Pain
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Randomized Controlled Trial Clinical Trial
Quantitative sensory examination of epidural anaesthesia and analgesia in man: effects of pre- and post-traumatic morphine on hyperalgesia.
The objectives of the study were: (1) comparison of hypoalgesic effects of pre- and post-traumatic epidural morphine (EM) on primary and secondary hyperalgesia, and (2) comparison of EM hypoalgesia in normal and injured skin. Burn injuries (25 x 50 mm rectangular thermode, 47 degrees C, 7 min) were produced on the calves of healthy volunteers, at 2 different days at least 1 week apart. In randomized order, the subjects received 4 mg of EM administered via the L2-L3 intervertebral space on one day and no treatment on the other day. ⋯ Following NAL, the areas of secondary hyperalgesia expanded beyond control size. It is suggested that the major effect of EM on secondary hyperalgesia is inhibition of C fibre-mediated activity which maintains the altered response properties of central neurons responsible for secondary hyperalgesia. Possible mechanisms of action of NAL in enhancement of hyperalgesia are discussed.
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To address the mechanisms of hyperalgesia and dorsal horn plasticity following peripheral tissue inflammation, the effects of adjuvant-induced inflammation of the rat hindpaw on behavioral nociception and nociceptive neuronal activity in the superficial dorsal horn were examined in neonatally capsaicin-treated rats 6-8 weeks of age. Capsaicin treatment resulted in an 82% loss of unmyelinated fibers in L5 dorsal roots, a dramatic reduction of substance P-like immunoreactivity in the spinal cord, and a significant decrease in the percentage of dorsal horn nociceptive neurons that responded to C-fiber stimulation and noxious heating of the skin. The thermal nociceptive threshold was significantly increased in capsaicin-treated rats, but behavioral hyperalgesia to thermal stimuli still developed in response to inflammation. ⋯ There was no difference in stimulation-induced expansion of the receptive fields for WDR neurons between vehicle- or capsaicin-treated rats. An N-methyl-D-aspartate receptor antagonist, MK-801, attenuated the behavioral hyperalgesia and reduced the receptive field size of dorsal horn neurons in inflamed capsaicin- and vehicle-treated rats. The data suggest that while capsaicin-sensitive primary afferents may be involved in neuronal plasticity induced by peripheral tissue inflammation, changes in the capsaicin-insensitive WDR and NS populations are sufficient to produce thermal and mechanical hyperalgesia after the loss of capsaicin-sensitive primary afferents.
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Prescribing long-term opioids for patients with chronic pain is controversial. The primary purpose of this study was to examine physicians' beliefs about and prescribing of the long-term use of opioids in the treatment of chronic pain patients. Concerns about regulatory pressure and appropriateness of education regarding opioids were also examined. ⋯ Differences were noted by region, specialty, and the requirement for the use of multiple prescriptions for schedule II drugs. Physicians in the Midwestern United States were the least likely to prescribe the long-term use of opioids. Rheumatologists and general practitioners were significantly more likely to prescribe long-term opioids than were surgeons, neurologists, or physiatrists and were more likely to emphasize the importance of symptom improvement as an appropriate goal even in the absence of functional improvements.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Chronic tension-type headache: amitriptyline reduces clinical headache-duration and experimental pain sensitivity but does not alter pericranial muscle activity readings.
In a double-blind, placebo-controlled trial, the effect of 75 mg of a slow-release formulation of amitriptyline on the clinical severity of chronic tension-type headache and on headache-associated neurophysiological parameters (EMG activity, exteroceptive suppression of temporal muscle activity, contingent negative variation (CNV) and experimental pain sensitivity) was investigated. All of the patients treated had a history of headaches of many years' standing and many of them had failed attempts at treatment. In the amitriptyline group, a significant reduction in daily headache duration was already found in the 3rd week of treatment, while in the placebo group no significant changes in headache duration were to be seen. ⋯ The sensitivity to suprathreshold experimental pain, however, was significantly reduced. The data show a statistically relevant reduction of daily headache duration. However, they also show that amitriptyline can only partly alleviate chronic headaches but cannot cure them.
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Case Reports
Difficult management of pain following sacrococcygeal chordoma: 13 months of subarachnoid infusion.
We report on a patient suffering severe pain following a long-standing sacral chordoma in whom management of therapy and pain was extremely difficult. Because orally administered morphine was observed to be ineffective in the early stages of treatment, we tried to achieve pain relief by using epidural morphine. This was also unsatisfactory. ⋯ Periods of analgesia were followed by occasional crises of intense sharp pain suggesting incomplete relief. No serious complications or meningitis occurred. This case emphasizes the difficulty in managing pain in this type of cancer.