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Sacral Neuromodulation

Sacral neuromodulation (SNM) is an implantable, adjustable therapy that usually targets the S3 sacral nerve root through a tined lead connected to a subcutaneous pulse generator.[1][2][3] It is used for urgency urinary incontinence (UUI), urgency-frequency syndrome, non-obstructive urinary retention, and fecal incontinence, with a test-stimulation phase before permanent implantation. AUA/SUFU allows minimally invasive OAB care by shared decision without mandatory earlier treatment trials, but individual device labeling may impose narrower eligibility: current InterStim urinary labeling requires failure or intolerance of more conservative treatments.[1][3][4][37]

SNM belongs in the same treatment family as Percutaneous Tibial Nerve Stimulation, but it is a different operation: SNM is an implanted sacral-root system; PTNS is tibial-nerve stimulation, usually office-based and non-implantable.

S3 neuromodulation leadOriginal schematic · v2026-09-11 · Clinical review pending

A tined quadripolar lead enters a sacral foramen and connects to an implanted pulse generator. Bellows and toe responses can support S3 targeting. Combine imaging, motor and sensory responses; device-specific lead and generator placement vary. (Original WARWIKI schematic)

See also: OAB & Urgency Urinary Incontinence, Underactive Bladder, and Fecal Incontinence.

Indications​

IndicationRegulatory / guideline rolePractical selection point
Urgency urinary incontinenceFDA-approved urinary indication with product-specific label conditions; AUA/SUFU lists SNM among minimally invasive OAB therapies[1][37]UUI and preference for implantable neuromodulation over repeat injections after checking the selected product's eligibility
Urgency-frequency syndromeFDA-approved urinary indication[2][3]Severe frequency / urgency without another explanatory pathology
Non-obstructive urinary retentionFDA-approved urinary indication; EAU 2026 strongly recommends SNM for women with underactive bladder refractory to conservative management[2][3][41]Idiopathic retention or selected detrusor underactivity after mechanical obstruction is excluded; Fowler-type functional outlet obstruction is a separate EAU weak-recommendation population[37][41]
Fecal incontinenceFDA-approved in 2011; ASCRS conditionally supports SNM as a first-line surgical option with or without a sphincter defect (low-quality evidence)[4]FI episodes despite conservative therapy; successful test phase is the best predictor

Off-label or emerging uses include IC/BPS frequency-urgency symptoms, selected neurogenic LUTD, chronic pelvic pain, low anterior resection syndrome, and selected pelvic-floor sexual dysfunction phenotypes.[5][6][7][8][9] The 2022 AUA IC/BPS guideline lists a trial of neuromodulation, with permanent implantation if the trial succeeds, as an option (Statement 21, Grade C) when other treatments have not given adequate control.[5] It notes that neuromodulation is not FDA-approved for IC/BPS and is much less effective, and possibly ineffective, for pain than for frequency and urgency. Counsel accordingly: voiding symptoms may improve, but pain response is less predictable.[5][6] EAU 2026 weakly recommends neuromodulation before more invasive interventions in primary bladder pain syndrome and weakly recommends SNM for chronic primary anal pain.[45] It cites a systematic review of 14 studies in chronic pelvic pain (403 patients, 42.2% with IC/BPS) in which 54.8% progressed from test stimulation to permanent implant; among 210 with pain scores, the overall improvement was significant. A separate 10-study SNS review reported adverse events from 0% to 50% and reoperation from 11% to 50%.[45] EAU rates the evidence for SNM in bladder pain at level 3 and reports that pudendal nerve stimulation was superior to SNM in one bladder pain trial (level 1b).[45]

For CP/CPPS, AUA 2025 calls for further studies to establish the role of sacral neuromodulation; this is an ungraded Future Directions discussion. For CSCP after all treatment options fail, consultation with a pain specialist about options including neuromodulation may be discussed .[58]

