Pain
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Spinal prostaglandin synthesis has been implicated in acute pain processes and in generation and maintenance of central sensitization, and intrathecal injection of cyclo-oxygenase (COX) inhibitors produce antinociception and reduce hypersensitivity in animals. We herein report a Phase I safety assessment of intrathecal injection of the COX inhibitor, ketorolac, in healthy volunteers, and demonstrate no serious side effects. Preclinical studies suggest a major site of action of COX inhibitors for analgesia lies in the central nervous system, especially the spinal cord. ⋯ One subject had a mild headache 24h after study, resolving the next day. There were no long-term side effects 6 months after study. These data suggest that intrathecal ketorolac does not produce a high incidence of serious adverse events, and they support further investigation for analgesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect of high and low frequency electroacupuncture in pain after lower abdominal surgery.
In the present study, we examined the effects of preoperative electroacupuncture (EA) at classical bilateral acupuncture points (Zusanli, also known as ST-36) on postoperative pain and opioid-related side effects. One hundred healthy consenting women undergoing lower abdominal surgery were randomly assigned to four treatment regimens: Group I (n=25), control; Group II (n=25), sham-EA (needle insertion without electrical stimulation); Group III (n=25), low-EA (2 Hz of electrical stimulation); and Group IV (n=25), high-EA (100 Hz of electrical stimulation). EA groups received needle insertion with or without electrical stimulation 20 min prior to anesthesia. ⋯ The incidence of nausea and dizziness during the first 24h after surgery was significantly reduced in both the low-EA and high-EA groups compared with the control and sham-EA groups. We also found that sham-EA exerts a beneficial effect with respect to its pain relieving quality but not the side effect profiles. Our findings demonstrates that preoperative treatment with low-EA and high-EA can reduce postoperative analgesic requirements and associated side effects in patients undergoing lower abdominal surgery.
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Comparative Study
Pain activation of human supraspinal opioid pathways as demonstrated by [11C]-carfentanil and positron emission tomography (PET).
The role of the supraspinal endogenous opioid system in pain processing has been investigated in this study using positron emission tomography imaging of [11C]-carfentanil, a synthetic, highly specific mu opioid receptor (mu-OR) agonist. Eight healthy volunteers were studied during a baseline imaging session and during a session in which subjects experienced pain induced by applying capsaicin topically to the dorsal aspect of the left hand. ⋯ This decrease varied directly with ratings of pain intensity. These results suggest that the supraspinal mu-opioid system is activated by acute pain and thus may play a substantial role in pain processing and modulation in pain syndromes.
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Comparative Study
Efficacy of systemic morphine suggests a fundamental difference in the mechanisms that generate bone cancer vs inflammatory pain.
Pain is the cancer related event that is most disruptive to the cancer patient's quality of life. Although bone cancer pain is one of the most severe and common of the chronic pains that accompany breast, prostate and lung cancers, relatively little is known about the mechanisms that generate and maintain this pain. Recently, we developed a mouse model of bone cancer pain and 16 days following tumor implantation into the intramedullary space of the femur, significant bone destruction and bone cancer pain-related behaviors were observed. ⋯ Humans suffering from bone cancer pain generally require significantly higher doses of morphine as compared to individuals with inflammatory pain and in the mouse model, the doses of morphine required to block bone cancer pain-related behaviors were ten times that required to block peak inflammatory pain behaviors of comparable magnitude induced by hindpaw injection of complete Freund's adjuvant (CFA) (1-3mg/kg). As these animals were treated acutely, there was not time for morphine tolerance to develop and the rightward shift in analgesic efficacy observed in bone cancer pain vs. inflammatory pain suggests a fundamental difference in the underlying mechanisms that generate bone cancer vs. inflammatory pain. These results indicate that this model may be useful in defining drug therapies that are targeted for complex bone cancer pain syndromes.