The Challenge of Measuring Pain in Humans

Abstract

Human pain reports are viewed by many as ‘subjective assessments of otherwise unmeasurable experiences’; however, various strategies have been developed to provide reliable and valid measures of clinical pain. Pain is a multidimensional experience that can be described in terms of both sensory intensity and unpleasantness qualities and can be further characterized physiologically and psychologically. Subjects can reliably rate both the pain intensity and unpleasantness of experimental pain stimuli (e.g., noxious heat ≥ 45° C and electrical toothpulp stimulation) independently using visual analogue scales or quantifiable words that describe various levels of pain intensity and unpleasantness. Patients also rate their clinical pain and experimental pain stimuli consistently using these methods. These psychophysical methods have provided useful tools for assessing changes in the nervous system (central sensitization) that are responsible for clinical presentation of persistent pain conditions such as fibromyalgia and temporomandibular disorders. Greater understanding of these changes may lead to novel treatment approaches for the control of chronic pain. Finally, sex, gender, ethnic and racial group differences have been reported in not only pain reports and behaviors but, also, clinicians’ assessments and management of clinical pain. Virtual human technology has provided a valuable tool for understanding the factors that influence clinical pain assessments. The chapter reviews how reliable and valid pain measurement has provided better understanding of clinical pain that will lead to more effective pain management approaches.