A comparison of common bile duct pressures after botulinum toxin injection into the sphincter of Oddi versus biliary stenting in a canine model.

BACKGROUND: Botulinum toxin A (Botox) functionally paralyzes the sphincter of Oddi in both animals and humans, resulting in reduced pressures. No study, however, has specifically addressed common bile duct (CBD) pressures after Botox injection into the sphincter of Oddi with regard to treating biliary leaks and fistulae. The goals of this present study are to compare, versus biliary stenting, the change in CBD pressures after Botox injection into the sphincter of Oddi, as well as to evaluate the timing of onset and duration of these effects on sphincteric relaxation.
METHODS: After midline laparotomy in 20 mongrel dogs, a pediatric umbilical catheter was inserted into the CBD via a small cholecystotomy and attached to a water-perfused pressure transducer. After baseline CBD pressure readings, a lateral duodenotomy was performed. A total of 100 units of Botox was injected with an endoscopic sclerotherapy needle into all four quadrants of the ampulla. The dogs were randomly divided into four groups to undergo repeat laparotomy at either postoperative day 1 (group I), postoperative day 3 (group II), postoperative day 7 (group III), or postoperative day 14 (group IV). At the time of second laparotomy, a pressure-sensing catheter was reinserted into the CBD and pressures recorded. Each dog then underwent transpapillary biliary stenting with a 7 Fr. x 5 cm Cotton-Leung biliary stent and CBD pressures were again recorded.
RESULTS: CBD pressures were significantly lower as compared with baseline for all groups after Botox injection and after biliary stenting (P <0.001) In addition, no significant differences in the degree of CBD pressure reduction were identified between groups I through IV after Botox injection. The measured decrease in CBD pressure from baseline after Botox injection as compared with biliary stenting was significantly different for groups I and II (P <0.05) but not for groups III and IV.
CONCLUSION: Botox injection into the sphincter of Oddi results in significant CBD pressure reduction within 24 hours and continues for 14 days. Also, after postoperative day 3, there is no significant difference in the reduction of CBD pressure from baseline between Botox injection and biliary stenting. Based on these findings, Botox injection into the sphincter of Oddi may be a beneficial alternative to biliary stenting for the treatment of biliary leaks and fistulae.