Neurosurgery
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The use of the intraventricular or subarachnoid administration of morphine in the treatment of intractable pain secondary to cancer is described. The drug, in doses ranging from 0.33 to 4.00 mg, was administered by the percutaneous injection of an Ommaya reservoir or by a spinal tap. The duration of analgesia ranged from 36 to 150 hours. The indications for and side effects of this type of therapy are considered.
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The authors report the results of DREZ thermocoagulation in 35 patients since March 1980. This technique was applied not only in patients with deafferentation pain after brachial plexus avulsion, but also for postamputation phantom limb pain and pain caused by injury to the spine and spinal cord, by peripheral nerve lesions, and by multiple sclerosis. Independent of etiology, the duration of the pain syndrome, and the quality and projection of the pain, the overall results have been satisfactory and long-lasting.
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The intrathecal (i.t.) administration of morphine inhibits nociceptive motor responses and activity in ascending axons evoked by stimulation of nociceptive afferent nerve fibers (nociceptive sensory response) in the rat. The i.t. administration of cholecystokinin octapeptide and ceruletide inhibits nociceptive motor responses, but does not affect ascending nociceptive activity. This shows that drug-induced depression of nociceptive motor responses is not always associated with depression of the nociceptive sensory response of the spinal cord. ⋯ Diazepam, 20 micrograms i.t., reduced activity evoked by afferent A delta and C fiber stimulation and by stimulation of afferent A beta fibers. The depressant effect caused by diazepam, 2 mg/kg i.v., on C fiber-evoked ascending activity was reduced by the i.t. injection of the benzodiazepine antagonist, Ro 15-1788 (40 micrograms), an imidazodiazepine. It is concluded that the depression by diazepam of C fiber-evoked ascending activity contributes to pain relief caused by the drug.
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Dorsal root entry zone coagulation (DREZ) lesions for pain were made in 41 patients at the National Hospitals during 1980 through 1983. In 34 patients the operation was an attempt to relieve pain due to avulsion of the brachial plexus. Of these patients, 95% were male and 91% had received their injury in road traffic accidents. ⋯ Postoperative motor or sensory changes occurred in 50% of the patients, but these were significant in only 12%. In later patients in this series, pre-, peri-, and postoperative monitoring of somatosensory evoked potentials was used. Evoked potential monitoring indicated subclinical posterior column damage ipsilateral to avulsion before DREZ lesion making in about 50% of the cases; in some cases, postoperative changes were detected.