Improvement of wound healing after hemorrhoidectomy: a double-blind, randomized study of botulinum toxin injection.

Purpose: Hemorrhoidectomy is usually associated with significant pain during the postoperative period. The spasm of the internal sphincter seems to play an important role in the origin of pain. This study was designed to evaluate the effectiveness of intrasphincter injection of botulinum toxin after hemorrhoidectomy in reducing the maximum resting pressure of the anal canal, accelerating wound healing, and decreasing postoperative pain when resting and during defecation.
Methods: Thirty patients with hemorrhoids of third and fourth degree were included in the study and randomized in two groups. Anorectal manometry was performed preoperatively and 5 and 30 days afterward in all patients undergoing Milligan-Morgan hemorrhoidectomy. One group received an injection of 0.4 ml of saline into the internal anal sphincter, the other group were injected with 0.4 ml of solution containing 20 units of botulinum toxin.
Results: After five days from hemorrhoidectomy, maximum resting pressure decreased in the group injected with botulinum toxin and increased in the placebo group. The time of healing and postoperative pain when resting and during defecation significantly decreased in the group treated with an injection of botulinum toxin.
Conclusions: Botulinum toxin injection into internal anal sphincter after hemorrhoidectomy is effective in reducing maximum resting pressure, time of healing, and postoperative pain both on resting and during defecation in absence of complications or side effects.