The journal of pain : official journal of the American Pain Society
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In certain patients with neuropathic pain, the pain is dependent on activity in the sympathetic nervous system. To investigate whether the spared nerve injury model (SNI) produced by injury to the tibial and common peroneal nerves and leaving the sural nerve intact is a model for sympathetically maintained pain, we measured the effects of surgical sympathectomy on the resulting mechanical allodynia, mechanical hyperalgesia, and cold allodynia. Decreases of paw withdrawal thresholds to von Frey filament stimuli and increases in duration of paw withdrawal to pinprick or acetone stimuli were observed in the ipsilateral paw after SNI, compared with their pre-SNI baselines. Compared with sham surgery, surgical lumbar sympathectomy had no effect on the mechanical allodynia and mechanical hyperalgesia induced by SNI. However, the sympathectomy significantly attenuated the cold allodynia induced by SNI. These results suggest that the allodynia and hyperalgesia to mechanical stimuli in the SNI model is not sympathetically maintained. However, the sympathetic nervous system may be involved, in part, in the mechanisms of cold allodynia in the SNI model. ⋯ The results of our study suggest that the SNI model is not an appropriate model of sympathetically maintained mechanical allodynia and hyperalgesia but may be useful to study the mechanisms of cold allodynia associated with sympathetically maintained pain states.
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Our study sought to 1) determine if deployment status is associated with chronic widespread pain (CWP), and 2) evaluate whether veterans with CWP have greater psychiatric comorbidity, higher health care utilization, and poorer health status than veterans without CWP. Five years after the conclusion of the first Gulf War (August 1990 to June 1991), we conducted a cross-sectional study of veterans who listed Iowa as the home of record using a stratified sampling design to determine their health status. We compared the prevalence of CWP between deployed and nondeployed veterans. Logistic and multiple linear regression models were constructed to test whether CWP was associated with comorbidities and health-related outcomes of interest. Five hundred ninety of 3695 veterans interviewed (16%) had CWP. Gulf deployment was associated with higher prevalence of CWP than deployment elsewhere (OR = 2.03, 95%CI = 1.60-2.58), after adjustment. Both deployed and nondeployed veterans with CWP reported more health care utilization and comorbidities and lower health-related quality of life scores than veterans without CWP. Deployed veterans were more likely to have CWP than nondeployed veterans, and CWP was associated with poor health outcomes. Military and medical personnel should be aware that efforts to prevent, identify, and treat CWP in veterans returning from the current war may be needed. ⋯ This article indicates that deployed veterans may have an increased risk for development of CWP, which is associated with greater healthcare utilization and comorbidity and lower quality of life. The risk of poor health outcomes suggests that veterans returning from the present conflict should be screened for CWP on their return.
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Physical exercise is often recommended to patients who have chronic pain. However, only a small number of studies report exercise-induced analgesia in the setting of inflammatory pain, and even fewer relate long-term exercise to reductions in neuropathic pain. To address these questions, we evaluated the effect of extended swimming exercise in animal models of inflammatory (intraplantar injection of dilute formalin) and neuropathic (partial peripheral nerve injury) pain. We found that 9 days of swimming exercise in 37 degrees C water for 90 min/d decreased licking and flinching responses to formalin, as compared with nonexercised control animals. In addition, 18 to 25 days of swimming decreased nerve injury-induced cold allodynia and thermal hyperalgesia in rats, and 7 days of swimming decreased nerve injury-induced thermal hyperalgesia in mice. Our data indicate that swimming exercise reduces behavioral hypersensitivity in formalin- and nerve injury-induced animal models of persistent pain. ⋯ Surprisingly, few animal studies have investigated the effects of extended exercise on chronic pain. Our results support the use of exercise as a nonpharmacological approach for the management of peripheral neuropathic pain.
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Randomized Controlled Trial Clinical Trial
A randomized clinical trial of targeted cognitive behavioral treatment to reduce catastrophizing in chronic headache sufferers.
This randomized clinical trial (RCT) examined the efficacy of a cognitive-behavioral treatment (CBT) specifically targeted toward reducing pain catastrophizing for persons with chronic headache. Immediate treatment groups were compared with wait-list control groups. Differential treatment gains based on the order of presentation of 2 components of CBT (cognitive restructuring and cognitive/behavioral coping) and the role of catastrophizing in treatment outcome were examined. Thirty-four participants enrolled in a 10-week group treatment and 11 completed a wait-list self-monitoring period. Participants reported significant reductions in catastrophizing and anxiety and increased self-efficacy compared with wait-list control subjects, and these were maintained at follow-up. Although we did not find overall differences in the reduction of headache frequency or intensity compared with wait-list control subjects, calculation of clinical significance on headache indicators suggest that approximately 50% of treated participants showed meaningful changes in headache indices as well. Order of treatment modules was not related to gains during treatment or at follow-up; however, almost all changes occurred during the second half of treatment, suggesting that duration of treatment participation is important. ⋯ Cognitive-behavioral treatment targeting reduction of catastrophizing for chronic headache pain reduced negative cognitive and affective variables associated with recurrent headache, increased headache management self-efficacy, and in half of the participants, produced clinically meaningful reductions in headache indicators. Length of treatment is an important factor to consider when providing CBT for chronic pain.
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Randomized Controlled Trial Comparative Study
Epidural labor analgesia: continuous infusion versus patient-controlled epidural analgesia with background infusion versus without a background infusion.
The purpose of this study was to compare the total epidural dose of 3 commonly used labor epidural modalities. After local institutional review board approval, 195 laboring parturients received an epidural catheter for labor analgesia. All patients received an initial bolus of 0.1% ropivacaine (10 mL) and fentanyl (100 microg). Maintenance of labor analgesia consisted of ropivacaine 0.1% with fentanyl 2 microg/mL. Patients were then randomly assigned into 3 groups: Group 1 (continuous epidural infusion [CEI]), continuous infusion at 10 mL/h; group 2 (CEI + patient-controlled epidural analgesia [PCEA]), CEI at 5 mL/h with a demand dose of 5 mL allowed every 20 minutes with a 20 mL/h maximum dose; group 3 (PCEA), demand doses only of 5 mL every 15 minutes with a 20 mL/h maximum dose. Measured variables included total epidural dose, total bolus requests and boluses delivered, number of staff interventions, pain Visual Analog Scale (VAS; 0-100), modified Bromage scores, stage I and II labor duration, delivery outcome, and maternal satisfaction after delivery. No differences were noted with respect to pain VAS, modified Bromage scores, stage I and II labor duration, number of staff interventions, delivery outcome, and maternal satisfaction score. Total infusion dose was lower in demand dose only PCEA compared with CEI and CEI + PCEA groups (P = < .01). Demand dose-only PCEA results in less total epidural dose compared with CEI and CEI + PCEA without affecting labor duration, motor block, pain VAS, maternal and neonatal outcomes, and maternal satisfaction. ⋯ This article compares 3 commonly used labor epidural delivery modalities (traditional continuous epidural infusion, patient-controlled epidural analgesia with a background infusion, and demand dose-only patient-controlled epidural analgesia). Benefits in epidural dose reduction with demand dose only PCEA does not translate into improved maternal and neonatal outcome.