Early botulinum toxin injection reduces pain after hemorrhoidectomy: a pilot study.

[BACKGROUND] Hemorrhoidectomy is the standard procedure for treating high-grade hemorrhoids. However, postoperative pain usually causes patients to delay or refuse surgical treatment. Because maximal resting pressure in the internal anal sphincter plays a major role in post-hemorrhoidectomy pain, Botulinum toxin injections have been proposed to reduce it. However, the optimal timing of Botulinum toxin injections is still unclear. The aim of the present study was to compare the effectiveness of early and intraoperative Botulinum toxin injections for postoperative pain control.

[METHODS] In this pilot study, we enrolled patients who had grade III or IV hemorrhoids and underwent Ferguson hemorrhoidectomy at a single tertiary care center from October 1, 2018 to November 30, 2020. The experimental group received 50 U Botulinum toxin injections to the internal anal sphincter 1 week before the operation, and the control group received injections intraoperatively. The primary endpoint was the daily maximal and resting visual analogue scale (VAS) score recorded from postoperative days 0-6. The secondary endpoints were analgesia requirements, number of bowel movements per day, healing time, and postoperative length of stay. Power of the daily resting VAS score is at least 93%, but the power of the daily maximal VAS is a little lower (71%) (calculated by G*Power 3.1.9.2).

[RESULTS] Sixty-two patients (male: female = 27:35; mean age = 47.6 ± 13.1 years) were randomized to the experimental group (n = 31) or control group (n = 31). The experimental group  (n = 31) showed significantly shorter postoperative hospital stay than the controls (n = 31; p = 0.019). A generalized estimating equations model revealed that the group that received Botulinum toxin  yielded a significantly lower maximal (OR 0.4, 95% CI 0.2-1.0, p = 0.041) and resting (OR 0.4, 95% CI 0.2-0.7, p < 0.001) VAS compared to controls at all time points. The Botulinum toxin group also had significantly less resting pain from postoperative days 1-5, and lower maximal subjective pain scores on postoperative days 1 (p = 0.024) and 4 (p = 0.044). Similar trends were observed on other days.

[CONCLUSIONS] Early Botulinum toxin injection produced shorter hospital stays, and less reported pain after hemorrhoidectomy than intraoperative injections, especially for pain at rest.

[TRIAL REGISTRATION] Identifier: NCT04485780 on ClinicalTrials.gov (retrospectively registered).