Evaluation of the intrinsic innervation of the internal anal sphincter using electrical stimulation

Abstract

Stimulation of the rectal mucosa with a bipolar electrode leads to relaxation of the internal anal sphincter. Intraoperative studies in two subjects showed that transmission of the impulse was independent of extrinsic nerves and was interrupted by circular myotomy. Characteristics of the reflex were studied in 11 healthy women and 19 women with severe idiopathic constipation. One control subject and two patients did not tolerate the test. In the remainder the stimulus caused a clearly defined fall in internal sphincter pressure. The mean resting maximum anal canal pressure before stimulation was the same in both groups (90 (10) v 104 (7) cm H2O, p = 0.3, controls v patients). The threshold s..