Faecal incontinence associated with reduced pelvic sensation.

Eight patients with faecal incontinence associated with high threshold of rectal sensation are described. All had a normal anal sphincter on clinical and physiological assessment including anal manometry, pudendal nerve latency estimation and single fibre electromyography. In each case however rectal sensation was abnormal. The threshold of rectal sensation was 143 +/- 33 ml (range 110-200 ml) compared with control values of 39 +/- 14 ml (range 25-65 ml) (P less than 0.005) in 12 normal age-matched individuals. The degree of rectal distension required to initiate the recto-anal reflex was no different in the incontinent patients (19 ml, range 15-25 ml, compared with 22 ml, range 15-30 ml, in the controls). There was also no difference in the maximal tolerated volume of rectal distension between the groups (291 +/- 87 ml and 279 +/- 91 ml respectively). These observations may have defined a small group of patients with incontinence in whom an abnormality of rectal sensation rather than sphincter incompetence could be a part of the pathophysiological disorder.