Latest Technologic and Surgical Developments in Using InterStim™ Therapy for Sacral Neuromodulation: Impact on Treatment Success and Safety

Results of a prospective, randomized, multicenter study evaluating sacral neuromodulation with InterStim therapy compared to standard medical therapy at 6-months in subjects with mild symptoms of overactive bladder

AIMS

This prospective, randomized, multicenter trial evaluated the 6-month success rate of sacral neuromodulation (SNM) with InterStim® Therapy versus standard medical therapy (SMT) for overactive bladder (OAB).

METHODS

Enrolled subjects discontinued OAB medications prior to and during baseline data collection and were randomized 1:1 to SNM or SMT. Subjects had bothersome symptoms of overactive bladder (OAB) including urinary urge incontinence (≥2 leaks/72 hr) and/or urgency-frequency (≥8 voids/day). Subjects failed at least one anticholinergic medication, and had at least one medication not yet attempted. The primary objective was to compare OAB therapeutic success rate at 6 months between SNM and SMT.

RESULTS

Overall, 147 subjects were randomized (70 to SNM and 77 to SMT); 93% were female and mean age was 58. The primary intent to treat analysis showed OAB therapeutic success was significantly greater in the SNM group (61%) than the SMT group (42%; P = 0.02). In the as treated analysis, OAB therapeutic success was 76% for SNM and 49% for SMT (P = 0.002). The SNM group showed significant improvements in quality of life versus the SMT group (all P < 0.001) and 86% of SNM subjects reported improved or greatly improved urinary symptom interference score at 6 months, compared to 44% for SMT subjects. The device-related adverse event rate was 30.5% and the medication-related adverse event rate was 27.3%.

CONCLUSIONS

This study demonstrates superior objective and subjective success of SNM compared to SMT. SNM is shown to be a safe and effective treatment for OAB patients with mild to moderate symptoms. Neurourol. Urodynam. 34:224-230, 2015. © 2014 Wiley Periodicals, Inc.

Long-term efficacy of electrical pudendal nerve stimulation for urgency-frequency syndrome in women

INTRODUCTION AND HYPOTHESIS

Electrical pudendal nerve stimulation (EPNS) was developed by combining the advantages of pudendal neuromodulation (PNM) and percutaneous tibial nerve stimulation (PTNS) and incorporating the technique of deep insertion of long acupuncture needles. The purpose of this study is to show the long-term efficacy of EPNS in treating urgency-frequency syndrome (UFS) in women.

METHODS

One hundred and six consecutive female UFS patients were enrolled and treated with EPNS. Long acupuncture needles were deeply inserted into four sacral points and electrified to stimulate the pudendal nerves. Evaluation of therapeutic effects was based on a questionnaire (including questions on storage, voiding, and postmicturition symptoms). Patients with ≥50 % posttreatment symptom improvement were followed up for at least 60 months.

RESULTS

Complete resolution and ≥50 % improvement rate were 42.5 % and 85.8 %, respectively, in the 106 patients after a mean of 21.2 sessions of EPNS treatment. Of the 91 patients with ≥50 % posttreatment improvement, 62 (29 with complete resolution, 15 with marked improvement, and 18 with moderate improvement) were available for follow-up at 60-126 (mean 99.5; median 98) months after the end of EPNS treatment. Of these 62 patients, 35 maintained the posttreatment effect, 18 changed from better to complete resolution, and seven changed back to <50 % improvement; only four of whom changed to <25 % improvement.

CONCLUSIONS

EPNS combines the advantages of PNM (better effect) and PTNS (minimally invasive, easily applicable, and well tolerated) in treating UFS. It has a good long-term therapeutic effect on UFS in women.

