Factors Associated with Symptom Response to Pyloric Injection of Botulinum Toxin in a Large Series of Gastroparesis Patients

Case series report symptom reductions after pyloric botulinum toxin injection in gastroparesis, but small controlled trials show no benefit. Factors that enhance response to therapy are undefined. A retrospective analysis of 179 gastroparetics undergoing pyloric botulinum toxin injection from 2001 to 2007 assessed responses relating to drug dosing, demographic factors, comorbidities, and gastric function. Overall, there was a decrease in gastroparetic symptoms 1-4 months after pyloric botulinum toxin injection in 92 patients (51.4%). Increasing the botulinum toxin dose significantly improved clinical responses of patients who provided information on symptoms after therapy (100 units: 54.2%; 200 units: 76.7%; P=0.02). Other factors that improved response to botulinum toxin included female gender, age <50 years, and nondiabetic nonpostsurgical etiology (all P<0.05). Eighty-seven patients received 307 follow-up injections. A clinical response to a second injection was observed in 73.4% of evaluable patients. In conclusion, responses to pyloric botulinum toxin depended on dose and were maintained on repeat injection. Subgroup analyses defined subgroups likely to benefit. These findings provide the foundation for large, controlled trials of high-dose botulinum toxin in selected gastroparesis subsets.