HUMAN BRAIN MEASURES OF CLINICAL PAIN - A REVIEW .2. TOMOGRAPHIC IMAGINGS

This paper (Parts I and II) reviews the measures employed in studying the brain neurophysiological activities of clinical pain. In Part II, these measures include the imaging and measurement of brain blood flow and hemodynamics in various regions of the brain, the scanning of gro ss and fine brain structures by computerized axial tomography or magne tic resonance imaging, and the imaging and measurement of brain metabo lic changes, energy uptake, and receptors bindings through positron em ission tomography or single-photon emission computerized tomography. M olecular chemical transformation by the nuclear magnetic resonance ana lysis of tissue changes and analgesic-receptor interactions is also no ted. Most studies of the cerebral measures of traumatic and pathophysi ological pain reported in the literature are concerned with headache. The relationships of brain activities among sensory processes of nocic eption, subjective experience of pain intensity and quality, emotional reaction, and cognitive coping often are complex and not well elucida ted in man. Although significant changes in the cerebral physiological parameters are frequently reported in pain patients, the specificity and sensitivity of these measures as objective markers for human pain, reviewed from Part I and Part II together, has not yet been conclusiv ely defined. Also, normative data basis and criteria for classifying a bnormality of these brain measures must be established and their valid ity and reliability be carefully examined so that they can be confiden tly applied in diagnosis and management of clinical pain. Nevertheless , advancement on measurement of temporal dynamics in 3-D topographic m apping of cortical activities and source localization modeling, togeth er with tomographic imaging of neurochemical metabolisms in the brain will further our scientific understanding of cerebral pain mechanisms. A window on the brain of human pain is being opened.