Mechanism of Action​

SNM does not simply "stimulate the bladder." Its effect is multifocal, with peripheral, spinal, and supraspinal modulation.[10][11]

LevelProposed effect
PeripheralActivates somatic afferent fibers in the S3 root at low thresholds; pelvic-floor afferent input modulates bladder and bowel reflexes
SpinalRebalances storage and voiding reflex arcs through interneuronal modulation of sacral parasympathetic output
SupraspinalAlters urgency and control networks involving anterior cingulate cortex, prefrontal cortex, insula, limbic circuitry, and periaqueductal gray
Neural plasticityMay produce longer-term changes in sensory processing and reflex gain, though the exact physiology remains incompletely defined

The clinical effect generally depends on active stimulation. Symptoms may recur when therapy is turned off, although some patients appear to develop longer-lasting neuromodulatory effects.[10][11]

Devices​

Current systems include non-rechargeable and rechargeable pulse generators. Modern Medtronic InterStim systems with SureScan leads and Axonics systems support conditional full-body MRI at 1.5T and 3T when device-specific conditions are met.[12][13][14]

Device familyBattery strategyPractical tradeoff
InterStim II / InterStim XNon-rechargeableNo charging burden; eventual generator replacement. Historical non-rechargeable devices averaged about 4.4 years[16][17]; Medtronic states InterStim X provides over 10 years at standard settings, up to 15 years at low-energy settings[39]
InterStim MicroRechargeableSmaller generator and manufacturer-estimated battery life of up to 15 years under expected therapy settings; requires regular charging[15][39][68]
Axonics r-SNM systemsRechargeable and newer non-rechargeable optionsLong-life systems with modern MRI labeling; rechargeable systems require patient charging competence. Manufacturer figures: F15 recharge-free about 17.6 years at 1 mA (Canadian manual table: 22, 15, 9 and 5 years at 0.5, 1.3, 2.0 and 3.0 mA); R20 rechargeable designed for 20+ years, with recharge intervals of 10, 8, 6 and 5 months at 0.1, 1, 1.5 and 2 mA; both MR Conditional at 1.5T and 3T[14][16][17][42][43]

Frailty, cognition, manual dexterity, access to follow-up, expected MRI needs, and willingness to recharge should all be part of the implant conversation.

Preoperative Evaluation​

Before SNM, define the phenotype and exclude problems SNM will not fix:

  • For urinary symptoms, a baseline voiding diary; for fecal incontinence, a 2–3-week bowel diary documenting leakage, stool pattern, urgency, and bowel medications before the test phase[59]
  • Urinalysis and treatment of infection if present
  • Postvoid residual
  • Pelvic and focused neurologic examinations when relevant; for fecal incontinence, inspect the perineum and anus for prolapse or other pathology and perform a digital rectal examination to estimate resting and squeeze tone and exclude impaction or a distal mass.[4]
  • Urodynamics for complex storage-emptying phenotypes, elevated PVR, prior surgery, suspected obstruction, or neurogenic disease
  • Cystoscopy or imaging when hematuria, pain, obstruction, recurrent UTI, or prior reconstruction changes the differential

Screen procedural risks and the selected system's actual contraindications separately.[37][67] For InterStim urinary control, mechanical obstruction is outside the intended use; for InterStim urinary and bowel control, diathermy, absent appropriate test response, and inability to operate the neurostimulator are manufacturer contraindications. Axonics separately contraindicates implantation without an appropriate test response or ability to operate its system and prohibits diathermy in implanted patients.[37][67] Pregnancy safety has not been established.[37][67] Active infection, bleeding risk, and ability to recharge a chosen rechargeable model require individualized assessment and its complete manual.[18][37]

Test Phase​

Permanent implantation is usually offered only after the patient demonstrates at least 50% improvement in the diary variable during test stimulation.[1][3][18]

