Effect of postanal repair on progress of neurogenic damage to the pelvic floor.

Physiological evaluation of the anorectum and pelvic floor muscles was carried out in 18 patients before and 9-35 months after postanal repair for anorectal incontinence. Thirteen patients (72 per cent) were improved, but in these patients the fibre density in the external anal sphincter muscle and the pudendal nerve terminal motor latency were both increased after surgery. In the five patients not improved after surgery only a few unstable motor unit potentials could be recorded in the external anal sphincter muscle. In two of these patients the pudendal nerve terminal motor latency could not be recorded after surgery. We suggest that this progression in the neurogenic damage to the pelvic floor muscles after postanal repair may be caused by the operation, and that it may be responsible for the poor functional outcome noted in some patients.