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Medtronic InterStim — Sacral Neuromodulation

The Medtronic InterStim is the pioneering and most extensively studied sacral neuromodulation (SNM) device — FDA-approved since 1997 for urinary dysfunction and 2011 for fecal incontinence. > 350,000 implants worldwide with > 25 years of clinical data.[1][2][3][4]

History & Evolution​

NIH-funded research at UCSF in the 1970s (Schmidt and Tanagho) demonstrated that stimulation of the S3 sacral nerve root modulates bladder and sphincter function through afferent pathways.[4]

  • 1981 — first chronic sacral nerve stimulation implant in a human.[4]
  • Early 1990s — initial trials required open surgery and general anesthesia.[5][6]
  • 1997 — FDA approval for urgency urinary incontinence (UUI).[1][3]
  • 1999 — FDA approval expanded to urgency-frequency and non-obstructive urinary retention.[1][2]
  • ~2002 — tined lead (Model 3889): self-anchoring percutaneous lead enabling local-anesthesia placement. Test-phase success rate ~60% → ~80%.[5][6]
  • 2006 — InterStim II: smaller non-rechargeable IPG.[5][7]
  • 2011 — FDA approval for fecal incontinence.[8][9]
  • 2019–2020 — InterStim Micro: miniaturized rechargeable IPG with full-body 1.5T and 3T MRI conditional labeling.[10][11]

Device Generations​

FeatureInterStim (original)InterStim IIInterStim Micro
IPG typeNon-rechargeableNon-rechargeableRechargeable
SizeLargestSmallerSmallest (~5 cm³)
Implant locationAbdomen / upper buttockUpper buttockUpper buttock
Battery lifeMedian 7.3 yrMedian 5.9 yrManufacturer-rated 15 yr
MRIHead only (1.5T)Head only (1.5T)Full-body 1.5T and 3T conditional
ChargingNoneNoneRequired (weekly)
LeadTined Model 3889Tined Model 3889Tined Model 3889
Patient appNoNoYes (Bluetooth)

References: [5][7][10][11]

Battery life note. The InterStim II median lifespan (5.9 yr) is significantly shorter than the original InterStim (7.3 yr, p < 0.05).[7]

MRI compatibility. Non-rechargeable InterStim devices are FDA-labeled only for head-only 1.5T MRI. Real-world Swiss data (191 MRIs, 92% at 1.5T, 58% non-head) with the device off: only 2 (1%) minor AEs (transient pain / heat).[12][13] InterStim Micro's full-body conditional labeling at both 1.5T and 3T is a major advance.[10]

Mechanism​

Continuous low-amplitude pulses to the S3 root via a quadripolar tined lead through the S3 foramen:[1][2][14][15]

  • Somatic-afferent activation — inhibits parasympathetic motor neurons in the sacral spinal cord, rebalancing excitatory and inhibitory reflexes for bladder, bowel, and pelvic floor.[14][15]
  • Supraspinal effects — fMRI shows modulation of anterior cingulate, mPFC, periaqueductal gray, and limbic system.[14]
  • Sympathetic-parasympathetic rebalancing.
  • Neural plasticity at peripheral, spinal, and supraspinal levels.[14]
  • Reversible — effect ceases when stimulation is off; off-device outcomes return to baseline.[14][16]
  • Typical parameters: 14 Hz, pulse width 210 μs, sub-sensory / sensory threshold amplitude.[1]

FDA-Approved Indications​

  1. Urgency urinary incontinence (1997)
  2. Urinary urgency-frequency (1999)
  3. Non-obstructive urinary retention (1999)
  4. Fecal incontinence (2011)[1][2][17]

Off-label use with emerging evidence:[1][18][19][20]

  • Interstitial cystitis / bladder pain syndrome — meta-analysis (n = 583): 84% success with significant ↓ pelvic pain / frequency / nocturia.[19]
  • Neurogenic bladder — meta-analysis (n = 573) with significant ↑ in storage parameters; pooled permanent SNM success 84.2%.[21][22]
  • Chronic constipation — limited evidence (Cochrane).[23]
  • Chronic pelvic pain, sexual dysfunction — emerging.[18][20]

