The journal of pain : official journal of the American Pain Society
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From a treatment perspective, it is highly relevant to pinpoint individual vulnerability factors for resistance to exposure treatment in highly fearful chronic pain patients. Previous fear conditioning research showed that healthy individuals scoring relatively high on trait anxiety display sustained fear to safety cues during extinction. In the context of fear of movement-related pain, this intriguing question has been largely neglected so far. Even more importantly, positive psychological traits such as trait positive affect may function as protective factors against the spreading of fear to safe movements and improve exposure treatment outcomes. In this study, healthy participants completed a trait anxiety and trait positive affect questionnaire and underwent acquisition and extinction of fear of movement-related pain using an experimental voluntary movement paradigm. During acquisition, one movement (CS+) was paired with a painful stimulus and another movement was not (CS-). During extinction, the CS+ was no longer reinforced. Results show failure of fear inhibition to the CS- during extinction in healthy individuals scoring relatively high on trait anxiety or relatively low on positive affect. These findings seem to suggest that safety learning is more vulnerable in healthy people with a high anxious disposition and/or relatively lower levels of positive affect. In addition, this is the first study to show that the negative impact of high trait anxiety on fear inhibition to safety cues during extinction can be countered by high levels of positive affect. These findings may have important clinical implications. ⋯ Both low positive affect and high trait anxiety are associated with impaired fear inhibition to nonpainful movements during fear extinction. Interestingly, high levels of positive affect buffer against the negative impact of trait anxiety. Increasing positive affect during exposure may counter the effects of trait vulnerabilities and improve treatment outcomes.
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Randomized Controlled Trial
Intranasal fentanyl versus fentanyl pectin nasal spray for the management of breakthrough cancer pain in doses proportional to basal opioid regimen.
The aim of this randomized, crossover, comparison study was to assess the analgesic and adverse effects of 2 nasal preparations, intranasal fentanyl (INFS) and fentanyl pectin nasal spray (FPNS), for breakthrough pain, given in doses proportional to opioid basal regimen. Each patient randomly received INFS or FPNS in doses proportional to opioid dosages used for background analgesia for 2 pairs of episodes. For each episode of breakthrough pain, pain intensity and adverse effects intensity were recorded just before starting the INFS or FPNS (T0) and 5 minutes (T5), 10 minutes (T10), and 20 minutes (T20) after the administration of the nasal drugs. Sixty-nine patients were studied. The mean age was 63.4 years, and 37 patients were males. For the present analysis, 188 episodes were considered. A statistical decrease in pain intensity was observed with both nasal drugs after 5, 10, and 20 minutes. A decrease in pain intensity of >33% was observed in 16, 102, and 159 treated episodes at T5, T10, and T20, respectively. Adverse effects were of mild nature in most cases or were preexistent because of basal opioid therapy. No differences were found in summed pain intensity difference 20 minutes after dosing. Most of patients did not find substantial preferences. INFS and FPNS were effective and well-tolerated treatments for breakthrough pain management. Both delivery systems, in doses proportional to the basal opioid regimen, provided significant analgesia within 10 minutes, without producing relevant adverse effects. ⋯ This article showed that INFS and FPNS in doses proportional to basal opioid regimen are equally safe and effective for the management of breakthrough pain in cancer patients. These data provide new insights on the use of nasal preparations of fentanyl.
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Central neuropathic pain (CNP) is believed to be accompanied by increased activation of the sensorimotor cortex. Our knowledge of this interaction is based mainly on functional magnetic resonance imaging studies, but there is little direct evidence on how these changes manifest in terms of dynamic neuronal activity. This study reports on the presence of transient electroencephalography (EEG)-based measures of brain activity during motor imagery in spinal cord-injured patients with CNP. We analyzed dynamic EEG responses during imaginary movements of arms and legs in 3 groups of 10 volunteers each, comprising able-bodied people, paraplegic patients with CNP (lower abdomen and legs), and paraplegic patients without CNP. Paraplegic patients with CNP had increased event-related desynchronization in the theta, alpha, and beta bands (16-24 Hz) during imagination of movement of both nonpainful (arms) and painful limbs (legs). Compared to patients with CNP, paraplegics with no pain showed a much reduced power in relaxed state and reduced event-related desynchronization during imagination of movement. Understanding these complex dynamic, frequency-specific activations in CNP in the absence of nociceptive stimuli could inform the design of interventional therapies for patients with CNP and possibly further understanding of the mechanisms involved. ⋯ This study compares the EEG activity of spinal cord-injured patients with CNP to that of spinal cord-injured patients with no pain and also to that of able-bodied people. The study shows that the presence of CNP itself leads to frequency-specific EEG signatures that could be used to monitor CNP and inform neuromodulatory treatments of this type of pain.
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Despite rapidly increasing intervention, functional disability due to chronic low back pain (cLBP) has increased in recent decades. We often cannot identify mechanisms to explain the major negative impact cLBP has on patients' lives. Such cLBP is often termed non-specific and may be due to multiple biologic and behavioral etiologies. Researchers use varied inclusion criteria, definitions, baseline assessments, and outcome measures, which impede comparisons and consensus. Therefore, NIH Pain Consortium charged a Research Task Force (RTF) to draft standards for research on cLBP. The resulting multidisciplinary panel recommended using 2 questions to define cLBP; classifying cLBP by its impact (defined by pain intensity, pain interference, and physical function); use of a minimum dataset to describe research participants (drawing heavily on the PROMIS methodology); reporting "responder analyses" in addition to mean outcome scores; and suggestions for future research and dissemination. The Pain Consortium has approved the recommendations, which investigators should incorporate into NIH grant proposals. The RTF believes that these recommendations will advance the field, help to resolve controversies, and facilitate future research addressing the genomic, neurologic, and other mechanistic substrates of chronic low back pain. We expect that the RTF recommendations will become a dynamic document and undergo continual improvement. ⋯ A task force was convened by the NIH Pain Consortium with the goal of developing research standards for chronic low back pain. The results included recommendations for definitions, a minimum dataset, reporting outcomes, and future research. Greater consistency in reporting should facilitate comparisons among studies and the development of phenotypes.
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The purpose of this study was to examine exercise-induced pain modulation in diabetic adults with painful diabetic neuropathy (PDN) compared to diabetic adults without PDN. Eighteen adults diagnosed with type 2 diabetes with and without PDN (mean age of 49 years) completed 2 sessions. During the familiarization session, participants completed questionnaires, were familiarized with the pain testing protocols, and completed maximal isometric contractions. During the exercise session, experimental pain testing was completed before and following exercise consisting of 3 minutes of isometric exercise performed at 25% maximal voluntary contraction. Ratings of perceived exertion and muscle pain were assessed every 30 seconds during exercise. Results indicated that ratings of perceived exertion and muscle pain during exercise were significantly higher (P < .05) for diabetic adults with PDN versus diabetic adults without PDN. Diabetic adults with PDN did not experience changes in thermal pain ratings following exercise, whereas diabetic adults without PDN reported significantly lower pain ratings following exercise. It is concluded that diabetic adults with PDN experienced high levels of muscle pain during exercise and a lack of exercise-induced hypoalgesia following exercise, in comparison to diabetic adults without PDN, who experienced lower levels of muscle pain during exercise and a hypoalgesic response following exercise. ⋯ Very little research has been conducted examining the impact of exercise on pain modulation in diabetic adults with PDN. This study provides support that adults with PDN exhibit exercise-induced endogenous pain modulatory system dysfunction.