Pain
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Comparative Study
Exaggerated nociceptive responses on morphine withdrawal: roles of protein kinase C epsilon and gamma.
On withdrawal from opioids many patients experience a heightened sensitivity to stimuli and an exaggerated pain response. The phenomenon has been little studied in infants. We present evidence that in postnatal day 7 rats an exaggerated nociceptive ventral root response of spinal cords in vitro and withdrawal-associated thermal hyperalgesia in vivo are dependent on protein kinase C (PKC), and we document the roles of PKC and gamma isozymes. ⋯ In contrast, thermal hyperalgesia during spontaneous withdrawal was inhibited by both PKC and gamma inhibitors. The consistency between the in vivo and in vitro findings with respect to naloxone-precipitated withdrawal provides further evidence that the sVRP reflects nociceptive neurotransmission. In addition the difference between naloxone-precipitated and spontaneous withdrawal in vivo suggests that in postnatal day 7 rats, morphine exposure produces an early phase of primary afferent sensitization dependent upon PKC translocation, followed by a later phase involving spinal sensitization mediated by PKC gamma.
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Comparative Study
Determinants of prescribing meperidine compared to morphine in hospitalized patients.
Morphine is a preferred narcotic since meperidine forms toxic metabolites. Determinants of meperidine use have been poorly described. The objective of this study is to explore factors associated with the ordering of meperidine versus morphine. ⋯ Though meperidine has little role in the routine management of hospital pain, we found it continues to be used frequently. Importantly, meperidine is ordered more frequently for patients who receive shorter courses of narcotics. Our study suggests that interventions targeted at more appropriate use of meperidine rather than complete elimination might be more acceptable to physicians while minimizing the risk of toxicity.
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Comparative Study
Cold and heat pain assessment of the human oesophagus after experimental sensitisation with acid.
The aim of the present study was to investigate the effect of thermal stimulation of the oesophagus before and after sensitisation with acid. In 17 healthy subjects a stimulation bag was used to re-circulate water at 5 and 60 degrees C for up to 90 s in the lower part of the oesophagus. The area under the temperature curve was used to assess the caloric load. ⋯ After sensitisation the words used to describe the sensations to heat pain stimuli shifted from a warmth quality towards a more burning quality in most subjects. This multi-modal sensory testing study showed that acid sensitises the oesophagus to heat but not to cold pain. This may account for the modality-specific symptoms and hypersensitivity reported in patients suffering from, e.g. gastro-oesophageal reflux disease.
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Little is known about the extent to which individuals vary versus remain stable in their pain-related catastrophizing, or to which catastrophizing is associated with pain and related problems on a daily basis. We used daily electronic interviews to examine the: (1) reliability and validity of a brief daily catastrophizing measure; (2) stability of catastrophizing; (3) patient characteristics associated with catastrophizing; (4) associations between catastrophizing and concurrent and subsequent outcomes (pain, activity interference, jaw use limitations, and negative mood), between and within patients; and (5) associations between pain and subsequent catastrophizing. One hundred patients with chronic temporomandibular disorder pain completed electronic interviews three times a day for 2 weeks [mean (SD) number of interviews=46 (15)]. ⋯ Daily catastrophizing was associated significantly with concurrent outcomes, between- and within-subjects (P < 0.001); however, associations with same-day subsequent outcomes were greatly attenuated after adjusting for prior outcome levels. Similarly, daily pain was associated significantly with subsequent catastrophizing, but this association was no longer statistically significant after adjusting for prior catastrophizing. The data indicate that catastrophizing is stable over short periods of time in the absence of substantial change in pain, and that within patients, times of greater catastrophizing are associated with worse pain, disability, and mood.
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Comparative Study
Neuroelectric source imaging of steady-state movement-related cortical potentials in human upper extremity amputees with and without phantom limb pain.
Whereas several studies reported a close relationship between changes in the somatotopic organization of primary somatosensory cortex and phantom limb pain, the relationship between alterations in the motor cortex and amputation-related phenomena has not yet been explored in detail. This study used steady-state movement-related cortical potentials (MRCPs) combined with neuroelectric source imaging to assess the relationship of changes in motor cortex and amputation-related phenomena such as painful and non-painful phantom and residual limb sensations, telescoping, and prosthesis use. Eight upper limb amputees were investigated. ⋯ Non-painful phantom sensations as well as painful and non-painful residual limb sensations were unrelated to motor cortical reorganization. A higher amount of motor reorganization was associated with less daily prosthesis use, which also tended to be related to more severe phantom limb pain. These results extend previous findings of a positive relationship between somatosensory reorganization and phantom limb pain to the motor domain and suggest a potential positive effect of prosthesis use on phantom limb pain and cortical reorganization.