Diverticular disease: electrophysiologic study and a new concept of pathogenesis.

The cause of diverticular disease (DD) is not exactly known, although colonic motor disorder has been proposed as a factor in the pathogenesis of the condition. We investigated the hypothesis that disordered colonic electrical activity is responsible for the colonic motor dysfunction and the development of DD. The electromyographic (EMG) activity and pressure of the sigmoid colon (SC) were recorded in 36 patients [16 early cases, 20 advanced cases; age (mean +/- SD) 53.3 +/- 5.6 years; 19 women, 17 men] and 22 healthy volunteers. The percutaneous route was used for recording the SC EMG. The healthy volunteers exhibited SC slow waves with a regular rhythm and the same frequency, amplitude, and conduction velocity from the three electrodes in the same subject. The SC basal pressure (7.9 cm H(2)O) was interrupted by bouts of high pressure (26.8 cm H(2)O). The early-DD cases showed slow waves with an irregular rhythm and significantly higher variables ( p < 0.05) than the volunteers. Action potentials followed randomly or were superimposed on the slow waves. The SC basal pressure was significantly higher than that of the volunteers (21.4 cm H(2)O, p < 0.01). Bouts of pressure (58.6 cm H(2)O) coupled with action potentials were recorded. No waves were recorded from 15 of 20 of the advanced-DD patients. In 5 patients, slow waves with an irregular rhythm and lower variables ( p < 0.05) than those of the volunteers were recorded. The basal SC pressure was significantly above normal. Three electrical activity patterns could be identified in DD patients: "tachyrhythmic" in the early-DD patients and "bradyrhythmic" or "silent" in the late-DD patients. These dysrhythmias may result from a disordered colonic pacemaker. The similarity between early DD and the irritable bowel syndrome suggests that DD is an advanced stage of the irritable bowel syndrome; studies are required to investigate this hypothesis further.