Pain
-
Use of opioids for chronic non-cancer pain is increasing, but the clinical epidemiology and standards of care for this practice are poorly defined. Psychiatric disorders are associated with increased physical symptoms and may be associated with opioid use. We performed a secondary analysis of cross-sectional data from the Health Care for Communities (HCC) survey conducted in 1997-1998 (N=9279) to determine the association of psychiatric disorders and self-reported regular use of prescribed opioids within the past year. ⋯ In multivariate logistic regression models controlling for demographic and clinical variables, the presence of a common mental disorder remained a significant predictor of prescription opioid use (OR=3.15, 95% CI=1.69, 5.88, P<0.001), among individuals reporting low pain interference (N=8307); but not (OR=1.27, n.s.) among those reporting high pain interference (N=972). Depressive, anxiety and drug abuse disorders are associated with increased use of regular opioids in the general population. Depressive and anxiety disorders are more common and more strongly associated with prescribed opioid use than drug abuse disorders.
-
The transient receptor potential vanilloid subfamily member 2 (TRPV2) is a cation channel activated by temperatures above 52 degrees C. To analyze the contribution of TRPV2 to the development of inflammation-induced hyperalgesia, the expression of TRPV2 in primary sensory neurons was analyzed after intraplantar injection of complete Freund's adjuvant (CFA). Using specific antibodies, an increase in TRPV2-expressing neurons was identified after inflammation. ⋯ Intraplantar injection of nerve growth factor increased TRPV1 expression but not TRPV2, suggesting that induction of TRPV2 expression is driven by a mechanism distinct from that for TRPV1. Heat hyperalgesia assessment after chemical desensitization of TRPV1 by resiniferatoxin demonstrates a possible role for TRPV2 in inflammation at high temperatures (>56 degrees C). These results suggest that TRPV2 upregulation contributes to peripheral sensitization during inflammation and is responsible for pain hypersensitivity to noxious high temperature stimuli.
-
Chronic muscle pain is common and often difficult to treat. In this study, we further characterize a model of chronic muscle pain induced by repeated intramuscular injection of acidic saline. Two injections of acid into muscle separated by 5 days result in secondary mechanical hyperalgesia that lasts for up to 4 weeks. ⋯ The second intramuscular injection evoked a calcium-dependent increase in both spinal glutamate and aspartate concentrations. Glutamate concentrations within the dorsal horn were also increased 1 week after the second acid injection. Our data suggest increased release of spinal EAAs in the dorsal horn contributes to the development and maintenance of hyperalgesia.
-
Randomized Controlled Trial
A randomized, double-blind, placebo-controlled trial of duloxetine in the treatment of women with fibromyalgia with or without major depressive disorder.
This was a 12-week, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of duloxetine, a selective serotonin and norepinephrine reuptake inhibitor, in 354 female patients with primary fibromyalgia, with or without current major depressive disorder. Patients (90% Caucasian; mean age, 49.6 years; 26% with current major depressive disorder) received duloxetine 60 mg once daily (QD) (N=118), duloxetine 60 mg twice daily (BID) (N=116), or placebo (N=120). The primary outcome was the Brief Pain Inventory average pain severity score. ⋯ Compared with patients on placebo, patients treated with duloxetine 60 mg QD or duloxetine 60 mg BID had significantly greater improvement in remaining Brief Pain Inventory pain severity and interference scores, Fibromyalgia Impact Questionnaire, Clinical Global Impression of Severity, Patient Global Impression of Improvement, and several quality-of-life measures. Both doses of duloxetine were safely administered and well tolerated. In conclusion, both duloxetine 60 mg QD and duloxetine 60 mg BID were effective and safe in the treatment of fibromyalgia in female patients with or without major depressive disorder.
-
Controlled Clinical Trial
Does medication overuse headache represent a behavior of dependence?
Medication overuse is relatively common in patients with frequent headache. To explore the prevalence of patients who meet the criteria for substance dependence in Diagnostic and Statistical Manual of Mental Disorders, Edition IV (DSM-IV), and to identify variables of substance dependence among patients with chronic daily headache, we recruited consecutive patients with chronic daily headache at a headache clinic from November 1999 to June 2004. Each patient completed a headache intake form, a dependence questionnaire modified from DSM-IV, and the Hospital Anxiety and Depression Scale (HADS). ⋯ Patients who fulfilled DSM-IV criteria of dependence had higher numbers of physician appointments in the past year. Multivariate logistic regression analyses revealed that migraine headache, frequent physician consultation, intensity of headache, and presence of a higher anxiety score were significant independent variables for substance dependence. Among patients with chronic daily headache, pMOH was associated with behaviors of substance dependence.