The purpose of this study was to investigate the function of the bulbocaver
nosus muscle in patients with faecal incontinence as a result of injury to
the external anal sphincter, and to find out whether faecal incontinence ha
d any role in erectile dysfunction. The study comprised 16 men (age 41.6 +/
- 6.8 Scars) whose erectile dysfunction and faecal incontinence followed an
operation for anal fistula. Erection could not be maintained until ejacula
tion, which,, if it did occur, was not in jets. Ten healthy volunteers acte
d as controls. Thc activity of the external anal sphincter and the bulbocav
ernosus muscle was recorded by electromyography; anal and penile bulb press
ures were also recorded. Investigations show:ed that erectile function Mras
normal. The external anal sphincter was repaired, and faecal control and e
rectile dysfunction were assessed. Patients were followed up for 19.6 +/- 3
.2 months. The results showed that the bulbocavernosus reflex elicited no r
esponse in either the sphincter or the bulbocavernosus muscle. Their activi
ty, recorded by electromyography, as well as anal and bulbar pressures at r
est and on voluntary squeeze, and electrostimulation of the external anal s
phincter, show ed a significant reduction compared to the controls. Sphinct
eroplasty made the patients continent and restored erectile function and ej
aculation to normal. We conclude from the current study. that the reduced a
ctivity of the bulbocavernosus muscle is probably caused Ly injury to the e
xternal anal sphincter. It is suggested that erectile dysfunction is caused
by the failure, during erection, of the contraction of the bulbocavernosus
muscle to raise cavernosal pressure above systolic blood pressure. The los
s of the rhythmical contractions of the bulbocavernosus muscle is probably
why ejaculation did not occur in jets. Repair of the external anal sphincte
r provided a cure for faecal incontinence and erectile dysfunction. Anorect
al disorders are believed to affect erectile function, a relationship that
needs further investigation.