Pain
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The McGill Pain Questionnaire consists primarily of 3 major classes of word descriptors--sensory, affective and evaluative--that are used by patients to specify subjective pain experience. It also contains an intensity scale and other items to determine the properties of pain experience. The questionnaire was designed to provide quantitative measures of clinical pain that can be treated statistically. ⋯ Correlation coefficients among these measures, based on data obtained with 297 patients suffering several kinds of pain, are presented. In addition, an experimental study which utilized the questionnaire is analyzed in order to describe the nature of the information that is obtained. The data, taken together, indicate that the McGill Pain Questionnaire provides quantitative information that can be treated statistically, and is sufficiently sensitive to detect differences among different methods to relieve pain.
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Controlled radiant heat stimulation for a combined psychophysical and electrophysiological research in pain was achieved by the use of an infrared Laser beam. The computer controlled stimuli, being of very brief duration (down to 5 msec) and sharply localized, are suitable for recording of averaged evoked responses as well as for determination of pain and thermal thresholds. ⋯ The threshold energy delivered by this technique is similar to that obtained by the Hardy-Wolff-Goodell method. Special precautions were taken to avoid injury to the skin and the eyes.
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In a group of 30 subjects suffering from sympathetic reflex dystrophies of the limbs, the sympathetic ganglia of the affected side were blocked with a local anesthetic. Using an original method, we measured the cutaneous pain threshold before the block and at prefixed intervals after the block during a period of 2 days. In all subjects the cutaneous pain threshold showed damped oscillations both in the limb ipsilateral to the block and in the contralateral one. The analysis of these oscillations showed: (a) that the sympathetic control of the cutaneous pain threshold may be exerted through a negative feedback loop (skin-afferent input-CNS-sympathetic output-skin); (b) that the afferent discharge of a limb controls the contralateral sympathetic output through central mechanisms.
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In the cat, electrical stimulation of the inferior central nucleus of the raphe induces a powerful analgesia. This stimulation totally suppresses the behavioural reactions elicited by strong pinches applied to the tail or to the four limbs; it strongly modifies the threshold of the jaw opening reflex obtained by tooth pulp stimulation and considerably affects the behavioural reactions elicited by continuing such stimulation. ⋯ The analgesia obtained by stimulation of raphe nuclei seems to be sustained by serotoninergic mechanisms and relationships between these are discussed. In preliminary experiments, analgesia induced by CI stimulation has been suppressed by administration of naloxone, a specific opiate antagonist.