Test approachHow it worksAdvantagesLimitations
Percutaneous nerve evaluation (PNE)Office temporary monopolar wire near a sacral root, commonly S3, connected to an external stimulator for approximately 3-7 days under the selected model's trial limitSimple, inexpensive, local anesthesiaLead migration, short test window, lower conversion rate
Staged tined-lead trialOR placement of a permanent quadripolar tined lead connected to an external generator for the selected system's labeled test periodMore reliable lead position, longer test, higher conversion rateRequires procedure-room / OR resources and later stage-2 implant

Success is indication-specific: reduction in UUI episodes, reduced frequency, increased voided volumes, fewer catheterizations or lower catheterized volumes, or reduced FI episodes. PNE is the lower-burden office trial; staged tined-lead testing is more sensitive and should be considered when a technically limited PNE is negative but the phenotype still fits SNM.

Lead Placement Technique​

Before the stage-1 incision, give an intravenous antibiotic covering skin flora within 60 minutes, guided by local susceptibility patterns and allergy history (ICS best practice, Level IV, Grade D).[59]

  1. Position prone on a radiolucent table with the buttocks taped apart. When motor responses guide lead placement, avoid neuromuscular blockade because it suppresses bellows and toe responses.[59]
  2. Identify S3 fluoroscopically on AP and lateral views.
  3. Insert the foramen needle toward the cephalad-medial S3 foramen, typically at about a 60-degree skin angle.
  4. Confirm S3 response with low-amplitude test stimulation.
  5. Advance the directional guide and introducer through the foramen.
  6. Place the quadripolar tined lead with a curved stylet.
  7. Confirm lead trajectory fluoroscopically.
  8. Deploy tines, remove stylet, and retest electrode responses.
  9. Connect to a percutaneous extension for staged testing or directly to the generator for single-stage implantation.

Correct S3 response​

FindingInterpretation
Bellows responsePelvic-floor / levator contraction with visible perineal inward movement; interpret with great-toe response and low-threshold responses across contacts[59]
Great toe plantar flexionSupports S3 placement
Perineal, vaginal, scrotal, or rectal sensationAppropriate sensory field
Lateral foot rotationSuggests S2 rather than S3
No toe movement with anal-only responseSuggests S4 rather than ideal S3

Optimal lead placement produces motor and sensory responses at low thresholds on multiple electrodes.[19][20][21]

Curving the staged-lead tunnel between the sacral entry site and the connection site, leaving slack in the lead, has been described as a way to reduce outward traction on the lead during movement or pressure over the pocket. In thin patients, a presacral lead knuckle compressed before the lead has healed can migrate inward; one described countermeasure is to make the presacral incision large enough to accommodate the lead introducer, lift the introducer while tracking back toward the insertion site, flatten the lead course at the fascial level, and tunnel deeply toward the generator pocket.[53]

Stage 2 Implantation​

If the test phase is successful, the pulse generator is implanted in an upper-buttock subcutaneous pocket, usually ipsilateral to the lead. Positioning for this stage is the same prone setup used for lead placement. For the upper-buttock pocket anterior to the muscle, the Axonics F15 manual calls for an approximately 4-cm incision and lateral lead entry when feasible to avoid kinking; the R20 manual calls for an incision slightly longer than the generator's 22-mm short dimension and its ceramic side away from the midline for charging and programming. Both call for blunt dissection, horizontal generator placement no deeper than 3.0 cm and parallel to skin, and at least 20 cm separation from a second implanted neurostimulator.[42][43] At stage 2, remove the temporary extension; irrigate the Axonics F15 pocket with sterile saline or water or the R20 pocket with antibiotic solution, without soaking the generator in antibiotic solution. Dry the lead and connector, fully seat the lead with its retention sleeve under the setscrew, tighten until the torque wrench clicks, place the generator in the pocket, check impedances, and close.[18][20][42][43] See the Axonics device page for other implant points.

