The level of agreement between the numerical rating scale and visual analogue scale for assessing pain intensity in adults with chronic pain.

The numerical rating scale and visual analogue scale are used to quantify pain intensity. However, it has not yet been explored whether these scores are interchangeable in adults with chronic pain. Data from the prospective multicentre cross-sectional INTERVAL study were used to evaluate the one-dimensionality and agreement between numerical rating scale scores and visual analogue scale scores in adults with chronic pain. Pain intensity scores using the numerical rating scale and visual analogue scale were provided by 366 patients with chronic pain for current, average, minimal and maximal pain. To evaluate whether pain intensity scales are completed in accordance with each other, the proportion of patients who satisfied the following condition was calculated: minimal pain intensity ≤ maximal pain intensity. A factor analysis confirmed the one-dimensionality of the pain measures. A significant difference was found between numerical rating scale and visual analogue scale scores for average, current, minimum and maximum pain. Intra-class correlation coefficient estimates ranged from 0.739 to 0.858 and all measures failed to show sufficient and acceptable agreement at the 95% level. The strength of agreement between pain severity categories was classified as 'moderate' for average and minimal pain and 'substantial' for current and maximal pain. The proportion of patients who scored minimal pain ≤ maximal pain was 97.5% for the numerical rating scale and 89.5% for the visual analogue scale. This study failed to show an acceptable agreement between the numerical rating scale and visual analogue scale when pain intensity was rated by adults with chronic pain, despite showing both scales measure the same information.

Docosahexaenoic acid (DHA) injection in spinal cord transection stimulates Na⁺,K⁺-ATPase in skeletal muscle via ß 1 subunit.

Spinal cord injuries (SCI) induce a loss of skeletal muscle mass and functional capacity. The muscle excitability and contractility depend on the plasma membrane potential, regulated by transmembrane ion gradients, and thus necessarily on the Na⁺,K⁺-ATPase activity. The aim of this work was to evaluate the consequences of a spinal cord transection (SCT) on the skeletal muscle Na⁺,K⁺-ATPase and the impact of collateral GlyceroPhosphoLipids enriched in DocosaHexaenoic Acid (GPL-DHA) administration. The Na⁺,K⁺-ATPase activity and membrane expression of Na⁺,K⁺-ATPase α1, α2 and ß1 isoforms were assessed by K⁺-stimulated paranitrophenyl phosphatase (pNPPase) measurements and Western Blotting, respectively. The results show that spinal cord transection increased significantly (p<0.05) Na⁺,K⁺-ATPase activity in muscle by 25% and decreased the amounts of α1 isoform and α2 isoform expressions by 50% (p<0.05) respectively compared to controls. The results also show that early injection of GPL-DHA after SCT decreases in membrane skeletal muscle the α1 and α2 isoforms expression but increases the membrane Na⁺,K⁺-ATPase activity. This treament partially restores the membrane expression of the ß1 subunit of the Na⁺,K⁺-ATPase. These data suggest that the increase of ß1 subunit expression is probably the main trigger to the membrane Na⁺,K⁺-ATPase activation following a trans-synaptic denervation.

Contribution of Minimally Invasive Bone Augmentation With PMMA Cement in Primary Fixation of Schatzker Type II Tibial Plateau Fractures.

