Pain
-
Randomized Controlled Trial Comparative Study
Effects of morphine on the experimental illusion of pain produced by a thermal grill.
We compared the effects of systemic morphine on normal (heat and cold) pain and paradoxical burning pain evoked by the simultaneous application of innocuous warm and cold stimuli to the skin. Twelve healthy volunteers participated in a randomised, double-blind, cross-over study to compare the effects of intravenous administration of morphine (0.025 or 0.1mg/kg) or placebo (saline). Stimuli were applied to the palm of the right hand with a thermode ("thermal grill") composed of six bars, whose temperatures were controlled by Peltier elements. ⋯ No differences were observed for non-painful thermal sensations. The paradoxical burning pain evoked by a thermal grill can be modified pharmacologically by analgesics and share some mechanisms with normal pain. This unique experimental "illusion of pain" may represent a new model to test analgesics in healthy volunteers.
-
The objective of this study is to identify subgroups of patients with non-specific neck pain who are more likely to benefit from either physiotherapy, spinal manipulation therapy, or usual care, on the short- and long-term. Data of three recently finished randomised controlled trials, with similar design and setting, were combined. The combined study population consisted of 329 patients with non-specific neck pain in an adult (18-70years) primary care population in the Netherlands. ⋯ The analysis revealed three predictors for recovery of which the effect is modified by treatment: pain intensity (0-10 scale) in the short-term model, age and (no) accompanying low back pain in the long-term model. With these predictors a clinically relevant improvement in recovery rate (up to 25% improvement) can be established in patients receiving a tailored instead of a non-advised treatment. In conclusion we identified three characteristics that facilitate a deliberate treatment choice, to optimise benefit of treatment in patients with non-specific neck pain: age, pain intensity, and (no) accompanying low back pain.
-
The Child Activity Limitations Interview (CALI) is a measure designed to assess functional impairment due to chronic pain in school-age children. In this study, we present a self-report questionnaire version of the CALI (the CALI-21) that extends the original interview measure. The purpose of this study was to provide internal consistency, cross-informant reliability and construct validity of the CALI-21 on a clinical sample of children and adolescents with chronic pain conditions. ⋯ The CALI-21 showed good internal consistency, high cross-informant reliability, and demonstrated construct validity. The CALI-21 provides increased flexibility via the questionnaire format in the assessment of pain-related activity limitations in children. Factor analysis extends information about specific types of activity limitations experienced by children.
-
Comparative Study
The role of heterosynaptic facilitation in long-term potentiation (LTP) of human pain sensation.
Long-term potentiation (LTP) of nociceptive synaptic transmission induced by high-frequency electrical stimulation (HFS) predominantly modulates natural somatosensory perceptions mediated by Adelta- and Abeta-fibers in humans at the site of conditioning stimulation. The relative contribution of homo- and heterosynaptic mechanisms underlying those perceptual changes remained unclear. We therefore compared changes of the somatosensory profile between a conditioned skin site (homotopic zone) and an area adjacent to conditioning HFS (heterotopic zone). ⋯ Moreover, a small decrease of thresholds to blunt pressure was found at both zones (p<0.05). Pain summation (windup ratio), mechanical detection threshold as well as vibration detection threshold remained unchanged. Because none of the changes in sensory parameters was unique for the site of conditioning stimulation, these data suggest that heterosynaptic interactions are the predominant mechanism of LTP in nociceptive pathways.
-
Previously, we demonstrated that placebo analgesia (PA) accompanies reductions in neural activity during painful stimulation. This study investigated areas of the brain where the neural activity was increased during PA. The literature has associated PA with two potential mechanisms of action; one sustained (e.g., engaged for the duration of PA), the other, transitory (e.g., a feedback mechanism). ⋯ Conversely, brain regions with transient activity included linguistic centers in the left hemisphere and frontal regions of the right hemisphere generally associated with executive functioning. Together, these mechanisms likely engage analgesic processes and then simply monitor the system for unexpected stimuli, effectively liberating resources for other processes. Identifying brain regions associated with pain-modulation with different temporal profiles is consistent with the multidimensionality of PA and highlights the need for continued investigation of this construct.