Pain
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We propose a blade as a noninjurious nociceptive stimulus modeling sharp mechanical pain and yielding acute pain and hyperalgesia responses with closer proximity to incision-induced pain/hyperalgesia than punctate or blunt pressure mechanical pain models. Twenty-six healthy men and women were investigated to compare a small incision in the left forearm with noninvasive stimuli of different shapes and modalities to the right forearm. The magnitude and time course of incisional and blade-induced pain were assessed by numerical rating scales. ⋯ Affective pain scores were significantly lower than sensory scores for all stimuli (P < 0.001). Comparing blade and incision, patterns of affective and sensory pain descriptors exhibited a remarkably similar pattern. Hence, we suggest the blade as novel model of sharp mechanical pain, which will be useful in investigating postoperative/mechanical pain and the role of self-injurious behavior in, eg, patients with borderline personality disorder.
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Multicenter Study
Frequency, Impact, and Predictors of Persistent Pain Following Root Canal Treatment: A National Dental PBRN Study.
Root canal treatment (RCT) is commonly performed surgery and persistent pain is known to occur, but little is known about how these patients are affected by this pain. Although biopsychosocial mechanisms are thought to be associated with the development of such pain, similar to persistent pain after surgery in other body sites, little is known about the baseline predictors for persistent pain. We assessed the frequency of persistent pain 6 months after RCT, measured the impact this pain had on patients, and determined predictive factors for persistent tooth pain in a multicenter prospective cohort study conducted within the National Dental Practice-Based Research Network. ⋯ After adjusting for the type of dental practitioner and patient age, gender, and household income, pain duration over the week before RCT significantly increased the risk of developing persistent pain (odds ratio = 1.19 per 1 day increase in pain duration, 95% confidence interval: 1.07-1.33), whereas optimism about the procedure reduced the risk (odds ratio = 0.39, 95% confidence interval: 0.22-0.67). Our data suggest that persistent pain 6 months after RCT is fairly common, but generally does not have a large impact on those experiencing it. Furthermore, patient age and gender did not predict persistent pain, whereas preoperative pain duration and the patient's expectation did.
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Painful diabetic neuropathy (PDN) affects nearly half of patients with diabetes. The objective of this study was to compare the cost-effectiveness of starting patients with PDN on pregabalin (PRE), duloxetine (DUL), gabapentin (GABA), or desipramine (DES) over a 10-year time horizon from the perspective of third-party payers in the United States. A Markov model was used to compare the costs (2013 $US) and effectiveness (quality-adjusted life-years [QALYs]) of first-line PDN treatments in 10,000 patients using microsimulation. ⋯ PSA showed that, at a willingness-to-pay (WTP) of $50,000/QALY, DUL was the most cost-effective option in 56.3% of the simulations, DES in 29.2%, GABA in 14.4%, and PRE in 0.1%. Starting with DUL is the most cost-effective option for PDN when WTP is greater than $22,867/QALY. Decision makers may consider starting with DUL for PDN patients.
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The rostral ventromedial medulla (RVM) exerts both inhibitory and excitatory controls over nociceptive neurons in the spinal cord and medullary dorsal horn. Selective ablation of mu-opioid receptor (MOR)-expressing neurons in the RVM using saporin conjugated to the MOR agonist dermorphin-saporin (derm-sap) attenuates stress and injury-induced behavioral hypersensitivity, yet the effect of RVM derm-sap on the functional integrity of the descending inhibitory system and the properties of RVM neurons remain unknown. Three classes of RVM neurons (on-cells, off-cells, and neutral cells) have been described with distinct responses to noxious stimuli and MOR agonists. ⋯ Furthermore, electrical stimulation of the periaqueductal gray produced analgesia in both derm-sap and saporin controls with similar thresholds. Microinjection of kynurenic acid, a glutamate receptor antagonist, into the RVM disrupted periaqueductal gray stimulation-produced analgesia in both saporin-treated and derm-sap-treated rats. These results indicate that MOR-expressing neurons in the RVM are not required for analgesia produced by either direct or indirect activation of neurons in the RVM.
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Review Meta Analysis
A systematic review and meta-analysis of the prevalence of chronic widespread pain in the general population.
Chronic widespread pain (CWP) is common and associated with poor general health. There has been no attempt to derive a robust prevalence estimate of CWP or assess how this is influenced by sociodemographic factors. This study therefore aimed to determine, through a systematic review and meta-analysis, the prevalence of CWP in the adult general population and explore variation in prevalence by age, sex, geographical location, and criteria used to define CWP. ⋯ There was some limited evidence of geographic variation and cultural differences. One in 10 adults in the general population report chronic widespread pain with possible sociocultural variation. The possibility of cultural differences in pain reporting should be considered in future research and the clinical assessment of painful conditions.