1、Chapter 7 understanding painThe Meaning of PainAbout 100 years ago,pain was most frequently considered a direct consequence of physical injury,specifically related to the degree of tissue damage.C.A.Strong(1895)hypothesized that pain was due to two factors:the sensation and the persons reaction to t
2、hat sensation.Definition of painPain is remarkably difficult to define.IASP(the International Association for the Study of Pain)Subcommittee on Taxonomy defined pain as“an unpleasant sensory and emotional experience associated with actual or potential tissue damage,or described in terms of such dama
3、ge.”The experience of painBeecher(1956):pain is a two-dimensional experience consisting of both a sensory stimulus and an emotional component.Individual differenceIndividual factors and personal experience make a difference for the experience of pain.Classical conditioningOperant conditioning:reward
4、s for pain,such as receiving attention,sympathy and so on,is important for building acute pain into chronic pain.Individual differenceIndividual variability tend to be exaggerated.there is no“pain-resistant personality”or“pain-prone personality”.Cultural and situational factors are more important.Cu
5、ltural differenceThe variation in pain behavior among different cultures may reflect behavioral differences in learning and modeling,differences in sensitivity to pain,or some combination of these factors.Gender differenceAre women more sensitive to pain than man?Researches showed that:women may rep
6、ort higher anxiety related to their experience of pain.Theories of painSpecificity theoryThe gate control theorySpecificity theorySpecific pain fibers and pain pathways exist,making the experience of pain virtually equal to the amount of tissue damage or injury.Pain is the result of transmission of
7、pain signals from the body to a“pain center”in the brain.Specificity theory fails to integrate the variability of the experience of pain with the physiology of the somatosensory system.The gate control theoryRon Melzack and Peter Wall in 1965:The gate control theory of painPain is not the result of
8、a linear process that begins with sensory stimulation of pain pathways and ends with the experience of pain.Structure in the spinal cord act as a gate for sensory input that the brain interprets as pain.The gate control theorySensory informationdorsal horns of the spinal cordamplifying or decreasing
9、 the incoming neural signals.The gate control theoryCentral control trigger:consisting of nerve impulses that descend from the brain and influence the gating mechanism.These impulses from the brain affect the opening and closing of the gate in the spinal cord and are affected by cognitive processes.
10、The measurement of painSelf-report ratingsBehavioral assessmentsPhysiological measure Self-report 0 1 2 3 4 5 6 7 8 9 10 0 不痛不痛 1-4 轻度疼痛轻度疼痛 5-6中度疼痛中度疼痛 7-10重度疼痛重度疼痛VASPain questionnaire and standardized psychological testsMPQMMPIThe beck depression inventoryThe symptom checklist-90Behavioral assess
11、mentGroanGrimaceRubSighLimpMiss workRemain in bedLower levels of activityUse of pain medicationBody postureFacial expressionsUseful especially for children and elder peoplePhysiological measuresEMG:electromyographyThrough other processes as hyperventilation,blood flow in the temporal artery,heart rate,hand surface temperature,finger pulse volume and skin resistance level.Used in children or infants