Urodynamic studies in spinal cord tethering

INTRODUCTION

Tethered cord syndrome (TCS) is of particular interest to urologists through its effects on the function of the lower urinary tract. Tethering of the spinal cord can result in bladder dysfunction with multiple manifestations, clinically raging from urinary retention and detrusor under-activity to urinary incontinence, over-activity of the detrusor, and sphincter dysfunction. Goals of management include protecting renal function and preserving patient quality of life.

METHODS

Evaluation of a TCS patient with urinary complaints begins with a thorough history and physical examination. Further characterization of urinary symptoms with a voiding diary provides vital information that helps to direct treatment while engaging the patient and family in the treatment plan. Urodynamic studies then provide key diagnostic data regarding bladder function, bladder outlet resistance, and urinary sphincter function. In the pediatric population, particular care must be paid to counseling patients and their families prior to the procedure to alleviate the often-considerable anxiety associated with an invasive procedure.

CONCLUSION

The armamentarium for management of neurogenic bladder associated with TCS includes behavioral training, biofeedback therapy, medications, patient-performed procedures, and surgical intervention. The choice of intervention depends on the patient's symptoms, urodynamic findings, and patient and family preferences. The primary problem of TCS should be addressed first through detethering, and then the urological team can use progressively more aggressive therapies as necessary. Interpretation and treatment by a dedicated, specialized, multidisciplinary team that includes the pediatric urologist, pediatric neurosurgeon and dedicated nurse practitioner, is critical for successful treatment.

Sacral nerve stimulation for urinary dysfunction: the first year of the Scottish national service

Sacral nerve stimulation (SNS) has become an established treatment option for patients with intractable detrusor overactivity and non-obstructive urinary retention. The Scottish Sacral Nerve Stimulation service was established in April 2010 to provide a service for the population of Scotland. We report our experience from the first year of this new national service. All patients referred for SNS from the inception of the service in April 2010 until the end of March 2011 were studied. During the one-year period, there were 50 referrals. Thirty-three percutaneous nerve evaluations, eight tined lead tests and 16 permanent implantation procedures were performed during this period. Morbidity was low and both incontinence and quality-of-life questionnaires demonstrated statistically significant improvements (International Consultation on Incontinence Questionnaire [ICIQ-SF], P = 0.005; Incontinence Impact Questionnaire [IIQ 7], P = 0.0007; Urogenital Distress Inventory [UDI 6], P = 0.0002). Referral pattern was skewed towards the west of Scotland with some health boards producing no referrals during the year. Results from the first year of the service have shown that it is a safe and efficient procedure with significant improvement in incontinence, voluntary voiding and quality-of-life parameters. The limitation of funding for permanent implants inevitably impacts on the role of the technique as a management option in these patients.

Optimizing the duration of assessment of stage-1 sacral neuromodulation in nonobstructive chronic urinary retention

OBJECTIVES

The duration of test stimulation using two-stage sacral neuromodulation (SNM) is not studied. This study will determine the restoration of normal bladder sensation and resultant voiding in chronic urinary retention (CUR) after stage-1 SNM.

MATERIALS AND METHODS

Two-stage SNM used in 24 female patients with CUR. After stage-1 SNM, patients were assessed over an eight-week period and asked to record the restoration of normal bladder sensation and voiding. Qualitative and quantitative statistics were used to assess the outcomes and the influence of prognostic factors.

RESULTS

The mean age of patients was 37.0 ± 9.7 years. Normal bladder sensation was restored on the same day as switching on the battery after stage-1 in seven patients (29.2%), while in 17 patients it occurred between day 2-31 (mean: nine days). Similarly, the mean onset of voiding was also nine days (range: 2-31 days). After day 15, 21% of patients voided. The mean lag time between the restoration of bladder sensation and voiding was 3.6 days. By day 17, a cumulative percentage of 90% of patients had a normalized bladder sensation and 80% had commenced voiding. Infection of the externalized lead occurred in only one case. There were no correlations between the outcome parameters with age (p > 0.05), symptom duration, or concomitant diagnosis of overactive bladder or chronic pelvic pain (p = 0.418, p = 0.114).