Surgical Technique​

Testing Phase Options[1][5][24][25]​

  • PNE (percutaneous nerve evaluation) — office; temporary wire near S3 for 3–7 days. Success ~46–60%.
  • Stage I tined lead (staged) — permanent tined lead in OR under fluoro; external stimulator ≥ 14 days. Success ~80%. 44% of PNE failures respond to tined-lead testing.[5][25]
  • Single-stage implantation — both lead + IPG in one procedure. Cost-minimization analysis: single-stage is cost-effective when success rate exceeds 61–65% (which contemporary rates do).[26][27]

Implantation Steps[1][5]​

  1. Prone position; fluoro identification of S3 foramen.
  2. Foramen needle confirmed by bellows response (pelvic-floor / anal-sphincter contraction) and great-toe plantar flexion.
  3. Tined lead advanced through the needle alongside S3.
  4. Lead connected to IPG in a subcutaneous upper-buttock pocket.
  5. Device programmed and activated.

Staged implants have a 17% lower likelihood of device-related reoperations vs PNE/full-implant in Medicare data.[28]

Clinical Outcomes by Indication​

OAB / UUI — InSite Trial (n = 340)​

5-yr outcomes:[29][30]

  • 5-yr therapeutic success 67% (modified completers) to 82% (completers).
  • Mean ↓ 2.0 leaks/day (UUI), 5.4 voids/day (urgency-frequency).
  • Significant improvement across all ICIQ-OABqol measures.

Worldwide prospective (n = 152, 17 centers) 5-yr success: 68% UI / 56% urgency-frequency / 71% retention.[31]

Non-Obstructive Urinary Retention​

  • Mean catheterization volume 380 → 109 mL; catheterizations 5.3 → 1.9/day at 5 yr.[31]
  • 5-yr success 71% — highest among urinary indications.[31]
  • Long-term single-center: 87.5% success for idiopathic retention.[32]

Fecal Incontinence​

  • Pivotal North American multicenter (n = 133): 86% therapeutic success at 3 yr; 40% complete continence; FI episodes 9.4 → 1.7/week at 12 mo.[33]
  • 10-yr French multicenter (n = 360): ITT favorable outcome 45%; Kaplan-Meier estimated favorable outcome 64% at 10 yr.[34]
  • ASCRS recommends SNM first-line surgical option for FI failing conservative treatment, irrespective of anal sphincter integrity.[9]

ROSETTA — SNM vs OnabotulinumtoxinA​

386 women, 9 US centers, refractory UUI:[35][36]

6 months:

  • OnaBT greater mean ↓ UUI episodes (3.9 vs 3.3/day; MD 0.63, p = 0.01).
  • OnaBT higher satisfaction and endorsement.
  • No differences in convenience, AE perception, or treatment preference.

24 months:

  • No difference in mean UUI reduction (−3.88 vs −3.50/day, p = 0.15).
  • No differences in UUI resolution, ≥ 75% / ≥ 50% reduction rates.
  • OnaBT maintained higher satisfaction / endorsement.
  • Recurrent UTI significantly higher with OnaBT (24% vs 10%, p < 0.01).

Cost-effectiveness: SNM was not cost-effective vs OnaBT at 2 yr ($35,680 vs $7,460) or 5 yr ($36,550 vs $12,020); no QALY difference.[37]

AUA/SUFU OAB guidelines recommend both as options for inadequate response to pharmacotherapy, guided by shared decision-making.[17]

Complications & Reintervention​

ComplicationRate
Implant site pain15–28%
Undesirable stimulation change12–22%
Lead migration3–12%
Infection2–10%
Paresthesias15%
Therapeutic ineffectiveness13%
StudynFollow-upRevision rateExplantation
Medicare women ≥ 65[28]32,4548 yr43% cumulative (9.4% at 1 yr, 20% at 3 yr)Included
Single-center 14-yr[32]9650.7 mo median39%20.8%
Multicenter[38]219164 d median16%Included
FI systematic review[39]3,770≥ 36 mo35.2%19.7%
French FI 10-yr[34]36010 yr64.7%26.1%

