Sacral Nerve Stimulation in Fecal Incontinence

Sacral nerve stimulation (SNS) has been used to treat urinary dysfunction by Tanagho EA and Schmidt RA since 1988. In 1995, Matzel et al. treated patients with functional bowel disorders with SNS, and this therapy was later proved to be also effective for fecal incontinence (FI) secondary to various functional or morphological causes, including large sphincter lesions (up to 180°). SNS delivers mild, non-painful, electrical pulses to the sacral nerves, ultimately improving or restoring function. Validated questionnaires should be administered to FI patients proposed for SNS, in order to assess the severity of FI and its impact on quality of life (QoL). Moreover, anorectal manometry, endoanal ultrasound, pelvic floor electromyography, pudendal nerve assessment, and also MRI should be performed, because every exam analyzes a specific aspect related to FI. Limited information is available to explain the mechanism of action of SNS, and the neurologic mechanism behind this procedure is still unclear. However, SNS is an easy surgical technique that can be performed under local anesthesia and totally reversible. InterStim® Therapy (Medtronic) is the only implantable system currently approved for SNS. As recommended by most of the authors, the optimal implantation site for the electrode is the third sacral foramen. SNS is usually performed with a two-stage procedure, where the first phase consists in a test stimulation period allowing the patient to evaluate the effectiveness of therapy, while at the second stage, the implantable pulse generator (IPG) is connected to the previously placed quadripolar wire. Device can be programmed in monopolar or bipolar configuration, with variable amplitude, frequency, and pulse width. The complications are sporadic and mainly consisting in sepsis and wire displacement. Patients are followed up regularly, 1 month, 6 months after the implant, and yearly thereafter. Long-term results are positive and prove SNS as significantly more effective than medical treatment on clinical outcomes and QoL. The cost of SNS, including diagnostic studies, implant, medication, and outpatient visits, amounts approximately to €14.973 per patient; however, the therapy is demonstrated to significantly reduce direct and indirect costs associated with FI, with respect to standard medical treatment.