Can manometric parameters predict response to biofeedback therapy in fecal incontinence?

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Abstract
Biofeedback therapy may improve fecal control in up to 50 percent to 92 percent of patients with fecal incontinence. Identification of favorable manometric parameters before biofeedback therapy may help in selection of patients suitable for such therapy. Twenty-eight patients with fecal incontinence (idiopathic, 11; iatrogenic trauma, 8; obstetric trauma, 9) who underwent biofeedback therapy were studied to determine whether manometric parameters could predict the result of therapy. Biofeedback was given using a computer software program designed to strengthen the external anal sphincter with auditory and visual feedback. Thirteen patients (46.4 percent) achieved excellent results; eight patients (28.6 percent) had good results, but seven patients (24.5 percent) failed to improve after biofeedback therapy. Resting or squeeze anal canal pressure, pressure volume, sphincter length, sphincter fatigue rate, and cross-sectional asymmetry of the entire sphincter before biofeedback failed to reveal any statistically significant differences between responders and nonresponders. However, the cross-sectional asymmetry of the high-pressure zone within the sphincter at rest was greater in nonresponders than in responders (not improved, 25.8 percent; good result, 20.2 percent; excellent result, 15.4 percent; P < 0.07). This difference was even greater on squeeze (not improved, 21 percent; good result, 17.6 percent; excellent result, 13.2 percent; P < 0.04). The number of biofeedback sessions, response on bearing down, and quality of rectoanal excitatory reflex were not reliable indicators of outcome. No statistical difference was found in mean resting and squeeze pressures after biofeedback between responders and non-responders. Except for increased cross-sectional asymmetry in the high-pressure zone, which may be a forerunner of adverse outcome, manometric parameters before biofeedback do not predict response to biofeedback therapy. Improvement in continence may be independent of resting and squeeze pressures achieved after biofeedback therapy.