Botulinum toxin (botox) reduces pain after hemorrhoidectomy: results of a double-blind, randomized study

Pain after hemorrhoidectomy appears to be multifactorial and dependent on individual pain tolerance, mode of anesthesia, postoperative analgesia, and surgical technique. Spasm of the internal sphincter is believed to play an important role. The aim of this study was to assess the role of botulinum toxin in reducing pain after Milligan-Morgan hemorrhoidectomy.

This was a double-blind study of 50 consecutive patients undergoing Milligan-Morgan hemorrhoidectomy and assigned to an internal sphincter injection of 0.4 ml of solution containing either botulinum toxin (20 U; Botox) or normal saline. Patients were managed according to standardized perioperative analgesic and laxative regimens. Pain was assessed by use of daily visual analog scores and analgesia requirements for the first seven postoperative days.

Patients randomized to receive botulinum toxin had lower daily average and maximal visual analog scores throughout the study period. The difference reached significance on both Day 6 (P < 0.05) and Day 7 (P < 0.05). There was no significant difference (P = 0.12) in morphine requirements in the first 24 hours (botulinum group, 16 (range, 6-27) mg; placebo arm, 22 (range, 13-41) mg). Patients who received Botox used 19 (range, 8-36) coproxamol tablets in the first seven days after surgery compared with 23 (range, 10-40) in the placebo arm (P = 0.63).

Those patients who had botulinum toxin had significantly less pain toward the end of the first week after surgery. Reduction in spasm within the internal sphincter is the presumed mechanism of action. This is the first reported randomized, controlled trial using botulinum toxin in hemorrhoidectomy.