Is there a Primal Face of Pain? A methodology answer.

Pain assessment is of high priority in the clinical setting. Facial Pain Scales (FPSs) are pain assessment tools generally used with school-aged children. The implicit theoretical bases for the success of FPSs have seldom been explored. Explanations why and how FPSs work (or do not work) have not been addressed. We support the existence of a universal pain expression--the Primal Face of Pain (PFP), which is present at birth, evolved in nature, and modulated through sociocultural factors. We propose it to be key in understanding the applicability of FPSs. We present here the design of a computer-assisted descriptive study that will observe, quantify and model the PFP as present in newborns. Measurement of the PFP will lead to exploration of the theoretical consequences of its existence, particularly as related to pediatric pain assessment and the valid use of FPSs. Further, this work can lay a foundation for the development of a new generation of FPSs.