Evaluation of the role of the puborectal part of the levator ani muscle in anal incontinence: a prospective study of 78 female patients with anal incontinence.

BACKGROUND: Anal incontinence is most often linked with sphincter rupture and/or stretching the pudendal nerves.

OBJECTIVE: The aim of our study was to investigate the involvement of the puborectal part of the levator ani muscle in anal incontinence.

PATIENTS AND MAIN OUTCOME MEASURES: Seventy-eight female patients were studied by anorectal manometry, 3-dimensional ultrasound examination, and concentric needle electromyography of the external anal sphincter, puborectal muscle, and bulbocavernous muscles, completing with the evaluation of the pudendal nerve terminal motor latencies. Damage to the puborectal muscle was defined by an abnormal ultrasound and/or abnormal electromyography.

RESULTS: Rupture of the anal sphincter apparatus and puborectal muscle was found in 23% and 3.8%. The EMG showed damage to the puborectal part in 39 cases: this was isolated in 4 cases and combined with external anal sphincter damage in 35 patients. Unilateral or bilateral increase in the terminal motor latencies of the pudendal nerves was found in 36% (28/78) of the patients. The frequency of peripheral neurogenic lesions varied from 36% to 90% according to the electromyographic tests used. There was no correlation between puborectal part damage and resting pressure, perception threshold, and maximum tolerable rectal volume. The mean Wexner index score was not increased by the existence of a defect involving the puborectal part found by echography or by damage to the puborectal part shown by the EMG. Investigating puborectal muscle lesions reduced the percentage of idiopathic anal incontinence to 2.5%.

CONCLUSION: Our study confirms the feasibility and usefulness of combined electromyography and 3-dimensional ultrasound examination of the puborectal muscle in anal incontinence.