Pain
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P2X receptors on dorsal root ganglion (DRG) neurons have been strongly implicated in pathological nociception after peripheral nerve injuries or inflammation. However, nothing is known of a role for purinergic receptors in neuropathic pain produced by a chronic compression of DRG (CCD) - an injury that may accompany an intraforaminal stenosis, a laterally herniated disc or other disorders of the spine leading to radicular pain. In a rat model of DRG compression, hyperexcitable neurons retain functioning axonal connections with their peripheral targets. ⋯ These currents were accompanied by the generation of action potentials - but only in the CCD neurons. U0126, a specific inhibitor of the MEK1/2, greatly down-regulated the enhanced current. Taken together, these observations suggest that enhanced purinergic responses after CCD are mediated by P2X 3 receptors.
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Peripheral nerve injury produces a persistent neuropathic pain state characterized by spontaneous pain, allodynia and hyperalgesia. In this study, we evaluated the possible involvement of A 2ARs in the development of neuropathic pain and the expression of microglia and astrocytes in the spinal cord after sciatic nerve injury. For this purpose, partial ligation of the sciatic nerve was performed in A 2A knockout mice and wild-type littermates. ⋯ However, a significant decrease of the mechanical allodynia and a suppression of thermal hyperalgesia and allodynia were observed in A 2AR deficient mice. The expression of microglia and astrocytes was enhanced in wild-type mice exposed to sciatic nerve injury and this response was attenuated in knockout animals. Taken together, our results demonstrate the involvement of A 2ARs in the control of neuropathic pain and propose this receptor as an interesting target for the development of new drugs for the management of this clinical syndrome.
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Multicenter Study
Severity of acute pain after childbirth, but not type of delivery, predicts persistent pain and postpartum depression.
Cesarean delivery rates continue to increase, and surgery is associated with chronic pain, often co-existing with depression. Also, acute pain in the days after surgery is a strong predictor of chronic pain. Here we tested if mode of delivery or acute pain played a role in persistent pain and depression after childbirth. ⋯ Women with severe acute postpartum pain had a 2.5-fold increased risk of persistent pain and a 3.0-fold increased risk of postpartum depression compared to those with mild postpartum pain. In summary, cesarean delivery does not increase the risk of persistent pain and postpartum depression. In contrast, the severity of the acute pain response to childbirth predicts persistent morbidity, suggesting the need to more carefully address pain treatment in the days following childbirth.
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Randomized Controlled Trial
A randomized trial of behavioral physical therapy interventions for acute and sub-acute low back pain (NCT00373867).
Psychological factors consistent with fear-avoidance models are associated with the development of chronic low back pain (LBP). As a result, graded activity (GA) and graded exposure (GX) have been suggested as behavioral treatment options. This clinical trial compared the effectiveness of treatment-based classification (TBC) physical therapy alone to TBC augmented with GA or GX for patients with acute and sub-acute LBP. ⋯ GX and TBC were associated with larger reductions in fear-avoidance beliefs at 6 months only. Six-month reduction in disability was associated with reduction in pain intensity, while 6-month reduction in pain intensity was associated with reductions in fear-avoidance beliefs and pain catastrophizing. This trial suggests that supplementing TBC with GA or GX was not effective for improving important outcomes related to the development of chronic LBP.
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Minimal pain content has been documented in pre-licensure curricula and students lack important pain knowledge at graduation. To address this problem, we have implemented and evaluated a mandatory Interfaculty Pain Curriculum (IPC) yearly since 2002 for students (N=817 in 2007) from six Health Science Faculties/Departments. The 20-h pain curriculum continues to involve students from Dentistry, Medicine, Nursing, Pharmacy, Physical Therapy, and Occupational Therapy as part of their 2nd or 3rd year program. ⋯ The DCPQ responses have also indicated consistently that most students (85-95%) rated highly the patient panel, expert-lead clinically focused sessions, and small interprofessional groups. Relevancy and organization of the information presented have been generally rated highly from 80.3% to 91.2%. This curriculum continues to be a unique and valuable learning opportunity as we utilize lessons learned from extensive evaluation to move the pain agenda forward with pre-licensure health science students.