Three-week test phase improves odds of success for sacral neuromodulation

“The present study clearly shows that test duration and reprogramming during the test phase increases the number of patients that benefit in the long term from sacral neuromodulation,” researchers wrote.

A supervised 3-week test phase improves the success rate of sacral neuromodulation in patients refractory to first-line conservative treatment for urinary dysfunction.

In a prospective study of 90 patients with either overactive bladder (OAB) wet or dry or nonobstructive urinary retention (NOUR) who underwent the supervised 3-week test phase, 45 (82%) of 55 patients with a successful test phase and 1 year of follow-up achieved the primary measure of success at 1 year.1

Success after 12 months was defined as 50% improvement in a key voiding diary variable combined with ≥80% satisfaction on visual analogue scale from 0 to 100% and no wish to receive alternate or add-on treatment.

The findings were published in the Journal of Urology by investigators led by Sam Tilborghs, MD, PhD, from the Department of Urology at Antwerp University Hospital, Belgium.

The authors noted that sacral neuromodulation is currently offered as a staged procedure involving a test phase to evaluate its benefits, after which an internal pulse generator is implanted if early success is achieved. The optimal duration of the test phase is uncertain, as is how to guide and follow-up patients during the test phase.

Limiting the duration of the test phase may fail to identify patients who are considered to be slow responders, they added. According to the International Continence Society best practice statement, the duration of the test period varies from 7 to 21 days, with a low level of evidence.

“The present study clearly shows that test duration and reprogramming during the test phase increases the number of patients that benefit in the long term from sacral neuromodulation,” wrote Tilborghs et al. “Although chances of responding to sacral neuromodulation are inversely related to duration and reprogramming, our findings have clinical important implications for the test phase of sacral neuromodulation. During this supervised 3-week test phase, 42% (24 of 57) of the initial nonresponders after the first week of testing became successful candidates with proven durable success after 1-year follow-up. This method clearly allows more patients to benefit from sacral neuromodulation.”

The study included 48 patients treated primarily for OAB wet, 8 for OAB dry, and 34 for NOUR. To be eligible, patients had to be refractory to at least two different antimuscarinics and/or onabotulinum toxin A, and patients with NOUR had to have been on clean intermittent catheterization.

The supervised test included weekly patient contacts and reprogramming in case of insufficient clinical benefit. Voiding diaries were evaluated after the first week of stimulation, and if a 50% improvement from baseline was not achieved, electrode settings were retested and another configuration was programmed. This procedure could be repeated after the second test week. Patients with >50% improvement after 3 weeks proceeded to the second stage and IPG implant. Troubleshooting and reprogramming was possible at 1, 3, 6, and 12 months postoperatively.

After the 3-week test phase, 56 (62%) patients (49 women and 7 men) met the criteria for success and were implanted.

After the first week, 57 patients failed to reach the success criteria, after which another electrode configuration was tried. After the second test week, 29 were successful and therefore did not require reprogramming. Fourteen patients failed to achieve success after 3 weeks, leaving 15 (52%) of the 29 for definitive implant. The 28 patients considered nonresponders after the first and second weeks were reprogrammed for a second time, nine (32%) of whom met success criteria at the end of the 3-week test phase 3 and received a definitive implant.

Overall, 24 (43%) of the 56 patients who were considered successful at the final analysis needed 1 or 2 reprogrammings during the test phase, before reaching the 50% success criteria.


1. Tilborghs S, Borne SVd, Vaganée D, Win GD, Wachter SD. A supervised three weeks test phase in sacral neuromodulation with a one-year follow-up [published online July 27, 2020]. J Urol. doi: 10.1097/JU.0000000000001317

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