The journal of pain : official journal of the American Pain Society
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The aim of this study was to examine whether gastric afferent information converged onto upper thoracic spinal neurons that received noxious cardiac input. Extracellular potentials of single upper thoracic (T3) spinal neurons were recorded in pentobarbital-anesthetized, paralyzed, ventilated male rats. Gastric distension (GD) (20, 40, 60 mm Hg, 20 seconds) was produced by air inflation of a latex balloon surgically placed in the stomach. A catheter was placed in the pericardial sac to administer bradykinin solution (10 microg/mL, 0.2 mL, 1 minute) as a noxious cardiac stimulus. Noxious GD (> or =40 mm Hg) altered activity of 26 of 31 (84%) spinal neurons receiving cardiac input. Twenty-two (85%) gastrocardiac convergent neurons were excited, and 1 neuron was inhibited by both intrapericardial bradykinin and GD; the remainder exhibited biphasic response patterns. Twenty-three of 26 (88%) gastrocardiac neurons also received convergent somatic input from the chest, triceps, and upper back areas. Bilateral cervical vagotomy did not significantly affect excitatory responses to GD in 5 of 5 neurons tested. Spinal transection at the C1 segment after vagotomy did not affect excitatory responses to GD in 3 of 4 neurons but abolished the GD response in 1 neuron. These data showed that a gastric stimulus excited T3 spinal neurons with noxious cardiac input primarily by way of intraspinal ascending pathways. ⋯ Convergence of gastric afferent input onto upper thoracic spinal neurons receiving noxious cardiac input that was observed in the present study may provide a spinal mechanism that explains stomach-heart cross-organ communication, such as postprandial triggering and worsening of angina pectoris in patients with coronary artery disease.
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Repetitive transcranial magnetic stimulation (rTMS) is an emerging technology that has been demonstrated to be useful in the treatment of depression and potentially useful in the management of several neurologic conditions. More recently, increasing attention has been directed at evaluating its efficacy in the treatment of patients with chronic neuropathic pain. We first discuss the literature examining the efficacy of rTMS in trials of experimentally induced acute pain as well as among patients with chronic pain. Examining frequency data obtained from the available literature, we attempted to identify some of the parameters of rTMS that appear to be related to its analgesic effects. An overview of the mechanisms underlying its potential analgesic role is discussed; generally, the influences of rTMS on cortical, and, indirectly, subcortical, neurons may reduce pain transmission ascending from spinothalamic tracts, thereby mitigating pain. Finally, we discuss some of the methodological issues and limitations of available studies and offer recommendations for further research. ⋯ The authors provide a comprehensive review of rTMS use in the treatment of neuropathic pain in the literature available to date. Although the clinical usefulness of rTMS in pain has, as yet, to be determined, it offers insights into the pathophysiologic processes involved in the maintenance and exacerbation of chronic pain.
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In children with advanced stages of cancer, pain control remains inadequate in many patients and a solution to this problem is sorely lacking. Factors related to progression of the primary disease and side-effects of high doses of opioids, the mainstay of pain therapy, contribute to the inadequacy of pain control. In addition, few studies suggest that opioids, by inducing tolerance, having pronociceptive effects and producing hyperalgesia in some patients, can also contribute to inadequacy of pain control. Researchers have shown that N-methyl-D-aspartate (NMDA) receptor antagonists may have a role in mitigating opioid-induced tolerance and hyperalgesia in adults. However, literature on NMDA antagonists to treat cancer pain in children and adolescents is scarce. We used subanesthetic doses of ketamine to treat 11 children and adolescents who were on high doses of opioids and yet had uncontrolled cancer pain. A low-dose ketamine infusion was administered to all patients to modulate the need for rapidly escalating opioid therapy. We found that in 8 of 11 patients, ketamine infusions used as an adjuvant to opioid analgesia was associated with opioid-sparing effects and apparent improvement in pain control and in the children's ability to interact with their family. This study suggests that infusions of ketamine may offer a promising therapeutic option in the treatment of appropriately selected children and adolescents with intractable cancer pain. ⋯ In many children with advanced stages of cancer, pain control remains inadequate. We used subanesthetic doses of ketamine to treat 11 children and adolescents who were on high doses of opioids and had uncontrolled cancer pain. In the majority of patients, ketamine appeared to improve pain control and to have an opioid-sparing effect.
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Variable use of pain scale anchors may influence recalled pain ratings, rating consistency, and agreement between actual rating change and ratings of pain relief. This investigation examined change in events that represent maximal pain scale anchors. Participants (N = 68, 50% women) provided events for maximal anchors of 0 to 100 pain scales, and cold pressor pain was rated by using self-selected event/s and an investigator-provided event. Participants then were allowed to change their self-selected event/s. The revised event/s or original events were then used to rate a second cold pressor trial. Forty-one percent of participants changed event/s, and the new event/s was more likely to involve cold or heat, but the painfulness of events and the pain ratings of the second trial did not change. The cold pressor pain ratings were higher when rated on the basis of self-selected event/s than the investigator-provided event for intensity (mean = 80.13, SD = 19.30; mean = 60.81, SD = 27.45) and unpleasantness (mean = 80.84, SD = 19.07; mean = 59.07, SD = 27.53), which could be due to the submaximal painfulness of the investigator-provided event. Therefore, the width of numerical scales is stable with maximal events regardless of the actual events. ⋯ This report identifies change in physical events that are used by participants to represent maximal pain scale anchors and suggests that the maximal nature of the events' painfulness is more important than variability in the actual events. We conclude that the numerical pain scales we used are understandable and stable, but we suggest that instructional sets for pain measurement may be improved by evaluation of the painfulness of events that respondents use to conceptualize maximal pain scale anchors.
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Multicenter Study
Pain in the emergency department: results of the pain and emergency medicine initiative (PEMI) multicenter study.
Pain is the most common reason for emergency department (ED) use, and oligoanalgesia in this setting is known to be common. The Joint Commission on Accreditation of Healthcare Organizations has revised standards for pain management; however, the impact of these regulatory changes on ED pain management practice is unknown. This prospective, multicenter study assessed the current state of ED pain management practice. After informed consent, patients aged 8 years and older with presenting pain intensity scores of 4 or greater on an 11-point numerical rating scale completed structured interviews, and their medical records were abstracted. Eight hundred forty-two patients at 20 US and Canadian hospitals participated. On arrival, pain intensity was severe (median, 8/10). Pain assessments were noted in 83% of cases; however, reassessments were uncommon. Only 60% of patients received analgesics that were administered after lengthy delays (median, 90 minutes; range, 0 to 962 minutes), and 74% of patients were discharged in moderate to severe pain. Of patients not receiving analgesics, 42% desired them; however, only 31% of these patients voiced such requests. We conclude that ED pain intensity is high, analgesics are underutilized, and delays to treatment are common. Despite efforts to improve pain management practice, oligoanalgesia remains a problem for emergency medicine. ⋯ Despite the frequency of pain in the emergency department, few studies have examined this phenomenon. This study documents high pain intensity and suboptimal pain management practices in a large multicenter ED network in the United States and Canada. These findings suggest that there is much room for improvement in this area.