Bilateral caudal epidural neuromodulation for refractory urinary retention: a salvage procedure

PURPOSE: Sacral neuromodulation with InterStim is approved for idiopathic urinary retention with a success rate of approximately 69%. To our knowledge currently no alternatives exist for patients in whom S3 neuromodulation fails. We report a new technique and our experience with bilateral caudal epidural neuromodulation in patients in urinary retention in whom unilateral or bilateral S3 InterStim failed. MATERIALS AND METHODS: Eight patients with multifactorial urinary retention in whom S3 InterStim previously failed underwent retrograde placement of bilateral tined leads into the caudal epidural space for sacral nerve stimulation. Patients with a 50% or greater clinical response underwent stage 2 Synergy-Versitrel implantable pulse generator placement. Patients were evaluated with voiding diaries, the Urinary Distress Inventory Questionnaire short form, quality of life assessment, need for catheterization and post-void residual urine preoperatively, and 6 months after implantation. RESULTS: Five of the 8 patients experienced return of micturition and underwent placement of a permanent implantable pulse generator. At 6-month followup 4 of the 5 patients voided to completion. One patient improved more than 50% and now catheterizes once daily with a post-void residual urine of 200 cc. There was a significant decrease in obstructive symptoms on the Urinary Distress Inventory Questionnaire short form and improved overall quality of life. CONCLUSIONS: To our knowledge this is the first report of the use of bilateral caudal epidural neuromodulation for refractory urinary retention. This therapy can be successful in patients in whom prior InterStim therapy failed.     

Implant infection after two-stage sacral nerve stimulator placement

To report our experience with implant infection after two-stage sacral nerve stimulator placement. We reviewed the records of all patients who underwent implantation with a sacral nerve stimulator for the management of refractory cases of urge urinary incontinence, urinary frequency, and non-obstructive urinary retention. Baseline demographic data, interval to the development of infection, and the organism cultured are reported. After stage II neurostimulator placement, 5 out of 37 (13.5%) women required device removal for culture positive wound infections. Patients returned an average of 147.4 days after device implantation with evidence of infection. Infection occurred a minimum of 33 days, a median of 76 days, and a maximum of 461 days after sacral nerve stimulator implantation. The most common pathogen cultured was Staphylococcus aureus. After device removal, all patients resolved their infections. Two patients underwent uncomplicated reimplantation in the contralateral buttock 14 and 16 days after stimulator removal. The risk of infection after tined lead pretest and neurostimulator placement may be higher than previously observed in older techniques. Funding: This study did not receive independent funding.     

Complications and troubleshooting of sacral neuromodulation therapy

As evident from the authors' series, the complications of sacral neuromodulation have changed with the introduction of the tined lead and the placement of the generator over the back. In the earlier series, most complications were related to pain at the generator site, which was rare in the authors' series. The posterior location of the generator seems to be better tolerated than the anterior location, which could explain the rare need for revisions for pain at the generator site. Lead migration was observed in 8.4% of the original sacral neuromodulation study group series. This was seen rarely in the authors' series in either stage-one or stage-two revisions. As part of the routine work-up of patients who present with decreased function after a successful period response in stage two, the authors obtain a lateral radiograph of the sacrum; the authors have made the diagnosis of lead migration rarely (1/130; 0.6%). Spinelli and colleagues reported on the use of the tined lead in 15 patients, and observed no lead migration during either the screening period (average 38.8 days) or during follow-up of IPG implantation cases (average 11 months). The total infection rate in the whole series was 18/180 (10%), which was slightly higher than that reported by the sacral neuromodulation study group (6.1%). Revision rates for stage one and stage two were 12.2% and 20%, respectively. The revision rate in the original study group was 33.3%. Thus, with advancing technology, new problems may arise, but the implanting physician should be aware of the ways to evaluate and manage these complications and appropriately troubleshoot patients with suboptimal responses.     