CONCLUSION

Stage-1 SNM may be left in situ for up to four weeks to ensure the maximum chance of restoring normal bladder function in this complex group of patients.

Real-time control of hind limb functional electrical stimulation using feedback from dorsal root ganglia recordings

OBJECTIVE

Functional electrical stimulation (FES) approaches often utilize an open-loop controller to drive state transitions. The addition of sensory feedback may allow for closed-loop control that can respond effectively to perturbations and muscle fatigue.

APPROACH

We evaluated the use of natural sensory nerve signals obtained with penetrating microelectrode arrays in lumbar dorsal root ganglia (DRG) as real-time feedback for closed-loop control of FES-generated hind limb stepping in anesthetized cats.

MAIN RESULTS

Leg position feedback was obtained in near real-time at 50 ms intervals by decoding the firing rates of more than 120 DRG neurons recorded simultaneously. Over 5 m of effective linear distance was traversed during closed-loop stepping trials in each of two cats. The controller compensated effectively for perturbations in the stepping path when DRG sensory feedback was provided. The presence of stimulation artifacts and the quality of DRG unit sorting did not significantly affect the accuracy of leg position feedback obtained from the linear decoding model as long as at least 20 DRG units were included in the model.

SIGNIFICANCE

This work demonstrates the feasibility and utility of closed-loop FES control based on natural neural sensors. Further work is needed to improve the controller and electrode technologies and to evaluate long-term viability.

Management of mixed urinary incontinence

Mixed urinary incontinence accounts for 33% of all incontinence and is the involuntary loss of urine associated with the sensation of urgency; it is also associated with exertion, sneezing or coughing. Risk factors include vaginal delivery, obesity, age and possible genetic factors. Treatment includes lifestyle changes, behavioral therapies, medication and nerve modulation. Surgery with midurethral slings can cure both stress and urge components in 40-50% of cases. Future therapies may include new medications adapting potassium and calcium channels and more widespread use of sacral neuromodulation. This review focuses on the investigation and optimal management of mixed urinary incontinence.

[Sacral neuromodulation for neurogenic bladder dysfunction]

Sacral neuromodulation (SNM) represents a promising option for managing treatment-refractory neurogenic bladder dysfunction. It remains to be seen, however, which types of neurogenic bladder dysfunction and which underlying neurological disorders best respond to SNM. Constant improvements in SNM have been achieved and it is now a minimally invasive approach performed under local anesthesia which should be considered before undertaking larger reconstructive procedures. An electrode is implanted in the S3 or S4 sacral foramen and during a test phase lasting for days to weeks the patient keeps a bladder diary to determine whether SNM has provided a relevant benefit. If the results of the test phase are positive, a neuromodulator is implanted in the gluteal area (or more rarely in the abdominal wall).The mechanism of action of SNM has not been completely clarified, but the afferent nerves most likely play a key role. It appears that SNM produces a modulation of medullary reflexes and brain centers by peripheral afferents. The implanted neuromodulation system does not lead to limitation of the patient's activities. However, it should be noted that high-frequency diathermy and unipolar electrocauterization are contraindicated in patients with neuromodulators, that during extracorporeal shock wave lithotripsy the focal point should not be in the direct vicinity of the neuromodulator or the electrode, that ultrasound and radiotherapy in the region of the implanted components should be avoided, that the neuromodulation should be discontinued in pregnancy, and that MRI examinations should only be conducted when urgently indicated and the neuromodulator is turned off.

Improved sexual and urinary function in women with sacral nerve stimulation

OBJECTIVES

  Urinary and sexual function improve following sacral nerve stimulation (SNS) for refractory overactive bladder. No significant associations between these changes have been found. Whether improvements in sexual function are independent of or secondary to improvements in urinary function remains unclear. The aim of this study was to analyze changes in urinary and sexual function in a homogeneous sample of patients undergoing SNS for urge urinary incontinence and subsequently identify associations between the two.