The Axonics manuals recommend perioperative IV antibiotics at generator implantation (not soaking the device itself in antibiotic solution, which can affect the lead connection) and 24 hours of postoperative prophylactic antibiotics.[42][43] In a 2025 multicenter retrospective cohort of 1,798 patients, postoperative prophylaxis was not associated with a lower observed 90-day surgical-site infection rate (3.6% versus 3.9%; age-adjusted OR 0.98, 95% CI 0.61–1.61).[70] For VTE prophylaxis after this short subcutaneous-pocket procedure, apply the general risk framework (age, obesity, prior VTE, malignancy, prolonged operation or immobility) on the VTE Prophylaxis page.

Most patients need postoperative programming and education. The Axonics manuals have the clinician check impedances and program the generator and remote control at the same stage-2 visit.[42][43]

Stage-1 temporary-extension handling has also been described: securing a loop of redundant extension wire to the stage-1 hub with silk to enlarge the hub and reduce migration from the pocket; avoiding skin glue over the pocket incision, because it must be reopened for stage 2 or for removal after an unsuccessful trial, while using glue over the permanent-lead insertion site; and, at stage 2, removing the temporary extension through its own separate exit site rather than cutting it at skin level and withdrawing it through the generator pocket, which risks carrying skin bacteria into the pocket. This is author-specific technique without comparative infection or migration outcome data and should be reconciled with the selected system's own instructions.[54]

Programming​

Typical starting parameters use low-frequency chronic stimulation:

ParameterCommon starting pointPractical note
Frequency14 HzStandard starting frequency; 31 Hz can be tried as rescue programming
Pulse width210 microsecondsShortening pulse width can reduce painful stimulation; pulse-width changes may salvage suboptimal response
AmplitudeSensory or subsensorySubsensory stimulation can preserve efficacy and improve battery life[22]
ConfigurationMonopolar or bipolarChange cathode/anode pattern first when efficacy fades or stimulation is uncomfortable

Rescue programming usually proceeds by changing electrode configuration, then amplitude, then frequency or pulse width. Programming changes can salvage a meaningful subset of patients with waning efficacy or uncomfortable stimulation.[23][24][25][26]

The 2018 International Continence Society best practice statement, written by a consensus panel of urologists, colorectal surgeons and urogynecologists from the published data and expert opinion, addresses post-implant management and troubleshooting of lost device function, as well as patient selection, test-phase screening, staged versus single-stage implantation and anesthesia.[59]

Outcomes​

Urinary indications​

In a prospective worldwide study, 163 patients enrolled; after test stimulation, 11 declined implantation and 152 underwent implantation (96 UUI, 25 urgency-frequency, 31 retention).[3] At five years after implantation, at least 50% improvement in the primary diary variable was reported for 68%, 56%, and 71% of those respective implanted groups.[3] Long-term single-center series report similar durability but substantial reprogramming and revision needs over time.[27][28][29] In one such single-center series of 217 patients (86% female, mean follow-up 46.9 months), success (persistence of the initial 50% or greater diary improvement) and complete cure rates were about 70% and 20% for urgency incontinence, 68% and 33% for urgency-frequency syndrome, and 73% and 58% for idiopathic retention; 41% of patients had at least one device- or treatment-related surgical reintervention, with 47% of reinterventions occurring within 2 years.[29]

A meta-analysis of sacral neuromodulation for nonobstructive urinary retention pooled 7 studies with outcome data (from 14 studies meeting inclusion criteria) and found the mean difference after implantation was a 236 mL decrease in postvoid residual (95% CI 219-253) and a 299 mL increase in voided volume (95% CI 280-318); the single included randomized trial (n = 51) showed a 270 mL PVR decrease and a 104 mL voided-volume increase versus control. These are pooled emptying outcomes, distinct from the treatment-success proportions above.[56]

