Spectrum of abnormal rectoanal reflex patterns in patients with fecal incontinence

Abnormalities of rectoanal inhibitory or excitatory reflex in patients with fecal incontinence are well described. A spectrum of abnormal responses, other than those already described in the literature, has been observed in some patients with fecal incontinence and forms the subject of this report.

Forty-three patients with idiopathic or traumatic fecal incontinence were studied to evaluate their reflex responses to balloon distention of the rectum, and results were compared with reflex responses of 29 control subjects with no anorectal complaints.

Control subjects revealed normal reflex responses consisting of initial excitation followed by inhibition in the proximal anal canal and an excitatory response in the distal anal canal. Patients who were incontinent revealed five different types of reflex patterns. Eleven patients (25.5 percent) with segmental sphincter defects from obstetric injuries exhibited no distal excitation but had normal response in the proximal anal canal (Group 1). Eleven patients (25.5 percent) with idiopathic incontinence exhibited normal proximal response but an inhibitory as opposed to excitatory response in the distal anal canal (Group 2). Three patients (7 percent) with iatrogenic trauma failed to register an excitatory response in the proximal or distal anal canal but revealed a normal inhibitory reflex (Group 3). Nine patients (21 percent) with idiopathic incontinence revealed excitatory response in the entire anal canal but no inhibition (Group 4). Nine patients (21 percent) with idiopathic incontinence had a normal reflex pattern (Group 5).

Excitatory and inhibitory components of rectoanal reflexes may selectively be abolished in neurogenic or traumatic insults to visceral and somatic anal sphincters, resulting in altered rectoanal reflex patterns.