Pain
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Twenty patients suffering from complex regional pain syndrome (CRPS) and 21 healthy control subjects were examined to evaluate sympathetic reflex vasoconstriction. The mean age of the 12 female and eight male patients was 48.9 (21-72) years. At the time of investigation the median duration of the disease was 8.5 weeks (2-70). ⋯ Sympathetic reflex vasoconstriction triggered by MA which represents cortical generated, moderate vasoconstrictor stimulus, was significantly reduced on the affected limb (102.9% of prestimulus period) when compared to the control limb (85.0%, P < 0.002) or to controls (84.8%, P < 0.001). VAR (pure postganglionic), IG and CP (both spinal and supraspinal), representing stronger vasoconstrictor stimuli, revealed no significant side to side difference of sympathetic vasoconstriction and no significant difference as compared to controls. In conclusion our findings prove impairment of sympathetic vasoconstrictor activity after central vasoconstrictor stimulation in CRPS, and possible mechanisms are discussed.
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The psychological assessment of chronic pain is often accomplished using questionnaires such as the (West Haven-Yale) Multidimensional Pain Inventory ((WHY)MPI) which is constructed to capture the multidimensionality of chronic pain. The (WHY)MPI theoretically originates from behavioural and cognitive behavioural theories of pain. It is divided into three parts and measures psychosocial and behavioural consequences of pain. ⋯ This part of the inventory is designed to measure the extent of different types of activities, and our results suggest that this section may only be used for assessing general activity level. We conclude that, with a few adjustments, the analyses yielded satisfactory results for sections 1 and 2 of the MPI-S regarding its factor structure, reliability and generalisability. For section 3 the hypothesised factor structure could not be confirmed.
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Gender differences in experimental pain sensitivity have been widely investigated, and the results generally indicate that females exhibit greater sensitivity to noxious stimuli than males. However, results using thermal pain procedures have been inconsistent, with some studies reporting greater responses among females and other studies reporting no gender differences. ⋯ The results indicated lower thermal pain threshold and tolerance and greater temporal summation of thermal pain among females, but no gender differences in thermal discrimination or real-time magnitude estimates of discrete heat pulses. These findings suggest that gender differences in thermal pain perception may be more robust for sustained, temporally dynamic thermal stimuli with a strong C-fiber component.
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Insomnia is a significant problem for many people with chronic pain. In this study, we used a combination of daily sleep diaries and ambulatory activity monitoring (actigraphy) to: (i) examine the nature and severity of the sleep disturbance in this patient group; (ii) determine the concordance between sleep diary and actigraph measures of different sleep parameters; (iii) assess the reliability of sleep parameters across nights; and (iv) identify the clinical correlates of insomnia severity. Forty subjects with insomnia associated with chronic musculoskeletal pain completed questionnaires addressing clinical issues of pain severity, medication use, sleep quality, and affective distress. ⋯ Subjects who reported high pain severity also reported greater sleep impairment than subjects with low pain severity, but this was not confirmed by actigraphy. In general, both methods of assessment point to the significance of insomnia associated with chronic musculoskeletal pain as a distinct clinical problem, but the activity monitoring and self-report procedures provide different information. These findings suggest that multi-method assessment is an important consideration for studies of insomnia in patients with chronic pain.
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Nociceptive electrical stimuli were applied to the sural nerve during hypnotically-suggested analgesia in the left lower limb of 18 highly susceptible subjects. During this procedure, the verbally reported pain threshold, the nociceptive flexion (RIII) reflex and late somatosensory evoked potentials were investigated in parallel with autonomic responses and the spontaneous electroencephalogram (EEG). The hypnotic suggestion of analgesia induced a significant increase in pain threshold in all the selected subjects. ⋯ No modification in the autonomic parameters or the EEG was observed. These data suggest that different strategies of modulation can be operative during effective hypnotic analgesia and that these are subject-dependent. Although all subjects may shift their attention away from the painful stimulus (which could explain the decrease of the late somatosensory evoked potentials), some of them inhibit their motor reaction to the stimulus at the spinal level, while in others, in contrast, this reaction is facilitated.