Articles: neuropathic-pain.
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The descending pain modulatory system represents one of the oldest and most fundamentally important neurophysiological mechanisms relevant to pain. Extensive work in animals and humans has shown how a functional imbalance between the facilitatory and inhibitory components is linked to exacerbation and maintenance of persistent pain states. Forward translation of these findings into clinical populations is needed to verify the relevance of this imbalance. ⋯ The current study used a multimodal clinical neuroimaging approach to interrogate whether the sensory phenotype of painful diabetic polyneuropathy involves altered function of the ventrolateral periaqueductal grey-a key node of the descending pain modulatory system. We found that ventrolateral periaqueductal grey functional connectivity is altered in patients suffering from painful diabetic polyneuropathy; the magnitude of which is correlated to their spontaneous and allodynic pain as well as the magnitude of the cortical response elicited by an experimental tonic heat paradigm. We posit that ventrolateral periaqueductal grey-mediated descending pain modulatory system dysfunction may reflect a brain-based pain facilitation mechanism contributing to painful diabetic polyneuropathy.
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Clinical Trial
Stimulation of the L2-L3 Dorsal Root Ganglia Induces Effective Pain Relief in the Low Back.
Chronic low back pain affects millions of people worldwide and can arise through a variety of clinical origins. In the case of failed back surgery syndrome (FBSS), previous surgical procedures can contribute to low back pain that is often unresponsive to intervention. Although spinal cord stimulation (SCS) can be an effective treatment modality, it does not provide sufficient pain relief for some intractable cases. Recently, alternative neuromodulation options have been developed, including dorsal root ganglion (DRG) stimulation. The objective of this report is to further investigate these clinical observations. ⋯ For the studied population, DRG stimulation at the L2-L3 levels was effective at relieving low back pain. These reductions in pain were associated with improvements in quality of life. Thus, DRG stimulation at these levels may be effective for low back pain by recruiting both segmental and nonsegmental neural pathways that are not otherwise accessible via traditional SCS.
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Many cultures throughout history have used cannabis to treat a variety of painful ailments. Neuropathic pain is a complicated condition that is challenging to treat with our current medications. Recent scientific discovery has elucidated the intricate role of the endocannabinoid system in the pathophysiology of neuropathic pain. As societal perceptions change, and legislation on medical cannabis relaxes, there is growing interest in the use of medical cannabis for neuropathic pain. ⋯ We examined current basic scientific research and data from recent randomized controlled trials (RCTs) evaluating medical cannabis for the treatment of neuropathic pain. These studies involved patients with diverse etiologies of neuropathic pain and included medical cannabis with different THC concentrations and routes of administration. Multiple RCTs demonstrated efficacy of medical cannabis for treating neuropathic pain, with number needed to treat (NNT) values similar to current pharmacotherapies. Although limited by small sample sizes and short duration of study, the evidence appears to support the safety and efficacy of short-term, low-dose cannabis vaporization and oral mucosal delivery for the treatment of neuropathic pain. The results suggest medical cannabis may be as tolerable and effective as current neuropathic agents; however, more studies are needed to determine the long-term effects of medical cannabis use. Furthermore, continued research to optimize dosing, cannabinoid ratios, and alternate routes of administration may help to refine the therapeutic role of medical cannabis for neuropathic pain.
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J Pain Symptom Manage · Feb 2018
Cancer pain with a neuropathic component: a cross-sectional study of its clinical characteristics, associated psychological distress, treatments and predictors at referral to a cancer pain clinic.
In patients with cancer pain, identifying a neuropathic pain component (NPC) may inform the selection of subsequent therapeutic interventions. ⋯ One in three patients with cancer have an NPC, which is independently associated with recent chemotherapy, surgery, adjuvant analgesic use, episodic incident and breakthrough pain, longer pain duration, higher pain intensity, and pelvic or perineal pain location.
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Neuroscience bulletin · Feb 2018
Expression and Role of Voltage-Gated Sodium Channels in Human Dorsal Root Ganglion Neurons with Special Focus on Nav1.7, Species Differences, and Regulation by Paclitaxel.
Voltage-gated sodium channels (Navs) play an important role in human pain sensation. However, the expression and role of Nav subtypes in native human sensory neurons are unclear. To address this issue, we obtained human dorsal root ganglion (hDRG) tissues from healthy donors. ⋯ To mimic Nav regulation in chronic pain, we treated hDRG neurons in primary cultures with paclitaxel (0.1-1 μmol/L) for 24 h. Paclitaxel increased the Nav1.7 but not Nav1.8 expression and also increased the transient Na+ currents and action potential firing frequency in small-diameter (<50 μm) hDRG neurons. Thus, the hDRG provides a translational model in which to study "human pain in a dish" and test new pain therapeutics.