High Dose Botox Injection for Patients with Internal Anal Sphincter Achalasia Persistent to Posterior Internal Anal Sphincter Myectomy

Abstract

Introduction: one of the most common reported chief complaints in visits to pediatricians is constipation. Although in a majority of cases with no anatomical defect, dietary manipulation, stool softeners, and oral laxatives are successful, some patients fail to respond. Internal Anal Sphincter (IAS) Achalasia is one of the causes of constipation.It results in failure of IAS relaxation and has similar clinical presentation to Hirschsprung’s disease with absence of rectosphincteric inhibitory reflex on anorectal manometry (ARM) and presence of ganglion cells on rectal biopsy. Although posterior internal anal sphincter myectomy (ISM) is considered the standard treatment for IASA, some cases fail to respond and present with intractable constipation which may be associated with soiling. This research aims to assess the role of botox injection for treatment of patients who presented with intractable constipation and have already beentreated by posterior IAS myectomy. Materials and Methods:Internal anal sphincter Botox injection was performed (with a dose of 20 U/Kg) in 14 patients with internal anal sphincter achalasia (IASA); who had presented with intractable constipationafter being treated by posterior internal anal sphincter myectomy. Patients were followed for 2 years after injection. Result: of all 14 patients with persistent constipation (resistant to oral laxatives), 12 patients (85.7%) had regular bowel function for more than 6 months after botox injection therapy (P < 0.05). Of all 14 patients that had needed rectal enema for defecation, no patient needed rectal enema after botox injection therapy (P < 0.05). Of 5 patients with fecal soiling before botox injection therapy (4 had occasionalsoiling, and 1 had soiling every day without social problems) only a single patient experienced transient fecal soiling for 2 weeks after botox injection therapy (P < 0.05). No patient needed another botox injection in 2 years of follow up. Conclusion: IAS Botox injection therapy (BIT) was successfully used to manage IASA patients who had presented with intractable constipation after posterior myectomy. This method significantly reduces the need for laxatives and rectal enema; and improves constipation, fecal soiling and bowel movements at the same time.

Keywords

• internal anal sphincter
• achalasia
• constipation
• myectomy
• botulinum toxin
• hirschsprung’s disease