[Pain neuroscience education : a practice in motion]. / Éducation neurophysiologique de la douleur : approche en mouvement.

Chronic pain is poorly explained by the pathological biomechanical model. Pain neuroscience education (PNE) aims to help patients reconceptualize their pain by understanding its physiology and dissociating it from the notion of threat. It must be combined with functional re-education. Catastrophism and kinesiophobia exacerbate the perception of pain and are an obstacle to movement. Gradual exposure to movement, whether virtual or real, is a tool for managing pain more effectively and regaining optimum functionality. According to the literature, PNE reduces pain intensity, catastrophizing, kinesiophobia, disability and improves functionality.

La douleur chronique est mal expliquée par le modèle biomédical. L'éducation neurophysiologique de la douleur (END) vise à aider les patients à reconceptualiser leur douleur en comprenant sa physiologie et en la dissociant de la notion de menace. L'association à de la rééducation fonctionnelle est nécessaire. Aggravant la perception de la douleur, le catastrophisme et la kinésiophobie sont des entraves à la remise en mouvement. L'exposition graduelle à la mobilisation, virtuelle ou réelle, constitue un outil permettant de mieux gérer la douleur et de retrouver une fonctionnalité optimale. Selon la littérature, l'END permet une diminution de l'intensité des douleurs, du catastrophisme, de la kinésiophobie, du handicap ainsi qu'une amélioration de la fonctionnalité.

[Use of transcutaneous nerve stimulation (TENS) in chronic pain]. / Douleur chronique : utilité de la neurostimulation électrique transcutanée (TENS).

The management of chronic pain is based on a biopsychosocial approach including pharmacological and non-pharmacological therapies such as Transcutaneous Electrical Nerve Stimulation (TENS). The effectiveness of TENS has been debated for over 50 years. While it provides symptomatic pain relief through physiological neuromodulation mechanisms, irrespective of the type of pain, there is no solid proof that it has curative effects specific to a pathology. There are no robust predictors of response to TENS depending on the type of pain, but reinforcing self-management skills in patients who benefit from it through an educational measure is a guarantee of satisfaction and retention.

La gestion de la douleur chronique repose sur une approche biopsychosociale incluant des thérapies pharmacologiques et non pharmacologiques comme la neurostimulation électrique transcutanée (TENS). Les débats sur l'efficacité de la TENS persistent depuis plus de 50 ans. Si celle-ci apporte un soulagement symptomatique de la douleur grâce à des mécanismes de neuromodulation physiologique et indépendamment du type de douleur. Il n'y a pas de preuve solide qu'elle ait des effets curatifs spécifiques à une pathologie. Il n'y a pas de prédicteurs robustes de la réponse à la TENS en fonction du type de douleur mais le renforcement des compétences d'autogestion chez les patients en bénéficiant par une mesure éducative est gage de satisfaction et de rétention.

Microglial STING activation alleviates nerve injury-induced neuropathic pain in male but not female mice.

Microglia, resident immune cells in the central nervous system, play a role in neuroinflammation and the development of neuropathic pain. We found that the stimulator of interferon genes (STING) is predominantly expressed in spinal microglia and upregulated after peripheral nerve injury. However, mechanical allodynia, as a marker of neuropathic pain following peripheral nerve injury, did not require microglial STING expression. In contrast, STING activation by specific agonists (ADU-S100, 35 nmol) significantly alleviated neuropathic pain in male mice, but not female mice. STING activation in female mice leads to increase in proinflammatory cytokines that may counteract the analgesic effect of ADU-S100. Microglial STING expression and type I interferon-ß (IFN-ß) signaling were required for the analgesic effects of STING agonists in male mice. Mechanistically, downstream activation of TANK-binding kinase 1 (TBK1) and the production of IFN-ß, may partly account for the analgesic effect observed. These findings suggest that STING activation in spinal microglia could be a potential therapeutic intervention for neuropathic pain, particularly in males.

Potassium channel modulation in macrophages sensitizes dorsal root ganglion neurons after nerve injury.

Macrophages and satellite glial cells are found between injured and uninjured neurons in the lumbar dorsal root ganglia (DRG). We explored the mechanism of neuro-immune and neuron-glia crosstalk leading to hyperexcitability of DRG neurons. After spared nerve injury (SNI), CX3CR1+ resident macrophages became activated, proliferated, and increased inward-rectifying potassium channel Kir 2.1 currents. Conditioned medium (CM) by macrophages, obtained from DRG of SNI mice, sensitized small DRG neurons from naïve mice. However, treatment with CM from GFAP+ glial cells did not affect neuronal excitability. When subjected to this macrophage-derived CM, DRG neurons had increased spontaneous activity, current-evoked responses and voltage-gated NaV 1.7 and NaV 1.8 currents. Silencing Kir 2.1 in macrophages after SNI prevented the induction of neuronal hyperexcitability from their CM. Blocking vesicular exocytosis or soluble tumor necrosis factor in CM or interfering with the downstream intracellular p38 pathway in neurons, also prevented neuronal hyperexcitability. Blocking protein trafficking in neurons reduced the effect of CM, suggesting that the hyperexcitable state resulted from changes in NaV channel trafficking. These results suggest that DRG macrophages, primed by peripheral nerve injury, contribute to neuron-glia crosstalk, NaV channel dysregulation and neuronal hyperexcitability implicated in the development of neuropathic pain.

