SIGNIFICANCE OF THE THICKNESS OF THE ANAL SPHINCTERS WITH AGE AND ITSRELEVANCE IN FECAL INCONTINENCE

Background: Ultrasonographic studies in healthy volunteers showed that the external anal sphincter (EAS) and internal anal sphincter (IAS) t hicknesses were inversely related at rest. The functional importance o f the two sphincters in continence control was demonstrated in the rel ationship between the sum of the thicknesses of the two sphincters and the anal canal resting pressure. The aims of the present study were t o assess the morphometric appearance of the anal sphincters by endoson ography in faecally incontinent patients and to contrast this with tha t of older healthy subjects. Methods: Twenty-eight female patients wit h neurogenic faecal incontinence (FI) were studied. An older group of 7 healthy women, aged 41-75 years, and a young group of 11 nulliparous healthy women, aged 20-23 years, served as control groups. Anal endos onography was performed with a radial rotating endoprobe, with the sub ject in the left lateral position. Conventional anal manometry was per formed in all subjects. Results: The EAS in the FI group was thicker t han the EAS in the old (p < 0.04) but did not differ from the EAS in t he young. The IAS thickness in the FI group did not differ from that i n the older group. In both these groups the IAS was thicker than in th e young women (p < 0.01). The anal pressures in the FI group were redu ced compared with the normal groups (p < 0.04). There was a direct rel ationship between the two sphincters in FI (p < 0.001). Conclusions: T he increased thickness of the IAS in the FI group does not seem to com pensate for function and results in a failure of the sphincter mechani sm to maintain continence, whereas in healthy elderly subjects the inc reased IAS thickness appears to be compensatory and important for cont inence control.