Pain
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We have treated 37 patients with intractable pain (35 with cancer-related pain) by continuous intrathecal morphine infusion via implanted pump. These patients were carefully selected according to specific criteria, and each demonstrated a significant reduction in pain following a test dose of intrathecal morphine. All patients had good pain relief from intrathecal morphine infusion, even with pain located in cervical dermatomes. ⋯ In these patients we observed a reduction in side effects associated with systemic opioids when continuous intrathecal opioid infusion was instituted. Intrathecal opioid administration may have fewer complications than ablative pain relief procedures. In properly selected patients, this method offers an effective alternative for pain relief.
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This study investigated antinociceptive effects of intrathecal morphine combined with intrathecal clonidine, noradrenaline, carbachol or midazolam in rats. Each animal received intrathecally, on 3 separate occasions (i) 2 micrograms morphine (M), (ii) a dose (D) of one of the non-opioid drugs, and (iii) a combination, 1/2(M+D), consisting of 1 microgram morphine plus half the dose of the non-opioid drug. Antinociceptive effects were assessed by the hot-plate and tail-flick tests over the duration of drug action. ⋯ Addition of morphine caused a left shift in the dose-response curves of all the non-opioid drugs, indicating at least some degree of additive effects. Effects were considered supra-additive when the effect of the combination, 1/2(M+D), was significantly greater than both the effect of 2 micrograms morphine and the dose of non-opioid. Evidence of supra-additive antinociceptive effects was obtained only with the clonidine-morphine combination.
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Case Reports Clinical Trial
Octreotide: a potent new non-opiate analgesic for intrathecal infusion.
Somatostatin-14 has been reported to relieve severe cancer pain when given intraspinally. We have studied a stable analog, octreotide, which is suitable for long-term infusion by a drug pump. In preclinical trials in dogs, chronic intrathecal and intraventricular perfusion at 40 micrograms/h did not produce neurotoxicity. ⋯ No central or systemic side effects of intrathecal administration were seen. The pain relief occurred in patients who had previously not obtained satisfactory pain control with systemic or intrathecal opiates, which is consistent with a non-opiate spinal pathway. These preliminary findings, if confirmed, suggest that octreotide is a potent non-opiate analgesic appropriate for long-term intrathecal infusion.
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Exposure to sauna heat during sauna bathing raises the skin temperature of the bather near the hot pain perception threshold and enhances sympathetic activity. Self-reports provided by regular bathers of changes in intensity of their ongoing pain might, therefore, add novel information on the effect of intense heat on various pain conditions. We interviewed consecutive patients attending our pain clinic over a period of 1 year about their pain-related responses to sauna bathing and controlled the results by quantitated somatosensory tests. ⋯ By contrast, mechanical allodynia was present in 48% of patients with peripheral neuropathic pain and in 54% of patients with central pain. The results speak against an important role for C-afferent or sympathetic postganglionic fibres in most subclasses of neuropathic pain. Animal models of neuropathic pain should be critically viewed against this finding.
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The local anesthetic lidocaine was injected into the dentate gyrus (DG) of alert, unrestrained rats 10 min prior to investigation within the formalin test. Regional anesthesia of the DG resulted in a reduction of pain scores when administered contralateral to the site of subcutaneous formalin injection. The analgesic effect was evident 30-50 min after central infusion. These results provide evidence of the involvement of the hippocampal formation (HF) in pain perception.