Risk factors for revision / explantation:[40][41][42]

  • Age < 55, female sex.
  • BMI change between implantation and revision.
  • History of trauma, pain-clinic enrollment.
  • Longer follow-up (cumulative revision rises).
  • Antimicrobial envelope did not reduce complication rates.[40]
  • The tined-lead technique reduced revision rates from 50% → 31% vs the older lead.[32]

Rechargeable vs Non-Rechargeable — A Critical Real-World Finding​

InterStim Micro promised longer life and full-body MRI. Real-world data raise concerns:[43][11]

  • Comparative study: rechargeable devices had significantly lower revision-free survival than non-rechargeable for OAB. By ~1,600 days, revision-free survival ~64% rechargeable vs 82% non-rechargeable. Over a third of rechargeable-group revisions were for difficulty charging and connecting.[43]
  • Single-center FI study (n = 37, InterStim Micro): 62% expressed regret, 96% reported charging challenges, 86% connectivity issues; modest continence improvement below expectations. Non-rechargeable systems with extended battery life may be the preferable first-line option.[11]

Neurogenic Bladder​

  • Meta-analysis (n = 573): significant improvement in voiding frequency, leakage, nocturia, compliance, max detrusor pressure.[21]
  • Pooled test-stimulation success 66.2%; permanent SNM success 84.2%.[22]
  • AUA/SUFU NLUTD: Conditional Recommendation (Grade C) in select patients with SUI and acceptable storage.[44]
  • Progressive neurological disease is generally a contraindication.[45]
  • Early bilateral SNM during spinal shock may prevent subsequent neurogenic detrusor overactivity (long-term data pending).[45]

Guideline Recommendations​

SocietyRecommendation
AUA/SUFU (OAB 2024)[17]Offer SNM for inadequate response to pharmacotherapy; may offer without prior medication failure
ASCRS (FI 2023)[9]First-line surgical option after failed conservative treatment, with or without sphincter defects
ACOG (FI 2019)[46]Consider for women with FI failing conservative treatment, irrespective of sphincter integrity
ACG (Anorectal 2021)[33]Recommended for FI refractory to medical therapy
AUA/SUFU (NLUTD 2021)[44]Conditional recommendation in select neurogenic patients
EAU (Female LUTS)[47]SNM and OnaBT both second-line options; choice guided by individual factors

Competitive Landscape​

  • Axonics (now Boston Scientific) — rechargeable SNM with full-body MRI compatibility, manufacturer-reported ≥ 15-yr battery life. ARTISAN-SNM pivotal: 90% responder rate at 6 mo.[48][49]
  • Medtronic InterStim X — non-rechargeable extended-battery generation positioned against Axonics' recharge-free era.
  • BetterStim (China) — comparable efficacy to InterStim for OAB.[50]

See also: Axonics SNM System, PTNS Systems, Altaviva, Revi System, eCoin.

References​

1. Noblett KL, Buono K. Sacral Nerve Stimulation as a Therapy for Patients With Refractory Voiding and Bowel Dysfunction. Obstetrics and Gynecology. 2018;132(6):1337-1345. doi:10.1097/AOG.0000000000002968

2. Noblett KL, Cadish LA. Sacral Nerve Stimulation for the Treatment of Refractory Voiding and Bowel Dysfunction. American Journal of Obstetrics and Gynecology. 2014;210(2):99-106. doi:10.1016/j.ajog.2013.07.025

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

4. Schmidt RA. The Winding Path to Sacral Foramen Neural Modulation: A Historic Chronology. International Urogynecology Journal. 2010;21 Suppl 2:S431-S438. doi:10.1007/s00192-010-1272-4

