Acute pain Factors predictive of post-operative pain and opioid requirement in multimodal analgesia following knee replacement.

Background: Despite the development of multimodal analgesia for postoperative pain management, opioids are still required for effective pain relief after knee arthroplasty. We aimed to identify the determinants of post-operative pain intensity and post-operative opioid requirement in this context.

Methods: In this observational prospective study, we recorded patient characteristics, pre-operative pain intensity, anxiety and depression levels, sensitivity and pain thresholds in response to an electrical stimulus, and mu-opioid receptor (OPRM1) and catechol-O-methyltransferase (COMT) single-nucleotide polymorphisms.

From pulses to pain relief: an update on the mechanisms of rTMS-induced analgesic effects.

Background: Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that allows cortical stimulation. Recent studies have shown that rTMS of the primary motor cortex or dorsolateral prefrontal cortex decreases pain in various pain conditions. The aim of this review was to summarize the main characteristics of rTMS-induced analgesic effects and to analyse the current data on its mechanisms of action.

[Pathophysiology of cluster headache].

The aetiology of cluster headache is partially unknown. Three areas are involved in the pathogenesis of cluster headache: the trigeminal nociceptive pathways, the autonomic system and the hypothalamus. The cluster headache attack involves activation of the trigeminal autonomic reflex.

Neuropathic pain phenotyping by international consensus (NeuroPPIC) for genetic studies: a NeuPSIG systematic review, Delphi survey, and expert panel recommendations.

For genetic research to contribute more fully to furthering our knowledge of neuropathic pain, we require an agreed, valid, and feasible approach to phenotyping, to allow collaboration and replication in samples of sufficient size. Results from genetic studies on neuropathic pain have been inconsistent and have met with replication difficulties, in part because of differences in phenotypes used for case ascertainment. Because there is no consensus on the nature of these phenotypes, nor on the methods of collecting them, this study aimed to provide guidelines on collecting and reporting phenotypes in cases and controls for genetic studies.

Are there different predictors of analgesic response between antidepressants and anticonvulsants in painful diabetic neuropathy?

Background: To investigate baseline demographics and disease characteristics as predictors of the analgesic effect of duloxetine and pregabalin on diabetic peripheral neuropathic pain (DPNP).

Methods: Based on data from the COMBO-DN study, a multinational clinical trial in DPNP, the potential impact of baseline characteristics on pain relief after 8-week monotherapy with 60 mg/day duloxetine or 300 mg/day pregabalin was assessed using analyses of covariance. Subgroups of interest were characterized regarding their baseline characteristics and efficacy outcomes.

Clinical, histological, and biochemical predictors of postsurgical neuropathic pain.

Surgical nerve injury sometimes leads to chronic postsurgical neuropathic pain (CPSNP). The risk factors for this condition are not well understood. We prospectively assessed 46 patients scheduled for iliac crest bone harvest, 2 days (D2) and 3 months (M3) after surgery, to determine the time course of nerve fiber degeneration and expression of the TNF-α and NGF genes in skin punch biopsies.

Who is healthy? Aspects to consider when including healthy volunteers in QST--based studies-a consensus statement by the EUROPAIN and NEUROPAIN consortia.

Clinical and human experimental pain studies often include so-called "healthy" controls in investigations of sensory abnormalities, using quantitative sensory testing (QST) as an outcome measure. However, the criteria for what is considered "healthy" vary among the different studies and between study centers and investigators, partly explaining the high variability of the results. Therefore, several aspects should be considered during inclusion of healthy volunteers in QST-based trials to have homogenous groups of healthy controls with less variability between human experimental studies, so that results are less likely to be false negative or false positive because of subject-related factors.

Thalamic Responses to Nociceptive-Specific Input in Humans: Functional Dichotomies and Thalamo-Cortical Connectivity.

While nociceptive cortical activation is now well characterized in humans, understanding of the nociceptive thalamus remains largely fragmentary. We used laser stimuli and intracerebral electrodes in 17 human subjects to record nociceptive-specific field responses in 4 human thalamic nuclei and a number of cortical areas. Three nuclei known to receive spinothalamic (STT) projections in primates (ventro-postero-lateral [VPL], anterior pulvinar [PuA], and central lateral [CL]) exhibited responses with similar latency, indicating their parallel activation by nociceptive afferents.

Thermoregulation and pain perception: Evidence for a homoeostatic (interoceptive) dimension of pain.

Background: Experimental and clinical observations of interactions between the nociceptive and thermoceptive systems have suggested that they could be part of the homoeostatic system relating to the condition of the body, described as 'interoception'. Homoeostatic physiological systems are extensively interconnected. Thus, consistent with this hypothesis, we would expect thermoregulatory challenges to be associated with changes in pain perception.

[Capsaicin Cutaneous Patch: a Cost-consequences Study in a French University Hospital].

Introduction: The capsaïcine 8% cutaneous patch (Qutenza®) was recently approved for the management of patients with peripheral neuropathic pain (PNP). Considering its limited clinical efficacy data, its improvement of medical benefit was determined to be 5 which was insufficient to support its reimbursement in addition to diagnosis related groups'tarifs. Nevertheless its commercialization was associated with a marked interest considering the unmet therapeutic needs for patients with PNP.

Transient Global Amnesia Triggered by Migraine in a French Tertiary-Care Center: An 11-Year Retrospective Analysis.

Objective: The etiology of transient global amnesia (TGA) remains unclear, and flow disturbances in the mesial temporal lobes secondary to venous congestion have been proposed as a potential cause. The occurrence of TGA during a migraine attack is a rare condition.

