Pain
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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.
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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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Central sensitization refers to enhanced excitability of dorsal horn neurons and is characterized by increased spontaneous activity, enlarged receptive field (RF) areas, and an increase in responses evoked by large and small caliber primary afferent fibers. Sensitization of dorsal horn neurons often occurs following tissue injury and inflammation and is believed to contribute to hyperalgesia. Windup refers to the progressive increase in the magnitude of C-fiber evoked responses of dorsal horn neurons produced by repetitive activation of C-fibers. ⋯ Enhanced responsivity to C-fiber input following windup produced by stimulation inside the RF at a frequency of 0.5 Hz could be maintained for approximately 100 s by stimuli delivered at 0.1 Hz, a frequency that itself cannot produce windup. It is concluded that neuronal events leading to windup also produce some of the classical characteristics of central sensitization including expansion of RFs and enhanced responses to C- but not A-fiber stimulation. Thus, windup may be a useful tool to study mechanisms underlying certain characteristics of central sensitization related to C-fiber activity.