5. Spinelli M, Sievert KD. Latest Technologic and Surgical Developments in Using InterStim Therapy for Sacral Neuromodulation: Impact on Treatment Success and Safety. European Urology. 2008;54(6):1287-1296. doi:10.1016/j.eururo.2008.01.076

6. Hetzer FH. Fifteen Years of Sacral Nerve Stimulation: From an Open Procedure to a Minimally Invasive Technique. Colorectal Disease. 2011;13 Suppl 2:1-4. doi:10.1111/j.1463-1318.2010.02517.x

7. Daikh A, Reymond F, Lombardo D, et al. Retrospective Study of Sacral Neuromodulator Implantations: Lifespan and Hospital Costs Assessment. International Journal of Colorectal Disease. 2023;38(1):273. doi:10.1007/s00384-023-04569-5

8. Committee on Practice Bulletins—Gynecology. ACOG Practice Bulletin No. 210: Fecal Incontinence. Obstetrics and Gynecology. 2019;133(4):e260-e273. doi:10.1097/AOG.0000000000003187

9. 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. Diseases of the Colon and Rectum. 2023;66(5):647-661. doi:10.1097/DCR.0000000000002776

10. De Wachter S, Knowles CH, Elterman DS, et al. New Technologies and Applications in Sacral Neuromodulation: An Update. Advances in Therapy. 2020;37(2):637-643. doi:10.1007/s12325-019-01205-z

11. Okocha M, La Raja C, Nikolaou S, et al. Outcomes of Rechargeable Sacral Neuromodulation for Faecal Incontinence: A Single-Centre Observational Study. Colorectal Disease. 2025;27(12):e70344. doi:10.1111/codi.70344

12. Karrer-Warzinek E, Abt D, Kim OC, et al. Safety of Magnetic Resonance Imaging in Patients Under Sacral Neuromodulation With an InterStim Neuromodulator. Urology. 2021;154:115-119. doi:10.1016/j.urology.2021.03.013

13. Guzman-Negron JM, Pizarro-Berdichevsky J, Gill BC, Goldman HB. Can Lumbosacral Magnetic Resonance Imaging Be Performed Safely in Patients With a Sacral Neuromodulation Device? The Journal of Urology. 2018;200(5):1088-1092. doi:10.1016/j.juro.2018.05.095

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

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

16. Martin S, O'Connor AD, Selvakumar D, et al. The Long-Term Outcomes of Sacral Neuromodulation for Fecal Incontinence: A Single-Center Experience. Diseases of the Colon and Rectum. 2024;67(1):129-137. doi:10.1097/DCR.0000000000002937

17. Cameron AP, Chung DE, Dielubanza EJ, et al. The AUA/SUFU Guideline on the Diagnosis and Treatment of Idiopathic Overactive Bladder. The Journal of Urology. 2024;212(1):11-20. doi:10.1097/JU.0000000000003985

18. Fu J, Li Z, Pu J, et al. Advancing Women's Health: Innovative Applications of Sacral Neuromodulation in Pelvic Floor Dysfunctions. Archives of Gynecology and Obstetrics. 2025. doi:10.1007/s00404-025-08182-5

19. 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. Scientific Reports. 2017;7(1):11031. doi:10.1038/s41598-017-11062-x

20. Wehbe SA, Whitmore K, Ho MH. Sacral Neuromodulations for Female Lower Urinary Tract, Pelvic Floor, and Bowel Disorders. Current Opinion in Obstetrics & Gynecology. 2010;22(5):414-419. doi:10.1097/GCO.0b013e32833e49d7

21. Sun P, Song W. A Meta-Analysis on the Efficacy and Safety of Sacral Neuromodulation for Neurogenic Bladder or Bowel Dysfunction. Neuromodulation. 2025;28(5):727-736. doi:10.1016/j.neurom.2024.11.004

22. van Ophoven A, Engelberg S, Lilley H, Sievert KD. Systematic Literature Review and Meta-Analysis of Sacral Neuromodulation in Neurogenic Lower Urinary Tract Dysfunction: Over 20 Years' Experience. Advances in Therapy. 2021;38(4):1987-2006. doi:10.1007/s12325-021-01650-9

