Patrick Culligan, MD, FACOG, FACS
Atlantic Health System
Morristown, New Jersey
van Kerrebroeck PE, van Voskuilen AC, Heesakkers JP, et al. Results of sacral neuromodulation therapy for urinary voiding dysfunction: outcomes of a prospective, worldwide clinical study. J Urol. 2007;178:2029-2034.
Over the last 10–15 years, sacral neuromodulation has emerged as a viable treatment option for patients with refractory urinary frequency, urge incontinence and non-obstructive voiding dysfunction – largely because of the quality of the original clinical research studies. However, few long-term studies have been published.
- Prospective, non-randomized, multicenter 5 year follow-up study
- Study initiated after FDA approval of device, however many of these subjects were part of the original pre-approval studies
- Out of 163 potential subjects, 11 declined enrollment in this study. Therefore the actual potential number of study subjects was 152
- 129 of these 152 had received their implant prior to this study initiation (ie, they were part of the original study group). Therefore, many of the patients received older versions of the device - such as having the implantable neurostimulator (INS) implanted in the abdomen rather than the buttocks
- 96/152 (63.2%) received the implant due to urge incontinence symptoms
- 25/152 (16.4%) received the implant due to urinary frequency
- 31/152 (20.4%) received the implant due to urinary retention
- “Success” was defined using the same criteria used in the original trials (namely 50% or greater improvement in voiding diary measures compared with baseline)
- Outcome measures included 3-day voiding diaries; simple uroflowmetry; SF-36 and Beck Depression Inventory scores
- 121/152 (80%) of the potential study group completed all 1-year endpoints; and 87/152 (57.2%) completed all endpoints at 5 years
- “Success” was achieved in 68% of the urge incontinence subjects; in 56% of the urinary frequency subjects; and in 71% of the urinary retention subjects
- Overall, 67% of patients had at least 1 device or therapy-related adverse events
- There were 110 adverse events requiring re-operation among 60 patients. Device exchange (including replacement of lead, extension or INS) was the most common reason for surgical intervention. These re-operations were for reasons such as pain at the implantation site; lead migration; undesirable changes in stimulation; etc
This study reflects the attitude expressed by many surgeons regarding sacral neuromodulation - namely that the technology should be used as a last resort (ie, in patients refractory to more conservative treatment approaches) due to the modest success rates (albeit within a very challenging group of patients) and significant risk of complications. The outcome measures used in this study are somewhat outdated in that they don’t directly reflect patients’ own assessment of success or failure.
The study includes an obvious selection bias that seems to cut both ways. Many of the patients who experienced poor results could have been lost to follow-up, yet many of the ones who completed the study did not have the benefit of newer/better iterations of the device.
Overall, sacral neuromodulation remains a very interesting treatment option, especially considering that there is still no general consensus as to the mechanism by which the technology actually works.