Pain
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Wallerian degeneration is required for both neuropathic pain and sympathetic sprouting into the DRG.
Chronic loose constriction of the sciatic nerve produces mechanoallodynia and thermal hyperalgesia in rats and mice, and the behaviour develops during the time in which the nerve distal to the ligature site is undergoing Wallerian degeneration. There is a sympathetic component to the pain generated by this and other rodent models of neuropathic pain, yet the site at which this sympathetic-sensory coupling remains unknown. It has been shown that following sciatic nerve transection or spinal nerve lesion, sympathetic axons invade the dorsal root ganglion (DRG) where they sometimes form pericellular baskets around mostly large diameter DRG neurons--a possible anatomical substrate for sympathetically maintained pain (SMP). ⋯ We found that both indices of neuropathic pain were significantly attenuated in Wld mice compared to wild-type mice, with the wild-type mice increasing in sensitivity to both thermal and mechanical stimulation in the first week post-operative (PO), while Wld mice showed marked hypoalgesia following CCI. Histological examination of the DRG showed that sympathetic sprouting into the DRG was also markedly delayed in Wld mice compared to wild-type mice: 1 week following injury, sympathetic fibres had invaded the ipsilateral DRG of wild-type mice, while sprouting in ipsilateral DRG of Wld mice was only slightly increased at 3 weeks PO. These results show that Wallerian degeneration is tightly linked to the development of both pain and sympathetic sprouting following CCI, and we speculate on the possible role of NGF as a mediator of both phenomena.
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Morphine (M) and hydromorphone (HM) are commonly used opioid analgesics for cancer pain. Opioid rotation is often necessary in the event of toxicity and/or inadequate analgesia. Equianalgesic reference tables based on single dose comparisons are possibly inadequate for patients on chronic treatment and developing tolerance. ⋯ Our data suggests that HM is 5 times more potent than M when given second (M-HM), but is only 3.7 times more potent when given first (HM-M). We therefore recommend a ratio of 5 for M/HM in rotating from M to HM and ratio of 3.7 for M/HM when rotating from HM to M in patients exposed to chronic dosing of these opioids. There was no correlation observed between M-HM and HM-M dose ratios and the level of previous opioid dose, in contrast to HM to methadone rotation where the dose ratio was higher in patients receiving higher doses of HM.
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Randomized Controlled Trial Clinical Trial
The visual analogue pain intensity scale: what is moderate pain in millimetres?
One way to ensure adequate sensitivity for analgesic trials is to test the intervention on patients who have established pain of moderate to severe intensity. The usual criterion is at least moderate pain on a categorical pain intensity scale. When visual analogue scales (VAS) are the only pain measure in trials we need to know what point on a VAS represents moderate pain, so that these trials can be included in meta-analysis when baseline pain of at least moderate intensity is an inclusion criterion. ⋯ For those reporting severe pain 85% scored over 54 mm with a mean score of 75 mm. There was no difference between the corresponding VAS scores of men and women. Our results indicate that if a patient records a baseline VAS score in excess of 30 mm they would probably have recorded at least moderate pain on a 4-point categorical scale.
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Randomized Controlled Trial Clinical Trial
Loss of analgesic effect of morphine due to coadministration of rifampin.
Methadone withdrawal symptoms have been reported in drug addicts treated with the tuberculostatic rifampin. Whereas this interaction can be explained by induction of phase I drug metabolism (CYP3A4), knowledge about induction of phase II metabolism (e.g., UDP-glucuronosyltransferases = UGTs) and its influence on drug effects in man, however, is very limited. The potent analgesic morphine is metabolized by more than one UGT to the active metabolite morphine-6-glucuronide and to morphine-3-glucuronide, which is devoid of analgesic activity. ⋯ Moreover, during treatment with rifampin a proportional reduction of AUCs of morphine-3-glucuronide (P < or = 0.01), morphine-6-glucuronide (P < or = 0.05) and morphine was observed. Since urinary recoveries of both morphine-3-glucuronide and morphine-6-glucuronide were also reduced during administration of rifampin, there is no evidence for a contribution of UGT induction to the observed interaction. In summary, a major drug interaction was observed between morphine and rifampin, which could not be attributed to induction of UGTs, but resulted in a complete loss of analgesic effects of the opioid.
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Comparative Study Clinical Trial Controlled Clinical Trial
Differences in patients' and family caregivers' perceptions of the pain experience influence patient and caregiver outcomes.
The purposes of this study were to determine if there were differences in pain intensity scores, pain duration scores, mood states, and quality of life of oncology outpatients whose pain intensity scores were congruent with their family caregivers compared to patients whose pain intensity scores were non-congruent and to determine if there were differences in mood states, health status, and caregiver strain between family caregivers whose pain intensity scores were congruent with their family members and those family caregivers whose pain intensity scores were non-congruent. A total of 78 patient-caregiver dyads participated in the study. Patients completed a Demographic Questionnaire, a Cancer Pain Questionnaire, the Profile of Mood States, and the Multidimensional Quality of Life Scale-Cancer 2. ⋯ Patients in the non-congruent dyads (i.e. difference of >10 on the VAS score) had significantly more mood disturbance and a poorer quality of life than patients in the congruent dyads. Family caregivers in the non-congruent dyads had significantly higher caregiver strain score than caregivers in the congruent dyads. These findings suggest that differences in the perception of the pain experience between patients and their family caregivers is associated with deleterious outcomes for the patient and their family caregivers.