Sacral neuromodulation for lower urinary tract dysfunction

Objectives

To review the technique, indications, results and working mechanisms of sacral neuromodulation (SNM) for lower urinary tract dysfunction.

Methods

The available literature on SNM for lower urinary tract dysfunction was searched. Based on the information available in the literature and also based on personal experience, the urological indications, technique, mechanisms of action and results of SNM are presented and discussed.

Results

SNM for lower urinary tract dysfunction involves stimulation of the 3rd sacral nerve with an electrode implanted in the sacral foramen and connected to a pulse generator. The technique is accepted by the FDA since 1997. Currently, SNM for lower urinary tract dysfunction has been successfully used in about 26,000 patients with various forms of lower urinary tract dysfunction, including urgency, frequency and urgency incontinence as well as non-obstructive urinary retention. The actual procedure of SNM consists of a minimal invasive technique and is effective in about 70% of the patients who have been implanted with a permanent system. Also, in pelvic pain, interesting results have been described. SNM modulates the micturition reflexes at different levels in the central nervous system.

Conclusions

Sacral neuromodulation is a safe and effective therapy for various forms of lower urinary tract dysfunction, including urgency, frequency and urgency incontinence as well as non-obstructive urinary retention. It should be the first choice after failure of maximal conservative therapy.     

Pregnancy in women with Fowler’s syndrome treated with sacral neuromodulation

Introduction and hypothesis

Our aim was to determine the impact of pregnancy on sacral neuromodulation (SNM) and vice versa in patients with Fowler’s syndrome (FS), which is typified by chronic urinary retention (CUR).

Methods

We performed a retrospective study of pregnancy in patients with FS who underwent a two-stage SNM implantation. Data were obtained using a standard questionnaire and clinical interview.

Results

There were a total of ten patients with 13 pregnancies. The SNM was switched off in ten of the 13 pregnancies, with CUR recurring in nine of the ten pregnancies and recurrent urinary tract infections (UTI) occurring in four of these pregnancies (more than three UTI in the pregnancy). Those in whom the device was left on continued to void normally. One woman had a first trimester miscarriage, eight pregnancies went to term, and four deliveries were premature. Caesarean section was performed in eight pregnancies for obstetric reasons. Four pregnancies resulted in a vaginal delivery. There were no congenital anomalies reported. Following delivery, four of nine women experienced dysfunction of their SNM device when it was switched back on.

Conclusion

Turing off the SNM during pregnancy results in recurrence of CUR, with an increased risk of recurrent UTI associated with preterm delivery. This did not impact foetal well-being. The option of keeping the SNM on during pregnancy should therefore be considered, and as caesarean section affects the SNM device, we advise that caesarean section should only be performed for obstetric reasons.     

Early versus late treatment of voiding dysfunction with pelvic neuromodulation

Introduction:

Pelvic neuromodulation is an established method of treating voiding dysfunction. Little is known about the pathophysiology associated with voiding dysfunction. Reports have suggested that a delay in treating patients with sacral neuromodulation therapy can impact the success rate of this type of treatment in voiding dysfunction. We examined patient response to pelvic neuromodulation when it was applied early versus late in the postdiagnosis of voiding dysfunction.

Methods:

We conducted a retrospective study of 42 patients (38 women and 4 men) with voiding dysfunction who underwent surgery for implant with the Interstim (Medtronic, Minneapolis, Minn.). Prior to implantation, patients were required to pass a percutaneous nerve evaluation (PNE) over a 1-week period. Patients were observed for 20–48 months postimplantation. All patients recorded their voiding parameters at baseline, after screening and every 6 months thereafter. Twenty patients (in the early group) underwent implant surgery with the neurostimulator 2–4 weeks post-PNE, and 22 patients (the late group) had the device implanted 6–24 months post-PNE owing to local logistical circumstances.

Results:

In the early group, 16 of 20 patients (80%) maintained a good response. In the late group, 13 of 22 (59%) patients showed a good response. Groups were well matched in terms of age, duration of voiding dysfunction and incidence of comorbidity.

Conclusion:

Patients who were delayed more than 6 months in receiving the neurostimulator implant showed a worse response than did patients who had the device implanted soon after PNE. This indicates the possibility of disease progression, which may limit the response to sacral neuromodulation.Sacral neuromodulation (SNM), using permanent foramen S3 electrode, offers an alternative treatment for patients with conditions refractory to conventional measures. SNM has been approved by the US Food and Drug Administration for 3 indications: urge incontinence (UI), urge frequency (UF) and nonobstructive urinary retention. Several reports have been published regarding the efficacy of SNM in the treatment of UI, UF and nonobstructive urinary retention.^1–4SNM is considered a minimally invasive procedure, and when compared with the more drastic procedures to control intractable overactive bladder symptoms, SNM has fewer complications and has provided patients with more durable and consistent bladder control over time.The purpose of the current study is to determine whether a delay in SNM can affect the long-term outcome of treatment in patients with voiding dysfunction.     

