Pain
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The mechanisms underlying the relief of neuropathic pain of peripheral origin by spinal cord stimulation (SCS) are poorly understood. The present study was designed to investigate the effects of SCS on evoked and spontaneous discharges in dorsal horn neurons in intact and in nerve-injured rats subjected to partial sciatic nerve ligation according to Seltzer et al. (1990). Tactile sensitivity in the hind paw was assessed in behavioral tests using von Frey filaments. ⋯ In non-allodynic and control rats, SCS had no significant depressive effects on the evoked responses and spontaneous discharge. The results suggest that SCS may provide a suppressive action on dorsal horn neuronal hyperexcitability associated with signs of peripheral neuropathy. The suppressive effect of SCS on tactile allodynia, as previously observed in behavioral experiments, presumably corresponds to a normalization of the excitability of WDR cells in response to innocuous stimuli.
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Previous work demonstrated that, in rats, intrathecal GR89696, a putative kappa-2 opioid receptor agonist, inhibited hyperalgesia to noxious heat in an inflamed hind paw (anti-hyperalgesic effect). Non-inflamed paws were not influenced by kappa-2 receptor activation. The question addressed in this study was whether GR89696 was as effective in blocking hyperalgesia and allodynia in nerve injury models as it was in the inflammation model. ⋯ Naloxone (1 mg/kg, i.p.) reversed the anti-hyperalgesic and anti-allodynic effects of GR89696. The mu agonist DAMGO (6 nmoles, i.t.) and the kappa-1 agonist U69593 (100 nmoles, i.t.) only partially reversed hyperalgesia and allodynia. These findings suggest that kappa-2 opioid receptors may be a useful target for the pharmacological control of hyperalgesia and allodynia.
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Randomized Controlled Trial Clinical Trial
Evaluation of the use of a pain diary in chronic cancer pain patients at home.
Systematic assessment of pain is the basis for adequate pain treatment. In the home situation, however, it is difficult to assess patients' pain intensity. A group of 159 cancer patients who had been admitted to a cancer hospital with pain caused by cancer, cancer therapy, or illness that persisted for at least 1 month received a pain diary. ⋯ When comparing pain scores obtained by patient interview with scores obtained by pain diary, results showed that Present Pain Intensity scores, rather than Average Pain Intensity scores, should be used in both the clinical and the home setting because patients' recall accuracy depends, in part, on the stability of the pain. Because the pain intensity scores fluctuate greatly during the day and over a period of time, the use of a pain diary is useful in the home setting. In 60% of the patients, completing the pain scores helped them to cope with the pain.
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Epidural and intrathecal techniques are well established techniques in cancer pain. However, several questions remain unresolved. The several problems of long-term spinal opioid treatment in advance cancer patients were reviewed. ⋯ Different ranges of technical complication rates have been reported in the literature, most of them being associated with epidural catheters. Subcutaneous tunneling and fixation of the catheter, bacterial filters, minimum changes of tubings, careful exit site care weekly, site protection and monitoring of any sign of infection to prevent infection, and training for family under supervision, are recommended. Areas for additional research include the use of spinal adjuvants, the ideal spinal morphine-bupivacaine ratio. methods to improve spinal opioid responsiveness and long-term catheter management with appropriate home care programs.
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Clinical Trial Controlled Clinical Trial
Assessment and treatment of neuropathic cancer pain following WHO guidelines.
Neuropathic pain syndromes are one of the major problems of cancer pain treatment. The present study surveys 593 cancer patients treated by a pain service following the WHO guidelines for relief of cancer pain. Of these, 380 presented with nociceptive, 32 with neuropathic and 181 with mixed (nociceptive and neuropathic) pain. ⋯ Analgesic treatment resulted in a significant pain relief in all groups of patients, as the mean pain intensity (NRS) decreased from 66 (nociceptive), 65 (mixed) and 70 (neuropathic) on admission to 26, 30 and 28 after 3 days and 18, 17 and 21 at the end of survey. The total outcome of pain treatment was not predicted by the designation to nociceptive, mixed or neuropathic pain. In conclusion, neuropathic cancer pain is not intractable and can be relieved in the majority of patients by treatment following the WHO guidelines.