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Chronic pain is a highly prevalent and complex health problem that is associated with a heavy symptom burden, substantial economic and social impact, and also, very few highly effective treatments. This review examines evidence for the efficacy and safety of magnesium in chronic pain. The previously published protocol for this review was registered in International Prospective Register of Systematic Reviews (PROSPERO), MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched until September 2018. We included randomized controlled trials (RCTs) comparing magnesium (at any dose, frequency, or route of administration) with placebo using participant-reported pain measures. A total of 9 RCTs containing 418 participants were included. Three studies examined neuropathic pain (62 participants), 3 examined migraines (190 participants), 2 examined complex regional pain syndrome (86 participants), and 1 examined low back pain with a neuropathic component (80 participants). Heterogeneity of included studies precluded any meta-analyses. No judgement could be made about safety because adverse events were inconsistently reported in the included studies. Evidence of analgesic efficacy from included studies was equivocal. However, reported efficacy signals in some of the included trials provide a rationale for more definitive studies. Future, larger-sized trials with good assay sensitivity and better safety assessment and reporting, as well as careful attention to formulations with optimal bioavailability, will serve to better define the role of magnesium in the management of chronic pain.
Learn More >There is a high prevalence of painful diabetic polyneuropathy (pDPN) with around one-third of all patients with diabetes suffering from pDPN. pDPN has debilitating consequences, with a major impact on morbidity and quality of life. Unfortunately, there is no globally licenced pharmacotherapy that modulates the underlying disease mechanisms to prevent or halt the progression of diabetic neuropathy. The cornerstone of treatment therefore remains optimising glycaemic control and cardiovascular risk factors, and symptom control. Evidence from placebo-controlled studies has shown that antidepressants and anticonvulsants are effective for alleviating pDPN. Current clinical guidelines recommend the treatment of pDPN through the use of amitriptyline (tricyclic antidepressant), duloxetine (serotonin norepinephrine reuptake inhibitor), gabapentin and pregabalin (α2-δ ligands), tramadol and tapentadol (μ receptor agonists and norepinephrine reuptake inhibitors) and topical agents such as capsaicin (transient receptor potential V1 receptor desensitizer), although the latter is known to cause degeneration of small nerve fibers. pDPN can be difficult to treat, which frustrates healthcare providers, patients and caregivers. There is an additional need for clinical trials of novel therapeutic agents and optimal combinations for the management of pDPN. This article reviews the pharmacological management of pDPN, emerging therapies, the difficulties of placebo response in clinical trials and novel proposed biomarkers of treatment response.
Learn More >Migraine is one of the most common neurologic disorders in children and adolescents. However, a quantitative comparison of multiple preventive pharmacologic treatments in the pediatric population is lacking.
Learn More >Occurrence, risk factors, and impact on daily life of chronic pain after critical illness have not been systematically studied.
Learn More >Osteoarthritis (OA) and pain are both made more severe by low-grade inflammation. We examined whether visceral fat, a major source of inflammatory cytokines and adipokines, was associated with an increased risk of knee OA or of musculoskeletal pain.
Learn More >Spinal cord injury (SCI) disrupts the communication between brain and body parts innervated from below-injury spinal segments, but rarely results in complete anatomical transection of the spinal cord. The aim of this study was to investigate residual somatosensory conduction in clinically complete SCI, to corroborate the concept of sensory discomplete SCI.
Learn More >The functional connectivity of the brain in chronic pancreatitis (CP) remains unknown. This study aimed to investigate functional connectivity in CP patients using resting state functional magnetic resonance imaging (fMRI) and explore the associations to clinical parameters and altered cerebral metabolites.
Learn More >Somatic symptom disorder (SSD) is characterized by a persistent and distressing psychological reaction to somatic symptoms. In pain disorders, the preoccupation with physical symptoms is associated with poor long-term outcomes. SSD may therefore be of use to identify and help chronic pain patients with particular needs.
Learn More >Vagal afferent sensory nerves, originating in jugular and nodose ganglia, are comprised of functionally distinct subsets whose activation evokes distinct thoracic and abdominal reflex responses. We used Cre-expressing mouse strains to identify specific vagal afferent populations and map their central projections within the brainstem. We show that Pirt is expressed in virtually all vagal afferents; whereas 5HT3 is expressed only in nodose neurons, with little expression in jugular neurons. TRPV1, the capsaicin receptor, is expressed in a subset of small nodose and jugular neurons. Tac1, the gene for tachykinins, is expressed predominantly in jugular neurons, some of which also express TRPV1. Vagal fibers project centrally to the nucleus tractus solitarius (nTS), paratrigeminal complex, area postrema and to a limited extent the dorsal motor nucleus of the vagus. nTS subnuclei preferentially receive projections by specific afferent subsets, with TRPV1+ fibers terminating in medial and dorsal regions predominantly caudal of obex, whereas TRPV1-negative fibers terminate in ventral and lateral regions throughout the rostral-caudal aspect of the medulla. Many vagal Tac1+ afferents (mostly derived from the jugular ganglion) terminate in the nTS. The paratrigeminal complex was the target of multiple vagal afferent subsets. Importantly, lung-specific TRPV1+ and Tac1+ afferent terminations were restricted to the caudal medial nTS, with no innervation of other medulla regions. In summary, this study identifies the specific medulla regions innervated by vagal afferent subsets. The distinct terminations provide a neuroanatomic substrate for the diverse range of reflexes initiated by vagal afferent activation. Vagal afferents transmit sensory information from visceral organs to the brainstem, where their activity alters sensation and visceral reflexes. Vagal afferents are comprised of distinct subsets which serve distinct functions. Little is known of the neuroanatomy of central projections of distinct vagal subsets, thus there remains an incomplete understanding of how visceral events evoke appropriate behavioral and reflex responses. This precludes rationally-developed pharmacological or electroceutical interventions to modify aberrant sensations/reflexes. Here, we used cell-specific reporter expression to identify the brainstem pathways of distinct vagal afferent subsets. We show that TRPV1+ vagal afferents innervate ipsilateral and contralateral dorsal/medial nTS subnuclei and the ipsilateral paratrigeminal complex, whereas TRPV1-negative vagal afferents innervate the ipsilateral rostral/ventral/lateral nTS subnuclei and the ipsilateral paratrigeminal complex.
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