Pain
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Multicenter Study
Health-related quality of life in 975 patients with Complex Regional Pain Syndrome type 1.
There are limited data available on health-related quality of life (QoL) in patients with complex regional pain syndrome (CRPS). In the present study we examined QoL in 975 CRPS patients attending 6 different clinics in the Netherlands. QoL was assessed using the MOS 36-Item Short-Form Health Survey (SF-36) with the Mental Health Summary Score (MHS) and the Physical Health Summary Score (PHS) as dependent variables. ⋯ A comparison with data available from the literature shows that CRPS patients generally report poorer QoL than patients with other chronic pain conditions, particularly in the physical domains. Pain correlated moderately with QoL and therefore deserves ongoing attention by physicians. Finally, patients meeting the diagnostic Budapest criteria have lower QoL scores than patients meeting the Orlando criteria, highlighting the impact of different sets of criteria on population characteristics.
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Randomized Controlled Trial
Using eye movements to investigate selective attention in chronic daily headache.
Previous research has demonstrated that chronic pain is associated with biased processing of pain-related information. Most studies have examined this bias by measuring response latencies. The present study extended previous work by recording eye movement behaviour in individuals with chronic headache and in healthy controls while participants viewed a set of images (i.e., facial expressions) from 4 emotion categories (pain, angry, happy, neutral). ⋯ Both participant groups showed a significantly greater bias to maintain gaze longer on happy images, relative to pain, angry, and neutral images. Results are consistent with a pain-related bias that operates in the orienting of attention on pain-related stimuli, and suggest that chronic pain participants' attentional biases for pain-related information are evident even when other emotional stimuli are present. Pain-related information-processing biases appear to be a robust feature of chronic pain and may have an important role in the maintenance of the disorder.
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Human brain imaging investigations have revealed that acute pain is associated with coactivation of numerous brain regions, including the thalamus, somatosensory, insular, and cingulate cortices. Surprisingly, a similar set of brain structures is not activated in all chronic pain conditions, particularly chronic neuropathic pain, which is associated with almost exclusively decreased thalamic activity. These inconsistencies may reflect technical issues or fundamental differences in the processing of acute compared with chronic pain. ⋯ Neuropathic pain was associated with CBF decreases in a number of regions, including the thalamus and primary somatosensory and cerebellar cortices. In contrast, chronic nonneuropathic pain was associated with significant CBF increases in regions commonly associated with higher-order cognitive and emotional functions, such as the anterior cingulate and dorsolateral prefrontal cortices and the precuneus. Furthermore, in subjects with nonneuropathic pain, blood flow increased in motor-related regions as well as within the spinal trigeminal nucleus.
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Randomized Controlled Trial
The Relationship between Fear of Social and Physical Threat and their Effects on Social Distress and Physical Pain Perception.
Past research has found that measuring individuals' fear of pain predicts their physical pain perceptions: those reporting higher levels of fear of pain report higher levels of pain. We investigated links between fear of social threat and fear of physical pain, testing whether these fears predict responses to social distress and physical pain. In 3 studies, we found that fear of social and physical threat were related yet distinct psychological constructs (study 1), that fear of social (but not physical) threat predicted the perception of social distress (study 2), and that fear of physical (but not social) pain predicted the perception of physical pain (study 3). ⋯ However, we also found that these effects were specific, such that each type of fear uniquely predicted the experience of the same type of distress. We argue that timely identification of high levels of social threat-related fear is critical for identifying individuals who will benefit most from preventative interventions aimed to limit negative cycles of high avoidance and increased social threat perception. Furthermore, our work sets a boundary condition to pain overlap theory by showing that high levels of fear of one type of pain (e.g., social) are specifically linked to increased perception of that particular type of pain (e.g., social) but not the other (e.g., physical).
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The α2δ-1 protein is an auxiliary subunit of voltage-gated calcium channels, critical for neurotransmitter release. It is upregulated in dorsal root ganglion (DRG) neurons following sensory nerve injury, and is also the therapeutic target of the gabapentinoid drugs, which are efficacious in both experimental and human neuropathic pain conditions. α2δ-1 has 3 spliced regions: A, B, and C. A and C are cassette exons, whereas B is introduced via an alternative 3' splice acceptor site. ⋯ Furthermore, this differential upregulation occurs preferentially in a small nonmyelinated DRG neuron fraction, obtained by density gradient separation. The α2δ-1 ΔA+BΔC splice variant supports CaV2 calcium currents with unaltered properties compared to α2δ-1 ΔA+B+C, but shows a significantly reduced affinity for gabapentin. This variant could therefore play a role in determining the efficacy of gabapentin in neuropathic pain.