The Endogenous Pain Modulatory System as a Healing Mechanism: A Proposal on How to Measure and Modulate It.

Background: Chronic pain is highly burdening and multifactorial in etiology. The endogenous-pain-healing system restores body tissue to a non-painful state after an injury leading to pain, and its disruption could represent a relevant mechanism, especially for nursing interventions.

Aim: To review the literature and summarize the results that support this hypothesis.

Cross-sectional and longitudinal analysis of conditioned pain modulation and pain in fibromyalgia: CPM as an effect modifier of pain changes over time.

Background And Purpose: Fibromyalgia (FM) is associated with altered descending pain modulatory pathways, which can be assessed through Conditioned Pain Modulation (CPM). In this study, we aimed to explore the relationship between CPM and self-reported baseline characteristics in patients with fibromyalgia. We also performed a longitudinal analysis exploring CPM as a potential predictor of clinical improvement over time in individuals with FM.

Does Transcranial Direct Current Stimulation reduce central and peripheral muscle fatigue in recreational runners? A triple-blind, sham-controlled, randomized, crossover clinical study.

Background: Runners seek health benefits and performance improvement. However, fatigue might be considered a limiting factor. Transcranial Direct Current Stimulation (tDCS) has been investigated to improve performance and reduce fatigue in athletes.

Exercise effects on cortical excitability in pain populations: A systematic review and meta-analysis.

Background: Transcranial Magnetic Stimulation (TMS) studies examining exercise-induced neuroplasticity in pain populations have produced contradictory findings. We conducted a systematic review to explore how exercise impacts cortical excitability in pain populations using TMS metrics. This review aims to summarize the effect sizes and to understand their sources of heterogeneity.

Brain compensatory mechanisms in depression and memory complaints in fibromyalgia: the role of theta oscillatory activity.

Background: The different clinical presentations of fibromyalgia syndrome (FMS) might play independent roles in the unclear etiology of cognitive impairments and depressive symptoms seen in patients with FMS. Understanding how these clinical presentations are associated with the clinical and neurophysiological aspects of FMS is important for the development of effective treatments.

Aim: To explore the relationship of memory complaints and depressive symptoms with the different clinical and neurophysiological characteristics of FMS.

Using Home-based, Remotely Supervised, Transcranial Direct Current Stimulation for Phantom Limb Pain.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses low-amplitude direct currents to alter cortical excitability. Previous trials have established the safety and tolerability of tDCS, and its potential to mitigate symptoms. However, the effects are cumulative, making it more difficult to have adherence to the treatment since frequent visits to the clinic or outpatient center are required.

The role of symptoms severity, heart rate, and central sensitization for predicting sleep quality in patients with fibromyalgia.

Background: Clinical predictors of sleep quality in patients with fibromyalgia syndrome (FMS) are still unknown. By identifying these factors, we could raise new mechanistic hypotheses and guide management approaches. We aimed to describe the sleep quality of FMS patients and to explore the clinical and quantitative sensory testing (QST) predictors of poor sleep quality and its subcomponents.

Association of Mu opioid receptor (A118G) and BDNF (G196A) polymorphisms with rehabilitation-induced cortical inhibition and analgesic response in chronic osteoarthritis pain.

Background/objective: Chronic pain due to osteoarthritis (OA) is a prevalent cause of global disability. New biomarkers are needed to improve treatment allocation, and genetic polymorphisms are promising candidates.

Method: We aimed to assess the association of OPRM1 (A118G and C17T) and brain-derived neurotrophic factor (BDNF [G196A]) polymorphisms with pain-related outcomes and motor cortex excitability metrics (measured by transcranial magnetic stimulation) in 113 knee OA patients with chronic pain.

Measuring Contralateral Silent Period Induced by Single-Pulse Transcranial Magnetic Stimulation to Investigate M1 Corticospinal Inhibition.

Contralateral silent period (cSP) is a period of suppression in the background electrical muscle activity captured by electromyography (EMG) after a motor evoked potential (MEP). To obtain this, an MEP is elicited by a suprathreshold transcranial magnetic stimulation (TMS) pulse delivered to the primary motor cortex (M1) of the target muscle selected, while the participant provides a standardized voluntary target muscle contraction. The cSP is a result of inhibitory mechanisms that occur after the MEP; it provides a broad temporal assessment of spinal inhibition in its initial ~50 ms, and cortical inhibition after.

Motor cortex inhibition as a fibromyalgia biomarker: a meta-analysis of transcranial magnetic stimulation studies.

Fibromyalgia (FM) is a common and refractory chronic pain condition with multiple clinical phenotypes. The current diagnosis is based on a syndrome identification which can be subjective and lead to under or over-diagnosis. Therefore, there is a need for objective biomarkers for diagnosis, phenotyping, and prognosis (treatment response and follow-up) in fibromyalgia.

Temporal Summation in Fibromyalgia Patients: Comparing Phasic and Tonic Paradigms.

