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Bone marrow transplant recipients were randomly assigned to receive morphine by either continuous infusion (32 patients) or self-administration of small boluses (patient-controlled analgesia (PCA), 26 patients) for control of chemoradiotherapy-induced oral mucositis pain. All patients received morphine for a minimum of 9 days and most required morphine for at least 14 days. Patients rated their pain and side-effect intensity daily using visual analogue scales. Patient pain ratings did not differ between the groups although PCA patients used only 53% as much morphine as the continuous infusion group. Tolerance did not develop in the PCA group; in patients receiving continuous infusion morphine dosage continued to increase throughout the study while pain scores remained constant, indicating that tolerance had developed. Nausea, alertness and respiratory rate measurements did not differ between groups. PCA appeared more effective than the hospital staff determined treatment at delivering the least amount of morphine required to produce maximal pain relief. Patients self-administering morphine did not appear to restrict morphine intake in order to minimize opioid side-effects.

The effects of electrical acupunctural stimulation (2 Hz) on pain judgments and evoked potentials are reported for two experiments using dental dolorimetry. In the first experiment subjects received acupuncture at points located in the same neurologic segment as the test tooth. In the second experiment subjects received acupuncture at points on the hands located on acupuncture meridians. In both instances acupuncture resulted in a reduction in pain intensity and smaller evoked potential amplitudes, but naloxone neither reversed the analgesia nor did it affect the evoked potentials. A pilot study was carried out to determine whether manual rather than electrical stimulation would produce an analgesia reversible by naloxone, but it failed to do so. These findings contribute to the growing evidence that acupunctural stimulation significantly reduces pain sensibility in volunteers undergoing dolorimetric testing, but they do not support the hypothesis that endorphin release is a mechanism by which acupuncture exerts analgesia.

This study was undertaken to determine whether different analgesic treatments result in a common change in the event-related potentials (ERP) elicited during painful dental stimulation. The effects of electrical acupuncture delivered at 2 Hz to LI-4, the opiate fentanyl 0.1 mg i.V., and the inhalation analgesia mixture of 33% nitrous oxide in oxygen were examined in volunteers undergoing painful tooth pulp stimulation. ERPs were recorded at vertex and subjects provided reports of pain intensity. Discriminant function analysis was used to determine which subset of the pain report and ERP variables could best discriminate baseline from treatment conditions without regard to specificity of treatment. Together with pain report, amplitude of the ERP positive deflection at 250 msec was a significant indicator of analgesia across the 3 treatments. Other changes specific to the individual treatments were also observed. Since the 250 msec amplitude measure was not redundant statistically with pain report, the ERP data provided significant new information about analgesia even though pain report was a very sensitive measure. Pain report alone could account for 48% of the variance across treatments while ERP measures alone accounted for 34%.

We were unable to demonstrate the reversal of dental acupunctural analgesia following the injection of 0.4 mg naloxone using evoked potential methodology. Since our findings differed from those of Mayer, Price and Rafii who used pain threshold methods, we attempted to replicate their study. Subjects who demonstrated acupunctural analgesia during electrical stimulation of the LI-4 point on the hands received either 1.2 mg naloxone or normal saline under double blind conditions. Pain thresholds elevated by acupuncture failed to reverse when naloxone was given. Review of experimental design issues, other related human subjects research, and animal studies on acupunctural analgesia provided little convincing evidence that endorphins play a significant role in acupunctural analgesia. Because endorphins can be released in response to a Stressor, endorphin presence sometimes correlates with acupunctural treatment in animal studies and some human studies, especially those involving pain patients. The primary analgesia elicited by acupunctural stimulation seems to involve other mechanisms.