Unilateral vs bilateral sacral neuromodulation in pigs with formalin-induced detrusor hyperactivity

OBJECTIVE

To investigate the efficacy of unilateral vs bilateral sacral neuromodulation (SNM) under standard experimental conditions by stimulating the dorsal sacral roots in pigs with formalin‐induced detrusor hyperactivity.

MATERIALS AND METHODS

After lumbosacral laminectomy in eight α‐chloralose‐anaesthetized Göttinger mini‐pigs, the dorsal roots of the nerve S3 were inserted into separate compartments of a size‐modified Brindley electrode. Detrusor hyperactivity was induced by intravesical instillation of a 0.25% formalin solution. Stimulation of the separated dorsal roots was performed on the unilateral right, respectively, the unilateral left side, as well as bilaterally and with stimulation off‐phases in a randomized pattern. A biphasic rectangular signal (impulse 200 µs, 20 Hz, 2.0 V) was used for SNM. The bladder pressure values were registered on a urodynamic unit and evaluated as contractions and amplitudes per minute.

RESULTS

During unilateral stimulation, the mean (sem ) number of contractions was reduced significantly from 4.73 (0.66) to 2.73 (0.62). The amplitude was also reduced significantly from 12.86 (1.23) to 8.32 (0.66). By contrast, bilateral stimulation lowered the mean (sem ) number of overactive detrusor contractions to 1.08 (1.02) and the amplitude to 3.08 (2.42), which are highly significant reductions.

CONCLUSION

In this porcine model, bilateral neurostimulation was a more effective method of SNM than unilateral stimulation. We assume that this is due to the additive effect of stimulating both sides, as well as the greater chance of stimulating the relevant dorsal roots of the sacral nerve fibres. By contrast, unilateral neuromodulation may be only partially effective by not being capable of influencing the entire bladder, or possibly by allowing new formation of neuronal pathophysiological pathways.     

Resection of giant invasive sacral schwannoma using image-based customized osteotomy tools

Background

Giant invasive sacral schwannomas are rare tumors. Surgical excision is the standard treatment and total resection is performed if feasible. Advances in three-dimensional (3D) imaging technology have facilitated treatment designs of complex surgical procedures.

Objective

Our aim was to evaluate virtual surgical planning, computer-aided design (CAD), and manufacturing with 3D printing technology of the customized osteotomy guiding device in giant invasive sacral schwannoma resection.

Methods

A digital 3D model of the sacrum, including the giant invasive sacral schwannoma, was rendered from patient computer tomography (CT) images. The surgeon chose excision margins of the tumor. Based on the virtual surgical planning, the customized guiding tool for osteotomy was designed and manufactured using the CAD and 3D printing.

Results

We used the guiding block to successfully excise a giant sacral schwannoma using only a posterior approach to achieve gross total resection. No augmented spinal instrumentation was used to prevent iatrogenic spinal instability. Clinical symptoms resolved dramatically after operation. No spinal instability occurred during follow-up.

Conclusion

With the assistance of an image-based customized osteotomy guiding device, we achieved both goals of tumor resection and bone preservation in giant sacral schwannoma resection. With thorough surgical planning, this technology can be applied to the complex surgical procedures easily and reliably.

     

Ergebnisse der sakralen Neuromodulation bei Therapie der überaktiven Blase

Currently, sacral nerve modulation (SNM) is an effective treatment for overactive bladder symptoms which are refractory to anticholinergic or muscarinergic treatment. However, SNM requires the implantation of stimulation electrodes at the sacral nerves and a subcutaneous impulse generator. The SNM procedure can be divided into three phases: the acute phase comprising the implantation of the test stimulation electrodes, the subchronic stimulation phase over a period of 7-14 days during which neurostimulation takes place by means of an external impulse generator, and finally chronic SNM after implantation of the final impulse generator.In 1981 the SNM technique for treatment of bladder dysfunctions was first developed by Tanagho and Schmidt and has since been refined, while the range of indications has been extended continuously. It has been shown that patients with neurogenic bladder dysfunctions are able to gain the greatest benefit from SNM. The long-term results of SNM are very encouraging so far. In addition, a highly innovative and promising technique is the implantation of a miniaturized impulse generator with integrated stimulation electrode at the n. pudendus. However, the outcome of these trials has not fully been capable of living up to the expectations so far.     

