[A method for differentiation between the participation of the smooth and the cross-striated anal sphincter muscles...

By means of simultaneous recordings of the external anal sphincter EMG activity and the anal resting pressure with at least ten voluntary sphincter contractions, it is possible to estimate by correlation calculation the resting pressure exerted by the internal anal sphincter. The value of the method had been proved by comparing investigations in conscious and curarized patients under general anesthesia. In patients with hemorrhoids and chronic constipation, the amount of internal pressure found in the resting tonus (91% in hemorrhoids, 55% in chronic constipation) was significantly different when compared with a health group. The comparison of only the resting pressure did not show a significant difference.