Pain
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The practice and theoretical basis of pain measurement is reviewed and critically examined in the areas of animal research, human subjects laboratory investigation and clinical study. The advantages and limitations of both physiological and behavioral methods are discussed in each area, and subjective report procedures are evaluated in human laboratory and clinical areas. The need for procedures that bridge these areas is emphasized and specific issues are identified. Progress in the technology of pain measurement over recent decades is reviewed and directions for future work are suggested.
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Low back pain and sciatica have been treated with peridural local anesthetics for over 80 years and with epidural and subarachnoid steroid injections for a quarter of a century. This review surveyed the literature concerning the evolution, pathophysiology, complications and results of this type of therapy. The volume injected and the method used vary with different physicians and no standard has been established. ⋯ It is the authors' opinion that the rationale for the use of spinal local analgesics or steroids or intramuscular steroids has not been scientifically proven. Complications with the use of subarachnoid steroids are sufficiently serious that this form of therapy should be condemned. In this age of accountability it is imperative that therapies with questionable benefits should be critically evaluated.
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The McGill Pain Questionnaire (MPQ), supplemented with a German version, was administered to 10 healthy subjects to evaluate two laboratory pain models. Ischemia pain was induced as a tonic pain model and electrical intracutaneous stimuli were applied as a model of phasic pain. In addition, both pain models were employed simultaneously in order to evaluate their mutual influence. ⋯ Differences were significant on the 5% level for the visual analog scales, the category scale and PPI. Evaluation of the MPQ subscales revealed that mainly the affective dimension of phasic pain was reduced under concurrent tonic pain. It is concluded that the MPQ is as well-suited to characterize differential analgesic effects as it is to differentiate properties of pain models.
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Comparative Study
The McGill Pain Questionnaire reconsidered: confirming the factor structure and examining appropriate uses.
A major problem in the understanding and psychological treatment of chronic pain patients is the inadequacy of available assessment procedures. Currently, the most frequently used instrument is the Pain Rating Index (PRI) of the McGill Pain Questionnaire, designed to assess 3 components of pain (i.e., sensory, affective, and evaluative) postulated by the Gate Control Theory. The PRI has been used in many studies to make differential diagnoses, to describe different groups of pain patients, and to identify the factor composition of the instrument itself. ⋯ Subsequent analyses revealed that the 3 components of the PRI do not display adequate discriminant validity. The current use of 3 subscales to establish differential diagnoses or patterns of different pain syndromes may lead to inappropriate classification and treatment decisions. The major conclusion of these findings is that use of only the total score of the PRI is appropriate for pain assessment.
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Non-verbal expressive behaviour may provide important information about pain not available through verbal report. Nevertheless, it has received little attention in pain research. In the present study, changes in expressive behaviour resulting from electric shock were related to shock intensity, self-report of discomfort, observers' judgements of subjects' distress and social modelling influences. ⋯ Change in expressive reactions to the shocks was directly related to stimulus intensity, self-report of pain, and observers' judgements of subjects' distress. Expressive behaviour resulting from high shocks was diminished by exposure to a tolerant model. These findings establish the feasibility of pain measurement based on expressive behaviour, suggest that expressive behaviour provides a sensitive and valid index of pain, and indicate that tolerant modelling reduces evidence of pain across multiple measures.