Pain
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A modified formalin test in mice was investigated. The pain response curve induced by 0.5% formalin was biphasic, having 2 peaks, from 0 to 5 min (first phase) and from 15 to 20 min (second phase). A low concentration of formalin was used, allowing the effects of weak analgesics to be detected. ⋯ The second phase was inhibited by compound 48/80 pretreatment, indomethacin and bradykinin inhibitor. Therefore, it is suggested that substance P and bradykinin participate in the manifestation of the first phase response, and histamine, serotonin, prostaglandin and bradykinin are involved in the second phase. These results indicate that the first and second phase responses induced by formalin have distinct characteristic properties, and it is a very useful method for examining pain, nociception and its modulation by pharmacological or other means.
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We report the results of a single session, non-blinded, trial of topical application of 10% lidocaine in gel form to the painful skin of 11 patients with well established post-herpetic neuralgia (PHN). Pain decreased as measured by 100 mm VAS pain scale and 100 mm VAS pain relief scale in both trigeminal and thoracic PHN patients.
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Randomized Controlled Trial Clinical Trial
Does intravenous methadone provide longer lasting analgesia than intravenous morphine? A randomized, double-blind study.
A prospective, randomized, double-blind trial was designed to compare the duration of analgesia produced by intravenous morphine and methadone. Patients with intractable cancer-related pain were studied for 5-6 days. One-eighth of the patient's daily opiate requirement was supplied as an i.v. infusion of either morphine or methadone over a period of 15 min. when initiated by the patient using a patient-controlled analgesia device. ⋯ All patients had adequate analgesia as determined by at least a 50% difference in pain intensity at peak relief. The duration of pain relief when repeated intravenous doses of these analgesics were given was similar throughout the entire study period although morphine and methadone have different serum half-lives (3 vs. 25 h). Parenteral methadone does not offer a clinically significant increase in the duration of analgesia in patients with severe pain secondary to cancer.
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Eighteen patients with the post-mastectomy pain syndrome (PMPS) form the basis of this study. PMPS probably occurs in a minority of women after mastectomy. The onset of persistent pain usually occurred immediately or very shortly after the operation. ⋯ Twelve of 14 patients completing treatment with topical 0.025% capsaicin showed improvement after 4 weeks and 8 (57%) were judged to be good or excellent responses. Six months after the trial's completion 50% of those followed continued to have good pain relief. This therapy should now be subjected to a randomized, double-blind, placebo-controlled trial.
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The nociceptive thresholds to mechanical and thermal stimuli in patients with chronic tension-type headache were compared. Palpation of pericranial tenderness was performed in 50 patients and a total tenderness score (TTS) was calculated. Palpation was repeated, and pressure pain thresholds (PPTs) were determined with a pressure algometer in the temporal and occipital regions. ⋯ A correlation was found between PPT and the corresponding cold pain thresholds, but no correlation could be demonstrated between TTS and thermal pain thresholds. In conclusion, headache patients had decreased pain perception thresholds. Chronic tension-type headache might be a result of dysmodulation of nociceptive impulses, but it is likely that sensitized nociceptors also play a role.