Characterisation of GFAP-Expressing Glial Cells in the Dorsal Root Ganglion after Spared Nerve Injury.

Satellite glial cells (SGCs), enveloping primary sensory neurons' somas in the dorsal root ganglion (DRG), contribute to neuropathic pain upon nerve injury. Glial fibrillary acidic protein (GFAP) serves as an SGC activation marker, though its DRG satellite cell specificity is debated. We employed the hGFAP-CFP transgenic mouse line, designed for astrocyte studies, to explore its expression within the peripheral nervous system (PNS) after spared nerve injury (SNI). We used diverse immunostaining techniques, Western blot analysis, and electrophysiology to evaluate GFAP+ cell changes. Post-SNI, GFAP+ cell numbers increased without proliferation, and were found near injured ATF3+ neurons. GFAP+ FABP7+ SGCs increased, yet 75.5% of DRG GFAP+ cells lacked FABP7 expression. This suggests a significant subset of GFAP+ cells are non-myelinating Schwann cells (nmSC), indicated by their presence in the dorsal root but not in the ventral root which lacks unmyelinated fibres. Additionally, patch clamp recordings from GFAP+ FABP7-cells lacked SGC-specific Kir4.1 currents, instead displaying outward Kv currents expressing Kv1.1 and Kv1.6 channels specific to nmSCs. In conclusion, this study demonstrates increased GFAP expression in two DRG glial cell subpopulations post-SNI: GFAP+ FABP7+ SGCs and GFAP+ FABP7- nmSCs, shedding light on GFAP's specificity as an SGC marker after SNI.

Somatosensory profiling of patients undergoing alcohol withdrawal: Do neuropathic pain and sensory loss represent a problem?

INTRODUCTION: Chronic heavy alcohol use is known to cause neurological complications such as peripheral neuropathy. Concerning the pathophysiology, few sural nerve and skin biopsy studies showed that small fibers might be selectively vulnerable to degeneration in alcohol-related peripheral neuropathy. Pain has rarely been properly evaluated in this pathology. The present study aims at assessing pain intensity, potential neuropathic characteristics as well as the functionality of both small and large nerve sensitive fibers. METHODS: In this observational study, 27 consecutive adult patients, hospitalized for alcohol withdrawal and 13 healthy controls were recruited. All the participants underwent a quantitative sensory testing (QST) according to the standardized protocol of the German Research Network Neuropathic Pain, a neurological examination and filled standardized questionnaires assessing alcohol consumption and dependence as well as pain characteristics and psychological comorbidities. RESULTS: Nearly half of the patients (13/27) reported pain. Yet, pain intensity was weak, leading to a low interference with daily life, and its characteristics did not support a neuropathic component. A functional impairment of small nerve fibers was frequently described, with thermal hypoesthesia observed in 52% of patients. Patients with a higher alcohol consumption over the last 2 years showed a greater impairment of small fiber function. DISCUSSION: Patients report pain but it is however unlikely to be caused by peripheral neuropathy given the non-length-dependent distribution and the absence of neuropathic pain features. Chronic pain in AUD deserves to be better evaluated and managed as it represents an opportunity to improve long-term clinical outcomes, potentially participating to relapse prevention.

[Chronic pain : from symptom to disease]. / La douleur chronique : du symptôme à la maladie.

At last, chronic pain, with its consequences and impact for patients and society, is now considered as a disease in its own in the 11th revision of the international classification of diseases (ICD). We present here in the light of two clinical cases, why the diagnosis of chronic primary pain is useful and how to utilize these new codes. We hope to rapidly see the awaited impact on the healthcare system (from the patient care to insurance issues), as on research and teaching.

La douleur chronique avec ses conséquences et son impact pour les patients et la société est enfin considérée comme une maladie à part entière dans la 11e révision de la Classification internationale des maladies (CIM). Nous présentons ici, à l'aide de deux vignettes, l'utilité du diagnostic de douleur chronique primaire et la façon d'utiliser les nouveaux codes. Nous espérons que l'impact attendu soit rapidement visible tant sur le système de santé (de la prise en charge des patients aux questions assécurologiques), que sur la recherche et l'enseignement.

