Pain
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Comparative Study
Differential effects of left/right neuropathy on rats' anxiety and cognitive behavior.
Chronic pain is frequently accompanied by a deterioration of emotional behavior and cognitive function. A small number of studies in humans concluded that pain-associated negative affect is more pronounced when pain is localized in the left side of the body. It has been suggested that such side bias results from cortical function lateralization. ⋯ On the contrary, SNI-R animals presented cognitive deficits in all tasks except in the reference memory, but displayed a normal anxiety-like profile. Our results show that left- and right-sided neuropathic pain differentially affects emotional behavior, which is in accordance with previous observations in human subjects, both in experimentally induced pain and in chronic pain conditions. Additionally, our results demonstrate that the cognitive function deterioration associated with unilateral neuropathic chronic pain conditions is also differentially affected.
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The role of psychosocial and physical factors in the development of shoulder pain has now been clearly demonstrated. However, only a few studies have analyzed these associations over time. The main goal of this study was to evaluate the predictive value of work-related psychological and mechanical factors on chronic shoulder pain. ⋯ Awkward posture (OR=1.43 [1.25 to 1.63]), psychological demand (OR=1.24 [1.09 to 1.40]), and decision latitude (OR=1.21 [1.04 to 1.41] work-related factors in 1990 were associated with the development of chronic shoulder pain between 1990 and 1995. These results suggest that awkward posture, forceful effort, job demand, and decision control are predictors of chronic shoulder pain at work. Interventions designed to reduce the incidence of chronic shoulder pain must include both mechanical and psychological factors.
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Emotion can modulate pain and spinal nociception, and correlational data suggest that cognitive-emotional processes can facilitate wind-up-like phenomena (ie, temporal summation of pain). However, there have been no experimental studies that manipulated emotion to determine whether within-subject changes in emotion influence temporal summation of pain (TS-pain) and the nociceptive flexion reflex (TS-NFR, a physiological measure of spinal nociception). The present study presented a series of emotionally charged pictures (mutilation, neutral, erotic) during which electric stimuli at 2 Hz were delivered to the sural nerve to evoke TS-pain and TS-NFR. ⋯ Although pain and NFR both summated in response to the 2-Hz stimulation series, the magnitude of pain summation (TS-pain) and NFR summation (TS-NFR) was not modulated by picture-viewing. These results imply that, at least in healthy humans, within-subject changes in emotions do not promote central sensitization via amplification of temporal summation. However, future studies are needed to determine whether these findings generalize to clinical populations (eg, chronic pain).