Myoelectric and motor activity of the terminal ileum after pelvic pouch for ulcerative colitis

Abstract

The electrical and motor activity of the terminal ileum after proctocolectomy and ileoanal reservoir was evaluated in seven patients who had undergone surgery for ulcerative colitis. Recordings were carried out with an intraluminal probe under fasting conditions, during stepwise distention of the pouch, in the postprandial state and after administration of Prostigmine^® and bisacodyl. Ileal sensitivity was also studied. Phase III of the interdigestive myoelectric motor complex, when detectable (four patients), was characterized by regular spike bursts superimposed on slow waves at a frequency of 9 cycles per minute. Two different types of motor patterns were observed: short phasic waves lasting 2 to 6 seconds and long tonic waves lasting up to 2 minutes. In most cases, the amplitude and frequency of the pressure events were higher in the efferent limb than in the reservoir. Electrical activity of the surrounding rectal muscle and striated sphincters was also recorded. When distended to the maximum tolerable volume, the reservoir showed spike bursts propagated aborally at a frequency of 15 per minute, leading to large propulsive waves. An overall increase of spike activity was observed after a meal, which did not affect the slow waves. Neostigmine caused an irregular increase of electrical and motor activity, more evident in the efferent limb. Bisacodyl, used to test the functional integrity of the myenteric plexus, elicited strong propulsive contractions and urgency. Leakage did not occur frequently either at rest or under stimuli. Onset of sensation was elicited with volumes of 271±149 ml (Mean±SD) in the reservoir and 17±6 ml in the efferent loop of small bowel (P<0.001). In conclusion: 1) most of the electrical and motor properties of the terminal ileum are retained after surgery; 2) due to its large capacity, the reservoir acts as a storage organ; and 3) overall motility is reduced in the pouch when compared with the distal ileum and propulsion in the triple-loop system is opposed by the activity of the anal sphincters.