VANCOUVER, B.C. – Stimulation of the sacral nerve can be an effective treatment for fecal incontinence, lasting for at least a decade, but percutaneous stimulation of the posterior tibial nerve may be a better alternative, according to results of two recent studies.
Although sacral nerve stimulation is considered a first-line procedure for fecal incontinence, the long-term effects are not well known, said Dr. Anil George at the annual meeting of the American Society of Colon and Rectal Surgeons. Nonetheless, in England, sacral nerve stimulation is the standard treatment for patients who have failed conservative treatment and biofeedback, said Dr. George of St. Mark’s Hospital, Harrow.
Previous research suggests that it works in about 30%-80% of patients (Colorectal Dis. 2010 [doi:10.1111/j.1463-1318.2010.02383.x]), but these studies have obtained only short- to medium-term results, according to Dr. George.
He and his colleagues followed 25 patients who underwent sacral nerve stimulation between January 1996 and January 2002 at St. Mark’s. The patients had two or more episodes of fecal incontinence per week, and had failed conservative treatment and biofeedback. Nine of the patients had had previous sphincter surgery.
Of the 25 patients, 23 improved during the trial phase and proceeded to permanent implant. At follow-up last year (88-150 months after the procedure), the researchers found that the treatment was still effective in 21 of the 23 patients.
From a baseline mean of 20 (standard deviation, 3.8), their St. Mark’s incontinence score (SMIS) declined to 7 (3.4) at 3 months, then stayed more or less steady at 8 (3.7) for the latest follow-up.
Similarly, their ability to defer defecation increased from a mean of less than 1 minute (0.9) to 12 minutes (4.7) after 3 months of treatment, and dropped only slightly to 9 minutes (6) at the most recent follow-up. Incontinence episodes dropped from a mean of 27 (3.4) per 2 weeks at baseline to 2 (4.8) at 3 months, and rose slightly to 4 (12.2) at the latest follow-up.
Only two patients lost efficacy, said Dr. George, for unknown reasons. "Our studies show that sacral nerve stimulation can provide a sustained improvement for up to 10 years," he concluded.
As good as these results seemed, Dr. George said that posterior tibial nerve stimulation may prove even better. He noted that it is effective in 60%-80% of patients, but so far the research has been limited to case series (Colorectal Dis. 2010;12:1236-41).
To further examine the possibilities, Dr. George and his colleagues administered the posterior tibial nerve stimulation to two groups of 11 patients twice a week for 30 minutes at a time over the course of 6 consecutive weeks. One group got percutaneous treatment, and the other got transcutaneous treatment.
The researchers used a fixed pulse width of 200 microseconds and a frequency of 20 Hz. A third group of eight patients received a sham transcutaneous treatment with adhesive pads attached and stimulation switched on for less than 10 seconds, then switched off. (The researchers couldn’t think of a sham percutaneous procedure.)
All patients had had two or more episodes of incontinence per week and had failed conservative treatment and biofeedback. Some had sphincter defects.
Of the 11 percutaneous patients, 9 (82%) achieved greater than a 50% reduction in episodes of incontinence. By comparison, 5 of the 11 transcutaneous patients (45%) achieved this response. Only one of the eight sham transcutaneous patients had this good a response.
The percutaneous patients’ ability to defer defecation increased from a mean 1.9 minutes (standard deviation, 0.9) to 6.7 (SD, 4.8), a statistically significant result (P = .009), whereas the transcutaneous patients went from 2.5 minutes (SD, 2.7) to 4.5 (SD, 4.8), a result that approached statistical significance (P = .06). The change in the placebo group was not statistically significant (P = .17), but the difference among the groups was significant (P = .01).
Only the percutaneous group had a statistically significant improvement in SMIS. There were no differences in threshold, urge, and maximal volumes; rectal and anal sensitivity; or resting, endurance squeeze, and involuntary squeeze pressures among the groups.
Although there were no major complications, the patients reported two episodes of mild, self-limiting abdominal pain.
"So what is your belief of why percutaneous is better?" asked an audience member.
"In percutaneous [therapy], we put the needle closer to the nerve," responded Dr. George. "That could be a reason." But he added that previous studies had not found a difference between the transcutaneous and percutaneous approaches.
And transcutaneous posterior tibial nerve stimulation may have at least one advantage, he said. At St. Mark’s, the cost per patient for percutaneous stimulation was £400 ($711), whereas transcutaneous was only £2 ($3) per patient. By comparison, sacral nerve stimulation was £1,500 ($2,423) per patient just for the kit.