Analgesic injection of botulinum toxin in anal fissures is efficient and can be performed safely in patients actively receiving chemotherapy.

PURPOSE: Injection of botulinum toxin into the internal anal sphincter is a well-documented intervention to reduce anal hypertonia in the treatment of anal fissures. In patients receiving chemotherapy, painful anal conditions are frequent, secondary to change in bowel habits and reduced immunity. However, injection of botulinum toxin is often not offered due to fear of complications. METHODS: In this retrospective longitudinal observational study, performed in a tertiary hospital setting, we analysed patient characteristics, outcome and complication rates of botulinum toxin injection in patients actively receiving chemotherapy. RESULTS: Twenty-six patients were treated with 20-50 IU botulinum toxin while actively receiving chemotherapy because of intractable pain and hypertonia. The fissure was located dorsally in 69% (n = 18) and ventrally in 19% (n = 5), while in 3 patients (12%), no fissure was documented. The majority of the patients (88%, n = 23) had complete (54%, n = 14) or partial (35%, n = 9) relief of pain. In three patients, additional anal pathology developed in the weeks following botulinum toxin injection: thrombosis of grade IV haemorrhoids, perianal haematoma and an intersphincteric abscess. CONCLUSIONS: Injection of botulinum toxin in the anal sphincters is a safe and effective analgesic option in patients with anal fissure while actively receiving chemotherapy.