Fecal incontinence. Studies on physiology, pathophysiology and surgical treatment.

The thesis consists of ten previously published studies and a review. The physiological and pathophysiological mechanisms in fecal incontinence has been studied by anal manometry, both by standard static anal manometry and by a new method, dynamic anal manometry, where anal sphincter pressure can be measured during simultaneous opening and closing of the anal canal. Patients with fecal incontinence showed abnormal sphincter pressures more frequently when dynamic anal manometry was used compared to standard anal manometry. The physiology and pathophysiology of the rectum was studied using rectal compliance measurements. Patients with normal anorectal function had a large variation in rectal compliance. Patients with fecal incontinence had as a group, lower rectal compliance than continent patients. This may lead to increased frequency of incontinence episodes in patients with fecal incontinence. The relationship between idiopathic fecal incontinence and pudendal nerve terminal latency was studied in 178 patients. The far majority of patients had normal latencies, and there was no correlation between latency and anal manometry. In contrast to previous suggestions, idiopathic fecal incontinence does not seem to be caused by pudendal nerve damage. Reconstruction of the external anal sphincter in patients with fecal incontinence due to obstetric sphincter lesion showed a poorer functional result among patients older than forty years compared to younger. This indicates that the general muscular weakening with age contribute to the incontinence in these patients. The treatment of more complicated forms of fecal incontinence consists of, apart from conservative treatment or colostomi, mainly in muscle transpositions or artificial anal sphincter. Transposition of the distal part of the gluteus maximus muscle to encircle the anal canal, did not lead to acceptable continence in any of the patients studied. Transposition of the gracilis muscle lead to acceptable continence in half the patients. Patients where the transposed muscle were stimulated by a neurostimulator had satisfactory continence in most cases. However, with this method several re-operations were necessary in some patients. In addition, some patients developed severe evacuation difficulties. Implantation of an artificial sphincter resulted in long-term improvement of continence in that half of patients in whom the artificial sphincter remained implanted. The other half of the patients had the artificial sphincter explanted due to various reasons, most frequently due to infection around the device. In selected patients with more complicated fecal incontinence, stimulated gracilis transposition or implantation of an artificial anal sphincter may be offered as an alternative to colostomy. Sacral nerve stimulation is a new method which seems to provide the best results among the more advanced procedures. Its minimally invasive character also contribute to the increasing use of this method in the last few years. Evaluation and treatment of fecal incontinence is presently in a state of rapid change with focus on more elaborate investigative methods and more diversified treatment.