MATERIALS AND METHODS

  A prospective database was created. Enrollees underwent a full history and physical examination at the first office visit. Multiple-day voiding diaries with validated and investigator-designed questionnaires were administered at baseline and follow-up as standard implantation procedures and to assess changes in urinary and sexual function, respectively. Analyses were completed using data from patients who were sexually active at baseline and follow-up.

RESULTS

  Statistically significant improvements in urinary and sexual function occurred according to multiple metrics. Patient global impression scales categorized all patients' urinary conditions as improved, with most being less severe. Validated urinary symptom and quality of life scores improved significantly. After treatment, most patients were incontinent less often with sexual activity and felt less restricted from sexual activity by fear of incontinence. Validated quantification of sexual function demonstrated significant improvements in overall sexual function, arousal, and satisfaction. No significant associations between changes in urinary and sexual function were noted; however, trends appeared to exist between the two.

CONCLUSIONS

  Improved sexual function was not significantly associated with improved urinary function after SNS despite apparent trends between the two. Larger samples are required to definitively demonstrate this conclusion.

Sacral neuromodulation as treatment for refractory idiopathic urge urinary incontinence: 5-year results of a longitudinal study in 60 women

PURPOSE

We evaluated the results of sacral neuromodulation after 5-year followup in women with refractory idiopathic urge urinary incontinence.

MATERIALS AND METHODS

A neuromodulation system with an original (nontined) lead was implanted by open surgery after a positive percutaneous nerve evaluation in 60 women from 1990 to 2004. Voiding incontinence diary parameters were used to evaluate efficacy. Success was defined as at least a 50% decrease in the number of incontinence episodes or pads used daily. Safety was also evaluated.

RESULTS

The success rate gradually decreased from 52 patients (87%) at 1 month to 37 (62%) at 5 years. Complete continence persisted in 15% of patients. The system was still used by 80% of patients at 5 years. In 32 patients a total of 57 adverse events occurred, which were not severe (Clavien grade I and IIIb in 61% and 39%, respectively).

CONCLUSIONS

Sacral neuromodulation appears to be a safe technique for refractory idiopathic urge urinary incontinence in women. The success rate gradually decreased to 62% after 5 years with 15% of patients completely continent.

Sacral neuromodulation: Therapy evolution

Objectives:

Sacral neuromodulation has gained increased worldwide acceptance as the standard of care in patients with refractory overactive bladder (OAB) and non-obstructive urinary retention (NOUR). This review will detail the evolution of the technology.

Materials and Methods:

The mechanism of action and advances in treatment, including tined lead, fluoroscopic imaging, and smaller implantable pulse generator (IPG) are reviewed. This discussion also explores expanding indications and future advances including interstitial cystitis, chronic pelvic pain, neurogenic bladder, fecal incontinence, constipation, and dysfunctional elimination syndrome in children.

Results:

Sacral neuromodulation (SNM) exerts its influence by modulation of sacral afferent inflow on storage and emptying reflexes. The tined lead allows for placement and stimulation to be performed in the outpatient setting under local anesthesia with mild sedation. Lead migration has been minimal and efficacy improved. The use of fluoroscopy has improved accuracy of lead placement and has led to renewed interest in bilateral percutaneous nerve evaluation (PNE). Bilateral PNE can be performed in the office setting under local anesthesia, making a trial of therapy less expensive and more attractive to patients. A smaller IPG has not only improved cosmesis, but decreased local discomfort and need for revision. The role for SNM continues to expand as clinical research identifies other applications for this therapy.

Conclusions:

Our understanding of SNM, as well as technological advances in therapy delivery, expands the pool of patients for which this form of therapy may prove beneficial. Less invasive instrumentation may even make this form of therapy appealing to patients without refractory symptoms.

