The journal of pain : official journal of the American Pain Society
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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.
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The Douleur Neuropathique 4 (DN4) questionnaire was developed by the French Neuropathic Pain Group and is a simple and objective tool, with the ability to distinguish nociceptive from neuropathic pain. The purpose of this work was to validate the DN4 questionnaire in the Portuguese language in order to allow its use in clinical and research settings. A double-blind, accuracy study was conducted, consisting of translation, back-translation, literal evaluation, semantic equivalence, and communication with the target population. The Portuguese version of the questionnaire was applied in a sample of 101 patients with neuropathic (N = 42) or nociceptive pain (N = 59), ranked according to medical diagnosis. The reproducibility, reliability and validity of the instrument were analyzed, and showed a high diagnostic power for this version of the DN4 questionnaire. The Portuguese version of the DN4 questionnaire presented good validity and reliability, allowing it to identify neuropathic pain and neuropathic characteristics of mixed pain syndromes. ⋯ This article presents the first validated neuropathic pain questionnaire in the Portuguese language and represents a useful tool in the assessment of neuropathic pain both in the clinical setting and in population-based studies. The sensible and quick format of this instrument are key factors that will contribute to its widespread use, permitting a true recognition of patients with neuropathic pain.
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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.
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Randomized Controlled Trial Multicenter Study
Physician characteristics and variation in treatment outcomes: are better qualified and experienced physicians more successful in treating patients with chronic pain with acupuncture?
The aim of this paper was to quantify the influence of the physician's training and experience in the field of acupuncture on the outcome in patients with chronic pain. Patients visiting their physician because of chronic low back pain, headache, pain due to osteoarthritis of the knee or hip, or neck pain, were included in 4 multicenter, randomized, controlled studies. All patients received routine care; patients in the acupuncture groups received additional acupuncture treatment (on average 10 sessions). The data was pooled, and the 3-month change from baseline of the SF-36 bodily pain subscale as the main outcome defined. A total of 9,990 patients (mean age 49.6 +/- 13.6 years, 68% female) treated by 2,781 physicians (mean age 46.3 +/- 7 years, 37% female) were analyzed. The physicians had 7.3 +/- 5.2 (mean +/- sd) years of experience in acupuncture and their mean duration of formal acupuncture training had been 287 +/- 321 hours. The outcome was markedly improved in the acupuncture group. We identified only 1 physician characteristic with a significant influence on the outcome: Internists performed better (odds ratio OR = 1.49, confidence interval CI: 1.01;2.18; P = .043); orthopedists worse (OR = .79, CI: .62;1; P = .043) than the average physician. Neither the duration of training nor the duration of experience had any impact on the extent of the acupuncture effect. ⋯ In this analysis, physician characteristics such as training did not influence patients' outcome after acupuncture, suggesting that formal training parameters have only a limited influence on treatment effect. Other skills such as the therapeutic relationship, which are difficult to measure, may probably play a more important role and should be taken into consideration.
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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.