Pain
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Chronic pain patients reported pain intensity on each of 3 pain intensity scales, the visual analog, numerical and adjectival scales, and then ranked the scales in order of perceived best communication of pain intensity. All patients were able to complete an adjectival scale but 11% were unable to complete a visual analog scale and 2% failed at a numeric scale. The intensity of the pain ratings on the 3 scales were significantly correlated and there were no reliable differences in reported intensity as a function of preference. ⋯ Patients completing all 3 scales indicated a significant preference for the adjectival scale but the basis for this preference did not appear related to sex, etiology of pain, affective variables nor selected psychological variables. These data indicate that pain scale preference does not influence pain intensity report. Nevertheless, there are some clinical situations in which a numeric scale is likely to yield a better measure of pain intensity.
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(1) The effects of stimulation of the nucleus raphe magnus (NRM) and the periaqueductal gray (PAG) were tested on the digastric (jaw-opening) reflex and on the activity of functionally identified single neurons recorded in trigeminal (V) subnucleus oralis in the brain stem. Reflex and neuronal responses evoked by tooth pulp stimulation could be readily suppressed for 250--1000 msec by PAG and NRM conditioning stimuli. ⋯ This suggests that some of the modulatory influences involve endogenous opiate-related mechanisms. (4) Many of the oralis neurons were identified as trigeminothalamic relay neurons on the basis of their antidromic response to ventrobasal thalamic stimulation; PAG and NRM conditioning produced not only a suppression of their orthodromic responses to oral-facial stimuli but also caused a decrease in the antidromic excitability of the relay neurons. This decrease may be indicative of raphe-induced postsynaptic inhibition of oralis neurons, and/or presynaptic facilitation of their thalamic endings.
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Simultaneous measurements of pain rating, withdrawal reflex, and skin resistance reaction with non-painful and painful electrical stimuli were performed on 15 healthy male volunteers. Eight different intensities were delivered in standardized randomized order. Each intensity appeared 10 times. ⋯ Graphical evaluation in double logarithmic scales led to systematic errors causing higher exponents. Compound relations, like skin resistance reaction or withdrawal reflex amplitude as function of subjective estimation, could also be approximated by power functions, with parameters predictable from stimulus-reaction functions. No change in exponent was observed when subjective estimation turned from pre-pain to pain.
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Traction lesions of the brachial plexus are becoming more frequent. Many of the lesions involve avulsion of nerve roots from the spinal cord. This very often results in severe pain which is associated with deafferentation. ⋯ The single most effective manoeuvre that reduces pain is absorption by the patient in work. There remains a significant number of young men with severe pain who may expect to suffer such pain indefinitely. There is urgent need for new methods to be developed to control this pain.