Pain
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We performed a prospective study in 32 patients with Guillain-Barré syndrome (GBS) or its variants to correlate intraepidermal nerve fiber density (IENFD) at the distal leg and lumbar region with pain, autonomic dysfunction, and outcome. In the acute phase, IENFD was reduced in 60% and 61.9% of patients at the distal leg and lumbar region, respectively. In the acute phase, 43.7% of patients complained of neuropathic pain. ⋯ Double and triple staining confocal microscope studies showed diffuse damage of myelinated dermal nerves along with axonal degeneration, and mononuclear cell infiltration. Unmyelinated and myelinated skin nerves are diffusely affected in GBS and its variants, including the pure motor form. IENFD declines early, remains low over time, correlates with pain severity in the acute phase, and may predict long-term disability.
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Randomized Controlled Trial
A randomized controlled evaluation of an online chronic pain self management program.
Internet-based educational and therapeutic programs (e-health applications) are becoming increasingly popular for a variety of psychological and physical disorders. We tested the efficacy of an online Chronic Pain Management Program, a comprehensive, fully self-directed and self-paced system that integrates social networking features and self-management tools into an interactive learning environment. Of 305 adult participants (196 women, 109 men), a total of 162 individuals with chronic pain were randomly assigned unsupervised access to the program for approximately 6 weeks; 143 were assigned to the wait-listed control group with treatment as usual. ⋯ Further, program use led to significant declines in depression, anxiety, and stress. Finally, as compared to the wait-listed control group, the experimental group displayed a significant increase in knowledge about the principles of chronic pain and its management. Study limitations are considered, including the recognition that not all persons with chronic pain are necessarily good candidates for self-initiated, self-paced, interactive learning.
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The combination of pain and depression or anxiety is commonly seen in clinical practice. Little is known about the influence of pain on psychopathology over time, as previous studies have been mainly cross-sectional. The objectives of this study are to determine the impact of pain on the course of depressive and/or anxiety disorders, and investigate to what extent the association between pain and course of these mental disorders is mediated by psychiatric characteristics. ⋯ This study shows that patients with pain are more prone to a chronic course of depressive and anxiety disorders. More attention to pain seems to be necessary when diagnosing and treating these disorders. Future research should focus on treatment modalities for this co-occurrence, with joint pain in particular.
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Comparative Study
Differential effects of experimental central sensitization on the time-course and magnitude of offset analgesia.
Pain perception is temporally altered during states of chronic pain and acute central sensitization; however, the mechanisms contributing to temporal processing of nociceptive information remain poorly understood. Offset analgesia is a phenomenon that reflects the presence of temporal contrast mechanisms for nociceptive information and can provide an end point to study temporal aspects of pain processing. In order to investigate whether offset analgesia is disrupted during sensitized states, 23 healthy volunteers provided real-time continuous visual analogue scale responses to noxious heat stimuli that evoke offset analgesia. ⋯ Increased latencies to maximal offset analgesia and prolonged aftersensations were observed only in the primary regions directly treated by capsaicin-heat or heat alone. However, contrary to the hypothesis that offset analgesia would be reduced following capsaicin-heat sensitization, the magnitude of offset analgesia remained remarkably intact after both capsaicin-heat and heat-only sensitization in zones of both primary and secondary mechanical allodynia. These data indicate that offset analgesia is a robust phenomenon and engages mechanisms that interact minimally with those supporting acute central sensitization.