The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial Comparative Study
Treatment response in antidepressant-naïve postherpetic neuralgia patients: double-blind, randomized trial.
In 47 patients with postherpetic neuralgia (PHN) who had never had an adequate trial of any antidepressant, we performed a randomized, double-blind, parallel design trial comparing desipramine, amitriptyline, and fluoxetine. Patients were titrated to a maximum of 150 mg/day for desipramine and amitriptyline and 60 mg/day for fluoxetine over a 3-week period and then treated for an additional 3 weeks before tapering off study medication. A total of 38 subjects (81%) completed the entire trial. The modified intent-to-treat analysis of percent change in daily diary pain intensity scores showed no significant differences among the 3 drugs (ANOVA P = .120). Desipramine produced the greatest reduction in pain intensity (47%), followed by amitriptyline (38%) and fluoxetine (35%). Clinically meaningful pain relief (moderate or better) was significantly more likely with desipramine (12/15 patients) than with amitriptyline (9/17) or fluoxetine (5/15); chi(2)P = 0.036). The 11 subjects using opioids at study entry had smaller reductions in pain than those not using concomitant opioids. The fluoxetine group had the highest noncompletion rate (33%), with 1 subject hospitalized for hyponatremia. Although the magnitude of pain reduction and the category pain relief rating was not significantly different among the 3 drugs, the tricyclics desipramine and amitriptyline were well tolerated and provided clinically meaningful pain relief in 53% to 80% of subjects. ⋯ Few clinical trials focus on patients who are naïve to an entire class of medication. In this randomized blinded trial, the tricyclic antidepressants desipramine and amitriptyline were compared to the serotonin-selective antidepressant fluoxetine. All 3 drugs reduced PHN pain, with desipramine providing satisfactory relief in 80% of those treated.
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The main objective of this research was to determine the initial psychometric properties of the Spanish Version of the Faces Pain Scale-Revised (FPS-R) as a measure of pain intensity for use with the elderly. To assess the scaling properties, validity, and reliability of the FPS-R, a total sample of 177 subjects aged 65 years or older participated in this study. Ranking procedures, placement tasks, and test-retest methods were used. The participants were asked to rate their pain intensity by using the FPS-R and a pain thermometer (PT) and to inform about their affective state. They were also asked to imagine themselves in 5 hypothetical painful situations (Geriatric Painful Events Inventory) and rate the degree of pain by using the FPS-R and the PT at 2 different times. Rank ordering tasks for the individual faces showed excellent agreement between the expected ranking and the one provided by the participants (Kendall's W = 0.75, P < .0001). The pain intensity ratings reported with FPS-R and the PT were very similar, and the relationship between the intensity of pain experienced and participant's negative affective state was statistically significant (r = 0.32, P < .01). Test-retest correlations on the Geriatric Painful Events Inventory ranged from 0.44 to 0.7. All the participating subjects were asked to choose the pain scale they preferred. Our data suggest that, regardless of their age and/or gender, the subjects preferred the FPS-R to the PT. Overall, these results provide preliminary evidence of its reliability and convergent and criterion-related validity as well as its strong ordinal properties with a sample of elderly subjects. ⋯ This article presents the evaluation of reliability, validity, and preference for a pain intensity scale for use with the elderly, the Faces Pain Scale-Revised. This scale could help clinicians to assess the intensity of pain in cognitively intact elderly patients and might also be helpful in making decisions about treatment. Likewise, it could be used by researchers who wish to evaluate the effects of available treatments.
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Randomized Controlled Trial
Activation of naloxone-sensitive and -insensitive inhibitory systems in a human pain model.
We investigated naloxone effects in a model of electrically induced pain and hyperalgesia. In a double-blind, placebo-controlled, cross-over study, 15 volunteers underwent four 150-minute sessions of high-current-density electrical stimulation of their forearms. After 60 minutes, naloxone or placebo was given intravenously (increasing plasma concentrations of 0.1, 1, and 10 ng/mL; 30 minutes each) in 3 of the 4 sessions. Pain ratings and areas of mechanical hyperalgesia were assessed at regular intervals during all sessions. The low doses of naloxone did not cause any significant change of pain rating of areas of hyperalgesia. In terms of intrasession effects, pain ratings and areas of hyperalgesia significantly decreased during the sessions to 62% (pain rating), 70% (area of punctuate hyperalgesia), and 82% (area of allodynia) of the initial values. Naloxone (10 ng/ml) reversed these decreases. In terms of between-session effects, the time course of pain ratings remained constant from session to session. In contrast, the areas of punctate hyperalgesia successively decreased to 60% of initial value at the fourth repetition. The session effect was not reversed by naloxone. High-current-density electrical stimulation provokes central sensitization, but in addition inhibitory systems are activated that are only partly naloxone-sensitive. ⋯ Endogenous inhibitory systems are of major importance for clinical pain conditions, but are not reflected in traditional human pain models. Here we show activation of a naloxone-sensitive short-term and a naloxone-insensitive long-term inhibitory system in a new model of electrically induced pain and hyperalgesia.
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Cancer pain is a significant clinical problem because it is the first symptom of disease in 20% to 50% of all cancer patients, and 75% to 90% of patients with advanced or terminal cancer must cope with chronic pain syndromes related to failed treatment and/or tumor progression. One of the most difficult to treat cancer pains is metastatic invasion of the skeleton that can generate ongoing and bone breakthrough pain, which represents one of the most debilitating cancer-related events. Because bradykinin has been shown to be released in response to tissue injury and plays a significant role in driving acute and chronic inflammatory pain, we focused on bradykinin antagonists in a model of bone cancer pain. In our model of bone cancer, which involves the injection and confinement of 2472 sarcoma cells to the mouse femur, pharmacologic blockade of the bradykinin B1 receptor is effective in reducing pain-related behaviors at both early and advanced stages of bone cancer. ⋯ Bone cancer pain can be severe and difficult to control fully. With a mouse model of bone cancer pain we demonstrate that pharmacologic blockade of the bradykinin B1 receptor is effective in reducing bone cancer pain-related behaviors, suggesting that B1 antagonists might be useful in attenuating bone cancer pain in humans.
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Seventy-one percent of 122 patients with central post-stroke pain (CPSP) had allodynia that was tactile-, cold-, or movement-evoked. Site of thalamic (and some infratentorial) lesions as revealed by magnetic resonance imaging (MRI) was correlated in some cases with allodynia type and sensory perception threshold testing (QST). Notably, patients with cold allodynia tend to have more dorsally placed thalamic lesions than those without, and those with movement allodynia more anteriorly placed lesions. Suggestions are made for improved correlation. ⋯ Only about half of patients with CPSP have allodynia (pain caused by innocuous stimulation); such stimulation is usually tactile- or cold-evoked or due to activation of stretch receptors (movement). We have found that, in some of our cases, the type of allodynia may depend on lesion location within the thalamus.