Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Amitriptyline effectively relieves neuropathic pain following treatment of breast cancer.
The effectiveness of amitriptyline in relieving neuropathic pain following treatment of breast cancer was studied in 15 patients in a randomised, double-blind placebo-controlled crossover study. The dose was escalated from 25 mg to 100 mg per day in 4 weeks. The placebo and amitriptyline phases were separated by a 2-week wash-out period. ⋯ The 'poor responders' reported significantly more adverse effects with amitriptyline and placebo than the good responders. It is concluded that amitriptyline effectively reduced neuropathic pain following treatment of breast cancer. However, the adverse effects of amitriptyline put most of the patients off from using the drug regularly.
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Clinical Trial
Concerning the homology of painful experiences and pain descriptors: a multidimensional scaling analysis.
How is the sensory (or other) experience of pain related to the words used to describe such experiences? Answering this question would not only improve our general understanding of the relationship between the experience of pain and the report of pain, but also would allow one to quantify inaccuracies or idiosyncracies in this regard. A continuous multidimensional scaling model was used to examine the similarity between noxious electrocutaneous stimuli and the words used to describe them. If these two types of stimulus objects were homologous, one would expect that physical and verbal stimuli with the same meaning would be scaled with similar values along a single dimension; if not, the two types of stimuli would be scaled at opposite poles of a dimension which distinguished between them. ⋯ A single dimension in the group stimulus space scaled both physical and verbal stimulus objects from least to greatest intensity. Since this (or any higher) dimension failed to segregate verbal from physical stimuli, the words appear to be homologous with experience. While conclusions are limited to these specific stimuli, results suggest that the INDSCAL model offers a valuable method for exploring the relationship between pain report and pain experience.
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Randomized Controlled Trial Clinical Trial
A new method of recording somatosensory evoked potentials by randomized electrical tooth stimulation with 6 levels of intensity.
Dental somatosensory evoked potentials (SEPs) corresponding to the stimulus intensity levels were recorded at 6 different levels of intensity presented in a randomized order. The relationships between the amplitude of the late SEP component with latency between 150 and 300 msec and each stimulus intensity level were also compared in conditions of randomized intensity and constant intensity. The amplitude of the late component increased significantly with the increased stimulus intensity both in the randomized and constant intensity stimulation. ⋯ The latency of the late positive component significantly increased with the randomized stimulation with a 3-sec ISI. This phenomenon might be attributable to the psychological contamination. SEP recording in the randomized dental stimulation with a 1-sec ISI may have applications in neuropharmacological research or physiological research on pain and evaluation of the effects of analgesics, anesthetics, acupuncture and transcutaneous electrical nerve stimulation (TENS).
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Nerve growth factor (NGF) is known to produce hyperalgesia as well as to stimulate synthesis of neuropeptides in dorsal root ganglia (DRG). In the present study, we wanted to determine the effects of local NGF administration and assess to which extent mast cell-dependent factors are mediating NGF responses. Rats received 1 daily unilateral intraplantar injection for 3 days. ⋯ We suggest therefore that NGF-induced local edema was caused by mast cell-derived vasoactive compounds which act together with afferent neuron-derived CGRP to increase vascular permeability. NGF-induced thermal hyperalgesia most likely was caused by an increased sensitivity of peripheral endings of capsaicin sensitive afferents. This effect of NGF was not mediated by products of the cyclooxygenase pathway, and was also observed in mast cell-depleted rats.
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Randomized Controlled Trial Comparative Study Clinical Trial Controlled Clinical Trial
NMDA receptor blockade in chronic neuropathic pain: a comparison of ketamine and magnesium chloride.
Ten patients (4 female, 6 male) aged 34-67 years suffering from peripheral neuropathic pain participated in a double-blind placebo-controlled study where ketamine or magnesium chloride were administered by a 10 min bolus infusion (ketamine: 0.84 mumol/kg = 0.2 mg/kg, magnesium: 0.16 mmol/kg) followed by a continuous infusion (ketamine: 1.3 mumol/kg/h = 0.3 mg/kg/h, magnesium: 0.16 mmol/kg/h). Ongoing pain determined by VAS score, area of touch-evoked allodynia, detection and pain thresholds to mechanical and thermal stimuli were measured before and during drug infusion. Ketamine produced a significant reduction of spontaneous pain (57%) and of the area of allodynia (33%). ⋯ Following ketamine there was a significant correlation between the reduction in ongoing pain and reduction in area of touch-evoked allodynia. Detection and pain thresholds to mechanical and thermal stimuli were not significantly changed by the drugs. These findings suggest that both ongoing pain and touch-evoked pain (allodynia) in neuropathic pain are inter-related phenomena, which may be mediated by the same mechanism and involving a N-methyl-D-aspartate receptor.