Fecal incontinence​

ASCRS summarizes 61 FI studies with per-protocol median study proportions among selected implanted patients of about 79% achieving at least 50% improvement at 0-12 months and 84% at more than 36 months.[4] These different follow-up samples are not a single cohort. In the 2025 SUBSoNIC crossover trial of adults with FI, 39 were randomized but only 16 had complete primary diaries; across two 16-week periods, active subsensory stimulation versus sham yielded a mean difference of −0.8 FI episodes per week (95% CI −1.5 to 0.0; p=0.06), leaving comparative efficacy inconclusive.[60] SNM can improve fecal incontinence with or without sphincter defects, and test response remains the main selection gate.[4][30] A 2026 meta-analysis associated prior sphincteroplasty, external sphincter defects >120°, and low resting anal pressure with less improvement; comparative evidence against sphincteroplasty remains insufficient.[69]

Mechanistically, SNM for FI is associated with an improved rectosigmoid brake: in a manometry study of 15 patients, suprasensory stimulation significantly increased retrograde propagating contractions in the distal colon compared with baseline.[50] At 6 months, one cohort of 29 patients showed significantly increased anal resting pressure and higher rectal volumes for desire to defecate and maximal tolerable volume; the first-sensation threshold also rose numerically but not significantly, and maximum squeeze pressure did not significantly change.[51] A separate acute-stimulation study found the opposite direction for sensory thresholds — lower volumes needed to reach first sensation, desire to defecate, and maximal tolerable volume during active stimulation.[52]

SNM vs Intradetrusor OnabotulinumtoxinA​

ROSETTA randomized women with refractory UUI to SNM or 200 U onabotulinumtoxinA[31]; the US label recommends 100 U for OAB.[65] At 6 months, toxin produced a modestly greater reduction in UUI episodes but more UTI and intermittent catheterization; SNM avoids injection-related retention but carries device revision or removal risk. The planned 24-month extension, in women who had responded initially, reported similar sustained episode improvements (toxin retained higher satisfaction), with no detected between-group episode difference across 24 months among initial responders.[31][38] The AUA/SUFU guideline cites a 263-patient retrospective OAB cohort: test-phase success was 66.7% after prior botulinum toxin versus 72.9% in toxin-naive patients; among those implanted after a successful test, 43/50 (86%) versus 115/137 (83.9%) were still using SNM to their satisfaction at last follow-up (mean 40.7 versus 54.18 months).[1][63]

Cost. ROSETTA's planned economic evaluation (386 women, health-system perspective, 2018 US dollars) found no difference between arms in urgency incontinence episode reduction or QALYs at 2 years, but two-stage SNM cost significantly more than 200 U onabotulinumtoxinA: $35,680 versus $7,460 at 2 years within the trial and a modeled $36,550 versus $12,020 at 5 years (p < 0.01 at both horizons). Modeled willingness-to-pay thresholds put the probability that SNM is cost-effective relative to toxin below 2.5% for any value under $580,000/QALY at 2 years and $204,000/QALY at 5 years, similar clinical effectiveness notwithstanding.[48]

IssueFavors SNMFavors Botox
Avoiding CIC / retentionNo injection-induced retention in ROSETTAHigher UTI and catheterization risk
Avoiding implanted hardwareNoYes
Need for complete UUI resolutionA 2025 meta-analysis reported a higher pooled complete-resolution signal with SNM; this conflicts with ROSETTA's direct six-month comparison.[66][31]In ROSETTA, 35/178 (20%) with 200 U toxin versus 6/166 (4%) with SNM had complete resolution at six months; among initial responders, both groups were approximately 5% at 24 months.[31][38]
Maintenance burdenProgramming, battery, possible revisionsRepeat cystoscopic injections every several months

Complications​

ComplicationPatternManagement
Loss or change of efficacyCommon over long follow-upReprogramming first; lead revision if needed
Implant-site painEarly or delayedReprogramming, pocket revision, or explantation if severe
Lead migration / suboptimal leadOften earlyReprogramming or lead revision
InfectionUsually earlyAntibiotics for superficial infection; explantation for pocket or device infection
Undesirable stimulationLeg, perineal, or painful stimulationProgram change, amplitude / pulse-width change, lead revision
Battery depletionExpected for non-rechargeable systemsGenerator replacement
MRI restrictionsDevice-specificVerify exact device and lead model before MRI