Background: The most common type of fracture of the lateral tibial plateau is the Schatzker type II split-depressed fracture. Minimally invasive surgery using balloon reduction appears to be very promising compared to the gold standard using a bone tamp. This surgery aims to have the best reduction and stabilization to benefit from an early passive and active rehabilitation to avoid stiffening and muscle wasting. Using a balloon for fracture reduction has allowed the use of semi-liquid Injectable Bone Cement (IBC) fillers. These fillers can be phosphocalcic or polymethyl methacrylate (PMMA). The latest recommendations on these IBCs in spinal surgery increasingly rule out phosphocalcic fillers because of their low mechanical strength. Questions/purposes: 1) What is the mechanical influence of IBC filling (PMMA) regarding the split and depression components of a Schatzker type II fracture? 2) What is the mechanical influence of osteosynthesis regarding the split and depression components of a Schatzker type II fracture with or without PMMA filing in three different kinds of percutaneous fixations? Methods: This biomechanical study was performed on 36 fresh frozen tibia/fibula specimens. Six groups were formed according to the type of percutaneous osteosynthesis or possible PMMA filling. Mechanical strength tests were carried out using a Unicompartmental Knee prosthesis and displacement components were measured on either side of the separation on the anterolateral facet by optical method. Results: We found a significant difference between cementless and cemented osteosynthesis for depression fracture stabilization (difference -507.56N with 95% confidence interval [-904.17; -110.94] (p-value = 0.026)). The differences between the different types of osteosynthesis were not significant (p-value = 0.58). There was a significant difference between osteosynthesis without cement and osteosynthesis with cement on separation (difference -477.72N [-878.52; -76.93] (p-value = 0.03)). The differences between the different types of fixations were not significant regarding separation (p-value = 0.99). Conclusion: PMMA cement significantly improves primary stability, regardless of the type of osteosynthesis for a Schatzker type II plateau fracture. Filling with PMMA cement during tuberoplasty seems to be a very promising strategy in association with percutaneous osteosynthesis to allow rapid recovery after surgery.

Relation between α-isoform and phosphatase activity of Na+,K+-ATPase in rat skeletal muscle fiber types.

In skeletal muscle the relationship between Na+,K+-ATPase activity and isoform content remains controversial (9,6). It could be due to the fiber-type content, membrane isolation and analytical methods. We investigated the distribution of subunit α1 and α2 Na+,K+-ATPase catalytic isoforms and the Na+,K+-ATPase activity in isolated membranes from white ( type I and glycolitic fibers) and red (type II and oxidative fibers) skeletal muscles. Red Gastrocnemius and White Gastrocnemius muscles were sampled from 8 week-old female Wistar rats and crude membranes were performed. The Na+,K+-ATPase activity and membrane distribution of Na+,K+-ATPase α1 and α2 isoforms were assessed by ouabain sensitive K-phosphatase (Kpase) measurements and Western Blot respectively. The Na+,K+-ATPase activity was 6 fold lower in White Gastrocnemius membranes than in Red Gastrocnemius membranes. The α1 and α2-isoform levels are higher in RG than in White Gastrocnemius. The α1 and α2-subunit Red Gastrocnemius content was significantly higher than in WG. The correlation between crude membrane Kpase activity and both catalytic α-subunit of the Na+,K+-ATPase exist.These data suggest that the Na+,K+-ATPase phosphatase activity correlates with the α1 and α2 isoforms levels in Red Gastrocnemius and White Gastrocnemius and confirms the fiber-specific Na+,K+-ATPase catalytic α-subunits and α2-isoform as the major catalytic isoform in rat skeletal muscle.

Fracture behavior of cancellous bone and cancellous bone-PMMA bone cement interface: An experimental study using an integrated methodology (wedge splitting test and Heaviside-based digital image correlation).

Minimally invasive methods, such as balloon kyphoplasty (BKP) and percutaneous sacroplasty (PS), which are now widely used for the surgical treatment of compression fractures, involve injection of a bolus of poly (methyl methacrylate) bone cement (hereafter, "bone cement") into the fractured tissue. Many of the common complications following these surgeries, such as cement leakage and adjacent-level fractures (in the case of BKP), have been postulated to be related to the quality of the cancellous bone-bone cement interface, which, in turn, is a function of its fracture resistance. It is common to use bovine cancellous bone or polyurethane foam (PF) as a substitute for human cancellous bone in biomechanical studies of these surgical methods. The literature is lacking in studies of determination of fracture properties of human cancellous bone-bone cement interface, bovine cancellous bone-bone cement interface, and PF-bone cement interface. In the present work, an integrated methodology (combination of wedge splitting test and Heaviside-based digital image correlation) was used to make these determinations as well as those for the bone cement, bones and the PF alone. The fracture properties determined were maximum fracture load (Fmax), fracture toughness (Kc), and specific fracture energy (Gf). For example, Gf values for human cancellous bone and human cancellous bone-bone interface were 0.48±0.14 N/mm and 0.38±0.05 N/mm, respectively, whereas in the case of bovine cancellous bone and bovine cancellous bone-bone cement interface, they were 1.08±0.11 N/mm and 0.22±0.05 N/mm, respectively, and for PF (Grades 12.5 and 15.0) and PF-bone cement interface, they were 0.81±0.12 and 0.55±0.06 N/mm, respectively. The same trends were seen in the Fmax and Kc results. These results suggest that it may not be justified to use either bovine cancellous bone or either of the PF grades as a substitute for human cadaveric cancellous bone in biomechanical studies of BKP, PS, and similar surgical methods.

