Scandinavian journal of pain
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Quantification of intraepidermal nerve fibre density (IENFD) is an important small fibre measure in distal symmetric polyneuropathies (DSP), but quantitative evaluation of additional structural and functional factors may help in elucidating the underlying mechanisms, and in improving the diagnostic accuracy in DSP. The literature reports a weak or moderate relationship between IENFD and spontaneous and evoked pain in neuropathies, but the relationship between functional and structural small fibre parameters in patients with DSP is unclear. The objectives of the current study, therefore, were to determine morphological and functional parameters related to small nerve fibres in subjects with distal symmetric polyneuropathy (DSP) and healthy controls, and to characterize the interplay among these parameters in these two groups. ⋯ Combining small fibre parameters may improve the diagnostic accuracy of DSP.
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Osteoarthritis (OA) of the knee is a common and increasingly prevalent condition that is one of the primary causes of chronic pain. Staying physically active protects against disability from knee OA but is also very challenging. A critical but unexamined question is whether patients at greatest risk for becoming less active are those with a genetic predisposition for greater sensitivity to daily pain. ⋯ Previous clinical research has focused primarily on differences in average level of pain between patients with and without a specific genotype. Assessment of within-person variability through repeated measurements in daily life enhances the reliability, power, and ecological validity of phenotypic measurement.
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Pain catastrophizing is linked to heightened pain and poorer coping among individuals with chronic pain, yet little is known about how pain catastrophizing associates with sleep and pain over the course of treatment for chronic pain. Previous research employing a cross-sectional design suggests that sleep mediates the association between pain catstrophizing and pain, but there have been no longitudinal studies examining the directionality of these associations. Thus, the aim of this study was to test two competing theoretical models. The first model specified that pain catastrophizing leads to increased pain via poor sleep. The second model specified that poor sleep leads to increased pain catastrophizing via increased pain. ⋯ These results call into question previous evidence that pain catastrophizing indirectly affects pain by way of its impact on sleep. Rather, our findings suggest that pain mediates the relationship between sleep and levels of pain catastrophizing. These results therefore underscore importance and value in collecting longitudinal data and potential influence on the conclusions gained with regards to sleep, pain and psychological variables. These findings may be of clinical importance when tailoring interventions for individuals with chronic pain and perhaps even more so for those with comorbid pain and sleep disturbance; prioritizing the treatment of sleep difficulties could result in improvements to pain-related outcomes.
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Although neuropathic pain is known to negatively affect cognition, the neural mechanisms involved are poorly understood. Chronic pain is associated with changes in synaptic plasticity in the brain which may impact on cognitive functioning. The aim of this study was to model neuropathic pain in mid-aged rats using spinal nerve ligation (SNL). Following establishment of allodynia and hyperalgesia, behaviour was assessed in a battery of cognitive tests. Expression of the presynaptic protein, synaptophysin, and its colocalisation with the vesicular GABA and glutamate transporters (vGAT and vGLUT, respectively), was investigated in the medial prefrontal cortex (mPFC) and hippocampus. ⋯ Cognitive complaints are common amongst chronic pain patients. Here we modelled cognitive impairment in a well-established animal model of neuropathic pain and investigated the neural mechanisms involved. A better understanding of this phenomenon is an important prerequisite for the development of improved treatment of patients affected.