Revision rates vary widely by era, device, follow-up duration, and definition. Older long-term series report high cumulative reintervention rates, while modern tined leads, MRI-compatible systems, and rechargeable batteries aim to reduce some historical revision drivers.[27][28][29][32] The EAU 2026 female LUTS guideline offers SNM for OAB/UUI refractory to anticholinergic therapy and advises lifelong surveillance of implanted women for lead displacement, malfunction and battery wear.[41] It regards test stimulation as the only reliable predictor of success, notes that the OAB trials it reviewed lacked sham controls, and cites surgical revision in roughly 30–40% by three to four years (level 3).[41] In the InSite cohort of 272 implanted SNM patients, which included randomized and open-enrollment participants, one-year device-related events included undesirable change in stimulation (32/272, 12%), implant-site pain (20/272, 7%) and implant-site infection (9/272, 3%), with permanent explantation in 13/272 (5%).[1][64]

In a retrospective cohort comparing 32 diabetic and 211 non-diabetic patients treated for voiding dysfunction, long-term success rates after implantation did not differ significantly by diabetes status, but device explantation was more frequent in diabetic patients (9 of 24 implanted, 37.5%, versus 36 of 141, 25.5%; p = 0.224), and infection-related explantation occurred in 16.7% of implanted diabetic patients versus 4.3% of implanted non-diabetic patients (p = 0.018).[55]

Revision decision-making. After reprogramming options are exhausted, a clearly better response during the test phase than after permanent implantation, together with an identifiable technical problem in permanent-lead position on AP and lateral radiographs, has been described as a reason to correct the lead position and connect to the generator in a single-stage revision; if the original test response is uncertain in retrospect, a new staged trial with diary confirmation before connecting the generator has been suggested instead. As sensory-guided cues, stimulation felt excessively in the foot or leg has been described as suggesting the lead should be redirected more caudally, while rectal-only sensation suggests a more cephalad orientation.[53]

Removing a chronically implanted lead. Extraction after a lead has been in place for months or years differs from removal after a short failed trial: fibrosis can make connector-site traction more difficult, and fracture can leave a retained fragment. One described approach uses a separate incision over the original presacral insertion point, dissects along the lead until a tine is visible, and applies slow, steady traction opposite the original insertion direction, with a stylet reinserted to stiffen the lead if needed; electrocautery along an inadequately insulated lead can stimulate the nerve.[53]

Infection management. A low threshold to remove a lead and defer permanent implantation has been described when wound infection is suspected while converting a first-stage procedure to permanent implant; for obvious infection or a persistent or recurrent draining sinus after implantation, removing the entire system has been recommended. One described post-explant approach excises the pseudocapsule, leaves the wound open to heal by secondary intention, uses negative-pressure wound therapy when feasible, and generally waits at least 3 months before considering reimplantation.[53]

Special Considerations​

MRI​

Current-generation systems can be compatible with 1.5T and 3T full-body MRI under manufacturer conditions, but compatibility depends on the exact generator, lead, lead integrity, and scan conditions.[12][13][33][34]

