Comparison of botulinium toxin injection and posterior anorectal myectomy in treatment of internal anal sphincter achalasia.

OBJECTIVE: We compared the efficacy of intra-sphincteric botulinum toxin (BT) injection and posterior anorectal myectomy (PARM) for the treatment of internal anal sphincter achalasia (IASA).

METHODS: Twenty eight of 120 patients (23%) with chronic constipation, who were referred to our clinic from September 2005 to December 2006, were evaluated. Patients had an absence of rectoanal inhibitory reflex on anorectal manometry (ARM) and showed no transitional region on barium enema. Fourteen patients each underwent rectal biopsy, and were treated with either intrasphincteric BT injection (Group I) or PARM (Group II). Nine patients were excluded because of absent ganglion cells on histology or positive acetylcholinesterase staining (AChE). The remaining 19 patients were followed up. All patients underwent ARM and constipation severity score (CSS) assessment 2 weeks before, and 1 and 6 months after the treatment. Patients were followed up telephonically at 12 months after treatment.

RESULTS: Clinically good response was seen after 12 months in 3 patients each in Groups I and II. The median values of resting rectal pressure in Group I before and 6 months after BT injection were 60 mmHg and 40 mmHg (p< 0.0001), respectively, while in Group II the corresponding values were 60 mmHg and 45 mmHg (p< 0.0001), respectively. Compared to pre-treatment, median CSS improved in both Group I (14 to 13) and Group II (16 to 14) at 6 months after treatment (p< 0.0001 for both). However, there was no difference in resting rectal pressure and CSS between the groups. Three patients in Group II developed local abscess, postoperatively.

CONCLUSIONS: BT injection has a similar efficacy as compared with PARM for the treatment of IASA, is less invasive and, is also associated with fewer complications.