Pain
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Sleep disturbances are highly prevalent in chronic pain patients. Understanding their relationship has become an important research topic since poor sleep and pain are assumed to closely interact. To date, human experimental studies exploring the impact of sleep disruption/deprivation on pain perception have yielded conflicting results. ⋯ TSD selectively modulated nociception, since detection thresholds of non-nociceptive modalities remained unchanged. Our findings show that a single night of TSD is able to induce generalized hyperalgesia and to increase State Anxiety scores. In the future, TSD may serve as a translational pain model to elucidate the pathomechanisms underlying the hyperalgesic effect of sleep disturbances.
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Meta Analysis
Efficacy of Qutenza® (capsaicin) 8% patch for neuropathic pain: A meta-analysis of the Qutenza Clinical Trials Database.
Qutenza® is a capsaicin patch used to treat peripheral neuropathic pain, including postherpetic neuralgia (PHN) and human immunodeficiency virus-associated neuropathy (HIV-AN). The Qutenza Clinical Trials Database has been assembled to more fully characterize the effects of Qutenza. We conducted a within-subject meta-analysis of Qutenza studies to further define the medication's efficacy profile across studies. ⋯ The overall between-group difference in percentage change from baseline in pain intensity was 8.0% (95% confidence interval 4.6, 11.5; P<.001), which statistically significantly favored Qutenza over low-dose control. Qutenza superiority was demonstrated for both PHN and HIV-AN patients for the primary end point and the end point proportion of 30% pain reduction response, and for PHN patients for the end point of proportion of 50% pain reduction response. These results confirm that Qutenza is effective for the treatment of both PHN and HIV-AN compared to low-dose control patch.
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Pontospinal noradrenergic neurons form part of an endogenous analgesic system that suppresses acute pain, but there is conflicting evidence about its role in neuropathic pain. We investigated the chronology of descending noradrenergic control during the development of a neuropathic pain phenotype in rats following tibial nerve transection (TNT). A lumbar intrathecal cannula was implanted at the time of nerve injury allowing administration of selective α-adrenoceptor (α-AR) antagonists to sequentially assay their effects upon the expression of allodynia and hyperalgesia. ⋯ Contralateral thermal hyperalgesia was also reversibly uncovered by yohimbine administration in a contact heat ramp paradigm in anaesthetised TNT rats. Following TNT there is an engagement of inhibitory α2-AR-mediated noradrenergic tone which completely masks contralateral and transiently suppresses the development of ipsilateral sensitization. This endogenous analgesic system plays a key role in shaping the spatial and temporal expression of the neuropathic pain phenotype after nerve injury.
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Randomized Controlled Trial
A phase III placebo- and oxycodone-controlled study of tanezumab in adults with osteoarthritis pain of the hip or knee.
Tanezumab is a humanized monoclonal antinerve growth factor antibody in development for treatment of chronic pain. In a phase III, placebo- and active-controlled study, we investigated the efficacy and safety of tanezumab for osteoarthritis (OA) hip or knee pain. Patients (N=610) received up to 2 doses of intravenous tanezumab (5 or 10mg in 8-week intervals), controlled-release oral oxycodone (10 to 40 mg every 12 hours), or placebo. ⋯ Adverse event frequency was higher with oxycodone (63.3%) than tanezumab (40.7% to 44.7%) or placebo (35.5%); serious adverse event frequency was similar among treatments. The adverse event profile for tanezumab was similar to previous tanezumab studies. Results indicate that tanezumab is efficacious in the treatment of OA pain; no new safety signals were identified.
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To explore whether chronic pain is associated with cardiovascular risk factors and identify whether increased distribution or intensity of pain is associated with cardiovascular risk, participants in Generation Scotland: The Scottish Family Health study completed pain questionnaires recording the following: presence of chronic pain, distribution of pain, and intensity of chronic pain. Blood pressure, lipids, blood glucose, smoking history, waist-hip ratio, and body mass index were recorded; Framingham 10-year coronary heart disease (CHD) risk scores were calculated and a diagnosis of metabolic syndrome derived. Associations between chronic pain and cardiovascular risk were explored. ⋯ However, cardiovascular disease risk factors contributing to metabolic syndrome were more prevalent in those reporting high-intensity chronic pain. This large population-based study has demonstrated that chronic pain, and in particular high-intensity chronic pain, is associated with an increased prevalence of cardiovascular risk factors and metabolic syndrome. The 10-year CHD risk score and metabolic syndrome correlate well with increased pain intensity, but not with widespread pain.