ABSTRACT
The external anal sphincter (EAS) is a skeletal muscle capable of voluntary contraction
to prevent accidental defecation. Current reconstructive options for a severely damaged
EAS using local muscle flaps are not always adequate for functional repair. The present
preliminary experimental model was designed to assess the feasibility of a neuromicrovascular
latissimus dorsi muscle transfer for functional external spincter muscle reconstruction.
In nine mongrel dogs, the anal sphincter muscles were totally resected, leaving a
mucosal canal in place. A segmental latissimus dorsi muscle was shaped around the
anal canal in a circular fashion, with coaptation to the pudendal nerve, and vessel
anastomosis at the ischiorectal fossa. Functional evaluation was performed using electromyogram,
sphincter manometry, video documentation, and histologic examination with standard
and immunohistochemical staining. After 8 months, the remaining three eligible dogs
were continent. Muscle function was verified by means of electromyogram, sphincter
manometry, and a video record. Histologic and immunohistochemical examination confirmed
the functional results, showing only minor zones of fatty and fibrous degeneration.
Transplantation of a segmental latissimus dorsi muscle with vascular anastomosis and
coaptation to the pudendal nerve has proved to be successful in restoring (voluntary)
anal continence experimentally in dogs. Its feasibility for perfect orientation as
a neosphincter seems to be superior to any pedicled muscle flap. However, these preliminary
results deserve further investigation prior to considering application in humans.
KEYWORDS
Anal sphincter muscle repair - neuromicrovascular muscle transplantation - latissimus
dorsi
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