New tined lead electrode in sacral neuromodulation: experience from a multicentre European study

The use of a new tined lead electrode for sacral neuromodulation (SNS) was evaluated in a European study including 127 patients with chronic voiding dysfunction. The tined lead can be implanted during the first stage of the SNS procedure, which makes a longer test period possible before implanting the pulse generator in a second stage. Implantation of the tined lead was performed under local anaesthesia in 89% of patients. Screening lasted on average 30 days. Screening with the tined lead was considered successful by the physicians in 77% of patients (n=72). In 74% of first stage patients (n=70), at least 50% improvement in the main symptoms versus baseline was obtained. This was sustained for up to 6 weeks. All of these patients received the pulse generator in a second stage. The outcome of this study supports the use of the tined lead electrode as a screening tool in SNS therapy.     

Latest technologic and surgical developments in using InterStim Therapy for sacral neuromodulation: impact on treatment success and safety

Objectives

This article accompanies a “surgery in motion” DVD on sacral neuromodulation (SNM) with InterStim™ Therapy, which visualizes the implantation of the InterStim II system. The article describes the technical and surgical developments of SNM and their impact on treatment success, safety, and patient's quality of life (QoL).

Methods

Relevant literature on SNM with regard to technical changes and related clinical outcomes has been reviewed.

Results

Since its introduction in the early 1990s, SNM has proven useful in the treatment of several types of chronic urinary (and bowel) dysfunction. Recent technical improvements in devices and, in particular, the introduction of the tined lead 5 yr ago made SNM progress from an elaborate, open-surgery, general anesthesia, one-stage implant procedure to a minimally invasive, local anesthesia, percutaneous technique in two stages. The permanent tined lead implant enables a longer patient testing period (minimum of 14 d recommended) and less lead migration. This has considerably reduced technical failures and improved the success rate of the test phase; the response rate was almost doubled to approximately 80%. These improvements also affected tolerability, resulting in increased QoL for the patient. The use of the recently introduced smaller implantable neurostimulator InterStim II seems to further improve patient comfort and makes the implant procedure for the physician easier and shorter. However, this must be further addressed in clinical studies.

Conclusions

SNM with InterStim Therapy using the tined lead offers an efficient treatment modality for patients in whom conservative treatment has failed.     

Predictors of success for first stage neuromodulation: motor versus sensory response

PURPOSE: We investigated whether intraoperative motor or sensory response is more predictive of successful sacral neuromodulation using the InterStim system. MATERIALS AND METHODS: A total of 35 patients with medically refractory frequency, urgency and urge incontinence were enrolled in the study. All patients underwent lead placement for quadripolar test stimulation under local anesthesia with intravenous sedation. Confirmation of correct lead placement was by observation of known motor and sensory responses that result from third sacral nerve stimulation. Motor and sensory responses were documented intraoperatively. Patients had a 1-week trial of stimulation, and those who had greater than 50% improvement in symptoms had placement of the implantable pulse generator. Those without at least 50% improvement in their symptoms had the quadripolar lead removed. RESULTS: Of the 35 patients enrolled 21 had successful quadripolar test stimulation and went on to permanent implantable pulse generator placement. Of the patients who had successful quadripolar test stimulation 95% demonstrated positive intraoperative motor response whereas only 21.4% of patients with unsuccessful quadripolar test stimulation demonstrated positive motor response. If only a positive sensory response was elicited, patients had only a 4.7% chance of having a positive quadripolar test stimulation. CONCLUSIONS: A positive quadripolar test stimulation (greater than 50% improvement in symptoms) with InterStim sacral neuromodulation is more likely when intraoperative lead placement results in positive motor response vs only sensory response.     

