Neuromodulation uses a mild electrical impulse on various nerves to help maintain appropriate nerve function in the bladder. Two different forms of neuromodulation are available: post-tibial nerve stimulation (Urgent PC® by Congentix Medical) and sacral or pudendal nerve stimulation (Interstim® by Medtronic). Both procedures are FDA and Medicare approved for urinary frequency, urgency, incontinence and overactive bladder. While not specifically approved for interstitial cystitis, they are frequently suggested for symptom management hence their inclusion as a Step Four treatment option in the AUA Guidelines.

In general, patients start with the least invasive and more affordable form of neuromodulation known as post tibial nerve stimulation (PTNS). Invented by Dr. Marshall Stoller (UCSF) in the early 1990’s, it uses an acupuncture needle inserted carefully at the SP6 point above the ankle bone. A nerve stimulation device (aka TENS unit) is then attached to the needle where it delivers a mild, electronic pulse to the nerve. The original protocol required that it be done for just 30 minutes, one day per week for up to ten weeks.

Post tibial nerve stimulation offers several benefits. It requires no surgery. The risk of adverse event is minimal. The cost of Urgent PC® is substantially less than the cost of a surgically implanted device. If found ineffective, treatment can be terminated without requiring an additional surgery.

If post tibial nerve stimulation is ineffective, a more aggressive, surgical approach may be considered. Interstim® requires two surgical procedures: a trial during which a lead is implanted on either the sacral or pudendal nerve and, if successful, an implantation of the stimulator device near the hip or upper buttock. With thousands of procedures now performed, patient reports have been very mixed. Hundreds have reported serious and/or life threatening side effects (i.e. MRSA infection at the implant site, changes in heart rhythm, etc.) to the FDA Maude Database while others have found success with the device.

Three Studies Consistently Find Unexpected Revisions and Removals

For the patient considering Interstim®, one of the key questions worth considering is how many surgeries, on average, a patient should expect over a period of time. Clearly, two would be required to implant and remove the device. In the past decade, however, patients have consistently reported two, three or more additional surgeries to revise the leads, add an additional implant unit and/or to replace batteries.

  • Dr. Ken Peters (Beaumont Hospital, Royal Oak MI) released the largest study to date from his large clinical population.  Of 407 implant patients followed in this study, 134 (33%) had at least one reoperation. 78/407 (19%) had revision surgery and 56/407 (14%) had their device removed.  The most common reason for reoperation was lack of efficiency or worsening symptoms. These patients were more often women than men, had a lower body mass index, had experienced more reprogramming events, had a higher proportion of interstitial cystitis and used hormone replacement therapy.
  • Clinicians in Seattle shared their results of a similar study. They reported that out of 142 patients, 55 (38.2 %) required reoperation for revision or removal of the device.(2)  Revisions were performed in 30 (21.1%) of patients, most commonly for mechanical failure of the device, battery replacement and/or pain with stimulation or at the surgical site. Of those 30 who underwent revision, 14 had successful results, 6 had persistent symptoms and 10 progressed to device removal.  Device removal (aka explantation) occurred in 35 out of 142 patients (24.6%) due to poor symptom control. They did not find any consistent predictors for device failure or removal.
  • Researchers at UCLA found that surgical revisions were required in 24% of patients and that an additional 26% had their devices removed.(3)

While no national data has been released, as yet, by Medtronic, it’s crystal clear that Interstim patients do experience a significant risk of adverse event, additional surgeries and/or device removal. Of major concern are the many reports of infection at the surgical site, including MRSA infections. Some have suggested that the location of the surgical site (i.e. upper buttock) is more prone to bacterial contamination due to proximity to the rectum. In contrast,  only two adverse event reports have been reported to the FDA for Urgent PC.

Proactive Patients Must Ask For Data Before Surgery

Patients considering either form of neuromodulation should ask their clinician about their experience level, success and failure rates.  Here are some sample questions


  • How long has your clinic offered PTNS?
  • Who will be doing the procedure? Nursing staff? Physician?
  • How many weeks will be required?
  • What side effects have you noticed?
  • What success rates have you experienced?
  • What failures or complications have you seen?
  •  Will this be covered by insurance?
  • If I change or lose my health insurance, will you still provide treatment?

For Interstim:

  • How many implantation procedures have you done?
  • What training have you received for the care and maintenance of this device?
  • What complications have you experienced in patients during both trial and implant procedures?
  • Were those complications all resolved?
  • How often have your InterStim® patients required additional revision surgeries?
  • How often have your InterStim® patients required explantation (removal)?
  • When doing an explantation, have you encountered any difficulties in removing either the leads or the unit? If so, how did you resolve these?
  • Have any of your patients experienced side effects which persisted after explantation?
  • Have any of your patients developed infections at the surgery sites?
  • Who will I be working with if my device needs reprogramming?
  • Who will I see for care if you are not available?
  • Who should I contact if my device malfunctions?
  • Will you provide care for me if I lose my health insurance? If not, who would treat me?

Budget conscious patients should anticipate that additional surgeries may be needed. They should ask their insurance company if they will cover additional surgeries, not only if the device is malfunctioning but also if they would like to remove the device. One patient reported to our office that their insurance company refused to pay for explant surgery unless the patient was suffering a severe/life threatening complication.


If you’re considering either device and/or are currently looking for success stories and/or failure reports for your research, please visit the ICN Forum. You’ll find four message boards dedicated to neuromodulation including:


  1. Peters KM, et al. Predictors of reoperation after sacral neuromodulation: A single institution evaluation of over 400 patients. Neurourol Urodyn. 2015 Nov 20.
  2. . Shih, C, et al. Reoperation after sacral neuromodulation therapy: a single-institution experience. Female Pelvic Med Reconstr Surg. 2013 May-Jun;19(3):175-8.
  3. Yazdany T, et al. Determining outcomes, adverse events, and predictors of success after sacral neuromodulation for lower urinary disorders in women. Int Urogynecol J. 2011 Dec;22(12):1549-54.