Botulinum Toxin Injection for Chronic Anal Fissure: A Prospective Case Series with 18 Month Follow Up

Abstract

Chronic anal fissure is a common anorectal condition traditionally managed with lateral internal sphincterotomy, which carries a risk of fecal incontinence. Botulinum toxin type A (BTX A) has emerged as a minimally invasive alternative, inducing chemical sphincter relaxation and promoting healing. This prospective interventional case series was conducted over 18 months (July 2024–December 2025) and included 36 patients (10 males, 26 females; mean age 35.8 years) with chronic anal fissure refractory to conservative therapy. Patients received 20–40 units of BTX A injected into the internal anal sphincter under local anesthesia. Follow up assessments were performed at 1 week, 1 month, and 3 months. The primary outcome was fissure healing at 3 months; secondary outcomes included symptom improvement, need for surgery, and detection of underlying pathology. Complete healing was achieved in 27 patients (75%). Three patients (8.3%) showed no improvement, four (11.1%) required surgical intervention, and two (5.6%) were diagnosed with rectal cancer. The observed healing rate aligns with previously reported outcomes in the literature, confirming BTX A as an effective non surgical option. BTX A injection is a safe, effective, and outpatient procedure for chronic anal fissure, offering high healing rates and reduced risk of incontinence compared to sphincterotomy. Careful follow up remains essential, particularly to identify non responders and to detect underlying pathology such as malignancy.