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San Antonio--Initial encouraging results of sacral neuromodulation for interstitial cystitis may not hold up in the long term, according to a study from The Cleveland Clinic Foundation presented at the AUA annual meeting. The variable results raise questions about which patients may benefit best from the therapy and what the best techniques may be, but they don't preclude these urologists from offering sacral neuromodulation to these IC patients as a treatment option.
"We still offer this form of neuromodulation, but we inform them that it may only provide short-term benefit, and realistically, only 50% of patients will maintain a durable response," said Raymond Rackley, MD, co-section head of The Cleveland Clinic's Section of Voiding Dysfunction and Female Urology.
He and his team members currently regard sacral neuromodulation as part of multimodality treatment that includes in-stillations and medical therapy, not as a stand-alone therapy to be used when other therapies have failed.
Twenty-two of the 27 patients went on to implantation of the pulse generator after a successful testing phase on the basis of at least a 50% improvement in symptoms of pain, urgency, or frequency. Although some surgeons use test stimulation for a1-week trial period, the CCF team typically tests for 2 to 6 weeks to ensure that patients are able to get over a false positive or "honeymoon" period of response and to ensure a durable time period of the trial evaluation.
After a minimum follow-up of 3 months following placement of the pulse generator device, five devices were explanted-three for failure to maintain efficacy and two for infection. After a median follow-up of 10 months, four more devices were explanted for loss of efficacy, leaving 13 patients with the device. Excluding the two patients who had the devices explanted because of infection, 13 of 25 retained the device, yielding an objective success rate of 52%.
The team also looked at whether the devices were effective for patients who still had them by assessing their status with O'Leary-Sant Symptom and Problem Indices and Pelvic Pain and Urgency/Frequency questionnaires. For two of these patients, treatment was unsuccessful, yielding a symptom-based, subjective success rate of only 44%.
"Despite relatively high trial success of sacral nerve stimulation with progression to implantation, long-term follow-up revealed a significant decrease in clinical success," research fellow Ashwin Vaze, MD, who presented the results, told Urology Times.
Implications of the results
Some urologists experienced in implanting these devices in IC patients were surprised by the results and wondered whether testing was sufficient or whether lead migration occurred. Dr. Rackley said that the patients who had devices explanted had undergone multiple reprogramming events, that all patients who wanted the device explanted were advised to turn the device off for 1 to 2 weeks before making their final decision to be sure that the device wasn't effectively working for them, and that patients did, indeed, undergo radiography to check for lead migration when they complained of ineffective stimulation.
"We have an algorithm that ensures the localization was the same and that the efficacy did, in fact, fall. We've not seen extensive lead migration, which is consistent with other current reports. Even in our larger experience, lead migration is probably less than 1%," said Sandip Vasavada, MD, also a co-section head of the female urology group.
He suggested two ways to account for the unexpectedly low success rate. First, IC patients who come to The Cleveland Clinic for treatment typically have long-standing symptoms, have had many treatment failures, and may have had their disease longer than patients at other centers as reflected in the large number of referred end-stage IC patients who request and undergo a cystectomy.