New sacral neuromodulation lead for percutaneous implantation using local anesthesia: description and first experience

PURPOSE: In functional urology today chronic stimulation of the sacral nerves has become one of the most accepted methods of stimulation treatment. Many studies have described the advantage of test stimulation prior to implanting the definitive system to enable effective patient selection. We studied a method aimed at improving lead anchoring by developing a self-blocking electrode with a simple placement procedure, in the process creating a 2-stage approach to full percutaneous implantation that allows a long screening period during the first temporary stimulation stage. MATERIALS AND METHODS: A new tined lead was specifically designed to allow minimally invasive percutaneous lead placement requiring no incision and no additional fascial anchoring. From September 2001 to November 2002, 15 consecutive patients (3 males and 12 females) 27 to 70 years old (mean age 49) underwent this procedure and were prospectively evaluated. No PNE test was performed. RESULTS: Following the first stage screening phase 12 patients were implanted with the implantable pulse generator (IPG), while 3 who did not respond positively to test stimulation (neurogenic voiding dysfunction, urge incontinence and neurogenic urge incontinence in 1 each) did not undergo IPG implantation and had the tined lead removed under local anesthesia. We did not observe any lead displacement during the screening period (average 38.8 days) or during followup of IPG implanted cases (average 11 months, range 5 to 19). CONCLUSIONS: Our results show that the new tined anchoring system is a reliable way to allow truly minimally invasive placement of the chronic lead.     

New percutaneous technique of sacral nerve stimulation has high initial success rate: preliminary results

OBJECTIVE: We report on the new technique of sacral nerve stimulation in the treatment of voiding dysfunction. This new technique is characterized by percutaneous approach to the sacral nerves resulting in minimally invasiveness of the procedure and the ability to have patient awake during the electrode placement. METHODS: Since December 1999, we prospectively evaluated patients who underwent this novel percutaneous technique approach. Thirty-two patients (10 male, 22 female, mean age 43 years) were included and no complications were reported. Average follow-up time was 11 months (range 2-25 months).Main elements of the new technique are also described. The needle is inserted into the sacral foramen to a desired location (usually S3) and metal stylet is then inserted through the needle. With metal stylet only in the foramen, two dilators are successively inserted and the chronic lead is placed through the plastic dilator. Only a very small skin incision is necessary to allow the anchor fixation. RESULTS: Out of the 32 patients who underwent the percutaneous lead placement, 22 received the neurostimulator (IPG). Out of the remaining 10 patients, 4 are still in screening and 6 had unsuccessful results (<50% improvement) and therefore did not undergo the second stage (neurostimulator placement). From the 22 implanted patients, 20 reported 90% improvement in their primary voiding symptoms, 1 had an improvement between 50 and 70% and 1 patient was explanted due to IPG damage following magnetic resonance imaging. There were total of four lead displacements, two occurred where the silicone anchoring was used and the other two occurred when no anchoring was done. CONCLUSION: Success rate of this technique in selecting patients for the permanent implant is significantly higher than currently reported in the literature. Very beneficial clinical outcome of the implanted patients confirms better patient selection with no complications. Our experience with this technique shows the feasibility of percutaneous lead placement with major advantages such as: (1) use of local anesthesia and possibility to test sensitive responses during implant, (2) the possibility for more accurate patient selection by using the definitive lead for a longer test period before proceeding with the neurostimulator (IPG) implant.The presented percutaneous technique requiring fascial lead fixation represents a safe and effective method of Sacral Neuromodulation Therapy.     

Sacral nerve root stimulation for lower urinary tract dysfunction: overcoming the problem of lead migration

OBJECTIVE: To evaluate lead migration for two different test electrodes and the response to trial stimulation of the S3 nerve root during the selection of patients for a sacral neuromodulation implant to manage lower urinary tract dysfunction. PATIENTS AND METHODS: Twelve women (mean age 49 years, range 23-79; seven with detrusor instability and five with sensory urgency) undergoing peripheral nerve evaluation for refractory lower urinary tract symptoms were recruited. Urodynamics and a urinary diary were completed before and during test stimulation. Two electrodes (the original 041830-002 and new 3057 models, Medtronics Inc, USA) were inserted under local anaesthesia into the S3 nerve roots bilaterally. The location was determined by the functional response to stimulation. Stimulation was applied for one week using the new lead; a positive response was defined as a subjective improvement (> 50%) in urinary symptoms. Lateral sacral X-rays were taken after placement and before removing the lead. The distance from the lead tip to the ventral aspect of the S3 sacral foramen was measured by two assessors. RESULTS: Ten of the women had a positive response; the mean (range) migration of the new lead (on X-ray) was 4 (2-11) mm, and of the old lead was 12 (10-45) mm (P = 0.02). CONCLUSION: The response rate to trial stimulation was greater than in previous studies, possibly reflecting reduced migration of the new lead. The new electrode may reduce the number of test failures caused by lead migration rather than no response.     

