Efficacy of sacral nerve stimulation for urinary retention: Results 18 months after implantation

Purpose: We investigate the efficacy of sacral neurostimulation in patients with idiopathic urinary retention in a prospective, randomized multicenter trial. Materials and Methods: A total of 177 patients with urinary retention refra ctory to standard therapy were enrolled in the study. Greater than 50% impr ovement in baseline voiding symptoms during a 3 to 7-day percutaneous test stimulation qualified a patient for surgical implantation of an InterStim p arallel to system. Of the patients who qualified for implantation 37 were r andomly assigned to a treatment and 31 to a control group. Patients in the treatment group underwent early surgical implantation of the sacral nerve s timulation system, while implantation was delayed in the control group for 6 months. Followup evaluations, including voiding diary analysis and tempor ary deactivation of the stimulator at 6 months, were conducted at 1, 3, 6, 12 and 18 months after implantation in the treatment group, and after 3 and 6 months in the control group. Results: Compared to the control group, patients implanted with the InterSt im system had statistically and clinically significant reductions in the ca theter volume per catheterization (p <0.0001). Of the patients treated with implants 69% eliminated catheterization at 6 months and an additional 14% had a 50% or greater reduction in catheter volume per catheterization. Ther efore, successful results were achieved in 83% of the implant group with re tention compared to 9% of the control group at 6 months. Temporary inactiva tion of sacral nerve stimulation therapy resulted in a significant increase in residual volumes (p <0.0001) but effectiveness of sacral nerve stimulat ion was sustained through 18 months after implant. Conclusions: Results of this prospective, randomized clinical study demonst rate that sacral nerve stimulation is effective for restoring voiding in pa tients with retention who are refractory to other forms of treatment.