Sacral nerve stimulation for treatment of fecal incontinence - A novel approach for intractable fecal incontinence

Many patients with fecal incontinence demonstrate a functional deficit of t he internal anal sphincter or the external sphincter muscles without any ap parent structural defects. Few patients are amenable to repair or substitut ion of the sphincter. However, sacral nerve stimulation appears to offer a valid treatment option for fecal incontinence. The objectives of this study were: to evaluate the efficacy of temporary stimulation of the sacral nerv e roots (percutaneous nerve evaluation) in patients with functional fecal i ncontinence; to determine the mechanisms of possible improvement; and to ev aluate if temporary stimulation could be reproduced and maintained by impla nting a permanent neurostimulation system. METHODS: Twenty-three patients w ith fecal incontinence, 18 females and 5 males, median age of 54.9 years (r ange 28-71), underwent a per cutaneous nerve evaluation test. Eleven patien ts (47.8 percent) also had urinary disorders: urge incontinence (4), stress incontinence (3), and retention (4). Associated disorders included perinea l and rectal pain (1), spastic paraparesis (1), and syringomyelia (1). All patients underwent a preliminary evaluation using stationary anal manovolum etry, pudendal nerve terminal motor latency measurements and anal ultrasoun d. A percutaneous electrode for the stimulation of the sacral nerve roots w as positioned at the level of the third sacral foramen (S3) in 20 patients and S2 in 2 patients (1 patient missing). Stimulation parameters used mere: pulse width 210 mu sec, frequency 25 Hz, and average amplitude of 2.8 V (r ange 1-6). The electrode was left in place for a minimum of 7 days, Five pa tients were successively implanted with a permanent sacral electrode with a stimulation frequency of 16 to 18 Hz and amplitude of 1.1-4.9 V. V. RESULT S: Seventeen of the 19 patients (89.4 percent) who completed the minimum pe rcutaneous nerve evaluation period of 7 days (median 10.7 (range 7-30)), ha d a reduction of Liquid or solid stool incontinence by more than 50 percent , and fourteen (73.6 percent) were completely continent for stool. The most important changes revealed by manovolumetry were an increase in resting pr essure (P < 0.001) and voluntary contraction (P = 0.041), reduction of init ial pressure for first sensation (P = 0.049) and urge to defecate (P = 0.00 2), and a reduction of the rectal volume for urge sensation (P = 0.006). Th e percutaneous nerve evaluation results were reproduced at a median follow- up of 19.2 months (range 5 to 37) in the 5 patients who received a permanen t implant. CONCLUSIONS: Temporary stimulation of the sacral roots (percutan eous nerve evaluation) can be of help in those patients with fecal incontin ence, and the results are reproduced with permanent implantation. The posit ive effect on continence seems to be derived from not only the direct effer ent stimulation on the pelvic floor and the striated sphincter muscle, but also from modulating afferent stimulation of the autonomous neural system, inhibition of the rectal detrusor, activation of the internal anal sphincte r, and modulation of sacral reflexes that regulate rectal sensitivity and m otility.