Pain
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Randomized Controlled Trial Clinical Trial
Patients initially diagnosed as 'warm' or 'cold' CRPS 1 show differences in central sensory processing some eight years after diagnosis: a quantitative sensory testing study.
We used quantitative sensory testing (QST) to gain further insight into mechanisms underlying pain in CRPS 1. Specific goals were: (1) to identify altered patterns of sensory processing some 8 years after diagnosis, (2) to document differences in sensory processing between 'warm' and 'cold' diagnostic subgroups, (3) to determine relationships between changed sensory processing and disease progression regarding pain. The study was performed on a cohort of patients (n=47) clinically diagnosed with CRPS 1 of one upper extremity approximately 8 years previously. ⋯ The latter is not the case for warm CRPS 1 patients. Both diagnostic subgroups show greater pressure hyperalgesia on the affected limb and with disease progression. QST may prove useful in the subdiagnosis of CRPS 1 and in quantifying its progression, with both applications warranting further investigation for clinical and research use.
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Multicenter Study Clinical Trial
Possible selves in chronic pain: self-pain enmeshment, adjustment and acceptance.
The aim of this study was to test whether enmeshment of self and pain predicted adjustment (depression and acceptance) in a chronic pain population. 89 chronic pain patients completed standardized self-report measures of depression and acceptance and generated characteristics describing their current actual self, hoped-for self and feared-for self, and made judgments about the degree to which their future possible selves (hoped-for and feared-for) were dependent on the absence or presence of pain, i.e. enmeshed with pain. Hierarchical multiple regression analyses showed that after accounting for the influence of demographics (age, gender), pain characteristics and the degree of role interference attributable to pain, the proportion of hoped-for self characteristics that could be achieved even with the presence of pain predicted the magnitude of depression and acceptance scores. The findings are discussed with reference to the enmeshment hypothesis and theories of self-discrepancy, self-regulation and hopelessness.
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Clinical Trial
Identification of cut-points for mild, moderate and severe pain due to diabetic peripheral neuropathy.
This study identified discrete categories of pain severity in a sample of patients with painful diabetic peripheral neuropathy (DPN), through derivation of cut-points on a 0-10 scale of pain severity (Brief Pain Inventory-DPN, BPI-DPN). Subjects were participants in a burden of illness survey (N=255). Serlin and colleagues' method establishing cut-points for cancer pain was adapted, considering all possible cut-points between 4 and 8. ⋯ Patients in the three categories differed significantly on patient-rated outcomes (Medical Outcomes Study Short Form-12v2 Mental and Physical Component Summaries and EuroQOL utility score), and on DPN-related healthcare visits (P<0.001). The labels 'mild, moderate and severe' Worst and Average Pain corresponded with patients' ratings of their pain using a verbal rating scale. This research shows that three categories of DPN pain severity can be identified based on interference with daily function, and that these categories are associated with patient outcomes and medical utilization.
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Activated glial cells (microglia and astroglia) in the spinal cord play a major role in mediating enhanced pain states by releasing proinflammatory cytokines and other substances thought to facilitate pain transmission. In the present study, we report that intrathecal administration of minocycline, a selective inhibitor of microglial cell activation, inhibits low threshold mechanical allodynia, as measured by the von Frey test, in two models of pain facilitation. In a rat model of neuropathic pain induced by sciatic nerve inflammation (sciatic inflammatory neuropathy, SIN), minocycline delayed the induction of allodynia in both acute and persistent paradigms. ⋯ In a model of spinal immune activation by intrathecal HIV-1 gp120, we show that the anti-allodynic effects of minocycline are associated with decreased microglial activation, attenuated mRNA expression of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-1beta-converting enzyme, TNF-alpha-converting enzyme, IL-1 receptor antagonist and IL-10 in lumbar dorsal spinal cord, and reduced IL-1beta and TNF-alpha levels in the CSF. In contrast, no significant effects of minocycline were observed on gp120-induced IL-6 and cyclooxygenase-2 expression in spinal cord or CSF IL-6 levels. Taken together these data highlight the importance of microglial activation in the development of exaggerated pain states.
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Comment Letter Comparative Study
Comment on: Gilron I, Orr E, Tu D, O'Neill JP, Zamora JE, Bell AC. A placebo-controlled randomized clinical trial of perioperative administration of gabapentin, rofecoxib and their combination for spontaneous and movement-evoked pain after abdominal hysterectomy. Pain 113 (2005) 191-200.