Short-term sacral nerve stimulation for functional anorectal and urinary disturbances: Results in 40 patients

Abstract

PURPOSE: There are several options in the treatment of fecal incontinence; it is often difficult to choose the most appropriate, adequate treatment. The consolidated experience gained in the urologic field suggests that sacral nerve stimulation may be a further option in the choice of treatment. The aim of our study was to evaluate the preliminary results of the peripheral nerve evaluation test obtained in a multicenter collaborative study on patients with defecatory and urinary disturbances. METHODS: Forty patients (9 males; mean age, 50.2; range, 26–79 years) underwent the peripheral nerve evaluation test, 28 (70 percent) for fecal incontinence and 12 (30 percent) for chronic constipation. Fourteen (35 percent) patients also had urinary incontinence; six had urge incontinence, two had stress incontinence, and six had retention incontinence. Associated diseases were scleroderma (2 patients), spinal injuries (4 patients), and syringomyelia (1 patient). All the patients underwent preliminary investigations with anorectal manometry, pudendal nerve terminal motor latency testing, anal ultrasound, defecography, and if required, urodynamic tests. The electrode for sacral nerve stimulation was positioned percutaneously under local anesthesia in the S2 (4), S3 (34), or S4 (1) foramen unilaterally (1 patient not accounted for because of no response to acute test), based on the best motor and subjective responses of paresthesia of the pelvic floor. Stimulation parameters were average amplitude, 2.8 (range, 1–6) V and average frequency, 15 to 25 Hz. RESULTS: The mean duration of the tests was 9.9 (range, 7–30) days; tests lasting fewer than seven days were not evaluated. There were four early displacements of the electrode. In 22 of the 25 evaluable patients with fecal incontinence, there was an improvement of symptoms (88 percent), and 11 (44 percent) were completely continent to liquid or solid stools, whereas in 7 symptoms were unchanged. Mean number of episodes of liquid or solid stool incontinence per week was 8.1 (range, 4–18) in the prestimulation period and 1.7 (range, 0–12) during the peripheral nerve evaluation test. (P=0.001; Wilcoxon's signed-rank test). The most important manometric findings were: increase of maximum rest pressure (39.4 ± 7.3vs. 54.3 ± 8.5 mmHg;P=0.014, Wilcoxon's test) and maximum squeeze pressure (84.7 ± 8.8vs. 99.5 ± 1.1 mmHg;P=0.047), reduction of initial threshold (63.6 ± 5.2vs. 42.4 ± 4.7 ml;P=0.041) and urge sensation (123.8 ± 0.6vs. 78.3 ± 8.9 ml;P=0.05). An improvement was also found in patients with constipation, with reduction in difficulty emptying the rectum, with prestimulation at 7 (range, 2–21) episodes per week and end of peripheral nerve evaluation test at 2.1 (range, 0–6) episodes per week, (P<0.01) and in the number of unsuccessful visits to the toilet, which dropped from 29.2 (7–24) to 6.7 (0–28) per week (P=0.01). The most important manometric findings in constipated patients were an increase in amplitude of maximum squeeze pressure during sacral nerve stimulation (prestimulation, 63 ± 0 mm Hg; end of peripheral nerve evaluation test, 78 ± 1 mm Hg;P=0.009) and a reduction in rectal volume for urge threshold (prestimulation, 189 ± 52 ml; end of peripheral nerve evaluation test, 139 ± 45 ml;P= 0.004). CONCLUSIONS: In functional bowel disorders short-term sacral nerve stimulation seems to be a useful diagnostic tool to assess patients for a minor invasive therapy alternative to conventional surgical procedure.