Introduction: Fibromyalgia (FM) is associated with dysfunctional pain modulation mechanisms, including central sensitization. Experimental pain measurements, such as temporal summation (TS), could serve as markers of central sensitization and have been previously studied in these patients, with conflicting results. Our objective in this study was to explore the relationships between two different protocols of TS (phasic and tonic) and test the associations between these measures and other clinical variables.

Burden of epilepsy in Latin America and The Caribbean: a trend analysis of the Global Burden of Disease Study 1990 - 2019.

Background: The epilepsy prevalence in Latin America and the Caribbean (LAC) had remained high over the last 20 years. Data on the burden of epilepsy are needed for healthcare planning and resource allocation. However, no systematic analysis had been performed for epilepsy burden in LAC.

Recruitment characteristics and non-adherence associated factors of fibromyalgia patients in a randomized clinical trial: A retrospective survival analysis.

Introduction: Fibromyalgia is a complex pain condition that affects mostly women. Given the disease's lack of understanding, patients report poor adherence to medication and mistrust of medical services. This study aims to describe the recruitment characteristics and non-adherence associated factors of fibromyalgia patients to an RCT.

Electroencephalography Signatures for Conditioned Pain Modulation and Pain Perception in Nonspecific Chronic Low Back Pain-An Exploratory Study.

Unlabelled: Conditioned pain modulation (CPM) can discriminate between healthy and chronic pain patients. However, its relationship with neurophysiological pain mechanisms is poorly understood. Brain oscillations measured by electroencephalography (EEG) might help gain insight into this complex relationship.

Barriers and facilitators for clinical trial participation of underrepresented and non-underrepresented fibromyalgia patients: A cross-sectional internet survey.

Background: There is a need of well-powered randomized clinical trials in fibromyalgia. However, challenges for recruitment are presented. This study aims to describe and assess the perception of barriers and facilitators and the associated factors for the participation of underrepresented and non-underrepresented fibromyalgia patients.

Home-based transcranial direct current stimulation (tDCS) and motor imagery for phantom limb pain using statistical learning to predict treatment response: an open-label study protocol.

Background: Phantom limb pain (PLP) management has been a challenge due to its response heterogeneity and lack of treatment access. This study will evaluate the feasibility of a remotely home-based M1 anodal tDCS combined with motor imagery in phantom limb patients and assess the preliminary efficacy, safety, and predictors of response of this therapy.

Methods: This is a pilot, single-arm, open-label trial in which we will recruit 10 subjects with phantom limb pain.

COVID-19 pandemic and Farr's law: A global comparison and prediction of outbreak acceleration and deceleration rates.

The COVID-19 outbreak has forced most of the global population to lock-down and has put in check the health services all over the world. Current predictive models are complex, region-dependent, and might not be generalized to other countries. However, a 150-year old epidemics law promulgated by William Farr might be useful as a simple arithmetical model (percent increase [R1] and acceleration [R2] of new cases and deaths) to provide a first sight of the epidemic behavior and to detect regions with high predicted dynamics.

Methods and strategies of tDCS for the treatment of pain: current status and future directions.

Introduction: Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique that has been widely studied for the treatment of chronic pain. It is considered a promising and safe alternative pain therapy. Different targets have been tested, each having their own particular mechanisms for modulating pain perception.

Decreased neural inhibitory state in fibromyalgia pain: A cross-sectional study.

Objectives: Chronic pain is one of the most common and challenging symptoms in fibromyalgia (FM). Currently, self-reported pain is the main criterion used by clinicians assessing patients with pain. However, it is subjective, and multiple factors can affect pain levels.

Noninvasive motor cortex stimulation effects on quantitative sensory testing in healthy and chronic pain subjects: a systematic review and meta-analysis.

One of the potential mechanisms of motor cortex stimulation by noninvasive brain stimulation (NIBS) effects on pain is through the restoration of the defective endogenous inhibitory pain pathways. However, there are still limited data on quantitative sensory testing (QST), including conditioned pain modulation (CPM), supporting this mechanism. This systematic review and meta-analysis aimed to evaluate the effects of noninvasive motor cortex stimulation on pain perception as indexed by changes in QST outcomes.

Brain perfusion during manic episode and at 6-month follow-up period in bipolar disorder patients: Correlation with cognitive functions.

Background: Patterns of altered cerebral perfusion and cognitive dysfunction have been described in Bipolar Disorder (BD) acute episodes and euthymia. Knowledge of the relationship between cognitive function and perfusion in a manic state and status when followed up is still limited.

Objective: To describe brain perfusion alterations and its relationship with cognitive impairment in patients with BD during manic episodes and after 6 months.

Noninvasive brain stimulation combined with exercise in chronic pain: a systematic review and meta-analysis.

: The use of noninvasive brain stimulation (NIBS) combined with exercise could produce synergistic effects on chronic pain conditions. This study aims to evaluate the efficacy and safety of NIBS combined with exercise to treat chronic pain as well as to describe the parameters used to date in this combination.: The search was carried out in Medline, Central, Scopus, Embase, and Pedro until November 2019.