Pain
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Approximately 70-80% of women meeting criteria for borderline personality disorder (BPD) report attenuated pain perception or analgesia during non-suicidal, intentional self-mutilation. The aim of this study was to use laser-evoked potentials (LEPs) and psychophysical methods to differentiate the factors that may underlie this analgesic state. Ten unmedicated female patients with BPD (according to DSM-IV) and 14 healthy female control subjects were investigated using brief radiant heat pulses generated by a thulium laser and five-channel LEP recording. ⋯ This study confirms previous findings of attenuated pain perception in BPD. Normal nociceptive discrimination task performance, normal LEPs, and normal P3 potentials indicate that this attenuation is neither related to a general impairment of the sensory-discriminative component of pain, nor to hyperactive descending inhibition, nor to attention deficits. These findings suggest that hypoalgesia in BPD may primarily be due to altered intracortical processing similar to certain meditative states.
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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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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
Prostaglandin E2 in the midbrain periaqueductal gray produces hyperalgesia and activates pain-modulating circuitry in the rostral ventromedial medulla.
Recent years have seen significant advances in our understanding of the peripheral and spinal mechanisms through which prostaglandins contribute to nociceptive sensitization. By contrast, the possibility of a supraspinal contribution of these compounds to facilitated pain states has received relatively little attention. One possible mechanism through which prostaglandins could act supraspinally to facilitate nociception would be by recruitment of descending facilitation from brainstem pain-modulating systems. ⋯ Microinjection of PGE(2) (50 fg in 200 nl) into the PAG produced a significant decrease in paw withdrawal latency. The PGE(2) microinjection activated on-cells, RVM neurons thought to facilitate nociception, and suppressed the firing of off-cells, RVM neurons believed to have an inhibitory effect on nociception. These data demonstrate a prostaglandin-sensitive descending facilitation from the PAG, and suggest that this is mediated by on- and off-cells in the RVM.
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Comparative Study
Site 1 sodium channel blockers prolong the duration of sciatic nerve blockade from tricyclic antidepressants.
Many recent reports in the literature address the local anesthetics efficacy of tricyclic antidepressants (TCAs). Here we investigated whether nerve block from TCAs is prolonged by site 1 sodium channel blockers such as tetrodotoxin and saxitoxin, which are known to prolong block from conventional local anesthetics. Tetrodotoxin and saxitoxin greatly prolonged block from TCAs. ⋯ Systemic (subcutaneous) delivery of tetrodotoxin or amitriptyline did not result in prolongation of block from the other class of drug injected at the sciatic nerve. In TCA-containing formulations, motor blockade was consistently longer than thermal nociceptive block; motor blockade was also prolonged by tetrodotoxin and saxitoxin. In summary site 1 sodium channel blockers prolong the duration of TCAs via a locally mediated mechanism.