The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
The association between negative affect and prescription opioid misuse in patients with chronic pain: the mediating role of opioid craving.
Over the past decade, considerable research has accumulated showing that chronic pain patients experiencing high levels of negative affect (NA) are at increased risk for prescription opioid misuse. The primary objective of the present study was to examine the factors that underlie the association between NA and prescription opioid misuse among patients with chronic pain. In this study, 82 patients with chronic musculoskeletal pain being prescribed opioid medication completed the Current Opioid Misuse Measure, a well-validated self-report questionnaire designed to assess prescription opioid misuse. Patients were also asked to complete self-report measures of pain intensity, NA, and opioid craving. A bootstrapped multiple mediation analysis was used to examine the mediating role of patients' pain intensity and opioid craving in the association between NA and prescription opioid misuse. Consistent with previous research, we found a significant association between NA and prescription opioid misuse. Interestingly, results revealed that opioid craving, but not pain intensity, mediated the association between NA and opioid misuse. The Discussion addresses the potential psychological and neurobiological factors that might contribute to the interrelationships among NA, opioid craving, and prescription opioid misuse in patients with pain. The clinical implications of our findings are also discussed. ⋯ Our study provides new insights into the factors that underlie the association between negative affect and prescription opioid misuse in patients with chronic pain. Our findings could have important clinical implications, particularly for patients being prescribed opioid medication, and for reducing rates of opioid misuse in patients with pain.
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Randomized Controlled Trial
Altered cortical activation in adolescents with acute migraine: a magnetoencephalography study.
To quantitatively assess cortical dysfunction in pediatric migraine, 31 adolescents with acute migraine and age- and gender-matched controls were studied using a magnetoencephalography (MEG) system at a sampling rate of 6,000 Hz. Neuromagnetic brain activation was elicited by a finger-tapping task. The spectral and spatial signatures of magnetoencephalography data in 5 to 2,884 Hz were analyzed using Morlet wavelet and beamformers. Compared with controls, 31 migraine subjects during their headache attack phases (ictal) showed significantly prolonged latencies of neuromagnetic activation in 5 to 30 Hz, increased spectral power in 100 to 200 Hz, and a higher likelihood of neuromagnetic activation in the supplementary motor area, the occipital and ipsilateral sensorimotor cortices, in 2,200 to 2,800 Hz. Of the 31 migraine subjects, 16 migraine subjects during their headache-free phases (interictal) showed that there were no significant differences between interictal and control MEG data except that interictal spectral power in 100 to 200 Hz was significantly decreased. The results demonstrated that migraine subjects had significantly aberrant ictal brain activation, which can normalize interictally. The spread of abnormal ictal brain activation in both low- and high-frequency ranges triggered by movements may play a key role in the cascade of migraine attacks. ⋯ This is the first study focusing on the spectral and spatial signatures of cortical dysfunction in adolescents with migraine using MEG signals in a frequency range of 5 to 2,884 Hz. This methodology analyzing aberrant brain activation may be important for developing new therapeutic interventions for migraine in the future.
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Randomized Controlled Trial
Pain relief is associated with improvement in motor function in complex regional pain syndrome type 1: secondary analysis of a placebo-controlled study on the effects of ketamine.
There are indications of motor circuit changes in patients with complex regional pain syndrome (CRPS). Nevertheless, although several studies have analyzed motor behavior in CRPS, a relation with pain could not be detected. This might be explained by the use of cross-sectional designs in these studies, in which pain is considered as a trait- rather than a state-dependent variable. We therefore studied the time-dependent relation between pain and motor function in affected arms of 29 CRPS patients during their participation in a placebo-controlled ketamine study. Movement parameters (velocity, frequency, amplitude, and number of arrests) were assessed during a finger tapping task. Linear mixed model analysis of the effects of pain (numerical rating scale score), treatment (ketamine/placebo), and week (1, 3, 6, and 12 weeks after treatment) on the movement parameters revealed that pain intensity was significantly (inversely) related to motor function, irrespective of whether patients had received ketamine or placebo. Movement parameters changed 3-12% per point numerical rating scale change. Because patients were unaware of possible effects of ketamine on motor function, these findings suggest that motor function changes were mediated by, or occurred simultaneously with, changes in pain intensity. By improving motor function, pain relief may offer a window of opportunity for rehabilitation programs in CRPS. ⋯ This article provides evidence for a direct relation between pain and motor function in CRPS, which indicates that pain relief may be an important factor in the treatment of motor disturbances in this condition. These findings may help to advance our understanding of the pathways underlying motor disturbances in CRPS.
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Randomized Controlled Trial
Determinants of pain treatment response and nonresponse: identification of TMD patient subgroups.
The purpose of the present study was to determine if we could identify a specific subtype of temporomandibular disorder (TMD) pain patients that does not respond to treatment. Patients were 101 men and women with chronic TMD pain recruited from the community and randomly assigned to 1 of 2 treatment conditions: a standard conservative care (STD) condition or a standard care plus cognitive-behavioral therapy condition (STD + CBT) in which patients received all elements of STD but also received cognitive-behavioral coping skills training. Growth mixture modeling, incorporating a series of treatment-related predictors, was used to distinguish several distinct classes of responders or nonresponders to treatment based on reported pain over a 1-year follow-up period. Results indicated that treatment nonresponders accounted for 16% of the sample and did not differ from treatment responders on demographics or temporomandibular joint pathology, but that they reported more psychiatric symptoms, poorer coping, and higher levels of catastrophizing. Treatment-related predictors of membership in treatment responder groups versus the nonresponder group included the addition of CBT to STD, treatment attendance, and decreasing catastrophization. It was concluded that CBT may be made more efficacious for TMD patients by placing further emphasis on decreasing catastrophization and on individualizing care. ⋯ This article provides evidence that the TMD chronic pain population is heterogeneous and that a subsample of patients will be unresponsive to standard or psychosocial approaches. The addition of CBT to treatment may be helpful for this group, but new individualized approaches will be needed to treat all patients effectively.
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Randomized Controlled Trial
TENS attenuates repetition-induced summation of activity-related pain following experimentally induced muscle soreness.
This study sought to determine whether repetition-induced summation of activity-related pain (RISP) could be demonstrated in healthy individuals in response to experimentally induced musculoskeletal pain. This study also assessed the effects of transcutaneous electrical nerve stimulation on RISP. The relation between the index of RISP and psychological factors such as catastrophizing and fear of pain was also explored. The sample consisted of 56 healthy (35 women, 21 men) participants who underwent 2 testing sessions, separated by 24 hours. In the first session, musculoskeletal pain was induced with a delayed-onset muscle soreness protocol. During the second session, participants were randomly assigned to the transcutaneous electrical nerve stimulation or placebo condition and were asked to rate their pain as they lifted a series of 18 weighted canisters. An index of RISP was derived as the change in pain ratings across repeated lifts. Approximately 25% of participants showed evidence of RISP. Results also revealed that transcutaneous electrical nerve stimulation attenuated the RISP effect. Psychological measures (fear of pain, catastrophizing) were not significantly correlated with the index of RISP, but the index of RISP was significantly correlated with a measure of physical tolerance. Discussion addresses the clinical implications of the findings as well as the potential mechanisms underlying RISP. ⋯ This study showed that RISP could be demonstrated in healthy individuals in response to experimentally induced musculoskeletal pain with delayed-onset muscle soreness. Transcutaneous electrical nerve stimulation led to a significant reduction in RISP.