[Tapering of opioid-based pain treatment for chronic pain patients in an outpatient setting]. / Sevrage en ambulatoire d'un traitement par opiacés chez des patients souffrant de douleur chronique.

Caring for chronic pain patients under opioid therapy is challenging. Opioid treatments above 50 milligrams morphine equivalents (MME) per day are associated with an increased risk of morbidity and mortality. A tapering or a discontinuation should be discussed. Shared decision-making with individualized goals and motivational interviewing principles should be used. Tapering should be slow, with initial rate based on the duration of opioid use and with regular monitoring of patients. Inability to taper may require further reassessment of opioid dependence. Temporary increases in pain may occur at the start of tapering, but pain may improve or remain unchanged upon completion of tapering.

La prise en charge des patients souffrant de douleurs chroniques et traités par des opiacés pose souvent un défi aux cliniciens. Les traitements par des opiacés au-delà de 50 milligrammes d'équivalents de morphine (MME) par jour sont associés à des taux de morbidité et mortalité élevés. Une réduction ou un arrêt doivent être discutés. Cette approche doit se faire en collaboration avec le patient, avec des objectifs individualisés, utilisant des principes d'entretien motivationnel. La diminution doit être lente en tenant compte de la durée préalable du traitement et suivie de manière régulière. L'incapacité à réduire progressivement peut nécessiter l'évaluation d'une possible dépendance. Des augmentations temporaires de la douleur peuvent survenir au début de la réduction, mais la douleur peut rester inchangée ou même s'améliorer une fois la réduction terminée.

[Chronic cancer pain: pathophysiology and ICD-11 classification]. / Douleurs chroniques liées au cancer : physiopathologie et classification CIM-11.

Chronic cancer pain is one of the most common symptoms affecting oncology patients and cancer survivors. Epidemiological trends show that its recognition and management are increasingly important. The ICD-11 provides a better analysis of this problem based on the pathophysiological characteristics of cancer-related pain. This article proposes to review the mechanisms of cancer-related pain in relation to this classification.

La douleur chronique liée au cancer est l'un des symptômes les plus fréquents chez les patients oncologiques et survivants d'un cancer. L'évolution épidémiologique montre que sa reconnaissance et sa prise en charge représentent des enjeux grandissants. La CIM-11 (Classification internationale des maladies) permet une meilleure analyse de cette problématique en se basant sur les caractéristiques physiopathologiques de la douleur liée au cancer. Cet article propose de rappeler, à la lumière de cette classification, les mécanismes de la douleur associée à un cancer.

[Cancer pain therapy: beyond conventional pharmacological approaches]. / Traitement de la douleur cancéreuse : au-delà des approches médicamenteuses conventionnelles.

Pain management in oncology is evolving progressively thanks to integrative approaches. In accordance with the type of pain and patient specifics, treatment possibilities are thus multiplied by combining conventional pharmacology, interventional approaches, physical and psychological treatments as well as complementary medicines, in a holistic perspective. International Societies Guidelines and scientific literature lend their support to such treatment plans. This article covers a number of interventional treatments and complementary options that are available. Their relevance is all the more important in view of the necessity to limit secondary effects and long-term opioids, especially in cancer survivors.

La prise en charge de la douleur en oncologie s'enrichit progressivement grâce à une approche intégrative. Celle-ci permet d'élargir la palette des outils thérapeutiques du praticien en combinant, selon les caractéristiques de la douleur et les spécificités du patient, les approches conventionnelles et complémentaires dans une vision holistique du patient. Les recommandations des sociétés internationales et la littérature scientifique s'étayent dans cette direction. Cet article couvre une partie des thérapies interventionnelles et des options complémentaires possibles. Leur pertinence est d'autant plus grande dans l'optique de limiter les effets secondaires des traitements médicamenteux et les opioïdes au long cours, prioritairement chez les patients en rémission ou avec une maladie contrôlée.

Prehospital Use of Ketamine in Mountain Rescue: A Survey of Emergency Physicians of a Single-Center Alpine Helicopter-Based Emergency Service.