Evaluation of fracture properties of cancellous bone tissues using digital image correlation/wedge splitting test method.

The fracture mechanics (FM) parameters of cancellous bone tissues are very important from a clinical point of view especially for the bone cement augmentation. From the literature review, one can observe that the experimental determination of fracture mechanic parameters of cancellous bone are still lacking. This can be due to the conditions associated with the unstable crack propagation in the cancellous bone and lack of tools to extract and measure the parameters (like crack opening displacement (COD) and crack length) in the course of fracture tests, which are necessary to evaluate the fracture properties. To address above mentioned, a platform was developed integrating an optical measurement technique like digital image correlation (DIC) with classical wedge splitting test (WST) method to extract precise and real crack tip positions, crack opening displacement (COD) at each load step. These indeed used for the evaluation of the fracture mechanic properties (fracture toughness, specific fracture energy (Gf)) of the cancellous bone. Two approaches were used to evaluate the fracture mechanic properties of the bone. The first method is based on the global approach, which was widely used in the literature and the second method is based on the local approach. In this local approach, the local fracture energy (Gi) during the course of the test was evaluated, which give access to local fracture mechanics. The results evaluated by both the methods were in good accordance and compared with available literature. In addition, an attempt made to retrieve the real crack tip position at each load step during the test.

[Review of the peripheral nerve]. / Rappels sur le nerf périphérique.

The peripheral nerve provides the pathway for motor, sensory, and vegetative axons belonging to the peripheral nervous system. It transmits information between these neurons and their peripheral effectors in both directions (sensory receptors, skeletal muscles, and viscera). The afferences to the periphery correspond to the nerve motor content, whereas efferences from the periphery, in charge of delivering information to the central integrators, correspond to nerve-sensitive content. This information support depends on the intrinsic properties of the nerve itself. Peripheral nerve injuries are frequent and generate significant deficits. Their treatment sometimes leads to functional recovery but is mostly incomplete or unpredictable, despite the regular use of sophisticated repair techniques. The clinician must clearly understand the peripheral nervous system's responses to injury, which reveal surprising degenerating and spontaneous regenerating abilities. This potential recovery is a peripheral nervous system specificity and follows a relatively complex process. Peripheral neurons depend on glial cell structure and metabolism, inducing the global and dynamic response of the whole axon environment, even in cases of focal lesion, modulated by the initial type and mechanism of injury. Today's progress remains insufficient to improve functional prognosis significantly, but a better understanding of peripheral nerve regenerating processes obtained in cellular and molecular biology has opened the door to new medical and surgical advances.

[Peripheral nerve tumors]. / Tumeurs des nerfs périphériques.

Peripheral nerve tumors are most often benign tumors of the nerve sheath; uncommonly they come from the nerve cells or are metastatic tumors. A precise diagnosis is required for well-adapted and effective treatment, as is good knowledge of fibromatosis diseases. In some cases, the diagnosis of the nerve tumor will lead to a diagnosis of phakomatosis. Surgical treatment must be clearly discussed, which, in case of schwannomas gives very good functional results. Primitive malignant tumors remain an unsolved therapeutic problem.

[Retrospective study of the long-term results of selective peripheral neurotomy for the treatment of spastic upper limb]. / Etude rétrospective du résultat à long terme des neurotomies sélectives périphériques dans le traitement du membre supérieur spastique.

