Endoscopic injection of botulinum toxin for biliary sphincter of Oddi dysfunction

Endoscopic sphincterotomy is not without risks, and is also ineffective in about half of patients with type III sphincter of Oddi dysfunction (SOD), i.e. those without clinical evidence of biliary obstruction (normal liver tests, normal bile duct diameter, and regular drainage time at endoscopic retrograde cholangiography). The present study therefore investigated the efficacy and safety of endoscopic botulinum toxin (BTX) injection into the papilla of Vater, and analyzed whether the symptomatic response to BTX injection might be a predictor of outcome for endoscopic sphincterotomy.

Twenty-two patients who had undergone cholecystectomy and had manometrically confirmed type III SOD were enrolled during a three-year study period. All patients received treatment with an endoscopic single-shot injection of 100 mouse units of BTX into the papilla of Vater. Initial symptomatic responses were analyzed six weeks later. If the BTX injection had been ineffective, or if biliary symptoms recurred after initial benefit during the follow-up period, endoscopic manometry and endoscopic sphincterotomy were performed. All patients then received further prospective clinical follow-up examinations.

With the exception of one patient with mild pancreatitis (4.5%), no side effects were observed after endoscopic BTX injection. Six weeks after BTX injection, 12 SOD patients (55%) were symptom-free, but ten patients (45%) were not. However five of these ten SOD patients who did not experience symptomatic benefit from BTX injection had normal basal sphincter of Oddi pressures (< 40 mmHg) at this time, and none of these five patients was free of complaints after subsequent endoscopic sphincterotomy. Two of the remaining five patients with sustained sphincter hypertension after BTX injection benefitted from endoscopic sphincterotomy. Eleven of the 12 SOD patients who had initially responded to BTX injection developed recurrent symptoms after a median period of six months. Manometry revealed sphincter hypertension in all 11 cases, and all patients became free of complaints again after endoscopic sphincterotomy during a median follow-up of a further 15 months. Overall, 11 of the 12 patients who responded to BTX injection, versus two of the ten patients who did not gain pain relief after BTX injection, later benefitted from endoscopic sphincterotomy (p < 0.01).

Endoscopic injection of botulinum toxin into the papilla of Vater is a safe procedure and provides short-term relief of symptoms in half of patients with type III SOD. Our results also indicate that the clinical response to BTX injection can predict whether SOD patients will gain long-term benefit from endoscopic sphincterotomy.