Effectiveness and safety of botulinum neurotoxin for treating dyssynergic defecation: A systematic review and meta-analysis

Dyssynergic defecation (DD) is a common cause of chronic constipation. Owing to the lack of a comprehensive synthesis of available data on the effectiveness of botulinum neurotoxin (BoNT) for treating DD, we performed a systematic review and meta-analysis. We searched the PubMed, Embase, and Cochrane databases from inception to May 9, 2023. The outcomes comprise short-term and long-term symptom improvement, various anorectal function measurements, complications of fecal incontinence, and symptom improvement after repeated BoNT injections. A meta-analysis comparing BoNT injection with either surgery or biofeedback (BFB) therapy in treating DD was also conducted. Subgroup analysis and meta-regression were performed to identify possible moderator effects. We included five randomized controlled trials, seven prospective studies, and two retrospective observational studies. Short-term potential improvement in symptoms (event rate [ER], 66.4%; 95% CI, 0.513 to 0.783) was identified, but in the long-term (>12 months), this effect was decreased (ER, 38.2%; 95% CI, 0.267 to 0.511). Short-term improvements in objective anorectal physiologic parameters were also observed. Repeated BoNT injection was effective for patients with symptom recurrence. Subgroup analysis revealed enhanced long-term symptom improvement with high-dose BoNT, but this treatment also increased the risk of complications and recurrence compared with low doses. The effectiveness, complications, and recurrence of symptoms associated with BoNT injection and surgery did not differ significantly. BoNT injection significantly provided short-term symptom improvement but also heightened the risk of incontinence compared with BFB therapy. Our systematic review and meta-analysis indicated that BoNT could be beneficial for short-term symptom improvement in patients with DD, but this effect tended to decline 12 months after injection. Standardized BoNT intervention protocols remain warranted. Among the several treatments for DD, we concluded that BoNT injection is not inferior to other options considering its effectiveness in relieving symptoms, the associated complication development, and the risk of symptom recurrence.