BACKGROUND/OBJECTIVE: Peripheral selective neurotomy is commonly used to treat the equinus spastic foot (tibial nerve), but is less frequently used in treating upper limb spasticity, because of the complexity of the articular deformities and the complex innervations of the different muscles. We present our experience and the long-term results of this surgery based on a retrospective series of 22 patients with a disabling spasticity of the upper limb. METHODS: Between 2003 and 2006, neurotomies were performed in 22 patients with disabling spasticity of the upper limb despite optimal medical treatment. Patients were evaluated before and after the surgical procedure. Twelve clinical parameters were studied for describing deformity (resting position and amplitude of each joint), spasticity (Ashworth and Tardieu scores), and the functional impacts of the spasticity. RESULTS: At long-term follow-up, all parameters were improved from the surgery, both in terms of spastic symptoms (highly significantly decreased in Ashworth and Tardieu scores) and the deformity of the upper limb (e.g., 60 degrees increase in the extension of the elbow). Pain, active amplitude, and functional impact scores were also statistically significantly improved after surgery. The mean satisfaction index was 7/10 (+/-1.6). CONCLUSIONS: Selective neurotomy is an effective treatment for patients with a disabling and excessive spasticity in the upper limb. It provides a long-term, objective improvement based on analytical and functional parameters. We emphasize the importance of accurate clinical evaluation and surgical planning. Finally, excessive time to treatment seems to be an important factor for recurrence or incomplete efficiency of the procedure.

[Molecular architecture of the sarcoplasmic reticulum and its role in the ECC]. / Architecture moléculaire du réticulum sarcoplasmique et son rôle dans le couplage excitation-contraction.

The sarcoplasmic reticulum (SR) plays a fundamental role in excitation-contraction coupling, which propagates the electric signal conversion along the muscle fiber's plasmic membrane to a mechanical event manifested as a muscle contraction. It plays a crucial role in calcium homeostasis and intracellular calcium storage control (storage, liberation and uptake) necessary for fiber muscle contraction and then relaxation. These functions take place at the triad, made up of individualized SR subdomains where the protein-specific organization provides efficient and fast coupling. Ryanodine receptors (RyR) and dihydropyridine receptors (DHPR) mainly act in calcium exchanges in the SR. This particular structural and molecular architecture must be correlated to its functional specificity.

[The main tunnel syndromes]. / Les principaux syndromes canalaires.

Several tunnel syndromes are responsible for substantial functional impairment. The diagnosis has to be made and treatment is most often very simple--nerve decompression--with excellent results. Of these syndromes, the most common are median and ulnar tunnel syndromes of the wrist and ulnar tunnel syndrome of the elbow, but other syndromes must be identified at the risk of therapy failure due to poorly adapted treatment. Finally, good knowledge of this pathology must lead to prevention of the iatrogenic forms (sequelae of inguinal hernia treatment, ileac crest graft harvesting) by educating all surgeons interested in peripheral nerve surgery.

[Experimental and pathological changes of the neuromuscular junction]. / Remaniements expérimentaux et pathologiques de la jonction neuromusculaire.

The objective of our study was to investigate the cellular communication between the axon and its postsynaptic targets in the synapse. We used the neuromuscular junction (NMJ) model, which is a highly specialized structure between the nerve, the muscle, and the Schwann cell terminal where the motor neuron orders the muscle to contract. We used experimental models of motor nerve reimplantation in a denervated muscle to determine whether 1) the formation of new NMJ could participate in reinnervation of the muscle necessary to contraction or 2) the blockage of neurotransmitter release using botulinum toxin could be compensated by the formation of new NMJ. We also studied human genetic diseases that affect neuromuscular transmission--congenital myasthenic syndromes--to identify the mutations in the genes coding for synaptic molecules and to analyze the compensatory processes involved in NMJ dysfunction so that muscle contraction can occur in these conditions.

[Physiology of the injured peripheral nerve]. / Physiologie du nerf traumatisé.

