Effects of stress on pain threshold and tolerance in children with recurrent abdominal pain.

Models of stress-induced hyperalgesia state that exposure to stress can exaggerate subsequent pain experiences. Studies using both animal and human subjects have shown evidence for hyperalgesia as a function of stress [e.g., Jorum E. Analgesia or hyperalgesia following stress correlates with emotional behavior in rats. Pain 1988;32:341-48; Peckerman A, Hurwitz BE, Saab PG, Llabre MM, McCabe PM, Schneiderman N. Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response. Psychophysiology 1994;31:282-90; Gameiro et al. Nociception and anxiety-like behavior in rats submitted to different periods of restraint stress. Physiol. Behav. 2006;87:643-49; Lucas et al. Visceral pain and public speaking stress: neuroendocrine and immune cell responses in healthy subjects. Brain Behav. Immun. 2006;20:49-56]. However, the role of stress in pediatric pain is not well understood. This study examined stress reactivity and pain tolerance and sensitivity in a population of children with Recurrent abdominal pain (RAP). Forty-nine children meeting criteria for RAP (28 female; mean age 13years; range 9-17years) were randomly assigned to either a condition in which they completed an experimental stressor paradigm (stress interview, serial subtraction task) followed by a pain task (cold pressor) or a condition in which they received the pain task prior to the stress tasks. Children who underwent the stress tasks before the pain task exhibited lower levels of pain tolerance than those who received the pain task first (p<.01); no differences were found between the two groups in pain threshold or pain intensity ratings. Further, pain tolerance was not related to individual differences in physiological reactivity (heart rate change) to the stressor. The present research demonstrates the first evidence of the occurrence of stress-induced hyperalgesia in a pediatric pain population.