Role of botulinum toxin-A in refractory idiopathic overactive bladder patients without detrusor overactivity

BACKGROUND

To evaluate the efficacy of intradetrusor botulinum toxin-A (BTX-A) in idiopathic overactive bladder patients (OAB) refractory to anti-muscarinic therapy, without detrusor overactivity (DOA) on urodynamics.

METHODS

Patients with refractory idiopathic OAB without DOA on urodynamics were prospectively enrolled. Subjects completed a 3-day voiding diary (3-VD), urogenital distress inventory-6 questionnaire (UDI-6) and graded their quality of life on a 10-cm visual analog scale (VAS) prior to study enrollment and at week 12 postinjection. All patients underwent multichannel urodynamics at study enrollment and 12 weeks postinjection. Improvement was analyzed based on 3-VD, UDI-6 questionnaire, VAS scores, and urodynamic parameters at week 12 postinjection compared to study enrollment.

RESULTS

The study included 32 patients. Mean ± SD age was 56 ± 16. There were 27 women and 5 men. Nineteen patients had OAB without incontinence (OAB-dry) and 13 patients had OAB with incontinence (OAB-wet). In OAB-dry patients, mean ± SD urinary frequency dropped from 24 ± 11 to 10 ± 4 by week 12. In OAB-wet patients, mean ± SD urge incontinence episodes dropped from 7.9 ± 5 to 0 ± 2.6 by week 12. Mean UDI-6 and VAS scores improved significantly in both groups by week 12 (P = 0.0001). On comparing urodynamic parameters, OAB-wet patients showed significant decrease in maximum detrusor pressure during the voiding phase at week 12 compared to baseline values (P = 0.02).

CONCLUSIONS

Refractory idiopathic OAB patients without DOA on urodynamics may benefit from intradetrusor BTX-A.

Pelvic electrical neuromodulation for the treatment of overactive bladder symptoms

Overactive bladder syndrome negatively affects the daily life of many people. First-line conservative treatments, such as antimuscarinics, do not always lead to sufficient improvement of the complaints and/or are often associated with disabling adverse effects leading to treatment failure. Electrical stimulation of the sacral nerves has emerged as an alternative and attractive treatment for refractory cases of bladder overactivity. Few theories attempted to explain its mechanism of action which remains elusive. It involves percutaneous posterior tibial nerve stimulation and more commonly sacral neuromodulation. For the latter, temporary sacral nerve stimulation is the first step. If the test stimulation is successful, a permanent device is implanted. The procedure is safe and reversible. It carries a durable success rate. The technique should be combined with careful followup and attentive adjustments of the stimulation parameters in order to optimize the clinical outcomes. This paper provides a review on the indications, possible mechanisms of action, surgical aspects and possible complications, and safety issues of this technique. The efficacy of the technique is also addressed.

Sacral neuromodulation in patients with multiple sclerosis

PURPOSE

We present a case series of patients with multiple sclerosis (MS) and neurogenic lower urinary tract dysfunction treated by sacral neuromodulation (SNM).

METHODS

We reviewed charts of 25 patients who were treated for refractory lower urinary tract symptoms; during the SNM testing phase, patient management included evaluation of number of daily voiding, number of episodes of incontinence, residual urine and quality of life score. Patients who experienced greater than 50% improvement in symptoms of frequency and incontinence episodes and/or a greater than 50% decrease in the number of catheterizations and a greater than 50% increase in voided volumes were offered placement of the permanent InterStim(TM) .

RESULTS

Fifteen patients were implanted with InterStim(TM); mean duration of MS was 13.66 years; mean follow-up of patients was 49.4 months. Nine patients were on clean intermittent catheterization, and in all of them, a significant decrease in residual volume with increase in voided volume and number of voiding per day; in 6 patients, the main problem was incontinence, and in them incontinence, episodes decreased and voided volume increased. Sixty-six per cent of patients have a functioning device after a mean follow-up of 61.2 months.

