CONSTIPATION BY COLONIC INERTIA OR DISTAL OBSTRUCTION - ELECTROMYOGRAPHIC STUDY

Abstract

Colonic motility was evaluated in 15 patients with chronic constipation and 12 healthy subjects by measuring the transit time of 20 radiopaque markers and recording the colonic myoelectric signals by means of a silastic tube equipped with 4 ring contact electrodes. The tube was introduced by flexible sigmoidoscopy so as the electrodes be located at 50, 40, 30 and 20 cm from the anal verge. Constipation resulted from colonic inertia in 7 patients, the markers being delayed over the whole length of the colon. In the 8 other patients, constipation was due to distal obstruction, the markers accumulating electively in the rectum. The myoelectric tracings showed in the control subjects, on 1 hand rhythmical stationary spike potentials that occurred at only 1 electrode site at a mean rate of 10/min, on the other hand sporadic (non-rhythmic) spike potentials that were either propagating over the colonic segment (sporadic propagating potentials) or not (sporadic non-propagating potentials). In the constipated patients, the following changes were observed: the number of sporadic propagating potentials was significantly decreased in colonic inertia (2.5 .+-. 1.3 bursts of spike/h) vs. the controls (8.5 .+-. 1.1 bursts/h) or distal obstruction (7.9 .+-. 1.3 bursts/h); sporadic propagating potentials usually moved aborally; 19.8 .+-. 0.9/100 moved orally in colonic obstruction, while 4.6 .+-. 0.2/100 in the controls and 4.7 .+-. 0.1/100 in colonic inertia; the recording time occupied by the rhythmical stationary potentials was significantly increased in distal obstruction (20.2 .+-. 7.1 min/h of recording time) and in colonic inertia (17.0 .+-. 8.4 min/h)compared to the control subjects (5.8 .+-. 9.0 min/h). The results showed that colonic inertia was associated with a decrease in the production of propagating spike bursts, indicating a decrease in propulsive activity. In distal obstruction, the bursts propagating towards the oral direction may be at the origin of the recto-colonic reflux that is often observed in such patients.