate the acute effects of low-level laser therapy (LLLT) on the functional capacity to exercise tested by incremental shuttle walking test (ISWT) after coronary artery bypass graft (CABG) surgery.

METHODS

Fifteen male patients (60 ± 9 years) were crossed over during the experiment, to compare the outcomes after active LLLT and placebo LLLT treatments. LLLT (850 nm, 200 mW, 30 J to each point, resulting in a total of 240 J per quadriceps muscle), using a multidiode cluster (five spots; 6 J/spot) in eight points per leg was performed 3 min before the ISWT. We analyzed distance walked, Borg scale of perceived exertion, heart rate, and brachial arterial blood pressure. Markers of tissue damage [lactate dehydrogenase (LDH)] and oxidative stress [lipid peroxidation, total thiol levels, and antioxidant enzyme activity of superoxide dismutase (SOD) and catalase (CAT)] were also measured in peripheral blood.

RESULTS

Comparison of the distances walked revealed no significant differences between the LLLT and placebo LLLT groups (p = 0.779). Regarding the Borg scale (p = 0.567), heart rate (p = 0.506) as well as systolic and diastolic blood pressure (p = 0.164 and p = 0.140, respectively), no differences were observed between LLLT and placebo LLLT groups. Application of LLLT was not able to change levels of LDH (p = 0.214), oxidative lipid damage (p = 0.733), total thiol levels (p = 0.925), SOD (p = 0.202), and CAT (p = 0.825) enzyme activities.

CONCLUSIONS

Acute LLLT improved neither functional capacity to exercise nor the markers of oxidation after CABG.

TRIAL REGISTRATION

Registered as a clinical trial (NCT02688426).

A nontoxic pain killer designed by modeling of pathological receptor conformations

Indiscriminate activation of opioid receptors provides pain relief but also severe central and intestinal side effects. We hypothesized that exploiting pathological (rather than physiological) conformation dynamics of opioid receptor-ligand interactions might yield ligands without adverse actions. By computer simulations at low pH, a hallmark of injured tissue, we designed an agonist that, because of its low acid dissociation constant, selectively activates peripheral μ-opioid receptors at the source of pain generation. Unlike the conventional opioid fentanyl, this agonist showed pH-sensitive binding, heterotrimeric guanine nucleotide-binding protein (G protein) subunit dissociation by fluorescence resonance energy transfer, and adenosine 3',5'-monophosphate inhibition in vitro. It produced injury-restricted analgesia in rats with different types of inflammatory pain without exhibiting respiratory depression, sedation, constipation, or addiction potential.

Emergent biomarker derived from next-generation sequencing to identify pain patients requiring uncommonly high opioid doses

Next-generation sequencing (NGS) provides unrestricted access to the genome, but it produces 'big data' exceeding in amount and complexity the classical analytical approaches. We introduce a bioinformatics-based classifying biomarker that uses emergent properties in genetics to separate pain patients requiring extremely high opioid doses from controls. Following precisely calculated selection of the 34 most informative markers in the OPRM1, OPRK1, OPRD1 and SIGMAR1 genes, pattern of genotypes belonging to either patient group could be derived using a k-nearest neighbor (kNN) classifier that provided a diagnostic accuracy of 80.6±4%. This outperformed alternative classifiers such as reportedly functional opioid receptor gene variants or complex biomarkers obtained via multiple regression or decision tree analysis. The accumulation of several genetic variants with only minor functional influences may result in a qualitative consequence affecting complex phenotypes, pointing at emergent properties in genetics.

Methodological Quality of Randomized Clinical Trials of Respiratory Physiotherapy in Coronary Artery Bypass Grafting Patients in the Intensive Care Unit: a Systematic Review

OBJECTIVE

To assess methodological quality of the randomized controlled trials of physiotherapy in patients undergoing coronary artery bypass grafting in the intensive care unit.

METHODS

The studies published until May 2015, in MEDLINE, Cochrane and PEDro were included. The primary outcome extracted was proper filling of the Cochrane Collaboration's tool's items and the secondary was suitability to the requirements of the CONSORT Statement and its extension.

RESULTS

From 807 studies identified, 39 were included. Most at CONSORT items showed a better adequacy after the statement's publication. Studies with positive outcomes presented better methodological quality.

CONCLUSION

The methodological quality of the studies has been improving over the years. However, many aspects can still be better designed.