Gastroenterology

Gastroenterology

Volume 132, Issue 4, April 2007, Pages 1546-1556
Gastroenterology

Basic–liver, pancreas, and biliary tract
Pain in Chronic Pancreatitis: The Role of Reorganization in the Central Nervous System

https://doi.org/10.1053/j.gastro.2007.01.037Get rights and content

Background & Aims: In various chronic pain conditions cortical reorganization seems to play a role in the manifestations. The aim of this study was to investigate cortical reorganization in patients with pain caused by chronic pancreatitis. Methods: Twelve healthy subjects and 10 patients with chronic pancreatitis were included. The esophagus, stomach, and duodenum were stimulated electrically at the pain threshold using a nasal endoscope. The electroencephalogram was recorded from 64 surface electrodes and event-related brain potentials (EPs) were obtained. Results: As compared with healthy subjects, the patient group showed decreased latencies of the early EP components (N1, P < .001; P1, P = .02), which is thought to reflect the exogenous brain pain processing specifically. Source analysis showed that the dipolar activities corresponding to the early EPs were located consistently in the bilateral insula, in the anterior cingulate gyrus, and in the bilateral secondary somatosensory area. The bilateral insular dipoles were localized more medial in the patient group than in the healthy subjects after stimulation of all 3 gut segments (P < .01). There also were changes in the cingulate cortex where the neuronal source was more posterior in patients than in controls to stimulation of the esophagus (P < .05). Conclusions: The findings indicate that pain in chronic pancreatitis leads to changes in cortical projections of the nociceptive system. Such findings also have been described in somatic pain disorders, among them neuropathic pain. Taken together with the clinical data this suggests a neuropathic component in pancreatic pain, which may influence the approach to treatment.

Section snippets

Subjects

Seventy patients who potentially could be enrolled in the study were included from the medical and surgical departments at Aalborg, Herning, and Aarhus hospitals in Denmark. The Marseille-Rome/Cambridge diagnostic criteria for CP were used.24 The patients were all well known by the researchers, but most suffered from diseases with the potential to confound the experiment such as long-lasting diabetes or low back pain, or they used analgesics or had intermittent alcohol intake, and so forth.

Pain Intensity and Description

All subjects reported painful sensations from the electrical stimulation in all 3 gut segments. The impedance between the stimulation electrodes was less than 2 KΩ in all experiments. The mean current intensities for the controls in the esophagus, stomach, and duodenum were 12.8 ± 3.9, 24.9 ± 8.2, and 23.1 ± 12.1 mA, respectively. For the patients the mean current intensities were 10.2 ± 1.2, 24.4 ± 11.9, and 16.3 ± 7.6 mA, respectively. Between controls and patients there were no statistical

Discussion

This article addresses cortical reorganization in patients suffering from pain caused by a well-defined organic GI disease. The stimulation technique allowed us to stimulate 3 regions of the upper GI tract with the same methodology. The evoked brain potentials differed in latency and topographic distribution between patients with CP and controls. The dipolar sources in the cingulate cortex and in the insula also differed between the groups. The neuronal sources in the insula were changed most

Conclusions

The pathogenesis of pain in CP is poorly understood. There is a growing body of evidence that neuroplastic changes such as those seen in neuropathic pain and other chronic pain disorders may be of importance. The current findings of cortical reorganization in the insula together with reduced EP latency support the theory that cortical reorganization is a mechanism involved in patients with CP. This insight may lead to changes in the current concept for treatment of pain originating from the

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