Functional reorganization of brain networks in patients with painful chronic pancreatitis

BACKGROUND: The underlying pain mechanisms of chronic pancreatitis (CP) are incompletely understood, but recent research points to involvement of pathological central nervous system processing involving pain-relevant brain areas. We investigated the organization and connectivity of brain networks involved in nociceptive processing in patients with painful CP.

METHODS: Contact heat-evoked potentials (CHEPs) were recorded in 15 patients with CP and in 15 healthy volunteers. The upper abdominal area (sharing spinal innervation with the pancreatic gland) was used as a proxy of 'pancreatic stimulation', while stimulation of a heterologous region remote to the pancreas (right forearm) was used as a control. Subjective pain scores were assessed by visual analogue scale. The brain source organization and connectivity of CHEPs components were analysed.

RESULTS: After pancreatic area stimulation, brain source analysis revealed abnormalities in the cingulate/operculo-insular network. A posterior shift of the operculo-insular source (p = 0.004) and an anterior shift of the cingulate source (p < 0.001) were seen in CP patients, along with a decreased strength of the cingulate source (p = 0.01). The operculo-insular shift was positively correlated with the severity of patient clinical pain score (r = 0.61; p = 0.03). No differences in CHEPs characteristics or source localizations were seen following stimulation of the right forearm.

CONCLUSIONS: CP patients showed abnormal cerebral processing after stimulation of the upper abdominal area. These changes correlated to the severity of pain the patient was experiencing. Since the upper abdominal area shares spinal innervation with the pancreatic gland, these findings likely reflect maladaptive neuroplastic changes, which are characteristic of CP.