  • Medtronic InterStim: full-body 1.5T and 3T scanning applies only to InterStim Micro with a 978A1 SureScan lead and InterStim X or InterStim II with a 978B1 SureScan lead. With an older lead (3093 or 3889), InterStim X and InterStim II are limited to 1.5 T head-only scanning with a detachable head transmit/receive coil, and the InterStim Twin is not MRI eligible. For full-body eligible SureScan systems, the patient activates MRI mode with the communicator and patient app before entering the scanner room and brings both to the appointment. For older head-only eligible InterStim systems, turn stimulation off as directed by the model-specific MRI manual.[13][46][47] The US MRI guidelines (April 2025, summarized in the UK checklist) list 1.5 T or 3 T horizontal cylindrical scanners, a maximum slew rate of 200 T/m/s, a maximum spatial gradient of 20 T/m, 30 minutes of continuous scanning then a 5-minute wait, body temperature of 38 °C or lower, prone or supine position, and at least 30% charge for the Micro.[47] They set separate RF limits above and below C7. They do not require an impedance check before a full-body scan. A retained lead fragment is not considered an abandoned component only if it is 6 cm or shorter, is sacral, is at least 2 cm from other metallic components, and came from Medtronic tined lead model 3093, 3889, 978A1, or 978B1.[46][47] MRI has not been evaluated with test-phase components; the external neurostimulator is MR Unsafe, and all evaluation components are removed before MRI. The InterStim device page tabulates these conditions.[46][47]
  • Axonics: For eligible 1101, 4101, and 5101 generators with 1201/2201 leads, whole-body MRI requires a horizontal cylindrical proton scanner with a whole-body transmit coil, maximum spatial gradient 25 T/m, and maximum slew rate 200 T/m/s. At 1.5 T, use circularly polarized RF excitation and whole-body SAR ≤2 W/kg. At 3 T, use circularly polarized or multichannel-2 excitation; B1+rms must be ≤2.0 µT for 1101/5101 or ≤1.7 µT for 4101, or, when B1+rms is unavailable, whole-body SAR must be ≤1.6 or ≤1.2 W/kg, respectively.[40] Use normal operating mode for no more than 30 minutes of continuous scanning, then wait 5 minutes if that limit is reached; confirm the current model-specific IFU before scanning. Turn stimulation off and confirm the neurostimulator is in the posterior hip or upper buttock. Complete the MRI readiness check and eligibility worksheet. High impedance or a retained lead fragment requires the separate Appendix A criteria and RF limits; an intact disconnected lead, partially implanted lead, malfunctioning generator, or low-impedance system is not eligible for whole-body MRI.[40] External components are MR Unsafe.[40][44]

Pregnancy​

SNM is commonly turned off during pregnancy because safety data are limited, but activation or deactivation should be decided individually with the patient and obstetric team; stopping stimulation can be followed by recurrent urinary retention or UTI. Published pregnancy series are small and confounded. Reactivation can be considered postpartum if symptoms recur.[62][18]

Neurogenic LUTD​

AUA/SUFU 2021 advises against offering SNM to patients with SCI or spina bifida .[35] It permits selected NLUTD use for urgency, frequency, or UUI .[35] EAU 2026 gives a Strong recommendation to consider SNM in selected neurological patients (level 1b evidence that it is effective and safe in selective neurogenic LUT dysfunction), notes that MS patients with NDO are often good responders, and states that MRI-compatible generators and leads remove the old reason to avoid SNM in patients who need MRI follow-up; it also acknowledges that disease-specific studies are few and the best-suited patients remain unclear, and that urodynamic effects are uncertain.[36] A sham-controlled trial in selected neurogenic LUTD found that 65/124 (52%) passed testing; after implantation and optimization, 22/29 with stimulation on versus 13/31 with stimulation off retained at least 50% diary improvement over two blinded months.[7] This supports short-term benefit in selected patients, without establishing long-term outcomes or overriding disease-specific exclusions.[7] A systematic literature review and meta-analysis pooling 47 studies of SNM across neurogenic etiologies reported a pooled test-stimulation success rate of 66.2% (95% CI 56.9–74.4, 21 studies, 887 patients) and a per-protocol pooled permanent-implant success rate of 84.2% among selected implanted patients (95% CI 77.8–89.0, 24 studies, 428 patients), with success varying substantially by neurogenic etiology and symptom type and most included studies at lower levels of evidence (retrospective series, small samples, substantial heterogeneity).[49] An earlier 2010 systematic review and meta-analysis of 26 studies (357 patients, evidence level 2b to 4) reported a pooled success rate of 68% for the test phase and 92% among selected patients with permanent SNM at a mean follow-up of 26 months, with a pooled adverse-event rate of 24% after permanent implantation; the authors noted low patient numbers, high between-study heterogeneity, and a lack of randomized trials.[57]

