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Sexual assault (SA) is associated with increased risk for chronic pain, but the mechanisms for this relationship are poorly understood. To explore whether disrupted descending inhibition is involved, this study used a conditioned pain modulation (CPM) task to study inhibition of pain and the nociceptive flexion reflex (NFR; a correlate of spinal nociception) in 32 pain-free SA survivors. This group was compared to 32 pain-free, trauma-exposed persons without SA (no-SA group) and a group of 40 pain-free persons who reported no trauma exposure (no-TE). CPM was assessed from painful electric stimulations (test stimulus) delivered to the ankle before, during, and after participants submerged their hand in painful 10°C water (conditioning stimulus). Pain ratings and NFR were assessed in response to test stimuli. All groups demonstrated significant inhibition of pain during CPM. However, only the no-TE group demonstrated significant inhibition of NFR. The no-SA group showed no inhibition of NFR, whereas the SA group showed significant facilitation of NFR. These findings suggest that trauma exposure may impair inhibitory cerebrospinal circuits, but that SA may specifically promote facilitation of spinal nociception. Perspective: This study suggests trauma exposure disrupts cerebrospinal inhibition of spinal nociception but that exposure to sexual assault further promotes chronic pain risk by facilitating spinal nociception. This help may help elucidate the pain risk mechanisms in trauma survivors.
Learn More >Operant methods that allow animals to avoid painful stimuli are interpreted to assess the aversive quality of pain; however, such measurements require investigator-initiated stimuli to animals. Here we developed a shuttle maze test to repeatedly assess activity associated nociception without forced stimulation. Rats ambulate back and forth between two treat feeders by taking either a short route with a prickly surfaced arch or a longer route with a smooth floor. L5-L6 spinal nerve ligation (SNL) reduced the preference for the short route with the arch, correlated with hypersensitivity in the hind paw. Oral gabapentin restored the short route preference and reduced hypersensitivity in SNL rats, and blockade of spinal α2-adrenoceptors reduced gabapentin's effects on hypersensitivity but not on preference index. These results suggest that SNL injury alters behavior in the shuttle maze test and that the shuttle maze test shows comparable results to reflexive hypersensitivity after SNL in magnitude and response to gabapentin.
Learn More >Intensive interdisciplinary treatment is emerging as an effective treatment of chronic pain in youth. These programs often include a parental component with the belief that targeting parental distress and responses to a child's pain will improve outcomes. However, few studies have evaluated the impact of a parental intervention in the interdisciplinary treatment of pediatric chronic pain. The present study consists of a nonrandomized pre-post design to evaluate change in psychological and behavioral functioning of parents who participated in intensive parent programming that utilized Cognitive Behavioral Therapy (CBT) and Acceptance and Commitment Therapy (ACT), delivered within the context of an interdisciplinary intensive 3-week pain treatment program for youth with chronic pain.
Learn More >Hyperalgesia and allodynia are frequent in neuropathic pain. Some pain questionnaires like the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) and the Neuropathic Pain Scale (NPS) include self-assessment or bedside-testing of hyperalgesia/allodynia. The aim of this study was to determine to what extent LANSS and NPS data are congruent with findings upon quantitative Sensory Testing (QST).Self-reported presence of dynamic mechanical allodynia (DMA) and descriptors of hot, cold or deep ongoing pain (NPS, LANSS) as well as bedside findings of mechanical allodynia (LANSS) were compared to signs of DMA and thermal hyperalgesia upon QST in 617 neuropathic pain patients.Self-reported abnormal skin sensitivity (LANSS) showed a moderate concordance with DMA during bedside test (67.9%, k=0.391) or QST (52.8%, k=0.165). Receiver operating curve analysis for self-reported DMA yielded similar area-under-the-curve values for LANSS (0.65, CI: 0.59-0.97%) and NPS (0.71, CI: 0.66-0.75%) with high sensitivity but low specificity. Self-reported deep pain intensity was higher in patients with blunt pressure hyperalgesia, but not in patients with DMA or thermal hyperalgesia. No correlations were observed between self-reported hot or cold pain quality and thermal hyperalgesia upon QST.Self-reported abnormal skin sensitivity has a high sensitivity to identify patients with DMA, but its low specificity indicates that many patients mean something other than DMA when reporting this symptom. Self-reported deep pain is related to deep-tissue hypersensitivity, but thermal qualities of ongoing pain are not related to thermal hyperalgesia. Questionnaires mostly evaluate the ongoing pain experience while QST mirrors sensory functions. Therefore, both methods are complementary for pain assessment.
Learn More >Complex regional pain syndrome (CRPS) is a severely disabling disease characterized by pain, temperature changes, motor dysfunction and edema that most often occurs as an atypical response to a minor surgery or fracture. Inflammation involving activation and recruitment of innate immune cells, including both peripheral and central myeloid cells (i.e. macrophages and microglia, respectively), is a key feature of CRPS. However, the exact role and time-course of these cellular processes relative to the known acute and chronic phases of the disease are not fully understood. Positron emission tomography (PET) of translocator protein-18kDa (TSPO) is a method for non-invasively tracking these activated innate immune cells. Here, we reveal the temporal dynamics of peripheral and central inflammatory responses over 20 weeks in a tibial fracture/casting mouse model of CRPS through longitudinal TSPO-PET using [F]GE-180. PET tracer uptake quantification in the tibia revealed increased peripheral inflammation as early as 2 days post-fracture and lasting 7 weeks. Centralized inflammation was detected in the spinal cord and brain of fractured mice at 7 and 21 days post-injury. Spinal cord tissue immunofluorescent staining revealed TSPO expression in microglia (CD11b+) at 7 days, but was restricted mainly to endothelial cells (PECAM1+) at baseline and 7 weeks. Our data suggest early and persistent peripheral myeloid cell activation, and transient central microglial activation are limited to the acute phase of CRPS. Moreover, we show that TSPO-PET can be used to noninvasively monitor the spatiotemporal dynamics of myeloid cell activation in CRPS progression with potential to inform disease phase-specific therapeutics.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Learn More >Little is known about long-term physical activity (PA) maintenance in those with chronic widespread pain (CWP) following an exercise intervention. This study examined PA over time to identify the existence and characteristics of subgroups following distinct PA trajectories.
Learn More >A comparative cohort study with 13-year follow-up.
Learn More >Virtual Reality (VR) is now consumer ready and nearing ubiquity. In terms of clinical applications, several studies suggest that VR can be effective as a complementary adjunct or alternative non-pharmacologic analgesic in a range of pain-inducing procedures and in management of chronic pain. The increasing affordability and quality of portable VR headsets and the ongoing utility of pain therapy signals an exciting future for the use of VR for analgesia. However, further research is needed to establish its long-term benefits if VR is to be adopted into mainstream protocols for analgesia management. This research requires a range of study designs with collection of patient self-report and clinical data together to develop bespoke interventions for different cohorts.
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