The journal of pain : official journal of the American Pain Society
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Researchers have demonstrated that certain types of pain coping are correlated with less pain severity and disability and that there are differences between Caucasians and African-American pain patients in their use of specific coping strategies. However, the extent to which racial group differences exist in the associations between pain coping strategies and pain severity, interference, and disability is unclear. Furthermore, the role of education in these associations is uncertain. We recruited a diverse community sample of individuals with chronic pain and their spouses to examine this issue (N = 105). Participants completed the Coping Strategies Questionnaire, Multidimensional Pain Inventory, and Sickness Impact Profile. Results showed that African-American participants reported significantly more pain severity, interference, and disability and reported using diverting attention and prayer and hoping pain-coping strategies significantly more often than Caucasian participants; however, only the racial group difference in prayer and hoping remained when controlling for education. We also examined whether race and education interacted with coping strategies in relating to pain and disability. Significant three-way interactions were found for physical and psychosocial disability, suggesting that educational level should be included in analyses exploring racial group differences. The results suggest the need for pain treatments that take into account the educational and cultural context of pain. ⋯ This article demonstrates that demographic variables such as race and education should be considered together when evaluating the effectiveness of coping with pain. The findings have the potential to enhance research and clinical practice with diverse groups.
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Randomized Controlled Trial Comparative Study
Comparison of clinical and evoked pain measures in fibromyalgia.
Evoked pain measures such as tender point count and dolorimetry are often used to determine tenderness in studies of fibromyalgia (FM). However, these measures frequently do not improve in clinical trials and are known to be influenced by factors other than pain such as distress and expectancy. The purpose of this investigation was to determine whether evoked pain paradigms that present pressure stimuli in a random fashion (eg, Multiple Random Staircase [MRS]) would track with clinical pain improvement in patients with FM better than traditional measures. Sixty-five subjects enrolled in a randomized clinical trial of acupuncture were observed longitudinally. Clinical pain was measured on a 101-point numerical rating scale (NRS) and the Short Form McGill Pain Questionnaire (SF-MPQ), whereas evoked pressure sensitivity was assessed via manual tender point count, dolorimetry, and MRS methods. Improvements in clinical pain and evoked pain were assessed irrespective of group assignment. Improvement was seen in clinical pain during the course of the trial as measured by both NRS (P = .032) and SF-MPQ (P = .001). The MRS was the only evoked pain measure to improve correspondingly with treatment (MRS, P = .001; tender point count and dolorimeter, P > .05). MRS change scores were correlated with changes in NRS pain ratings (P = .003); however, this association was not stronger than tender point or dolorimetry correlations with clinical pain improvement (P > .05). Pain sensitivity as assessed by random paradigms was associated with improvements in clinical FM pain. Sophisticated pain testing paradigms might be responsive to change in clinical trials. ⋯ Trials in fibromyalgia often use both clinical and experimental methods of pain assessment; however, these two outcomes are often poorly correlated. We explore the relationship between changes in clinical and experimental pain within FM patients. Pressure pain testing that applies stimuli in a random order is associated with improvements in clinical pain, but this association was not stronger than other experimental techniques.
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Peripheral bee venom (BV) administration produces 2 contrasting effects, nociception and antinociception. This study was designed to evaluate whether the initial nociceptive effect induced by BV injection into the Zusanli acupoint is involved in producing the more prolonged antinociceptive effect observed in the mouse formalin test, and whether capsaicin-sensitive primary afferents are involved in these effects. BV injection into the Zusanli point increased spinal Fos expression but not spontaneous nociceptive behavior. BV pretreatment 10 minutes before intraplantar formalin injection dose-dependently attenuated nociceptive behavior associated with the second phase of the formalin test. The destruction of capsaicin-sensitive primary afferents by resiniferatoxin (RTX) pretreatment selectively decreased BV-induced spinal Fos expression but did not affect BV-induced antinociception. Furthermore, BV injection increased Fos expression in tyrosine hydroxylase immunoreactive neurons in the locus caeruleus, and this expression was unaltered by RTX pretreatment. Finally, BV's antinociception was blocked by intrathecal injection of 10 microg idazoxan, and this effect was not modified by RTX pretreatment. These findings suggest that subcutaneous BV stimulation of the Zusanli point activates central catecholaminergic neurons via capsaicin-insensitive afferent fibers without induction of nociceptive behavior. This in turn leads to the activation of spinal alpha2-adrenoceptors, which ultimately reduces formalin-evoked nociceptive behaviors. ⋯ This study demonstrates that BV acupuncture produces a significant antinociception without nociceptive behavior in rodents, which is mediated by capsaicin-insensitive afferents and involves activation of central adrenergic circuits. These results further suggest that BV stimulation into this acupuncture point might be a valuable alternative to traditional electrical or mechanical acupoint stimulation.
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Antidepressants such as tricyclic antidepressants have become used to treat a variety of chronic pain conditions. However, the side effects are dose-limiting in the treatment of chronic pain. Milnacipran is a norepinephrine/serotonin reuptake inhibitor that does not have the severe side effects associated with traditional tricyclic antidepressants. The effects of intrathecal and systemic administration of milnacipran on spinal nerve ligation (SNL)-induced thermal and mechanical hypersensitivity and shift in weight bearing were determined. Intrathecal administration of milnacipran was found to reverse both SNL-induced thermal and tactile (to von Frey filaments) hypersensitivity, as well as shift in weight bearing. Acute systemic administration of milnacipran also reversed nerve injury-induced thermal hypersensitivity for up to 5 hours but failed to reverse tactile hypersensitivity or shift in weight bearing. Of note, both intrathecal and subcutaneous administration of milnacipran induced thermal antinociception in both SNL and sham rats. Chronic (daily) systemic administration of milnacipran alleviated both thermal hypersensitivity and shift in weight bearing, with both acute and chronic effects observed on thermal hypersensitivity. However, chronic systemic milnacipran administration failed to alleviate tactile hypersensitivity to von Frey filaments. These results indicate that different mechanisms underlie shift in weight bearing, thermal hypersensitivity, and tactile hypersensitivity. ⋯ These results indicate that the ability of milnacipran to relieve nerve injury-induced allodynia, hyperalgesia, and shift in weight bearing depends on the route of administration and the duration of treatment, with alleviation of SNL-induced tactile hypersensitivity and shift in weight bearing as a result of activity within the central-rather than the peripheral-nervous system.