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In 2015, the United States of America (USA) Department of Health and Human Services (HHS) released an issue brief that addressed opioid addiction, opioid overdoses, and opioid-related deaths as a public health concern within the country. After collaboration with state and stakeholder organizations, the HHS identified three target initiatives aimed to mitigate the negative consequences of opioid use within the USA. One initiative included implementation of guidelines to help reduce inappropriate opioid prescribing with a goal to reduce morbidity and mortality. The aim of this commentary is to discuss the misapplication and unintended consequences of the USA CDC Guideline for Prescribing Opioids for Chronic Pain.
Learn More >The effects of exercise on mechanical hyperalgesia, joint contracture, and muscle injury resulting from immobilization are not completely understood. This study aimed to investigate the effects of cyclic stretching on these parameters in a rat model of chronic post-cast pain (CPCP). Seventeen 8-week-old Wistar rats were randomly assigned to (1) control group, (2) immobilization (CPCP) group, or (3) immobilization and stretching exercise (CPCP+STR) group. In the CPCP and CPCP+STR groups, both hindlimbs of each rat were immobilized in full plantar flexion with a plaster cast for a 4-week period. In the CPCP+STR group, cyclic stretching exercise was performed 6 days/week for 2 weeks, beginning immediately after cast removal prior to reloading. Although mechanical hyperalgesia in the plantar skin and calf muscle, ankle joint contracture, and gastrocnemius muscle injury were observed in both immobilized groups, these changes were significantly less severe in the CPCP+STR group than in the CPCP group. These results clearly demonstrate the beneficial effect of cyclic stretching exercises on widespread mechanical hyperalgesia, joint contracture, and muscle injury in a rat model of CPCP.
Learn More >Acute pain can transition to chronic pain, a potentially debilitating illness.
Learn More >Post-thoracotomy pain syndrome (PTPS) is defined as persistent pain following a thoracotomy and has an incidence of 21-61%. Dorsal root ganglion stimulation (DRG-S) is a form of neuromodulation that modulates pain signal transmission to the spinal cord. The aims of this study were to investigate the efficacy of DRG-S for the management of PTPS and to assess the role of thoracic paravertebral blocks (t-PVB) as a tool for prediction of success of DRG-S.
Learn More >Little is known about how primary care clinicians (PCCs) approach chronic pain management in the current climate of rapidly changing guidelines and the growing body of research about risks and benefits of opioid therapy.
Learn More >Chronic visceral pain is one of the primary symptoms of patients with irritable bowel syndrome (IBS), which affects up to 15% of the population world-wide. The detailed mechanisms of visceral pain remain largely unclear. Our previous studies have shown that neonatal maternal deprivation (NMD) followed by adult multiple stress (AMS) advances the occurrence of visceral pain, likely due to enhanced norepinephrine (NE)-β adrenergic signaling. This study was designed to explore the roles of P2X3 receptors (P2X3Rs) in the chronic visceral pain induced by combined stress. Here, we showed that P2X3Rs were co-expressed in β adrenergic receptor (β-AR)-positive dorsal root ganglion neurons and that NE significantly enhanced ATP-induced Ca signals. NMD and AMS not only significantly increased the protein expression of P2X3Rs, but also greatly enhanced the ATP-evoked current density, number of action potentials, and intracellular Ca concentration of colon-related DRG neurons. Intrathecal injection of the P2X3R inhibitor A317491 greatly attenuated the visceral pain and the ATP-induced Ca signals in NMD and AMS rats. Furthermore, the β-AR antagonist butoxamine significantly reversed the expression of P2X3Rs, the ATP-induced current density, and the number of action potentials of DRG neurons. Overall, our data demonstrate that NMD followed by AMS leads to P2X3R activation, which is most likely mediated by upregulation of β adrenergic signaling in primary sensory neurons, thus contributing to visceral hypersensitivity.
Learn More >Fibromyalgia is commonly considered a stress-related chronic pain disorder, and daily stressors are known triggers. However, the relation between stress and pain development remains poorly defined by clinical approaches. Also, the aetiology remains largely unknown.
Learn More >Electro-modulation of subcortical deep brain structures by surgically implanted electrodes is now standard evidence-based treatment for movement disorders such as Parkinson's disease and essential tremor and is approved for dystonia and obsessive-compulsive disorder under a humanitarian exemption. Historically, deep brain stimulation (DBS) for multiple indications has demonstrated acceptable complication rates, rare mortality, and reducing morbidity as the technology and the techniques of its application have advanced. DBS for the amelioration of pain has been performed since the early 1950s, and became widely used in the 1970s, when targeting the somatosensory thalamus was shown to be efficacious for intractable pain syndromes including facial pain. The technique fell out of favour in the late 1990s after 2 multicentre trials failed to meet end-point criteria. Since these trials, DBS for pain has remained for investigational or "off-label" use. Criticisms from previous literature have involved unsuitability of patient selection, as well as inconsistencies in neurosurgical technique. Clinical success with DBS for facial pain has been for the treatment of a variety of chronic neuropathic and nociceptive pain syndromes; including trigeminal neuropathy, post-herpetic neuralgia, deafferentation facial pain, "atypical" facial pain, cluster headaches and other trigeminal autonomic cephalalgias, as well as head and neck pathologies, most often which have been resistant to all other 1st- and 2nd-line medical and surgical treatments, when DBS has become a "last treatment option." An enhanced understanding of the mechanisms of action of DBS for pain will enhance outcome, and appropriately prescribe evolving novel nuclear brain targets.
Learn More >Since the first successful use of high-frequency electrical stimulation of trigeminal branches for treatment of facial pain in 1962, neuromodulation techniques become well established but remain greatly underutilised. Most subsequent implantation techniques and commercial devices for peripheral nerve stimulation, available until the last decade, utilised frequencies in the range 1-100 Hz. With the commercial introduction of 10-kHz spinal cord stimulation, there has been renewed interest in peripheral applications of kHz frequency neuromodulation. High-frequency biphasic stimulation causes rapid onset, reversible conduction block in mammalian nerves which might be useful in human peripheral neuromodulation applications, but the conduction block induced at kilohertz frequencies may not be the only mechanism contributing to analgesia. We discuss likely mechanisms of action of high-frequency peripheral nerve stimulation and present several clinical examples of successful use of this modality in various facial pain conditions. A change to sub-threshold higher frequencies in the 10 kHz range adds a number of distinct advantages. The lack of paresthesias is welcomed by patients. The ability to place the stimulating electrode approximately 1 cm away from the targeted nerve has an anatomical and surgical advantage.
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