23. Thaha MA, Abukar AA, Thin NN, Ramsanahie A, Knowles CH. Sacral Nerve Stimulation for Faecal Incontinence and Constipation in Adults. Cochrane Database of Systematic Reviews. 2015;(8):CD004464. doi:10.1002/14651858.CD004464.pub3

24. Rice TC, Quezada Y, Rafferty JF, Paquette IM. Percutaneous Nerve Evaluation Versus Staged Sacral Nerve Stimulation for Fecal Incontinence. Diseases of the Colon and Rectum. 2016;59(10):962-967. doi:10.1097/DCR.0000000000000668

25. Marcelissen T, Leong R, Serroyen J, van Kerrebroeck P, de Wachter S. Is the Screening Method of Sacral Neuromodulation a Prognostic Factor for Long-Term Success? The Journal of Urology. 2011;185(2):583-587. doi:10.1016/j.juro.2010.09.103

26. Lee W, Artenstein D, Tenggardjaja CF, et al. Single Institutional Experience With Single Stage Sacral Neuromodulation: Cost Savings and Outcomes. The Journal of Urology. 2020;203(3):604-610. doi:10.1097/JU.0000000000000576

27. Sun AJ, Harris CR, Comiter CV, Elliott CS. To Stage or Not to Stage? — A Cost Minimization Analysis of Sacral Neuromodulation Placement Strategies. Neurourology and Urodynamics. 2019;38(6):1783-1791. doi:10.1002/nau.24075

28. Bretschneider CE, Sheyn D, Lanki N, Volpe L, Gupta A. Device-Related Reoperations 8 Years Following Sacral Neuromodulation Implantation in Older Women. International Urogynecology Journal. 2024;35(12):2349-2355. doi:10.1007/s00192-024-05891-4

29. Siegel S, Noblett K, Mangel J, et al. Five-Year Followup Results of a Prospective, Multicenter Study of Patients With Overactive Bladder Treated With Sacral Neuromodulation. The Journal of Urology. 2018;199(1):229-236. doi:10.1016/j.juro.2017.07.010

30. Siegel S, Noblett K, Mangel J, et al. Three-Year Follow-Up Results of a Prospective, Multicenter Study in Overactive Bladder Subjects Treated With Sacral Neuromodulation. Urology. 2016;94:57-63. doi:10.1016/j.urology.2016.04.024

31. 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. The Journal of Urology. 2007;178(5):2029-2034. doi:10.1016/j.juro.2007.07.032

32. Al-zahrani AA, Elzayat EA, Gajewski JB. Long-Term Outcome and Surgical Interventions After Sacral Neuromodulation Implant for Lower Urinary Tract Symptoms: 14-Year Experience. The Journal of Urology. 2011;185(3):981-986. doi:10.1016/j.juro.2010.10.054

33. Wald A, Bharucha AE, Limketkai B, et al. ACG Clinical Guidelines: Management of Benign Anorectal Disorders. American Journal of Gastroenterology. 2021;116(10):1987-2008. doi:10.14309/ajg.0000000000001507

34. Desprez C, Damon H, Meurette G, et al. Ten-Year Evaluation of a Large Retrospective Cohort Treated by Sacral Nerve Modulation for Fecal Incontinence: Results of a French Multicenter Study. Annals of Surgery. 2022;275(4):735-742. doi:10.1097/SLA.0000000000004251

35. Amundsen CL, Richter HE, Menefee SA, et al. OnabotulinumtoxinA vs Sacral Neuromodulation on Refractory Urgency Urinary Incontinence in Women: A Randomized Clinical Trial. JAMA. 2016;316(13):1366-1374. doi:10.1001/jama.2016.14617

36. Amundsen CL, Komesu YM, Chermansky C, et al. Two-Year Outcomes of Sacral Neuromodulation Versus OnabotulinumtoxinA for Refractory Urgency Urinary Incontinence: A Randomized Trial. European Urology. 2018;74(1):66-73. doi:10.1016/j.eururo.2018.02.011

