Subtypes of constipation predominant irritable bowel syndrome based on rectal perception

Area of Science:

• Gastroenterology
• Neurogastroenterology
• Physiology

Background:

• Constipation presents as two distinct patient groups: those lacking the urge to defecate (no urge) and those feeling constant incomplete evacuation (urge).
• Both groups often have Rome-positive irritable bowel syndrome (IBS).

Purpose of the Study:

• To investigate differences in symptoms, colonic transit, and rectal distension perception between constipation patients with and without an urge to defecate.
• To compare these responses with healthy controls.

Main Methods:

• Forty-four constipation patients and 15 healthy controls underwent symptom questionnaires, colonic transit tests (radiopaque markers), and rectal balloon distension.
• Rectal distension assessed stool (S) and discomfort (D) thresholds using slow ramp (40 ml/min) and rapid phasic (870 ml/min) distensions.

Main Results:

• Patients with constipation were categorized into 17 'no urge' and 27 'urge' groups, all with IBS.
• While sensitivity to phasic rectal distension was similar between 'no urge' and 'urge' groups (mean D threshold ~28 mm Hg), it was higher in controls (46 mm Hg).
• The 'no urge' group exhibited hyposensitivity to slow ramp distension (D threshold 45 mm Hg) compared to the 'urge' group (31 mm Hg) and controls (30 mm Hg).

Conclusions:

• Patients with constipation and the 'no urge' symptom profile demonstrate hyposensitivity to slow rectal distension.
• This hyposensitivity occurs despite potentially increased sensitivity to rapid, phasic rectal distension.
• These findings highlight distinct sensory processing differences in constipation subtypes within IBS.