Preliminary results of sacral neuromodulation in 23 children

PURPOSE: Sacral nerve stimulation with InterStim is approved in the United States for use in adults. Limited data on the effectiveness of sacral nerve stimulation in children are available. We report our experience with patients who underwent InterStim placement for the treatment of severe dysfunctional elimination syndrome, which is defined as a constellation of functional urinary and gastrointestinal symptoms in patients without anatomical anomalies or obvious neurological disease, in whom intensive medical and behavioral therapies have failed to improve symptoms. MATERIALS AND METHODS: A total of 23 patients 6 to 15 years old with presenting symptoms of dysfunctional voiding, enuresis, incontinence, urinary tract infections, bladder pain, urinary retention, urgency, frequency, constipation and/or fecal soiling were followed for a mean of 13.3 months after InterStim placement. RESULTS: Of the 19 patients with urinary incontinence 3 (16%) had complete resolution, 13 (68%) had improvement, 2 (11%) were unchanged and 1 (5%) was worse (sign test, p = 0.002). Among the 16 patients with nocturnal enuresis 2 (13%) had resolution, 9 (56%) improved, 4 (25%) were unchanged and 1 (6%) was worse (sign test, p = 0.0063). Of the 15 patients with urinary retention requiring intervention 9 (60%) had improvement and 1 had worsening symptoms (sign test, p = 0.022), while 2 of 6 patients (33%) on intermittent catheterization were able to stop. One patient had development of new incontinence and enuresis. Bladder pain, urgency, frequency and constipation improved in 67% (8 of 12), 75% (12 of 16), 73% (11 of 15) and 80% (12 of 15) of the patients, respectively. Medications required postoperatively decreased by an average of 3 per patient (p < 0.001). The overall patient satisfaction rate was 64%, while that of the caregiver was 67%. Two leads were explanted from the 23 patients. Complications encountered included 1 seroma, 1 episode of skin sensitivity, 2 device failures and 1 lead revision. CONCLUSIONS: Sacral nerve stimulation in children is an option for carefully selected patients who have failed other therapies. Our results show that sacral nerve stimulation was effective in the majority of patients with the dysfunctional elimination syndrome. However, longer followup is needed.     

A prospective, single-blind, randomized crossover trial of sacral vs pudendal nerve stimulation for interstitial cystitis

OBJECTIVE: To compare sacral nerve stimulation (SNS) with pudendal nerve stimulation (PNS) for interstitial cystitis (IC). PATIENTS AND METHODS: Twenty-two patients with well-documented, refractory IC had a tined lead placed at S3 and a second electrode implanted at the pudendal nerve via a posterior approach. In a blinded, randomized design, each lead was tested for 7 days. The best lead was implanted to a pulse generator and patients were followed at 1, 3 and 6 months. RESULTS: The time required to place a sacral lead was 27.4 min, and a pudendal lead 19.6 min (P = 0.039). Of the 22 patients, 17 (77%) responded and had a permanent implant placed. PNS was chosen as the better lead in 77% and SNS in 24%. The order in which the lead was stimulated had no effect on the final lead implanted and there was no 'carry-over' effect. The overall reduction in symptoms was 59% for PNS and 44% for SNS (P = 0.05). At 6 months after implantation, voids improved by 41% (PNS) and 33% (SNS), and mean voided volume increased 95% and 21%, respectively; validated IC questionnaires improved markedly and complications were minimal. CONCLUSIONS: This is the first 'blinded' study of SNS vs PNS for IC. A pudendal lead was implanted successfully in all patients, and most chose PNS as better than SNS; the improvement was sustained over time.     

