Pj. Guelinckx et al., NEUROVASCULAR INTACT MUSCLE TRANSPOSITION FOR ANAL-SPHINCTER REPAIR -EXPERIMENTAL MODEL AND EXPERIENCE WITH DYNAMIC PACING, Diseases of the colon & rectum, 38(8), 1995, pp. 878-885
PURPOSE: To study muscle behavior for anal sphincter repair, radiologi
c, manometric, and histologic techniques in a dog animal model have be
en used. Special attention was given to the problem of resting length
of the transposed muscle. METHODS: The semitendinosus muscle of the do
g could be transposed successfully to create a new anal sphincter base
d on an intact neurovascular pedicle. The parallel-fibered muscle was
split at its distal end and encircled around the anal canal. Manometry
was performed intraoperatively and postoperatively. A sufficiently hi
gh basal and squeeze pressure had to be obtained intraoperatively to g
uarantee a final continent neosphincter. This could be realized by a p
rogressive stretching of the muscle until maximum squeeze is reached.
In one animal a pacemaker was implanted, and postoperatively a fixed s
phincter stimulation protocol was started. Muscle biopsies of the norm
al anal sphincter and the neosphincter were taken. RESULTS: 1) Muscle
transposition gave a high degree of continence in this experimental mo
del, with a mean resting pressure of +/- 40 mmHg and a mean squeezing
pressure of +/- 73 mmHg. 2) Electric stimulation of the neosphincter i
n one animal influenced the resting pressure but not the squeeze press
ure. 3) Muscle fiber type composition changed toward a slow fiber type
composition after transposition of the fast muscle and even more afte
r stimulation. CONCLUSIONS: 1) Creation of a muscle cuff around the an
al sphincter can substitute normal anal sphincter. 2) Adequate stretch
of muscle fibers is essential for continence. 3) Electrical pacing he
lps preserve resting tension and subsequent continence.