Abstract
PURPOSE OF REVIEW: Pain assessment is essential for patient care in many settings, but it proves difficult when the patient is cognitively compromised or otherwise unable to produce a conventional pain report. The present review describes the progress in pain assessment technology that involves the coding of human facial expression. RECENT FINDINGS: It is possible to quantify facial expression by coding patterns of facial muscle contraction and relaxation. These patterns are action units, and they can gauge the intensity of pain as well as signal its occurrence. The experience of pain seems to generate a unique facial expression comprising several action units. Concerns have existed about whether demented patients produce diagnostically meaningful facial expressions of pain because they tend to generate more nonspecific facial expressions and perhaps code pain intensity less well than normals. Recent work shows that facial expression reflects pain as well or better in demented patients compared with normals. SUMMARY: Although still nascent, coded facial expression appears to work reliably as a pain assessment tool with cognitively compromised patients. Clinical application awaits the development of technology that can automate facial coding and scoring.