Pain
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This review emphasizes how little we know about pain induced by a thermal stimulus. The study of the intensity of pain evoked by heat is relatively exhaustive: the influence of various local, stimulus-dependent or general factors upon threshold values has been well studied, as has the relation between pain and stimulus intensities. On the contrary, few studies have used very cold stimuli, since highly efficient stimulators allowing accurate control of the stimulus parameters have been obtainable only recently. ⋯ At supraspinal level, the thermal information reappears in the reticular formation; there it appears to be solely relative to the pain threshold and not to the intensity of a supraliminary stimulus [55]. In the posterior group of nuclei [134] and the ventroposterolateral nucleus of the thalamus [103], on the contrary, the activity of the neurons reflects the intensity of the stimulation. It has been proved that the neurons of the ventroposterolateral nucleus project onto the SI cortex [103].(ABSTRACT TRUNCATED AT 400 WORDS)
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Clinical Trial Controlled Clinical Trial
Postoperative pain control: contribution of psychological factors and transcutaneous electrical stimulation.
The influence of transcutaneous electrical stimulation (TES) and psychological factors in determining the intensity of acute postoperative pain was examined in a prospective, double-blind controlled trial completed by 30 patients having elective surgery. Psychometric tests were administered prior to surgery. Postoperative pain was assessed by cumulative morphine requirement (M48) administered intramuscularly, and the mean score of a visual analogue scale of pain (VAS), in the first 48 h following surgery. ⋯ When the contribution of neuroticism to the variance of M48 was adjusted using multiple regression analysis, the effect of TES became significant at the 0.05 level. Covariance analysis showed that TES contributed some 19% to the explained variance of M48 while neuroticism contributed about 80%, and there was no interaction between these two factors. These findings allow a degree of prediction of the individual patient's postoperative pain and narcotic requirement, and point to a strong correlation between postoperative pain perception and personality.
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Visual analogue scales (VAS) of sensory intensity and affective magnitude were validated as ratio scale measures for both chronic and experimental pain. Chronic pain patients and healthy volunteers made VAS sensory and affective responses to 6 noxious thermal stimuli (43, 45, 47, 48, 49 and 51 degrees C) applied for 5 sec to the forearm by a contact thermode. ⋯ The power functions were predictive of estimated ratios of sensation or affect produced by pairs of standard temperatures (e.g. 47 and 49 degrees C), thereby providing direct evidence for ratio scaling properties of VAS. Vas sensory intensity responses to experimental pain, VAS sensory intensity responses to different levels of chronic pain, and direct temperature (experimental pain) matches to 3 levels of chronic pain were all internally consistent, thereby demonstrating the valid use of VAS for the measurement of and comparison between chronic pain and experimental heat pain.
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Cognitive and behavioral pain coping strategies were assessed by means of questionnaire in a sample of 61 chronic low back pain patients. Data analysis indicated that the questionnaire was internally reliable. ⋯ These 3 factors were found to be predictive of measures of behavioral and emotional adjustment to chronic pain above and beyond what may be predicted on the basis of patient history variables (length of continuous pain, disability status, and number of pain surgeries) and the tendency of patients to somaticize. Each of the 3 coping factors was related to specific measures of adjustment to chronic pain.
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Comparative Study
The Headache Scale: a new approach to the assessment of headache pain based on pain descriptions.
A Headache Scale was developed to provide an assessment of both the quality and intensity of headache pain. Responses of 150 headache-prone subjects (49 migraine, 101 tension headache), were examined. Using a cluster analysis the adjectives were grouped into 7 clusters including 5 sensory and 2 affective subgroups. ⋯ Migraine and tension sufferers did not differ markedly in pain quality but intensity of pain differentiated these groups. The results did not support the traditional typology of headache, i.e., migraine/tension. An alternative method of classifying headache cases in terms of their psychological experiences rather than headache symptoms was put forward and implications for future research and treatment were discussed.