Dr Spencer Dorn and colleagues from New York, USA determined whether lower visceral pain thresholds in irritable bowel syndrome (IBS) primarily reflect physiological or psychological factors.
The team assessed 121 irritable bowel syndrome patients, and 28 controls.
The patients underwent balloon distensions in the descending colon using the ascending methods of limits to assess pain and urge thresholds.
|Ascending methods of limits pain thresholds were correlated with report criterion|
Sensory decision theory analysis was used to separate physiological from psychological components of perception.
Neurosensory sensitivity was measured by the ability to discriminate between 30 mm Hg vs 34 mm Hg distensions.
The team measured psychological influences by the report criterion.
This included the overall tendency to report pain, indexed by the median intensity rating for all distensions, independent of intensity.
Psychological symptoms were assessed using the Brief Symptom Inventory.
The researchers found that irritable bowel syndrome patients had lower ascending methods of limits pain thresholds.
However, patients with irritable bowel diseases had similar neurosensory sensitivity, and a greater tendency to report pain.
The team noted that ascending methods of limits pain thresholds were not correlated with neurosensory sensitivity, but were strongly correlated with report criterion.
Report criterion was inversely correlated with Brief Symptom Inventory somatisation and Brief Symptom Inventory global score.
The research team observed similar results were seen for the non-painful sensation of urgency.
Dr Dorn's team concluded, "Increased colonic sensitivity in irritable bowel syndrome is strongly influenced by a psychological tendency to report pain and urge rather than increased neurosensory sensitivity."