Computed tomography-guided S3 lead placement for sacral neuromodulation

Computed tomography (CT)-guided lead placement for sacral neuromodulation was used in a patient with arthritis and narrow S3 foramina. Bilateral S3 foramina were localized and guide needles were placed with CT guidance. Lead placement was further modified by placement of a tined, quadripolar lead through a dilated S3 tract without initial somatosensory testing. The lead was then interrogated to assess placement and to differentiate superiority of response between two leads. The patient has had greater than 50 % improvement in urinary symptoms by voiding diary. Using CT guidance, satisfactory localization of bilateral S3 foramina may be achieved where prior attempts with conventional fluoroscopy have failed.     

Computer-guidance in percutaneous screw stabilization of the iliosacral joint

Nine patients with instability and one patient with degeneration of the iliosacral joint were treated surgically. The posterior pelvic ring was stabilized with the assistance of an optoelectronic navigation system. Registration was ensured by using fiducial screws in the iliac crest or by collecting landmarks on the external fixator. Computed tomography scans taken postoperatively provided additional information regarding implant localization in all patients. Accurate placement of 21 of 22 implanted iliosacral screws was observed. Two of the 21 screws touched the wall of the second sacral foramen without perforating the canal. One screw perforated the anterior wall of the sacrum because the navigated guide wire was bent during implantation. The initial results indicate that computer-aided frameless navigation in surgery of the iliosacral joint can facilitate surgical performance during screw stabilization in selected patients. Two important issues must be considered in the clinical application of this technique: first, any relative migration of the iliac and sacral bone structures between computed tomography scans taken preoperatively and intraoperative navigation may result in an intolerable inaccuracy of computer guidance. Second, bending of the guide wire of the tracked power drive, which cannot be accommodated by the navigation system, will lead to misguidance; therefore, only navigated drill sleeves should be used.     

Canadian experience in sacral neuromodulation

The application of sacral nerve modulation and stimulation has gained wide acceptance asa tool to enhance the control of voiding. The simplicity of the technique has made the therapy appealing for refractory cases of voiding dysfunction. The percutaneous screening test is mandatory for the success of the therapy. Long-term follow-ups have shown efficacy and safety inpatients with voiding dysfunction. Sacral nerve modulation is an effective modality in the treatment of various voiding and storage dysfunction. The tined lead offers a minimally invasive implant procedure. The simplicity of the procedure and the patient's sensory awareness help to ensure best lead placement. Furthermore, local anesthesia instead of general anesthesia allows faster patient recovery and reduces complications. Finally, sacral neuromodulation offers a modality in the management of patients with voiding dysfunction.     

Sacral versus pudendal nerve stimulation for voiding dysfunction: a prospective, single-blinded, randomized, crossover trial

AIMS: The objective of the study was to compare sacral nerve stimulation (SNS) to pudendal nerve stimulation (PNS) for voiding dysfunction. METHODS: Thirty subjects with voiding dysfunction had a tined lead placed at S3 and a second electrode implanted at the pudendal nerve via a posterior approach. In a blinded, randomized fashion, each lead was tested for 7 days. Voiding diaries and questionnaires were completed and outcomes monitored. RESULTS: The time to place a sacral lead was 25.85 min, pudendal lead 23.71 min (P = 0.57). Twenty-four of 30 (80%) subjects responded and had a permanent implant placed. PNS was chosen as a superior lead in 79.2%, SNS was superior in 20.8%. The order in which the lead was simulated had no impact on the final lead implanted and no carry over effect was seen. Overall reduction in symptoms was 63% for PNS and 46% for SNS (P = 0.02). On a 7-point scale from markedly worse to markedly better, the pudendal lead was superior to sacral for pelvic pain (P = 0.024), urgency (P = 0.005), frequency (P = 0.007), and bowel function (P = 0.049). Complications were minimal. CONCLUSIONS: This is the first blinded study of sacral versus pudendal stimulation for voiding dysfunction. Successful implantation of a pudendal lead was achieved in all subjects. The majority of subjects chose PNS to be superior to SNS. More patients and longer term data is needed to confirm these promising results.     

