Electromyographic assessment of biofeedback training for fecal incontinence and chronic constipation.

INTRODUCTION: Biofeedback training is an effective modality for the treatment of chronic constipation and fecal incontinence. In general, patients express satisfaction and perceive functional improvement following biofeedback therapy; however, quantifying these observations has been difficult. AIM: This study was undertaken to evaluate the physiologic benefits of biofeedback therapy as reflected by noninvasive electromyography parameters.
METHODS: Fifty-five patients who underwent computerized electromyography-based biofeedback treatment at our institution between July 1993 and July 1995 were identified. Noninvasive electromyographic testing was performed before, during (weekly), and at completion of training. Mean number of weekly sessions was seven (range, 5-11). Short-term and ten-second contractions (amplitude/microV), sustained contractions (endurance, in seconds), and net strength (microV) of the external anal sphincter before and after biofeedback were compared for differences.
RESULTS: There were 30 patients with chronic constipation, mean age, 65.3 (range, 33-86) years, composed of 24 women, and 25 patients with fecal incontinence, mean age 66 (range, 34-85) years, composed of 12 males. Statistically significant improvement in endurance and net strength following biofeedback training was noted in both the constipated and the fecal incontinence groups. Fifty-three of 55 (96.4 percent) patients expressed 50 to 100 percent subjective satisfaction after biofeedback therapy. Forty-six of 55 (83.6 percent) patients demonstrated individually improved endurance.
CONCLUSIONS: Sphincter endurance and net strength, as measured by noninvasive electromyography, significantly improve following biofeedback therapy in both constipated and fecal incontinence patients. These data suggest that endurance and net strength may be useful tools in assessing a benefit from biofeedback training in these patients.