Peripheral nerve injuries are frequent and generate significant deficits. Their treatment sometimes leads to functional recovery but is mostly incomplete or unpredictable, despite the regular use of sophisticated repair techniques. The clinician must clearly understand the peripheral nervous system's responses to injury, which reveal surprising degenerating and spontaneous regenerating abilities. This potential recovery is a peripheral nervous system specificity and follows a relatively complex process. Peripheral neurons depend on glial cell structure and metabolism, inducing a global and dynamic response of the whole axon environment, even in cases of focal lesion, modulated by the initial type and mechanism of injury. Today's progress remains insufficient to improve functional prognosis significantly, but a better understanding of peripheral nerve regenerating processes has opened the door to new medical and surgical advances.

[Pathophysiological, molecular and metabolic changes at the neuromuscular junction and the peripheral nerve after central nervous system lesions in humans]. / Caractérisation physiopathologique, moléculaire et métabolique de la jonction neuromusculaire et du nerf périphérique après lésion du système nerveux central chez l'homme.

From the elaborate information processing that takes place in the brain to the contraction of skeletal muscles, the neurotransmission pathways involve, at least in part, (1) in tissue, Na+, K+-ATPase electrogenesis making action potential (AP) propagation possible and (2) in the cell, the synthesis, maturation, and renewal of an amazing number of molecules concentrated at the neuromuscular junction (NMJ). Our aim is to clarify CNS and peripheral nerve system (PNS) interactions by determining whether the partial motor recovery sometimes observed after a lesion of the first motoneuron is related to (1) changes in active transportation of the ions in peripheral nerve and/or muscle and (2) morphological and/or molecular changes at the NMJ, illustrating a dysfunction. Peripheral nerve surgery is proposed to some spastic patients who have recovered partially after CNS lesions to improve their gait. During these surgical procedures, the nerve and muscle samples that are usually resected can be collected and analyzed. Here, we report on eight patients who showed strictly similar motor recovery 2 years after massive CNS lesions and who underwent a selective tibial neurotomy for a spastic equinus foot. In these eight spastic patients, we performed a pathophysiological, molecular, and metabolic study of their neuromuscular junctions and peripheral nerves to characterize the dysfunction of the neuromuscular transmission after a permanent CNS injury.

[Mechanisms controlling axonal sprouting at the neuromuscular junction]. / Mécanismes contrôlant le bourgeonnement axonal à la jonction neuromusculaire.

This paper explores the specific roles of sprouting stimuli, perisynaptic Schwann cells and neuromuscular activity in axonal sprouting at the neuromuscular junction in partially denervated muscles. As for sprouting stimuli, insulin-like growth factor II which is generated from inactive muscle fibers in partially denervated and paralysed skeletal muscle is described. Likewise, perisynaptic Schwann cells can induce and guide axonal sprouting in partially denervated muscles. Finally, excessive neuromuscular activity significantly reduces bridging of the perisynaptic Schwann cell processes between denervated and innervated endplates and thereby inhibits axonal sprouting in partially denervated muscle. The lack of neuromuscular activity is also harmful in axonal sprouting, probably by impeding calcium influx into the nerve.

[Synapse formation and regeneration]. / Formation et régénération synaptique.

Synapse formation is probably the key process in neural development allowing signal transmission between nerve cells. As an interesting model of synapse maturation, we considered first the neuromuscular junction (NMJ), whose development is particularly dependent on intercellular interactions between the motor nerve and the skeletal muscle. Nerve and muscle have distinct roles in synaptic compartment differentiation. The initial steps of this differentiation and motor endplate formation require several postsynaptic molecular agents including agrin, the tyrosine kinase receptor MuSK and rapsyn. The agrin or motoneuron dependence of this process continues to be debated while the following steps of axonal growth and postsynaptic apparatus maintenance essentially depend on neuronal agrin and a neuron-specific signal dispersing ectopic AChR aggregate remainders, possibly mediated by acetylcholine itself. Neuregulin is essentially involved in Schwann's cell survival and guidance for axonal growth. In this paper, we will discuss the similarities between Central Nervous System (CNS) synaptic formation and Motor innervation. The limited ability of the CNS to create new synapses after nervous system injury will be then discussed with a final consideration of some new strategies elaborated to circumvent the limitations of lesion extension processes.

