Sacral neuromodulation for FI is effective long-term
Hull T, Giese C, Wexner SD, et al; for the SNS Study Group. Long-term durability of sacral nerve stimulation therapy for chronic fecal incontinence. Dis Colon Rectum. 2013;56:234-245.
In this multicenter, prospective cohort study, Hull and colleagues evaluated the 5-year efficacy of sacral neuromodulation (SNM), also known as sacral nerve stimulation, for treatment of FI. This study followed an earlier investigation by Wexner and colleagues, which reported that 83% of 120 patients treated with SNM had a 50% or greater improvement in FI episodes at 12 months.16
Details of the study
The investigators enrolled 133 participants (92% female) who had more than 2 episodes of FI per week for longer than 6 months (12 months after vaginal delivery). Participants were excluded if they had congenital anorectal malformations, prior rectal surgery within the past 12 months (or 24 months if due to cancer), defects greater than 120° of the external anal sphincter (EAS), IBD, unmanaged chronic watery diarrhea, stool consistency type 6 or type 7 on the Bristol Stool Scale, sequela of pelvic radiation, active anal abscess or fistula, pregnancy, or planned pregnancy.
Eligible participants underwent a 2-stage procedure with the InterStim bowel control device (Medtronic). If participants experienced a 50% or greater reduction in incontinence episodes with a wearable external SNM device in the test stimulation (stage 1), they received the chronic SNM implant device (stage 2).
Participants who underwent device implantation were followed at 1, 3, and 6 months and annually for 5 years or until they exited the study. Bowel diaries and quality of life assessments were completed at baseline and at follow-up.
The primary outcome was therapeutic success, defined as 50% or greater improvement in FI episodes per week.
A total of 120 participants (90%) underwent implantation of the chronic lead and neuromodulator, and 76 (63%) were followed for 5 years. Baseline characteristics available in the initial study of 133 participants showed that the mean age was 60.5 years; 25% had undergone a prior anal sphincteroplasty; and 16.5% and 10.5% had EAS or internal anal sphincter (IAS) defects, respectively, on endoanal ultrasonography.16
Therapeutic success was high at 5 years
At the 5-year follow-up, 89% (64/72) of participants met therapeutic success, with a reduction in weekly FI episodes from 9.1 at baseline to 1.7 at 5 years. The number of incontinence pads required decreased, and more participants wore no pads at 5 years. In the intention-to-treat analysis, carrying forward the baseline FI rate in participants who lacked follow-up data, the therapeutic success rate was 69%. Quality-of-life measures improved at 5 years, both statistically and by minimal clinical difference.
Adverse events. Sixty-eight percent of participants experienced device-related adverse events, including implant site pain, change in sensation of stimulation, change in efficacy, implant site infection, or neurostimulator battery depletion (neurostimulator use commonly expires after 3 to 5 years). Of these events, 80% were successfully treated with medications, reprogramming, or no intervention. The 5-year probability of device revision or replacement was 24.4%, and the 5-year probability of device explant was 19.0%.
Strengths and limitations. Overall, this study was a well-designed, multicenter trial with long-term follow-up that showed significant improvement in FI with the use of SNM. Its strengths include the enrollment of postmenopausal women who had current defects in EAS and/or IAS on endoanal ultrasonography and 25% who had a prior sphincteroplasty. The findings therefore are relevant to the gynecologic population in whom anal sphincteroplasty would not be recommended. The study also accounted for dropouts and reported the adjusted success rate of 69% at 5 years in that group.
The lack of a control arm to rule out the placebo effect is a limitation of this study, although randomized trials comparing the effect of SNM "on" versus "off" showed greater improvement with the device "on."17
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Sacral neuromodulation is an excellent therapy for women with daily FI who have failed noninvasive options and desire to proceed to a more durable, long-lasting device therapy. Although adverse events may occur, they are mild and most often resolve with device reprogramming.
Sacral neuromodulation is an excellent therapy for women with daily FI who have failed noninvasive options and desire to proceed to a more durable, long-lasting device therapy. Although adverse events may occur, they are mild and most often resolve with device reprogramming.