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Relationship between anal canal tone and rectal motor activity
A Ferrara1, J H Pemberton, K E Levin
1Section of Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota 55905.
Diseases of the Colon and Rectum
|April 1, 1993
Summary
Rectal motor complexes (RMCs) increase anal canal pressure, enhancing fecal continence. This study reveals a direct link between rectal activity and anal sphincter function, crucial for maintaining continence.
Area of Science:
- Gastroenterology
- Physiology
Background:
- The anal sphincters maintain fecal continence via a pressure barrier.
- The influence of proximal contractile events on this barrier is not well understood.
Purpose of the Study:
- To investigate the relationship between anal canal pressures and rectal motor activity.
- To determine if rectal motor complexes impact anal sphincter function.
Main Methods:
- Developed a fully ambulatory system for prolonged pressure recording.
- Used a flexible transducer catheter with sensors at multiple anal canal locations.
- Recorded 24-hour spontaneous motor activity in 12 healthy subjects.
- Analyzed data using computerized methods to characterize anal pressures and rectal motor complexes (RMCs).
Main Results:
- Mean anal canal resting pressure was 75 ± 12 mmHg.
- Cyclic decreases in anal pressure occurred during sleep (periodicity 1.6 hours).
- Rectal motor complexes (RMCs) were identified in all subjects (mean frequency 16/24 hours).
- Importantly, RMCs were consistently associated with increased anal canal pressure and contractile activity.
- Anal canal pressure remained higher than rectal pressure during RMCs, and relaxations did not occur during RMCs.
Conclusions:
- Rectal motor activity and anal canal motor activity are interrelated.
- The onset of rectal contractions is accompanied by increased anal canal resting pressure and contractile activity.
- This temporal relationship is a key mechanism for preserving fecal continence.