BACKGROUND: Sacral neuromodulation might be effective to palliate low anterior resection syndrome after rectal cancer surgery, but robust evidence is not available. OBJECTIVE: To assess the impact of sacral neuromodulation on low anterior resection syndrome symptoms as measured by validated scores and bowel diaries. DESIGN: Randomized, double-blind, 2-phased, controlled, multicenter crossover trial (NCT02517853). SETTINGS: Three tertiary hospitals. PATIENTS: Patients with major low anterior resection syndrome 12 months after transit reconstruction after rectal resection who had failed conservative treatment. INTERVENTIONS: Patients underwent an advanced test phase by stimulation for 3 weeks and received the pulse generator implant if a 50% reduction in low anterior resection syndrome score was achieved. These patients entered the randomized phase in which the generator was left active or inactive for 4 weeks. After a 2-week washout, the sequence was changed. After the crossover, all generators were left activated. MAIN OUTCOME MEASURES: The primary outcome was low anterior resection syndrome score reduction. Secondary outcomes included continence and bowel symptoms. RESULTS: After testing, 35 of 46 patients (78%) had a 50% or greater reduction in low anterior resection syndrome score. During the crossover phase, all patients showed a reduction in scores and improved symptoms, with better performance if the generator was active. At 6- and 12-month follow-up, the mean reduction in low anterior resection syndrome score was -6.2 (95% CI -8.97 to -3.43; p < 0.001) and -6.97 (95% CI -9.74 to -4.2; p < 0.001), with St. Mark's continence score -7.57 (95% CI -9.19 to -5.95, p < 0.001) and -8.29 (95% CI -9.91 to -6.66; p < 0.001). Urgency, bowel emptiness sensation, and clustering episodes decreased in association with quality-of-life improvement at 6- and 12-month follow-up. LIMITATIONS: The decrease in low anterior resection syndrome score with neuromodulation was underestimated because of an unspecific measuring instrument. There was a possible carryover effect in sham stimulation sequence. CONCLUSIONS: Neuromodulation provides symptoms and quality-of-life amelioration, supporting its use in low anterior resection syndrome. See Video Abstract