[Major mechanisms involved in the synaptic transmission of the neuromuscular apparatus]. / Principaux mécanismes impliqués dans la transmission synaptique au sein de l'appareil neuromusculaire.

Neuromuscular transmission results from a double signal transduction from electric impulses to chemical messengers, taking place at a highly differentiated region, the neuromuscular junction (NMJ). A nerve cell responds to a specific stimulus by modifications of its plasmic membrane properties, generating an action potential (AP). This electric signal is transmitted along the axon to the NMJ, where it induces the voltage-gated calcium channels to open. Intracellular calcium entry leads to acetylcholine release in the synaptic space at the active zones but all scientists do not consider it the major release factor. Acetylcholine binding with its receptor at the muscle membrane generates an endplate potential when the induced depolarization is greater than the sodium voltage channel opening threshold. Muscle AP causes a muscle contraction involving the three phases. This paper will successively review the electrophysiological and molecular mechanisms involved at the pre-, inter- and postsynaptic levels. The last part of the article will discuss electromechanical considerations directly affecting the mechanical properties of the muscle fiber, most particularly the factors influencing the predetermined involvement of motor units, motor neuron electrical properties determining responses to synaptic inputs and finally the impact of recruited motor neurons and their electrical impulse rates on muscle contraction strength and velocity.

[Structural and molecular organization, development and maturation of the neuromuscular junction]. / Organisation structurale, moléculaire, formation et maturation de la jonction neuromusculaire.

The neuromuscular junction is made up of the apposition of highly differentiated domains of three types of cell: the motor neuronal ending, the terminal Schwann cell and the muscle postsynaptic membrane. These three components are surrounded by a basal lamina, dedicated to molecular signal exchanges controlling neuromuscular formation, maturation and maintenance. This functional and structural differentiated complex conducts synaptic neurotransmission to the skeletal muscle fiber. Nerve and muscle have distinct roles in synaptic compartment differentiation. The initial steps of this differentiation and the motor endplate formation require several postsynaptic molecular agents including agrin, the tyrosine kinase receptor MuSK. Neuregulin is essentially involved in Schwann cell survival and guidance for axonal growth.

[Medical and economic reflections on Restore and Itrel neurostimulation systems for neuropathic pain treatment]. / Réflexion sur l'intérêt médicoéconomique des boîtiers de neurostimulation Restore et Itrel dans le traitement des douleurs neuropathiques chroniques.

In 2007, four patients where implanted with the Restore neurostimulation system for intractable chronic leg pain at the Poitiers Hospital. The potential for improving the patients' quality of life and medical-economic concerns motivated this choice for these highly selected patients. In this paper, we propose brief clinical case reports and discuss the reasons for choosing this new rechargeable system, even though it was initially more expensive than the standard neurostimulation system (Itrel 3). All patients receiving implants declared that they were very satisfied with the quality of stimulation provided by Restore and noted a significant improvement in their quality of life. If this solution becomes advantageous from an economic point of view, clinical data should lend support to the utility of this technological innovation for patients who have hitherto been in treatment failure.

[Anatomy and physiology of the peripheral nerve]. / Organisation anatomique et physiologique du nerf périphérique.

The peripheral nerve provides the pathway for motor, sensory and vegetative axons belonging to the peripheral nervous system. It transmits information between these neurons and their peripheral effectors in both directions (sensory receptors, skeletal muscles and viscera). The afferences to the periphery correspond to the nerve motor content, whereas efferences from the periphery, in charge of delivering information to the central integrators, correspond to nerve-sensitive content. This information support depends on intrinsic properties of the nerve itself. Recent advances in cellular and molecular biology have provided a better understanding of nerve physiology, which are reviewed here as an indispensable basis to the study of its pathology.