Can Baseline Electromyography Predict Response to Biofeedback for Anorectal Disorder? A Long-Term Follow-Up Study

Biofeedback has been recommended for the treatment of anorectal disorders, especially constipation and fecal incontinence (FI). The objective of this study was to assess the long-term efficacy of biofeedback and evaluate baseline electromyography (EMG) as a predictor for maintenance of long-term improvement.

A retrospective chart review was performed on randomly selected patients who underwent biofeedback between the years 1990 and 2000. Clinical characteristics, including EMG values at baseline (resting and contraction) as well as EMG after exercises, were collected. Patients were contacted and were classified as "improved" if they had self-reported symptomatic improvement and "not-improved" if their symptoms were unchanged or worsened.

A total of 41 subjects were included. Majority (85.4%) were female, the mean age was 48.95 ± 15.46 (range 22 - 77 years) and the median follow-up was 4 years (range 4 - 5 years). Constipation was the primary indication for biofeedback in 27/41 (65.9%), FI in 9/41 (22%) and "other" in 5/41 (12.1%). Within constipation, 55.6% reported long-term improvement as compared to 66.7% of FI and 80% of the other patients. There was borderline difference in the baseline EMG (3.11 ± 1.85 µV, improved, and 7.41 ± 11.01 µV, not improved, P = 0.06) but no significant difference in post-exercise resting (3.13 ± 3.21 µV, improved, and 4.28 ± 3.63 µV, not improved, P = 0.33) and contraction EMG between the two groups.

Biofeedback is an important treatment tool in anorectal disorders. Over 50% of our subjects maintained their improvement 4 - 5 years after completing biofeedback therapy. A lower resting baseline EMG showed a trend of association with improvement in the long term.