Potential biobehavioral mechanisms of recurrent abdominal pain in children.

To explain why otherwise healthy children experience recurrent episodes of abdominal pain (the recurrent abdominal pain syndrome, or RAP), it has been hypothesized that the child with RAP demonstrates: (1) a deficit in autonomic nervous system recovery to stress, and/or (2) an enhanced behavioral and subjective response to pain. To evaluate the validity of these assumptions, children with RAP (9-14 years) and hospital and healthy controls matched for age, sex, ethnicity and SES were exposed to a cold pressor stimulus (0 +/- 1 degree C). Autonomic (peripheral vasomotor and heart rate), somatic (forearm EMG), subjective (pain intensity and distress), and behavioral (facial expression) responses were recorded during baseline, stressor and recovery periods. At all 4 levels of observation, the cold pressor stimulus resulted in significant autonomic, somatic, subjective and behavioral arousal. However, no significant differential response across the 3 groups was noted for any measure and, in particular, no recovery deficit in autonomic arousal was demonstrated. These findings do not support the assumption of a differential response to an acute laboratory induced stress in children with RAP compared to control children.