Experimental model of pudendal nerve innervation of a skeletal muscle neosphincter for faecal incontinence.
BACKGROUND
Faecal incontinence is difficult to treat. A variety of reconstructive procedures has been described, but none is entirely satisfactory. This study evaluated the feasibility of cross-innervating a skeletal muscle neosphincter with the pudendal nerve in a canine model.


METHODS
Thirty dogs were rendered surgically incontinent (the pudendal nerve was cut and the external sphincter was partially excised). A neosphincter was then created using the semitendinosus muscle. In ten dogs pudendal nerve transposition (PNT) to the nerve to the semitendinosus muscle was performed. Ten dogs were given a dynamic neosphincter by inserting a pulse generator at 6 weeks. The remaining ten dogs served as controls with passive semitendinosus wraps. Anal manometry was performed before operation and monthly for 5 months. Muscle biopsies, performed at the initial operation and at 5 months, were stained for slow- and fast-twitch fibres, and were examined histologically.


RESULTS
At 1 month, mean sphincter function was 32 per cent of the preoperative value in the control animals, 34 per cent in the PNT group and 27 per cent in the electrostimulation group; all dogs were incontinent. At 5 months the mean recovery of sphincter function was 42 per cent of the preoperative value in controls, 100 per cent in dogs with PNT (P < 0.001) and 63 per cent in dogs having electrostimulation (stimulator on) (P = 0.02). Six dogs with PNT had squeeze pressures equal to or greater than preoperative levels. At 5 months the ratio of slow to fast fibres was significantly greater in all dogs (control P = 0.01, PNT P < 0.005, electrostimulation P < 0.001).


CONCLUSIONS
Use of the pudendal nerve to innervate a canine skeletal muscle anal wrap produced a functional anal sphincter that was superior to electrically stimulated and passive wraps.
Congilosi
S M
SM
Division of Colon and Rectal Surgery, University of Minnesota, St Paul 55114, USA.
Johnson
D R
DR
Medot
M
M
Tretinyak
A
A
McCormick
S R
SR
Wong
W D
WD
Rothenberger
D A
DA
Madoff
R D
RD
D001003:Anal Canal / Q000294:innervation*; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D005242:Fecal Incontinence / Q000601:surgery*; D008365:Manometry; D018482:Muscle, Skeletal / Q000294:innervation; D016067:Nerve Transfer / Q000379:methods*