Cortical correlates of an attentional bias to painful and innocuous somatic stimuli in children with recurrent abdominal pain.

Recurrent abdominal pain (RAP) is a common gastrointestinal problem during childhood. It is not only a pediatric health problem, but may represent a risk factor for chronic pain, psychosomatic symptoms, and psychopathological problems later in life. Alterations in central pain processing and an attentional bias to potentially aversive somatic sensations could contribute to the unfavorable outcome of RAP during childhood. Fourteen children with RAP and 15 control children (age: 10-15 year) participated in an attentional task. Children had to respond to rare targets (tones) and ignore frequent either painful (pain threshold) or non-painful mechanical stimuli delivered at the hand. Event-related cortical potentials in response to the somatic stimuli and the tones were measured and stimulus intensity ratings, reaction time and number of errors were obtained. Painful as compared to non-painful stimuli elicited significantly larger N1, P2 and P3 components of the somatosensory-evoked potential (SEP) in all children. The RAP children responded with a significantly larger P3 to both painful and non-painful stimuli. No group differences were found for the auditory-evoked potentials. Perceived stimulus and pain intensity, reaction time and number of errors did not differ between groups. Similar to findings in adults with functional gastrointestinal disorders (FGIDs), children with RAP did not show somatic hyperalgesia as revealed by unaltered pain thresholds and middle latency pain-evoked SEPs. However, they displayed an attentional bias to painful and non-painful (innocuous) somatic stimuli as indicated by an enhanced P3. This may represent an important mechanism not only for the maintenance of RAP, but also for the development of psychosomatic symptoms.