The journal of pain : official journal of the American Pain Society
-
Cortical pain processing is associated with large-scale changes in neuronal connectivity, resulting from neural plasticity phenomena of which brain-derived neurotrophic factor (BDNF) is a central driver. The common single nucleotide polymorphism Val66Met is associated with reduced BDNF activity. Using the trigeminal pain-related evoked potential (tPREP) to repeated electrical painful stimuli, we investigated whether the methionine substitution at codon 66 of the BDNF gene was associated with changes in cortical processing of noxious stimuli. Fifty healthy volunteers were genotyped: 30 were Val/Val and 20 were Met-carriers. tPREPs to 30 stimuli of the right supraorbital nerve using a concentric electrode were recorded. The N2 and P2 component latencies and the N2-P2 amplitude were measured over the 30 stimuli and separately, by dividing the measurements in 3 consecutive blocks of 10 stimuli. The average response to the 30 stimuli did not differ in latency or amplitude between the 2 genotypes. There was a decrease in the N2-P2 amplitude between first and third block in the Val/Val group but not in Met-carriers. BDNF Val66Met is associated with reduced decremental response to repeated electrical stimuli, possibly as a result of ineffective mechanisms of synaptic memory and brain plasticity associated with the polymorphism. ⋯ BDNF Val66Met polymorphism affects the tPREP N2-P2 amplitude decrement and influences cortical pain processing through neurotrophin-induced neural plasticity, or through a direct BDNF neurotransmitter-like effect. Our findings suggest that upcoming BDNF central agonists might in the future play a role in pain management.
-
Randomized Controlled Trial Multicenter Study
Viscerosomatic facilitation in a subset of IBS patients, an effect mediated by N-methyl-D-aspartate receptors.
Irritable bowel syndrome (IBS) is a common gastrointestinal disorder in which the pathophysiological mechanisms of the pain and hypersensitivity are incompletely understood. IBS patients frequently complain of pain in body regions somatotopically distinct from the gut, suggesting involvement of central hyperalgesic mechanisms. We tested the role of tonic peripheral impulse input by using both repetitive thermal stimuli to the leg and repetitive stimuli to the rectum. Changes in thermal/visceral pain sensitivity after nociceptive thermal/visceral repetitive stimulation were determined. A subset of IBS patients showed enhanced rectal/thermal pain sensitivity after repetitive thermal/rectal stimulation, respectively. IBS patients then received 60 mg dextromethorphan and placebo (diphenhydramine) in a randomized, double-blind, crossover trial. The results showed that 1) a subset of IBS patients had increased visceral/cutaneous hypersensitivity following a series of repetitive nociceptive stimuli and that 2) this increased pain sensitivity was blocked by administration of dextromethorphan. This is the first human study indicating that repetitive stimulation enhances a bidirectional mechanism of secondary hyperalgesia due to viscerosomatic facilitation in IBS patients. These unique findings elucidate mechanisms of somatic hypersensitivity in IBS patients and support an etiologic basis for abnormal N-methyl-D-aspartate receptor mechanisms that may be the target of future therapies for IBS. ⋯ Repetitive stimulation enhances a bidirectional mechanism of secondary hyperalgesia due to viscerosomatic convergence in IBS patients. The findings elucidate unique mechanisms of somatic/visceral hypersensitivity in a subset of IBS patients and further support an etiologic basis for abnormal N-methyl-D-aspartate receptor mechanisms that may be future targets of therapies for IBS.
-
Multicenter Study
Pain assessment and intensity in hospitalized children in Canada.
Numerous acute pediatric pain assessment measures exist; however, pain assessment is not consistently performed in hospitalized children. The objective of this study was to determine the nature and frequency of acute pain assessment in Canadian pediatric hospitals and factors influencing it. Pain assessment practices and pain intensity scores documented during a 24-hour period were collected from 3,822 children aged 0 to 18 years hospitalized on 32 inpatient units in 8 Canadian pediatric hospitals. Pain assessment was documented at least once within the 24 hours for 2,615/3,822 (68.4%) children; 1,097 (28.7%) with a pain measure alone, 1,006 (26.3%) using pain narratives alone, and 512 (13.4%) with both a measure and narrative. Twenty-eight percent of assessments were conducted with validated measures. The mean standardized pain intensity score was 2.6/10 (SD 2.8); however, 33% of the children had either moderate (4-6/10) or severe (7-10/10) pain intensity recorded. Children who were older, ventilated, or hospitalized in surgical units were more likely to have a pain assessment score documented. Considerable variability in the nature and frequency of documented pain assessment in Canadian pediatric hospitals was found. These inconsistent practices and significant pain intensity in one-third of children warrant further research and practice change. ⋯ This article presents current pediatric pain assessment practices and data on pain intensity in children in Canadian pediatric hospitals. These results highlight the variability in pain assessment practices and the prevalence of significant pain in hospitalized children, highlighting the need to effectively manage pain in this population.
-
Developing educational interventions about pain may lead to improved pain management for older people. A public group educational session, entitled "Pain in the Older Person," was presented in 7 cities across Canada (Vancouver, Calgary, London, Toronto, Ottawa, Montreal, and Halifax). The presentation lasted approximately 90 minutes and was followed by a question and answer period of at least 20 minutes. Prior to the educational session, participants provided demographic data and completed measures of pain intensity, frequency, interference, and treatment; of subjective health; and of knowledge about pain. Following the session, participants completed the same knowledge items again as well as items assessing satisfaction. Data were provided by 54 health care workers (HCW) and 54 older community members (66.3 ± 10.2 years old). Prior to the educational session, knowledge gaps were evident among the older community members, especially about analgesic use. Among the HCW, knowledge gaps were found about addiction and the relationship between pain and aging. Comparison of knowledge scores before and after the educational session revealed that both groups demonstrated significant knowledge gains. Satisfaction scores were very high, with no significant difference between HCW and older community members. This is the first study to show that a brief educational intervention is associated with gains in knowledge about pain and aging among both older community members and HCW. These results suggest that a brief public educational session is a promising method of pain education that may reduce barriers to pain management in older people. ⋯ This article describes the results of a brief public educational session about pain and aging attended by older members of the community and health care workers. This intervention could potentially improve pain management for older people.
-
Current evidence supports the efficacy of placebo analgesia and illustrates that patients may be open to placebo use despite uncertainty regarding its mechanisms. Debate persists, however, concerning the ethics of placebo treatments. The purpose of the present web-based study was to expand upon the empirical literature on placebo analgesia ethics and acceptability. Participants (n = 100) provided their definition of a placebo and responded to 24 questions addressing placebo analgesia perceived knowledge, acceptability, effectiveness, and likelihood of placebo use among different health care providers. Results support previous research on the effects of placebo on negative mood and health care provider attributions, with findings illustrating that negative consequences of administration were largely mitigated by a beneficial treatment outcome. Results showed that participants conceptualized placebo as predominately inert and were mixed regarding interpretations of placebo effectiveness. Though acceptability ratings were dependent on the context of placebo administration, participants endorsing even moderate placebo acceptability were more open to placebo interventions and reported overall more positive treatment outcomes. Participants believed that placebos were used differentially among health care providers. Additional studies are needed to determine if placebo education can beneficially impact perceptions of placebo analgesia knowledge, acceptability, and treatment effectiveness. ⋯ This study presents an examination of analgesic placebo treatment perceived acceptability, efficacy, and knowledge among lay individuals. Our findings highlight the importance of assessing placebo conceptualizations and treatment perceptions in evaluating placebo ethics-a highly relevant finding that informs the clinical use of placebo components in managing pain.