Randomized clinical trial of botulinum toxin injection for pain relief in patients with thrombosed external haemorrhoids.

BACKGROUND: Thrombosed external haemorrhoids are one of the most frequent anorectal emergencies. They are associated with swelling and intense pain. Internal sphincter hypertonicity plays a role in the aetiology of the pain. This study evaluated the efficacy and safety of an intrasphincteric injection of botulinum toxin for pain relief in patients with thrombosed external haemorrhoids. METHODS: Thirty patients with thrombosed external haemorrhoids who refused surgical operation were randomized into two groups. Patients received an intrasphincteric injection of either 0.6 ml saline or 0.6 ml of a solution containing 30 units botulinum toxin. Anorectal manometry was performed before treatment and 5 days afterwards. RESULTS: After 5 days of treatment, the maximum resting pressure fell in both groups, but was significantly lower in the botulinum toxin group (P = 0.004). Pain intensity was significantly reduced within 24 h of botulinum toxin treatment (P < 0.001), but only after 1 week in the placebo group (P = 0.019). CONCLUSION: A single injection of botulinum toxin into the anal sphincter seems to be effective in rapidly controlling the pain associated with thrombosed external haemorrhoids, and could represent an effective conservative treatment for this condition. Registration number: NCT00717782 (http://www.clinicaltrials.gov).