The journal of pain : official journal of the American Pain Society
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The objective of this international, multicenter, open-label trial was to assess the efficacy and safety of up to 12 months of therapy with transdermal therapeutic system (TTS) fentanyl in patients (n = 532) with chronic noncancer pain. The trial was completed by 301 (57%) of the patients. The main outcome measures were pain control assessment, global treatment satisfaction, patient preference for TTS fentanyl, and quality of life. ⋯ It was preferred by the majority of patients compared with their previous opioid medication. Overall, long-term treatment with TDF was generally well tolerated, particularly in view of the low incidence of potentially serious side effects such as drug abuse/dependence and respiratory depression. However, at present, it is important that patients receiving TDF should still be subject to careful assessment and monitoring.
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Chronic-constriction injury (CCI) of the sciatic nerve causes mechanical and heat hyperalgesia and mechanical allodynia in the plantar surface of the hindpaw. The underlying mechanism thought to account for these phenomena include central sensitization induced by peripheral nerve injury, ie, the increase in neuronal activity of spinal dorsal horn neurons. As a marker of neuronal activation of the central nervous system, Fos expression has been used widely to monitor the change in neuronal activity evoked by peripheral input. ⋯ The number of noxious stimulus-evoked Fos-labeled neurons in both the superficial and deep laminae of the dorsal horn in the CCI rats was increased significantly compared with those in sham-operated rats, suggesting an increased excitability of dorsal horn neurons to noxious stimuli. Concurrent EA treatment to the Zusanli point with the pinch stimulus suppressed the increase in the number of Fos-labeled cells in the spinal dorsal horn in the CCI rats. The present results show that EA treatment has antinociceptive effects on both pain behavior and neuronal activation of the spinal dorsal horn neurons in CCI rats.
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According to the fear avoidance model, prolonged disability among patients with chronic nonmalignant pain is due, in part, to an exaggerated fear of pain. At issue in the present study was an attempt to refine the fear-avoidance hypothesis by eliciting estimates of anticipated pain as well as anticipated injury. Along with scores on the Fear Avoidance Beliefs Questionnaire-Work (FABQ-W), a validated measure of fear avoidance, pain and injury expectancies were used as predictors of work disability in a hierarchical regression model. ⋯ After controlling for pain duration, depression, somatization, and current pain severity, pain expectancy alone accounted for 16% of the variance in patients in the chronic group (P < .001) and 33% of the variance in patients in the acute group (P < .001). Both pain and injury expectancies were associated equally with work disability for patients in the acute group (P < .001), but only pain expectancy accounted for variance in the chronic group (P < .001). Fear-avoidance beliefs, in the form of cognitive expectancies, may have as much influence on the duration of disability in patients with acute pain as they do in patients with chronic pain.
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For years, transcutaneous electrical nerve stimulation (TENS) has been used clinically for the treatment of many types of pain. Although there have been many studies conducted on the efficacy of TENS in the clinical setting, the results are conflicting. The purpose of our investigation was to determine the effect of varying frequency and intensity of TENS on secondary mechanical hyperalgesia induced by acute joint inflammation. ⋯ Either low- or high-frequency TENS is equally successful in reducing secondary mechanical hyperalgesia. Similarly, either sensory- or motor-intensity TENS equally reduces secondary mechanical hyperalgesia. Thus, selection of TENS should be based on patient comfort and symptoms for relief of secondary mechanical hyperalgesia.
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Pretreatment with intraperitoneal (i.p.) indomethacin was used to determine whether indomethacin preferentially affected the development of edema and hyperalgesia to thermal and mechanical stimuli produced by injection of zymosan in the ispsilateral hindpaw of the rat. Indomethacin also was delivered intrathecally (i.t.) either 30 minutes before or 4 hours after intraplantar zymosan to determine whether spinal prostaglandin production was important for the induction and/or maintenance of hyperalgesia. Zymosan alone produced a robust edema, a monophasic mechanical hyperalgesia, and a biphasic thermal hyperalgesia in the ipsilateral hindpaw. ⋯ Once hyperalgesia was established, i.t. indomethacin also attenuated the mechanical hyperalgesia whereas it had no effect on thermal hyperalgesia or edema. These data suggest that peripheral, but not spinal prostaglandins contribute to the edema and development of thermal hyperalgesia produced by zymosan. In contrast, spinal prostaglandins contribute to the development and maintenance of mechanical hyperalgesia.