The journal of pain : official journal of the American Pain Society
-
Case Reports
Functional magnetic resonance imaging and diffusion tensor imaging in a case of central poststroke pain.
The role of the lesion location within functional pain systems is not fully understood for central poststroke pain (CPSP) pathogenesis. In a patient with CPSP we used data from both functional magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) for anatomo-functional correlations. Structural MRI showed a small residual cavity confined to the right thalamic ventral posterolateral nucleus and the adjacent posterior arm of the internal capsule. ⋯ These findings underline, for CPSP pathogenesis, the role of damage of lateral nociceptive thalamoparietal fibers together with the release of activity of anterior cingulate and posterior parietal regions. In a patient with CPSP, we combined noninvasive neuroimaging techniques (functional and diffusion MRI) to assess the anatomo-functional relationship in CPSP. Our investigations show, for CPSP pathogenesis, the role of damage of lateral nociceptive thalamoparietal fibers together with the release of activity of anterior cingulate and posterior parietal regions.
-
The present series of experiments examined whether the complement cascade might play a key role in the expression of mechanical allodynia. Soluble complement receptor 1 (sCR1) was used to block the activation of the membrane attack pathway of the complement cascade. In doing so, sCR1 prevents the formation of the biologically active end products C3a, C5a, and membrane attack complexes (MACs). ⋯ The mechanisms whereby complement activation might potentially affect the functioning of microglia, astrocytes, and neurons are discussed. The complement cascade has not been previously implicated in spinal sensitization. These data suggest that complement activation within the spinal cord might contribute to enhanced pain states and provide additional evidence for immune regulation of pain transmission.
-
Randomized Controlled Trial Clinical Trial
Electronic diary assessment of pain-related variables: is reactivity a problem?
Reactive measures (measures that change the phenomenon assessed) cause problems in interpreting any changes observed. This study examined whether electronic daily diary measures of pain, activity interference, mood, and pain beliefs were reactive in terms of both observable data and patient-reported effects. Patients with chronic temporomandibular disorder pain (N = 71, 86% female) completed electronic diaries 3 times daily for approximately 2 weeks and subsequently reported perceived effects on symptom-related variables. Seventy-three percent of patients reported that the assessment affected their pain, whereas 51%, 45%, and 39% thought that it affected their daily activities, mood, and beliefs, respectively. In contrast, there was little objective evidence of reactivity as observed in the electronic diary ratings; changes over 14 days were small (eg, predicted changes on 0 to 10 scales: positive mood, .1; pain, -.3; perceived control, -.5) and not statistically significant. Subjective reactivity was generally not significantly related to objective reactivity. The data suggest that patients view daily assessment as having positive and negative effects on pain-related variables, but pain-related measures do not show reactive effects. ⋯ Electronic daily diary assessment methods hold the potential to increase knowledge concerning patients' experiences with pain and sequential relations between pain-related variables, but only if the measurement process is nonreactive. This study provides evidence that electronic diary assessment of pain-related variables is nonreactive.
-
Clinical Trial Controlled Clinical Trial
Morphine responses and experimental pain: sex differences in side effects and cardiovascular responses but not analgesia.
Sex differences in analgesic responses to mu opioid agonists have been reported, although the direction of these differences varies across studies. To further characterize sex differences in responses to mu opioids, the analgesic effects of intravenous morphine (0.08 mg/kg) were determined in healthy women (n = 61) and men (n = 39) by using 3 experimental pain models, heat pain, pressure pain, and ischemic pain. Each pain procedure was conducted before and after double-blind administration of both morphine and saline, which occurred on separate days in counterbalanced order. Although morphine produced significant analgesic effects for all pain stimuli, no significant sex differences in morphine analgesia emerged. However, morphine attenuated cardiovascular reactivity to the ischemic pain task in men but not women, and women reported significantly more drug-related adverse effects than men. These findings are in contrast with some recent clinical and experimental results suggesting more robust analgesic response to mu opioids among women compared to men, although the data indicate that sex differences in non-analgesic effects of morphine were present. These results suggest that sex differences in responses to morphine might depend on the pain model and/or drug dose as well as the specific end point assessed. ⋯ This study examines morphine responses in women and men by using laboratory pain measures. The results indicate no sex differences in analgesia, but women reported greater side effects, and morphine attenuated cardiovascular responses more strongly among men than women. These results add to the literature regarding sex differences in response to opioids.
-
By elaborating on previous prospective and cross-sectional research, the primary aim of this study was to examine in the general community whether pain catastrophizing predicts the development of chronic pain complaints and other consequences of pain. The following health index values were examined as consequences of pain: specialist consultation, use of pain medication, and absenteeism. It was also examined whether these relationships were moderated by the number of pain problems and by pain intensity. The results demonstrated a generally low level of catastrophizing and a small but significant effect of catastrophizing on the development of chronic pain complaints. With respect to the health index values, no significant effects of catastrophizing were found, nor were the relationships between catastrophizing and chronicity and the health index values moderated by the number of pain problems or by pain intensity. ⋯ Because in the general community the level of catastrophizing is low, its role in the development of future pain problems is probably limited in this type of setting. More practically, the Pain Catastrophizing Scale, used to measure pain catastrophizing, is probably of limited use as a screening instrument in the general community. The disappointing results may indicate that, depending on the specific setting (eg, clinical, outpatient, or community) the role of pain catastrophizing is either more or less prominent.