INTRODUCTION: Although ketamine use in emergency medicine is widespread, studies investigating prehospital use are scarce. Our goal was to assess the self-reported modalities of ketamine use, knowledge of contraindications, and occurrence of adverse events associated with its use by physicians through a prospective online survey. METHODS: The survey was administered to physicians working for Air-Glaciers, a Swiss alpine helicopter-based emergency service, and was available between September 24 and November 23, 2018. We enrolled 39 participants (participation rate of 87%) in our study and collected data regarding their characteristics, methods of ketamine use, knowledge of contraindications, and encountered side effects linked to the administration of ketamine. We also included a clinical scenario to investigate an analgesic strategy. RESULTS: Ketamine was considered safe and judged irreplaceable by most physicians. The main reason for ketamine use was acute analgesia during painful procedures, such as manipulation of femur fractures. The doses of ketamine administered with or without fentanyl ranged from 0.2 to 0.7 mg·kg-1 intravenously. Most physicians reported using fentanyl and midazolam along with ketamine. The median dose of midazolam was 2 (interquartile range 1-2) mg for a 70-kg adult. Monitoring and oxygen administration were used infrequently. Hallucinations were the most common adverse events. Knowledge of ketamine contraindications was poor. CONCLUSIONS: Ketamine use was reported by mountain rescue physicians to be safe and useful for acute analgesia. Most physicians use fentanyl and midazolam along with ketamine. Adverse neuropsychiatric events were rare. Knowledge regarding contraindications to the administration of ketamine should be improved.

Pain Intensity in the First 96 Hours After Abdominal Surgery: A Prospective Cohort Study.

OBJECTIVE: Multimodal pain management strategies aim to improve postoperative pain control. The purpose of this study was to analyze pain scores and risk factors for acute postoperative pain after various abdominal surgery procedures. METHODS: Data on 11 different abdominal surgery procedures were prospectively recorded. Pain intensity (rest, mobilization) and patient satisfaction at discharge were assessed using a visual analog scale (VAS; 0-10), and analgesic consumption was recorded until 96 hours postoperation. Demographic, surgery-related, and pain management-related univariate risk factors for insufficient pain control (VAS ≥ 4) were entered in a multivariate logistic regression model. RESULTS: A total of 1,278 patients were included. Overall, mean VAS scores were <3 at all time points, and scores at mobilization were consistently higher than at rest (P < 0.05). Thirty percent of patients presented a prolonged VAS score ≥4 at mobilization at 24 hours, significantly higher than at rest (14%, P < 0.05). High pain scores correlated with high opioid consumption, whereas a variability of pain scores was observed in patients with low opioid consumption. The only independent risk factor for moderate and severe pain (VAS ≥ 4) was younger age (<70 years, P = 0.001). The mean satisfaction score was 8.18 ± 1.29. CONCLUSIONS: Among 1,278 patients, pain was controlled adequately during the first four postoperative days, resulting in high levels of patient satisfaction. Pain levels were higher at mobilization. Younger age was the only independent risk factor for insufficient pain control. Preventive treatment in patients <70 years old and before mobilization could be evaluated for potential improvement.

The steps until surgery in the management of Baastrup's Disease (kissing spine syndrome).

Baastrup's disease is a rare condition of the vertebral column often misdiagnosed and wrongly treated due to poor knowledge, characterized by low back pain arising from the close approximation of adjacent posterior spinous processes and resultant degenerative changes. Diagnosis rests on clinical examination and detailed imaging studies. Proposed therapies include conservative treatment, percutaneous infiltrations or surgical therapies. We present the case of a 31-year-old man with persistent chronic lumbago for several years. In whom, the diagnosis of Baastrup's disease was high suspected clinically, with a final surgical treatment despite the absence of inflammation on imaging studies, which allowed the diagnostic confirmation and the return to a normal social and professional life. We wish through this case, to expose the different steps of interventional diagnostic/therapeutical procedures until the surgical management in a clinical suspicion of Baastrup's diseases with unclear radiological findings.

[Physical activity and analgesia : mechanisms and clinical implications]. / Activité physique et analgésie : mécanismes et implications cliniques.

Physical activity is a protective factor in many diseases and a sedentary lifestyle can be an aggravating factor. Physical activity globally reduces mortality. Pain is not an exception and physical activity is in first lines in the treatment of certain type of chronic pain. However, it can be difficult to convince patients to make an activity that can potentially increase symptoms. We will recall the effects of physical activity on pain mechanisms in the nervous and immune system, as well as on frequent psychological comorbidities in patient with chronic pain. We will also see how to manage the increasing of pain while patients begin the practice of physical activity.

L'activité physique est un facteur protecteur dans de nombreuses maladies et, à l'inverse, la sédentarité peut être un facteur aggravant. L'activité physique réduit globalement la mortalité toutes causes confondues. La douleur ne fait pas exception et l'activité physique fait également partie de la première ligne de traitement dans certains types de douleurs chroniques. Il peut cependant être difficile de convaincre les patients douloureux chroniques de pratiquer une activité pouvant exacerber les symptômes. Nous allons rappeler les effets de l'activité physique sur les mécanismes de la douleur aux niveaux du système nerveux, de l'inflammation ainsi que sur les comorbidités psychologiques fréquentes chez les patients douloureux chroniques. Nous proposerons aussi des solutions pour gérer l'augmentation aiguë des symptômes lorsque les patients débutent la pratique de l'activité physique.