Does the Nociceptive Spinal Reflex Explain the Lack of Correlation between the Observational and Physiological Pain Assessment Scores in Neonates?

The nociceptive spinal reflex.

Background: In the US it is mandatory to assess and treat pain. UK, The Netherlands, Italy, France and Russia are also establishing similar guidelines. Physiological, behavioural, and biochemical tools have been used for pain assessment in neonates but no gold standard is yet available. Objectives To examine why the findings from behavioural and physiological responses during painful responses have been reported to be either uncorrelated or weakly correlated (Stevens et al 1994; Nurs Res, 43, 226-231, Johnston et al 1995;Pain, 61, 471-9, Barr et al 1998; Arch Dis Child Fetal Neonatal Ed, 79, 152-56).

Methods​: To theoretical compare the anatomical nociceptive spinal reflex to both the behavioural pain scores and the physiological pain assessment tools to understand why these pain assessment methods are uncorrelated. The reasons may be multiple; the caregiver may interpret the behavioural responses differently, and the behavioural responses may be less reactive in very ill patients, small-for-gestational age infants, and different for infants who have been exposed to severe and repetitive painful insults. Sedatives may blur the behavioural pain response. Observational pain assessment tools assess modulated responses from the cortico-cortical circuits and will be influenced from factors as illness of the infants, and inter-variability between the observers, different from pain assessment tools which assess responses from the nociceptive spinal reflex level. The physiological pain assessment tools may be more accurate to assess the size of the nociceptive stimulus.

Conclusions/Results: The physiological pain assessment tools may be most accurate to assess the size of the nociceptive stimulus.