European journal of pain : EJP
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A systematic evaluation of nociceptive withdrawal reflexes and pain rating was undertaken in order to explore the mechanisms underlying temporal summation of repetitive electrocutaneous stimulation in healthy individuals (n=12; age=27.5+/-1.5 years). Five-second subreflex threshold (RT) electrocutaneous stimulation at different frequencies (single stimulus, 5, 10, and 20 Hz) and intensities (0.6RT and 0.8RT) was applied on the dorsum of the foot, and the withdrawal reflex from the ipsilateral biceps femoris muscle was measured. The subjects scored the pain intensity on a visual analogue scale (0-100 mm) for the beginning, the middle and the end phase of the 5 s series of stimulation, and the respective averaged reflex size was calculated. ⋯ Profound activation of inhibition following electrocutaneous pain stimuli was demonstrated by reduction in pain intensity and reflex size during the last second as compared with the first second at 0.6RT current intensity (SNK, P<0.05). The pain intensity peaked between 5 and 10 Hz (P<0.05) and was reduced at 20 Hz for current intensities at 0.8RT (P<0.05). This study provides evidence for both frequency dependent central integration of the repetitive electrocutaneous stimuli and activation of a pain inhibitory system by psychophysical and electrophysiological means, demonstrating the delicate balance between neuronal facilitation and inhibition in the human pain system.
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Spinal cord stimulation (SCS) is a useful option in selected patients with chronic neuropathic pain. The aim of this questionnaire-based survey was to determine what assessment methods are used for patients being considered for SCS in pain management centres in the United Kingdom. This was in relation to the recommendations produced by the Task Force of the European Federation of IASP chapters (1998) on neuromodulation. ⋯ There was significant variation concerning absolute contraindications. The majority of respondents worked in a multi-disciplinary team and 61% stated their patients received a psychological assessment but although 96% of individuals worked with a specialist nurse only 25% reported that the nurse had an active role in the pre-assessment of patients for SCS. The development of national guidelines may provide a more standardised approach but further research into the role of the specialist nurse and the benefits of psychological assessment would also be useful.
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Patients and clinicians sometimes take coping with chronic pain primarily as a process of gaining more control over pain. An alternate approach might include helping the pain sufferer to discriminate parts of their situation that can be effectively controlled from those that cannot. When faced with situations that do not yield to attempts at direct control patients may gain better results from leaving those situations as they are and investing their efforts elsewhere. ⋯ Further results showed that a number of the responses assessed by the BPCI were reliable predictors of patient functioning. In general less frequent struggling to control pain, fewer palliative and avoidant coping responses, and more explicit persistence with activity despite acknowledged pain were associated with less depression and anxiety and greater life functioning. These results demonstrate that, in some instances, attempts at avoidance and control of chronic pain may be less helpful compared with a willingness to experience pain and focus on functioning.
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Clinical Trial
Predictive value of symptom level measurements for complex regional pain syndrome type I.
The validity with respect to presence or absence of CRPS I according to Veldman's criteria was assessed for measured pain, temperature, volume differences and limitations in range of motion. Evaluated were 155 assessments of 66 outpatients, initially diagnosed with CRPS I, but many of them not so on follow up visits. Pain was measured with VAS and McGill, temperature by infrared thermometry, volume differences by water displacement volumeters and limitations in range of motion by universal goniometers. ⋯ Using these cut off values, the highest value of sensitivity and of sensitivity and specificity combined, was found for a combination of VAS, McGill and ROM. The highest value of specificity was found for different combinations of 3, 4 and 5 instruments, all containing the VAS. We conclude that the measured pain, temperature, volume and range of motion can be used as diagnostic indicators for establishing presence or absence of CRPS I.