Botulinum toxin injection for the treatment of chronic anal fissure: uni- and multivariate analysis of the factors that promote healing

Abstract

Purpose Anal fissure is caused by a pathological contraction of the internal anal sphincter. Lateral internal sphincterotomy remains the gold standard for the treatment of fissure. Botulinum toxin injections have been proposed to treat this condition without any risk of permanent injury of the internal sphincter. We investigate clinical and pathological variables and the effects of different dosage regimens of botulinum toxin to induce healing in patients with idiopathic anal fissure. Methods This is a retrospective study at a single center. The patients underwent a pre-treatment evaluation that included clinical inspection of the fissure and anorectal manometry. We collected and analyzed demographic data, pathological variables, associated pathological conditions, and treatment variables. Success was defined as healing of the fissure, and improvement of symptoms was defined as asymptomatic persistent fissure. Results The findings of 1003 patients treated with botulinum toxin injections were reported. At 2 months evaluation, complete healing was evident in 780 patients (77.7%). Resting anal tone (77.1 ± 18.9 mmHg) was significantly lower from baseline (P < 0.0001) and from 1-month value (P = 0.0008). Thirty-nine not healed patients underwent lateral internal sphincterotomy, and 184 were re-treated with 50 UI of botulinum toxin. In these patients, the healing rate was 93.9% (171 patients). Dose and injection site of toxin correlates with healing rate. There were no relapses during an average of about 71 months. Conclusion Our data show that injection of botulinum toxin into the internal anal sphincter is a safe and effective alternative to surgery in patients with chronic anal fissure.

Can Botulinum Toxin Injection be considered a First-Line Treatment for the Management of Chronic Anal Fissure? A Prospective Controlled Study with 5-years Follow-up.

“…Brisinda et al in a recent retrospective study on 1.003 patients reported that toxin dose signi cantly correlates with healing rate: the higher the dose used, at least up to 50 IU, the more conspicuous the number of patients healed. The authors stated the best results were obtained when, in patients with posteriorly located ssure, the toxin was injected into the internal sphincter at the anterior commissure [29]. In the presented study all patients underwent injection of a total of 80 U of Botox A posteriorly, close to the ssure into two sites: 40 U at 5 o'clock and 40 U at 7 o'clock.…”

Effectiveness and safety of botulinum toxin injection in the treatment of recurrent anal fissure following lateral internal sphincterotomy: cohort study

“…Choosing an injection site different from the site of the fissure was based on the concept that fibrosis of the internal sphincter is more prominent in the zone of the anal fissure than in other sites in the smooth muscle 20 . The fibrosis may reduce compliance of the internal sphincter and block the action of the toxin 14 , 19 , 21 , 22 . In patients with posterior chronic anal fissures, anterior injection was more effective in inducing healing than posterior injection 18 .…”

Trends in Management of Anal Fissures

“…This may be due to surgical referrals as a general or colorectal surgeon may be more likely to recommend LIS to a patient at low risk of incontinence as this is the “gold standard,” 1 although guidelines suggest chemodenervation prior to LIS to avoid permanent damage to the internal anal sphincter. 2 Additionally, Botox has had variable results in different studies, with 1 recent retrospective single-center study 13 of over a thousand patients noting a dose-dependent high healing rate (93.9%) with no recurrences in 71 months and no incontinence. In contrast, a recent randomized control trial 4 comparing botulinum injection with topical diltiazem to botulinum injection alone noted only a 52% healing rate in the experimental group with a 30% transient incontinence rate and an 83.3% recurrence rate in 10 years.…”