The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial
A randomized, controlled trial of oxycodone versus placebo in patients with postherpetic neuralgia and painful diabetic neuropathy treated with pregabalin.
The aim of this randomized double-blind, placebo-controlled, parallel-group study was to evaluate the efficacy, safety, and tolerability of pregabalin in combination with oxycodone or placebo, in patients with either postherpetic neuralgia (PHN) or painful diabetic neuropathy (PDN). After a 7-day washout period, 62 patients were randomized to receive either oxycodone mixture 10 mg/day or placebo mixture for 1 week. Patients were then started on open-label pregabalin (75, 150, 300 and 600 mg/day) according to a forced titration dosing regimen, while continuing the same dosage of oxycodone or placebo for 4 weeks. The primary efficacy measure was a decrease in the pain-intensity score of at least 2cm and a pain score <4cm measured using a 10-cm visual analogue scale (VAS) following pregabalin dosage escalation and treatment for 4 weeks. Secondary efficacy measures included sleep interference and the Neuropathic Pain Scale. There were similar levels of overall efficacy between pregabalin/oxycodone and pregabalin/placebo groups in relieving PHN and PDN related pain. ⋯ Peripheral neuropathic pain presents commonly in clinical practice, and 2 of its most prevalent types are PHN and PDN. Currently available treatments provide some degree of pain relief in approximately 40-60% of patients, leaving the remainder with unremitting pain. Although this study supports the effectiveness of pregabalin in the treatment of PHN or PDN, it also shows that the addition of a low dose of oxycodone at 10mg/day does not enhance the pain-relieving effects of pregabalin.
-
Randomized Controlled Trial
Effects of anodal transcranial direct current stimulation on chronic neuropathic pain in patients with multiple sclerosis.
Neuropathic pain in patients with MS is frequent and is associated with a great interference with daily life activities. In the present study, we investigated whether anodal transcranial direct current stimulation (tDCS) may be effective in reducing central chronic pain in MS patients. Patients received sham tDCS or real tDCS in a 5-day period of treatment in a randomized, double blind, sham-controlled study. Pain was measured using visual analog scale (VAS) for pain and the short form McGill questionnaire (SF-MPQ). Quality of life was measured using the Multiple Sclerosis Quality of Life-54 scale (MSQoL-54). Depressive symptoms and anxiety were also evaluated as confounding factors using the Beck Depression Inventory (BDI) and VAS for anxiety. Evaluations were performed at baseline, immediately after the end of treatment, and once a week during a 3-week follow-up period. Following anodal but not sham tDCS over the motor cortex, there was a significant pain improvement as assessed by VAS for pain and McGill questionnaire, and of overall quality of life. No depression or anxiety changes were observed. Our results show that anodal tDCS is able to reduce pain-scale scores in MS patients with central chronic pain and that this effect outlasts the period of stimulation, leading to long-lasting clinical effects. ⋯ This article presents a new, noninvasive therapeutic approach to chronic, central neuropathic pain in multiple sclerosis, poorly responsive to current conventional medications. tDCS is known to cause long-lasting changes of neuronal excitability at the site of stimulation and in the connected areas in healthy subjects. This led us to hypothesize that pain decrease may be the result of functional plastic changes in brain structures involved in the pathogenesis of chronic neuropathic pain.
-
Altered function of endogenous pain modulation has been proposed as a mechanism that may underlie chronic pain conditions. Descending modulation of pain can be examined by diffuse noxious inhibitory controls (DNIC). DNIC comprises a spinal-medullary-spinal pathway that is activated when 2 concomitant painful stimuli are applied at the same time. This pain-inhibitory system can be easily triggered in an experimental setting. Therefore, studies on DNIC can help us to evaluate impairments in descending pain modulation, presumably primarily of inhibitory nature. This review summarizes recent findings on human DNIC trials with a specific focus on sex, age, and ethnic differences in DNIC effects and psychological mediators such as attention, expectation, and pain catastrophizing. Furthermore, the clinical relevance of DNIC studies will be discussed. Different methodological approaches used make it difficult to generalize results, but the research to date has shown good potential for DNIC to help in gaining insights in the underlying mechanisms of chronic pain conditions. ⋯ Recent literature on diffuse noxious inhibitory controls as a model of endogenous pain modulation in clinical pain syndromes was reviewed. DNIC may help to identify patients at risk for development of chronic pain and may open alternatives for treatment options.
-
Catastrophizing is widely recognized as an important risk factor for adverse pain-related outcomes. However, questions remain surrounding the details of its assessment. In particular, recent laboratory studies suggest that evaluation of "situational" catastrophizing (ie, catastrophizing measured during or directly after the administration of noxious stimulation) may provide information distinct from that obtained by standard, or "dispositional" measures, which assess individuals' recall of catastrophizing in daily life. However, comparatively little research has systematically investigated the interrelationships and properties of these 2 different forms of pain-related catastrophizing. The current study evaluated both situational and dispositional catastrophizing measures within multiple samples: healthy individuals (N = 84), patients with painful temporomandibular joint disorders (TMD; N = 48), and patients with painful arthritis (N = 43). All participants first completed the Pain Catastrophizing Scale (PCS), and then underwent psychophysical pain testing, which included heat, cold, and pressure pain. Participants then completed a situational catastrophizing measure with reference to the laboratory pain he/she had just undergone. Situational catastrophizing scores were not significantly correlated with dispositional PCS scores in the healthy participants and arthritis patients, though they were associated in TMD patients. Situational catastrophizing was more strongly associated with experimental pain responses than dispositional PCS scores for the healthy subjects and arthritis patients. In general, higher levels of situational catastrophizing were associated with lower pain thresholds and higher pain ratings across all 3 samples. The findings highlight the importance of multidimensional assessment of pain-related catastrophizing, and suggests a role for measuring catastrophizing related to specific, definable events. ⋯ This study adds to a growing literature examining catastrophizing. Our findings highlight the potential importance of the multidimensional assessment of pain-related catastrophizing, and suggest a role for measuring catastrophizing related to specific, definable events.
-
Research generally indicates that providers demonstrate modest insight into their clinical decision processes. In a previous study utilizing virtual human (VH) technology, we found that patient demographic characteristics and facial expressions of pain were statistically significant predictors of many nurses' pain-related decisions. The current study examined the correspondence between the statistically identified and self-reported influences of contextual information on pain-related decisions. Fifty-four nurses viewed vignettes containing a video of a VH patient and text describing a postsurgical context. VH sex, race, age, and facial expression varied across vignettes. Participants made pain-assessment and treatment decisions on visual analogue scales. Participants subsequently indicated the information they relied on when making decisions. None of the participants reported using VH sex, race, or age in their decision process. Statistical modeling indicated that 28 to 54% of participants (depending on the decision) used VH demographic cues. 76% of participants demonstrated concordance between their reported and actual use of the VH facial expression cue. Vital signs, text-based clinical summary, and VH movement were also reported as influential factors. These data suggest that biases may be prominent in practitioner decision-making about pain, but that providers have minimal awareness of and/or a lack of willingness to acknowledge this bias. ⋯ The current study highlights the complexity of provider decision-making about pain management. The VH technology could be used in future research and education applications aimed at improving the care of all persons in pain.