Sacral neuromodulation

This card describes sacral neuromodulation (also called sacral nerve stimulation), a device-based treatment for certain bladder and bowel control problems. It is written for patients, families and students who want a first map of the procedure. Whether it suits a particular person is a decision for that person and their clinician.

What it is

Sacral neuromodulation delivers mild electrical pulses to the sacral nerves, which carry signals between the spinal cord and the bladder and bowel. A 2024 review in the journal Medicina describes it as an option for people with idiopathic overactive bladder (OAB) syndrome, with or without incontinence, and for non-obstructive urinary retention, who are not responding to, or cannot comply with, conservative or medical therapies. "Idiopathic" means no clear underlying cause has been found.

The exact mechanism is not fully settled. The review notes that changes to spinal cord reflexes and brain networks are regarded as the main pathway. The NICE public information leaflet from 2004 also covers use for faecal (bowel) incontinence, and says the approach is only suitable for people who have a weak but intact anal sphincter. That leaflet is old, so current practice may differ.

Why it is done

The American Urological Association (AUA) guideline on idiopathic overactive bladder, issued with SUFU in 2024, says that when medications or behavioral therapy have not worked well enough, or cause intolerable side effects, clinicians should offer sacral neuromodulation, percutaneous tibial nerve stimulation, and/or botulinum toxin injection into the bladder. It grades this a moderate recommendation with Grade A evidence.

The NICE guideline on urinary incontinence in women takes a similar position. It advises offering percutaneous sacral nerve stimulation after review by a multidisciplinary team when overactive bladder has not responded to non-surgical management, including medicines, and either symptoms did not respond to botulinum toxin type A or the woman is not prepared to accept the risk of needing catheterization that comes with it. Terms used here are explained in the glossary.

How it is done, in outline

The procedure is staged, which lets a person try the therapy before committing to a permanent device. In the first stage, a thin lead (wire) is placed through a small opening in the sacrum, guided by X-ray imaging, while the person lies face down under local or general anesthesia. The lead connects to a stimulator worn outside the body. The review says this trial period usually lasts at least 3 days and can be extended up to 4 weeks.

If symptoms improve by at least 50 percent, the second stage connects the lead to a small implanted pulse generator, placed under the skin of the upper buttock or lower abdomen. The review says this is generally done under local anesthesia. If the trial does not reach that level of improvement, the permanent stage is not carried out. Details vary by device and by center.

Recovery

The sources reviewed for this card say little about day-to-day recovery, so this section stays short. The clinical team will explain wound care, activity limits and follow-up. The review says the trial result is judged against a 50 percent improvement in symptoms before the permanent stage goes ahead.

The treatment is a long-term commitment. NICE advises that people considering it discuss the need for test stimulation and the probability of its success, the risk of failure, the long-term commitment, the possible need for surgical revision, and the adverse effects. The 2024 review gives battery life from about 5 to 7 years for non-rechargeable systems, and up to 15 years or more for some rechargeable ones. It states that the devices it covers are MRI-compatible, though individual rules differ, so ask the clinic about scans.

For wider context, see recovery and rehabilitation and the card on pelvic floor muscle training.

Risks

The 2024 review reports a range of outcomes. A meta-analysis it cites found success rates of 46 percent at the test stage and 76 percent at the permanent stage. For urinary urge incontinence it reports a success rate of 82 percent at 5 years, and for non-obstructive retention 71 percent at 5 years. Definitions of success differ between studies, so these figures are not guarantees for any one person.

Reported problems include discomfort at the implant site (15 to 42 percent across studies, lower with buttock placement), pain where the lead was placed (5.4 to 19.1 percent), infection (about 5.7 to 6.1 percent in some series, with a wider 2 to 12 percent range after either stage), and lead migration (2.1 percent with a tined lead). The review adds that proper lead positioning reduced revisions from 32 percent to 3 percent.

Questions to ask your clinician

• What result in the trial phase would count as success for me, and how will it be measured?
• Which other treatments should I have tried first, and are any still worth trying?
• What are the chances that the device will need to be revised or removed?
• Which type of battery does the device use, and what will replacement or recharging involve?
• Can I have MRI scans in the future, and who should I tell before any scan?
• What happens if the trial does not help, and what options remain?