Pain
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Randomized Controlled Trial Comparative Study
The role of fear of movement in subacute whiplash-associated disorders grades I and II.
Fear and avoidance of activity may play a role in fostering disability in whiplash-associated disorders (WAD). This study examined the role of fear after WAD and assessed the effectiveness of 3 treatments targeting fear. People still symptomatic from WAD grade I-II injuries approximately 3months previously (n=191) completed questionnaires (eg, Neck Disability Index [NDI]) and were randomized to 1 of the treatments: (1) informational booklet (IB) describing WAD and the importance of resuming activities, (2) IB+didactic discussions (DD) with clinicians reinforcing the booklet, and (3) IB+imaginal and direct exposure desensitization (ET) to feared activities. ⋯ Reduction in fear was the most important predictor of improvement in NDI (β=0.30, P<.001), followed by reductions in pain (β=0.20, P=.003) and depression (β=0.18, P=.004). The mediational analysis confirmed that fear reduction significantly mediated the effect of treatment group on outcome. Results highlight the importance of fear in individuals with subacute WAD and suggest the importance of addressing fear via exposure therapy and/or educational interventions to improve function.
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microRNAs (miRNAs) are small noncoding RNAs that have been linked to a number of disease-related signal transduction pathways. Several studies indicate that they are also involved in nociception. It is not clear, however, which miRNAs are important and which genes are modulated by miRNA-associated mechanisms. ⋯ Knock-down of miRNA-124a by intravenous administration of a specific miRNA-124a inhibitor further increased the nociceptive behavior associated with an upregulation of the pain-relevant miRNA-124a target MeCP2 and proinflammatory marker genes. In contrast, administration of a miRNA-124a mimic counteracted these effects and decreased nociception by down-regulation of the target gene. In conclusion, our results indicate that miRNA-124a is involved in inflammatory nociception by regulation of relevant target proteins and might therefore constitute a novel target for anti-inflammatory therapy.
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Following nociceptive heat or laser stimulation, an early contralateral and later vertex potential can be recorded. Although more indicative of the nociceptive input, the acquisition of the contralateral N1 after contact heat stimulation (contact heat-evoked potentials [CHEPs]) remains difficult. An advantage of contact heat is that the baseline skin temperature preceding peak stimulation can be controlled. ⋯ Based on standard averaging, N2/P2 amplitudes were also significantly increased with and without an accompanying change in the rating of perceived pain when the baseline temperature was increased (P<.05). In contrast, automated single-trial averaging revealed no significant difference in N2 amplitude when the baseline temperature was increased to 42°C and the peak temperature reduced. These findings suggest that 2 mechanisms underlie the improved acquisition of CHEPs: increased synchronization of afferent volley, yielding larger-amplitude evoked potentials in response to the same rating of intensity; and reduced inter-trial variability.
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Recent evidence indicates that pain-related fear can be acquired through associative learning. In the clinic, however, spreading of fear and avoidance is observed beyond movements/activities that were associated with pain during the original pain episode. One mechanism accounting for this spreading of fear is stimulus generalization. ⋯ These data illustrate that spreading of pain-related fear is fostered by previously acquired movement-pain contingencies. Based on recent advances in anxiety research, we proposed an innovative approach conceptualizing predictable pain as a laboratory model for fear of movement in regional musculoskeletal pain, and unpredictable pain generating contextual pain-related fear as a prototype of widespread musculoskeletal pain. Consequently, fear generalization might play an important role in spreading of pain-related fear and avoidance behavior in regional and widespread musculoskeletal pain.