Long-term effectiveness of sacral nerve stimulation for refractory urge incontinence

OBJECTIVES: To evaluate the long-term efficacy of sacral nerve stimulation for refractory urinary urge incontinence. STUDY DESIGN AND METHODS: Urge incontinent patients qualified for surgical implantation of a neurostimulator system after trial screening with percutaneous test stimulation. Surgical implantation of the InterStim System (Medtronic Inc., Minneapolis, Minn., USA) was performed in cases where a >50% reduction in incontinence symptoms was documented during the 3- to 7-day test stimulation period. The InterStim System consists of an implantable pulse generator, a transforamenally placed quadripolar lead, and an extension that connects these two devices for unilateral stimulation of the S3 or S4 sacral nerve. Efficacy for 96 implanted patients was based on urinary symptom changes as quantified in voiding diaries collected at baseline and annually after surgical implantation. RESULTS: As compared to baseline, the group of 96 implanted patients demonstrated significant reductions in urge incontinent symptoms at an average of 30.8+/-14.8 (range 12-60) months with respect to the number of urge incontinent episodes per day, severity of leaking, and the number of absorbent pads/diapers replaced per day due to incontinence (all p<0.0001, respectively). Gender, pretreatment variables, and age were not found to be relevant factors that affected these results. 11 of the 96 patients underwent device explant due to lack of efficacy, pain or bowel dysfunction. These data were conservatively included in the efficacy results. No permanent injuries associated with the devices or therapy were reported. CONCLUSION: Sacral nerve stimulation is an effective treatment for refractory urge incontinence with sustained long-term benefit through an average of 30.8 months.     

A novel three‐dimensional printed guiding device for electrode implantation of sacral neuromodulation

Aim

The aim was to test the feasibility of a novel three‐dimensional (3D) printed guiding device for electrode implantation of sacral neuromodulation (SNM).

Method

A 3D printed guiding device for electrode implantation was customized to patients’ anatomy of the sacral region. Liquid photopolymer was selected as the printing material. The details of the device designation and prototype building are described. The guiding device was used in two patients who underwent SNM for intractable constipation. Details of the procedure and the outcomes are given.

Results

With the help of the device, the test needle for stimulation was placed in the target sacral foramen successfully at the first attempt of puncture in both patients. The time to implant a tined SNM electrode was less than 20 min and no complications were observed. At the end of the screening phase, symptoms of constipation were relieved by more than 50% in both patients and permanent stimulation was established.

Conclusion

The customized 3D printed guiding device for implantation of SNM is a promising instrument that facilitates a precise and quick implantation of the electrode into the target sacral foramen.     

下颈椎侧块螺钉固定与椎动脉、神经根的解剖关系及评价

目的　通过解剖学研究和影像学手段 ,了解下颈椎侧块螺钉固定与椎动脉之间的关系以及斜位片在置钉过程中对神经根的监测价值。方法　 (1)取 2 8具尸体的C3 ～C7标本 ,年龄 2 8～ 79岁。摄取标本各椎体的横断面片 ,测量X线片上C3 ～C7横突孔外缘与侧块背面中心内侧 1mm处的连线在横断面上与矢状轴之间的成角。 (2 )取 10具标本 ,以侧块背面中心点内侧 1mm处为入针点、横突与侧块相交处为出针点在C3 ～C6侧块内置入克氏针。当针尖未超出或超出侧块远侧皮质 2、4、6mm时 ,摄取标本左右 4 5°斜位片。把斜位片上椎间孔分为上、下两部分 ,上部实际是真正的椎间孔 ,下部则相当于横突间孔位置。观察针尖在斜位片上椎间孔内的位置并计数 ,同时与实际解剖比较两者的一致性。　结果　 (1)C3 ～C6横突孔外缘与侧块背面中心内侧 1mm处的连线在横断面上与矢状轴成外偏 5°～ 12°的角度 ,椎体间差别无统计学意义 (P >0 0 5 )。 (2 )以横突与关节突相交处为出针点 ,实际观察当针尖超出侧块远侧皮质 2mm时 ,未突入横突间孔 ;当超出距离为 4、6mm时 ,针尖则突入横突间孔。X片上显示当针尖未超出远侧皮质时 ,斜位片上有 15 %针尖出现于椎间孔下部 ;当针尖超出 2mm时 ,斜位片 4 1 3%针尖出现于椎间孔下部 ;当针尖超出 4mm     