Key Takeaways​

  1. SNM is an implanted, testable, adjustable therapy for OAB/UUI, urgency-frequency, non-obstructive retention, and fecal incontinence.
  2. A successful test phase is the established gate for implantation; in an analysis of 149 women with UUI who passed testing and received an IPG, the size of the short-term diary response alone poorly predicted patient-reported benefit at 24 months.[61]
  3. Lead placement lives or dies on correct S3 responses: bellows, great toe plantar flexion, and appropriate perineal sensation at low thresholds.
  4. Programming is part of the treatment; loss of efficacy should trigger systematic reprogramming before revision.
  5. Modern device selection should explicitly address MRI needs, recharge burden, cognition, dexterity, and expected lifetime revision risk.

Podcasts​

Exploring Neuromodulation: Sacral vs Tibial Approaches
BackTable Urology, Ep. 318 (2026) · Tracey Wilson, Kenneth Peters
backtable.com

Videos​

Overview of Axonics Sacral Neuromodulation Therapy
Grand Rounds in Urology (2025)

References​

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2. Van Kerrebroeck PE, Marcelissen TA. "Sacral Neuromodulation for Lower Urinary Tract Dysfunction." World J Urol. 2012;30(4):445-450. doi:10.1007/s00345-011-0780-2

3. 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(5):2029-2034. doi:10.1016/j.juro.2007.07.032

4. Bordeianou LG, Thorsen AJ, Keller DS, et al. "The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Management of Fecal Incontinence." Dis Colon Rectum. 2023;66(5):647-661. doi:10.1097/DCR.0000000000002776

5. Clemens JQ, Erickson DR, Varela NP, Lai HH. "Diagnosis and Treatment of Interstitial Cystitis/Bladder Pain Syndrome." J Urol. 2022;208(1):34-42. doi:10.1097/JU.0000000000002756

6. Wang J, Chen Y, Chen J, Zhang G, Wu P. "Sacral Neuromodulation for Refractory Bladder Pain Syndrome/Interstitial Cystitis: A Global Systematic Review and Meta-Analysis." Sci Rep. 2017;7(1):11031. doi:10.1038/s41598-017-11062-x

7. Liechti MD, van der Lely S, Knüpfer SC, et al. "Sacral Neuromodulation for Neurogenic Lower Urinary Tract Dysfunction." NEJM Evidence. 2022;1(11):EVIDoa2200071. doi:10.1056/EVIDoa2200071

8. Tutolo M, Ammirati E, Heesakkers J, et al. "Efficacy and Safety of Sacral and Percutaneous Tibial Neuromodulation in Non-Neurogenic Lower Urinary Tract Dysfunction and Chronic Pelvic Pain." Eur Urol. 2018;73(3):406-418. doi:10.1016/j.eururo.2017.11.002

9. Fu J, Li Z, Pu J, et al. "Advancing Women's Health: Innovative Applications of Sacral Neuromodulation in Pelvic Floor Dysfunctions." Arch Gynecol Obstet. 2025. doi:10.1007/s00404-025-08182-5

10. Dequirez PL, De Wachter S, Biardeau X. "Sacral Neuromodulation for Low Urinary Tract Dysfunction: Overview and Mechanisms of Action." Auton Neurosci. 2025;261:103337. doi:10.1016/j.autneu.2025.103337

11. Herbison GP, Arnold EP. "Sacral Neuromodulation With Implanted Devices for Urinary Storage and Voiding Dysfunction in Adults." Cochrane Database Syst Rev. 2009;(2):CD004202. doi:10.1002/14651858.CD004202.pub2

12. Huang X, Jiang GJ. "Magnetic Resonance Imaging Interactions With a Sacral Neuromodulation System." Neurourol Urodyn. 2021;40(8):1862-1868. doi:10.1002/nau.24756

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