By the end of 2003, sacral nerve stimulation had been used to treat more than 1,300 patients with fecal incontinence (145). Despite this large number, the analysis of the results was limited to several small case series. In all studies, significant improvements in continence scores lasting up to 99 months occurred. Most patients experienced at least a 75% improvement in continence scores, and improvement also occurred in the frequency of incontinence episodes, the ability to postpone defecation, and bowel emptying. Intent-to-treat analysis revealed 80% to 100% therapeutic success. There also were significant improvements in quality-of-life measures using validated measurement scales. Complications occurred in 0% to 50% of patients, with the most common complications consisting of pain at the electrode or IPG site, electrode migration, infection, or worsening of bowel symptoms. No permanent sequelae occurred, however. Effects of anorectal physiology varied among the published studies, highlighting the fact that the precise mechanism of action remains unclear.
A Cochrane review of three crossover trials concluded that the limited data suggest improvement in both fecal incontinence and constipation with sacral nerve stimulation (146). Large multi-center trials have been conducted to evaluate the efficacy of sacral nerve stimulation for fecal incontinence. Wexner et al. prospectively followed 120 patients (110 female, 10 male) for a mean of 28 (2-70) months (147,148). Participants completed validated quality-of-life measures and bowel diaries. Success, defined as a 50% or greater improvement and reduction in fecal incontinence episodes per week, was achieved in 83% at 1 year and 85% at 2 years. Forty-one percent achieved total continence at 1 year, and mean incontinent episodes decreased from 9.4 to 1.9 per week. The same group reported an overall 10.8% infection rate (13/120), with nine occurring within the first month and four occurring after 1 year. Among the early infections, five responded to antibiotics, one resolved spontaneously, and three were treated surgically. For the late infections, all four had to be removed. Another large multicenter study of 200 patients revealed decreased severity scores and improved quality of life with sacral nerve stimulation (149). Loose stool consistency and low stimulation intensity were predictive of successful outcomes on multivariate analysis. Ultrasound findings, manometry, age and gender did not impact outcomes. Tjandra et al. performed a randomized controlled trial of 120 participants with 1-year follow-up comparing sacral nerve stimulation to best supportive therapy consisting of pelvic ﬂoor exercises, bulking agent, and dietary manipulation (150). Fecal incontinence outcomes improved dramatically in the stimulation group, with 47% achieving complete continence. In contrast, there were no significant improvements observed in the supportive therapy group. Thus, sacral nerve stimulation appears to be a promising new treatment for fecal incontinence with relatively limited complications. FDA approval for fecal incontinence seems likely in the near future, and the minimally invasive nature of this procedure makes it a desirable first-line surgical option.
Therapeutic Approach to Constipation
As with fecal incontinence, it is imperative to attempt conservative management of constipation and defecatory dysfunction before performing surgery. Initial evaluation should focus on identifying any underlying systemic conditions (Table 28.1) associated with disordered defecation and optimizing treatment for these conditions. In the absence of systemic etiologies, it is reasonable to proceed with empiric, nonsurgical management, such as diet, fiber supplementation, and toileting behavior changes. Biofeedback and laxatives can be used in more severe cases. Initially, disimpaction with regular enemas or laxatives is essential if the patient