Sacral neuromodulation decreases narcotic requirements in refractory interstitial cystitis

OBJECTIVE: To assess the efficacy of long-term sacral neuromodulation (InterStim(R), Medtronic Inc., Minneapolis, MN) in treating chronic pelvic pain associated with interstitial cystitis (IC, a symptom complex of urinary urgency, frequency and pelvic pain, often necessitating narcotics) refractory to standard therapy. PATIENTS AND METHODS: Twenty-one patients (17 female, four male, mean age 45.5 years, range 17-68) with refractory IC with chronic pelvic pain were reviewed retrospectively. In these patients a mean of six previous treatments for IC had failed. All patients had had cystoscopy and hydrodistension to confirm their diagnoses. All had a permanent InterStim device implanted by one surgeon (K.M.P.) between 2000 and 2002, after responding to a temporary test. Data were collected from chart reviews and patient questionnaires. Intramuscular morphine dose equivalents (MDEs) were calculated before and after implantation. RESULTS: All 21 patients responded to the questionnaire; the mean (range) follow-up after implantation was 15.4 (7.4-23.1) months. Eighteen patients used chronic narcotics before the InterStim and 20 reported moderate or marked improvement in pain afterward. The mean MDE decreased from 81.6 to 52.0 mg/day (36%) after implantation (P = 0.015). Four of 18 patients stopped all narcotics after InterStim implantation. CONCLUSIONS: Sacral neuromodulation decreases narcotic requirements and subjective pelvic pain in patients with refractory IC. Further decreases in MDE are anticipated as dose reductions continue in patients who improved.     

Efficacy of sacral nerve stimulation for urinary retention: results 18 months after implantation

PURPOSE: We investigate the efficacy of sacral neurostimulation in patients with idiopathic urinary retention in a prospective, randomized multicenter trial. MATERIALS AND METHODS: A total of 177 patients with urinary retention refractory to standard therapy were enrolled in the study. Greater than 50% improvement in baseline voiding symptoms during a 3 to 7-day percutaneous test stimulation qualified a patient for surgical implantation of an InterStim parallel system. Of the patients who qualified for implantation 37 were randomly assigned to a treatment and 31 to a control group. Patients in the treatment group underwent early surgical implantation of the sacral nerve stimulation system, while implantation was delayed in the control group for 6 months. Followup evaluations, including voiding diary analysis and temporary deactivation of the stimulator at 6 months, were conducted at 1, 3, 6, 12 and 18 months after implantation in the treatment group, and after 3 and 6 months in the control group. RESULTS: Compared to the control group, patients implanted with the InterStim system had statistically and clinically significant reductions in the catheter volume per catheterization (p <0.0001). Of the patients treated with implants 69% eliminated catheterization at 6 months and an additional 14% had a 50% or greater reduction in catheter volume per catheterization. Therefore, successful results were achieved in 83% of the implant group with retention compared to 9% of the control group at 6 months. Temporary inactivation of sacral nerve stimulation therapy resulted in a significant increase in residual volumes (p <0.0001) but effectiveness of sacral nerve stimulation was sustained through 18 months after implant. CONCLUSIONS: Results of this prospective, randomized clinical study demonstrate that sacral nerve stimulation is effective for restoring voiding in patients with retention who are refractory to other forms of treatment.