Striated anal sphincter electromyography in idiopathic fecal incontinence

This study was designed to determine the importance of innervation of striated anal sphincters, one of the most important structures in idiopathic fecal incontinence.

Forty-three idiopathic, fecally incontinent patients (40 women and 3 men; mean age, 57.2 +/- 11 (range, 33-77) years) underwent anorectal manometry and sphincteric electromyography. On the basis of electromyographic findings, patients were subdivided into three groups: Group A consisted of 21 patients with normal electromyography; Group B consisted of 14 patients with moderate denervation; Group C consisted of 8 patients with severe denervation. Manometric results from the patients were compared with those from 15 healthy subjects (8 women and 7 men; mean age, 35 +/- 12 (range, 15-55) years).

Incontinent patients had a shorter anal canal (P = 0.005), and anal canal pressure was lower at rest (P < 0.001), at contraction (P < 0.001), and at coughing (P < 0.001); rectal distention and rectal compliance were reduced (maximum tolerated volume, P < 0.003; compliance at 200 ml, P = 0.03; at 250, P < 0.005; at 300 ml, P = 0.03). No statistically significant differences were found between the manometric results of the three different groups of patients. A statistically significant linear correlation was reached by comparing the clinical severity of fecal incontinence with age (P = 0.02) and some other manometric parameters: the pressure of the anal canal at rest (P < 0.001) and at contraction (P < 0.01); rectal compliance at 50 ml (P = 0.03), 100 ml (P = 0.004), and 150 ml (P = 0.004).

Clinical severity of fecal incontinence is correlated with some manometric parameters. Severity of denervation of the anal striated sphincters does not appear to influence severity of fecal incontinence.