CONCLUSIONS

SNM is a good option in the treatment of voiding dysfunction in patients with MS in a medium to long-term follow-up. Urinary retention due to detrusor underactivity is not a good indication for SNM; it should be offered to MS patients with refractory urgency urinary incontinence and MS patients with urinary retention due to detrusor-sphincter dyssynergia (DSD).

Expanding the Role of Neuromodulation for Overactive Bladder: New Indications and Alternatives to Delivery

From the time that it was granted US Food and Drug Administration approval, neuromodulation has secured a firm position in the treatment algorithm for overactive bladder. With neuromodulation, physicians were able to bridge the gap between the two ends of the treatment spectrum (medical therapy and open surgery). Sacral nerve stimulation has been the most widely used form of neuromodulation. Recent modifications to its design, namely the development of the tined lead and the launching of the refined InterStim II (Medtronic, Minneapolis, MN), have made sacral nerve simulation even less invasive and more effective. While InterStim is maintaining a level of success with these advancements, peripheral means of neuromodulation are being explored. The current literature takes a closer look at posterior tibial and pudendal nerve stimulation as alternatives to sacral nerve stimulation. The field of neuromodulation is also expanding in terms of the target patient population, as it is being used to treat children, patients with neurological disease, and others. As the role of neuromodulation increases, we must continue to assess its efficacy, safety, and cost-effectiveness in comparison to other therapeutic options.

Long-term outcome and surgical interventions after sacral neuromodulation implant for lower urinary tract symptoms: 14-year experience at 1 center

PURPOSE

Few reports address the reoperation rate after sacral neuromodulation implants. We report our long-term results and reoperations during our 14-year experience with sacral neuromodulation at our center.

MATERIALS AND METHODS

We retrospectively reviewed the patient database at our center to assess the long-term outcome, incidence and cause of surgical re-intervention after InterStim® sacral neuromodulation implantation for lower urinary tract dysfunction between 1994 and 2008.

RESULTS

A total of 96 sacral neuromodulation devices were implanted in 88 women and 8 men. Indications for implantation were bladder pain syndrome in 47.9% of cases, urgency urinary incontinence in 35.4% and idiopathic urinary retention in 16.7%. The explantation rate was 20.8% and median time to removal was 18.5 months. Reasons for explantation in all subgroups were poor result in 12 patients, painful stimulation in 6 and radiation of stimulation to the leg in 2. Median long-term followup was 50.7 months. The long-term success rate was 87.5%, 84.8% and 73% in patients with idiopathic urinary retention, urgency urinary incontinence and bladder pain syndrome, respectively. Overall 39% of patients needed revision of the sacral neuromodulation implant. The main reason for revision was loss of stimulation in 58.5% of cases. The revision rate decreased with the introduction of the tined lead technique from 50% using lead Model 3092 to 31% using lead Model 3893 (Medtronic, Minneapolis, Minnesota). The battery was changed in 8 patients. Mean battery life was 101.8 months.

CONCLUSIONS

Sacral neuromodulation is a minimally invasive procedure with a good long-term outcome. The reoperation rate has improved with advances in surgical technique and equipment.

First experiences with pudendal nerve stimulation in fecal incontinence: a technical report

Sacral nerve stimulation (SNS) is an established treatment for refractory lower urinary tract and bowel dysfunction. In some urological patients, SNS does not have satisfactory results. Pudendal nerve stimulation (PNS) has recently been proposed for these patients and successfully tested. Given the sometimes unsatisfactory results after SNS in fecal incontinence (FI), we tested PNS on patients suffering from FI. We used the device and implantation technique described by Spinelli et al. By making a slight change in the device, we developed a quick and easy-to-use method for successful PNS implantation, based on electrophysiological response. We present the results of a feasibility study, in which we tested the effectiveness of PNS with our modified implantation technique on 2 patients, with very satisfactory early results in a 4-month follow-up.