37. Harvie HS, Amundsen CL, Neuwahl SJ, et al. Cost-Effectiveness of Sacral Neuromodulation Versus OnabotulinumtoxinA for Refractory Urgency Urinary Incontinence: Results of the ROSETTA Randomized Trial. The Journal of Urology. 2020;203(5):969-977. doi:10.1097/JU.0000000000000656

38. Peeters K, Sahai A, De Ridder D, Van Der Aa F. Long-Term Follow-Up of Sacral Neuromodulation for Lower Urinary Tract Dysfunction. BJU International. 2014;113(5):789-794. doi:10.1111/bju.12571

39. Eggers E, Crouss T, Beausang J, et al. Long-Term Outcomes of Sacral Nerve Stimulation on the Treatment of Fecal Incontinence: A Systematic Review. Neuromodulation. 2025;28(5):715-726. doi:10.1016/j.neurom.2024.06.504

40. Nanda R, Chen A, Hernandez N, et al. Factors Contributing to Sacral Neuromodulation Revision: A Single-Center Study. International Urogynecology Journal. 2026;37(3):741-747. doi:10.1007/s00192-025-06376-8

41. Gevelinger MM, Sanderson DJ, Jaworski E, Doyle PJ. Evaluation of Sacral Nerve Stimulation Device Revision and Explantation in a Single Center, Multidisciplinary Study. Neuromodulation. 2020;23(8):1201-1206. doi:10.1111/ner.13050

42. White WM, Mobley JD, Doggweiler R, Dobmeyer-Dittrich C, Klein FA. Incidence and Predictors of Complications With Sacral Neuromodulation. Urology. 2009;73(4):731-735. doi:10.1016/j.urology.2008.11.047

43. Cohen T, Huang Z, Aalami-Harandi A, et al. Revision Rates for Rechargeable Versus Non-Rechargeable Sacral Neuromodulation Devices in the Management of Overactive Bladder. Neurourology and Urodynamics. 2025;44(5):1031-1035. doi:10.1002/nau.70053

44. Ginsberg DA, Boone TB, Cameron AP, et al. The AUA/SUFU Guideline on Adult Neurogenic Lower Urinary Tract Dysfunction: Treatment and Follow-Up. The Journal of Urology. 2021;206(5):1106-1113. doi:10.1097/JU.0000000000002239

45. Panicker JN, Fowler CJ, Kessler TM. Lower Urinary Tract Dysfunction in the Neurological Patient: Clinical Assessment and Management. The Lancet Neurology. 2015;14(7):720-732. doi:10.1016/S1474-4422(15)00070-8

46. Committee on Practice Bulletins—Gynecology. ACOG Practice Bulletin No. 210: Fecal Incontinence. Obstetrics and Gynecology. 2019;133(4):e260-e273. doi:10.1097/AOG.0000000000003187

47. Farag F, Sakalis VI, Arteaga SM, et al. What Are the Short-Term Benefits and Potential Harms of Therapeutic Modalities for the Management of Overactive Bladder Syndrome in Women? European Urology. 2023;84(3):302-312. doi:10.1016/j.eururo.2023.05.014

48. Cohn JA, Kowalik CG, Kaufman MR, et al. Evaluation of the Axonics Modulation Technologies Sacral Neuromodulation System. Expert Review of Medical Devices. 2017;14(1):3-14. doi:10.1080/17434440.2017.1268913

49. McCrery R, Lane F, Benson K, et al. Treatment of Urinary Urgency Incontinence Using a Rechargeable SNM System: 6-Month Results of the ARTISAN-SNM Study. The Journal of Urology. 2020;203(1):185-192. doi:10.1097/JU.0000000000000458

50. Meng L, Tian Z, Zhang Y, et al. Sacral Neuromodulation for Overactive Bladder Using the InterStim and BetterStim Systems. Scientific Reports. 2022;12(1):22299. doi:10.1038/s41598-022-26267-y