Botox injection treatment for anal outlet obstruction in patients with internal anal sphincter achalasia and Hirschsprung's disease

Botox injection treatment (BIT) is a potentially effective but yet unproven treatment of functional anal outlet obstruction that is caused by non-relaxing internal anal sphincter. We present a single institution experience of BIT from 2005 to 2008. Sixteen patients (11 males), eight with Hirschsprung's disease (HD) (one with total colon aganglionosis, TCA) and eight with internal sphincter achalasia (ISA) were included. Median ages were 3.8 years (0.4-9.3) for HD and 8.1 years (range 1.5-11.4) for ISA. ISA was defined as the absence of rectoanal inhibitory reflex with normal rectal biopsies. Seven HD patients had previous coloanal pull-through (CAPT), and one (TCA) colectomy and ileoanal J-Pouch anastomosis. Two of the ISA patients had undergone internal sphincter myectomy and two had Malone procedure [antegrade colonic enema (ACE)]. Indication for BIT in 16 patients was anal outlet obstruction (n = 11) with soiling and recurring HD-associated enterocolitis (n = 5) and in one patient (HD, TCA) soiling with enterocolitis (n = 1). Before BIT, all patients underwent anorectal manometry, rectal biopsies and barium enema. The effect of BIT was evaluated after 2 months and BIT was repeated if necessary. Effect of BIT was scored as follows: 0 no, 1 little, 2 significant effect and 3 symptoms disappeared. Median follow-up was 19 months (range 3-43). The median number of injections was two per patient (range 1-4) and the median Botox dose was 80 U (range 40-100). Scores of BIT effect were 3 or 2 in five (31%) and 0 or 1 in 11 (69%). After adjunctive treatment modalities (myectomy n = 1, CAPT n = 1, adjusted ACE/laxative treatment), the end result was good or satisfactory in 11 (69%) but remained poor in 5 (31%) patients. Patient age, diagnosis, anorectal resting pressure or findings in barium enema were not correlated with BIT efficiency score (R range -0.06 to 0.39, P = 0.12-0.91). Although successful in some patients, the role of BIT remains undetermined. It is difficult to predict which patients will profit from BIT. Continuing other treatment modalities after BIT may improve the results.