Methods: This 11-year retrospective study in one French center describes patients' characteristics, type of migraine, investigations, treatment with vasoconstrictor during the TGA/migraine attack, and outcome in patients who had TGA during a migraine attack.

Pharmacotherapy of neuropathic pain: which drugs, which treatment algorithms?

Neuropathic pain (NP) is a significant medical and socioeconomic burden. Epidemiological surveys have indicated that many patients with NP do not receive appropriate treatment for their pain. A number of pharmacological agents have been found to be effective in NP on the basis of randomized controlled trials including, in particular, tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitor antidepressants, pregabalin, gabapentin, opioids, lidocaine patches, and capsaicin high-concentration patches.

Effects of β2 agonists on post-thoracotomy pain incidence.

Background: Pre-clinical research has shown β2 -adrenoceptors to be essential for the antiallodynic action of antidepressant drugs in murine models of neuropathic pain and that sustained treatment with β2 -agonists has an antiallodynic action. Here, we clinically investigated whether chronic β2 -agonist treatments may influence the incidence of post-thoracotomy chronic pain, defined as pain that recurs or persists along a thoracotomy scar more than 2 months after surgery, either neuropathic or non-neuropathic.

Methods: We conducted an epidemiological study on patients operated by thoracotomy.

[Migraine and contraception].

Migraine is a common pathology in women. Migraine disease is well defined by the International Headache Society and has to be distinguished from others types of headaches. The occurrence of migraine attacks is frequently linked to the menstrual cycle.

Triptans use and overuse: A pharmacoepidemiology study from the French health insurance system database covering 4.1 million people.

Introduction: The objective of this study was to estimate and to characterize the actual patterns of triptan use and overuse in France using a drug reimbursement database.

Methods: We included all people covered by the French General Health Insurance System (GHIS) from the Provence-Alpes-Côte-d'Azur (PACA) and Corsica administrative areas who had at least one dispensed dose of triptans between May 2010 and December 2011. All dispensed doses of triptans, migraine prophylactic treatment and psychotropic medications were extracted from the GHIS database.

Rationale and design of a randomized double-blind clinical trial in breast cancer: dextromethorphan in chemotherapy-induced peripheral neuropathy.

Background: Anti-cancer chemotherapy often induces peripheral neuropathy and consequent cognitive and quality of life impairment. Guidelines recommend antiepileptics or antidepressants but their efficacy is limited.Dextromethorphan, a N-methyl-D-aspartate receptor antagonist, has shown its efficacy in painful diabetic neuropathy and in post-operative pain but has not been studied in chemotherapy-induced peripheral neuropathy.

Pharmacotherapy for neuropathic pain in adults: a systematic review and meta-analysis.

Background: New drug treatments, clinical trials, and standards of quality for assessment of evidence justify an update of evidence-based recommendations for the pharmacological treatment of neuropathic pain. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), we revised the Special Interest Group on Neuropathic Pain (NeuPSIG) recommendations for the pharmacotherapy of neuropathic pain based on the results of a systematic review and meta-analysis.

Methods: Between April, 2013, and January, 2014, NeuPSIG of the International Association for the Study of Pain did a systematic review and meta-analysis of randomised, double-blind studies of oral and topical pharmacotherapy for neuropathic pain, including studies published in peer-reviewed journals since January, 1966, and unpublished trials retrieved from ClinicalTrials.

Effect of combining tramadol and morphine in adult surgical patients: a systematic review and meta-analysis of randomized trials.

The role for tramadol in multimodal postsurgical analgesic strategies remains unclear. We undertook a systematic review to evaluate the utility of combining tramadol with morphine after surgery. We searched the MEDLINE, EMBASE, LILAC, Cochrane, and Clinical Trial Register databases for randomized, controlled studies comparing tramadol with placebo or active control in patients undergoing surgery.

Hyperalgesia induced by low-dose opioid treatment before orthopaedic surgery: An observational case-control study.

Background: Chronic pain and opioid consumption may trigger diffuse hyperalgesia, but their relative contributions to pain vulnerability remain unclear.

Objectives: To assess preoperative opioid-induced hyperalgesia and its postoperative clinical consequences in patients with chronic pain scheduled for orthopaedic surgery.

Design: A prospective observational study.

Prolonged continuous theta-burst stimulation is more analgesic than 'classical' high frequency repetitive transcranial magnetic stimulation.

Background: Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) at high frequency (>5 Hz) induces analgesic effects, probably by activating pain modulation systems. A new rTMS paradigm--theta burst stimulation (TBS)--consists of bursts of three pulses at 50 Hz repeated five times per second. Like high frequency rTMS, both intermittent and prolonged continuous TBS (iTBS and pcTBS) lead to a facilitation of cortical excitability.

Relationships between the paradoxical painful and nonpainful sensations induced by a thermal grill.

The simultaneous application of innocuous cutaneous warm and cold stimuli with a thermal grill can induce both paradoxical pain and paradoxical warmth (heat). The goal of this study was to investigate further the relationships between these paradoxical sensations. Stimuli were applied to the palms of the right hands of 21 volunteers with a thermode consisting of 6 bars, the temperature of which was controlled by Peltier elements.

Neuropathic pain phenotyping as a predictor of treatment response in painful diabetic neuropathy: data from the randomized, double-blind, COMBO-DN study.

Sensory profiles are heterogeneous in neuropathic pain disorders, and subgroups of patients respond differently to treatment. To further explore this, patients in the COMBO-DN study were prospectively assessed by the Neuropathic Pain Symptom Inventory (NPSI) at baseline, after initial 8-week therapy with either duloxetine or pregabalin, and after subsequent 8-week combination/high-dose therapy. Exploratory post hoc cluster analyses were performed to identify and characterize potential subgroups through their scores in the NPSI items.