骶神经调节术治疗顽固性便秘疗效观察

目的：观察骶神经调节术（SNM）治疗顽固性便秘的临床效果。方法第四军医大学西京消化病医院消化外科于2013年1月至2014年1月期间,采用骶神经调节测试系统经皮穿刺,刺激第3骶神经根,治疗7例复杂便秘患者,其中4例患者既往进行过至少1次的便秘手术。通过排粪日记、Cleveland便秘评分及视觉模拟评分（VAS）进行疗效评价。结果7例患者在接受体外临时测试治疗后,便秘症状均明显改善。其中6例接受永久性骶神经调节器植入术,围手术期未见并发症。术后随访中位时间4（2～12）月,6例患者的每周排粪次数由治疗前（0．6±0．5）次／周,增加到（8．0±2．5）次／周（P＜0．01）;排粪时间从（22．9±11．5） min减少到（3．7±0．8） min（P＜0．01）;Cleveland便秘评分从（24．6±4．2）分下降到（9．0±0．9）分（P＜0．01）;VAS评分从（8．1±0．9）分增加到（82．5±5．2）分（P＜0．01）。结论 SNM是治疗顽固性便秘的一种微创而安全有效的新方法。     

Psychological and psychiatric factors as predictors for success in sacral neuromodulation treatment

Study Type – Therapy (preference) Level of Evidence 4 What’s known on the subject? and What does the study add? Sacral neuromodulation (SNM) is a well‐established treatment for patients with chronic LUTS. The selection of eligible candidates could be improved by identifying factors that can predict a successful response. In the present study, we evaluated the role of various psychological and psychiatric factors in relation to SNM treatment.

OBJECTIVE

? To evaluate if psychological and psychiatric factors can predict the outcome of test stimulation or permanent treatment with sacral neuromodulation (SNM).

PATIENTS AND METHODS

? Between 2006 and 2009, patients with overactive bladder syndrome or non‐obstructive urinary retention who were eligible for test stimulation were included. ? All patients completed the Amsterdam Biographic Questionnaire (ABQ), which measures the personality traits of the patient, and the Symptom Check‐List‐90‐Revised (SCL‐90‐R), which is a screening instrument for neuroticism, and for current level of complaints. ? The results of the questionnaires were compared with the outcomes of test stimulation and permanent treatment. ? In addition to the questionnaires, we also included the psychiatric history as a potential predictive factor.

RESULTS

? On univariate analysis there was no relationship between the psychological characteristics and the outcome of test stimulation or the occurrence of adverse events (AEs) with permanent treatment. ? A history of psychiatric disease was not related to the outcome of test stimulation, but was shown to be a positive predictor for the occurrence of AEs with permanent SNM treatment.

CONCLUSIONS

? In the present study there was no evidence that psychological screening with the ABQ or SCL‐90‐R can predict the outcome of SNM treatment. ? Patients with a medical history of psychiatric disease appear to be more likely to encounter AEs with permanent SNM treatment.     

Differences in sacral neuromodulation device infection rates based on preoperative antibiotic selection

Introduction and hypothesis

After SNM implantation the most significant complication that can occur is wound infection, which typically requires removal of all components. Such infections have been reported in 5–11 % of patients, but little is known about risk factors. The objective of this analysis is to determine our postoperative wound infection rate after SNM implantation, and examined various potential predictive factors. Our hypothesis is that perioperative antibiotic selection is related to the risk of infections.

Methods

A retrospective review was performed of all patients who underwent SNM implantation by one of three surgeons from 2007 to 2010. Preoperative antibiotics were administered according to surgeon preference, and included cefazolin alone, vancomycin alone, or vancomycin with gentamicin. Predictors of wound infection were evaluated using multivariate techniques. Variables examined included preoperative antibiotic regimen, surgeon, location (outpatient surgery center vs university hospital), gender, comorbidities (diabetes mellitus, immunosuppression and smoking), history of urinary tract infections, and preoperative skin preparation.

Results

A total of 136 patients underwent SNM implantation, and 8 (5.9 %) experienced infections that required device explantation. Cefazolin alone was less effective in preventing infection compared with the other antibiotic regimens (p?=?0.03). The odds of having an infection in cefazolin-treated patients was 7.3 times that of other patients treated with another antibiotic regimen. Seven out of the eight infections with explant grew Staphylococcus aureus resistant to cephalosporins. None of the other variables proved to be a statistically significant contributor.

Conclusions

Preoperative antibiotic selection was a significant factor in preventing subsequent infection and explantation following SNM placement.     

The effect of sacral neuromodulation on pregnancy: a systematic review

Introduction and hypothesis

To evaluate the effects of sacral neuromodulation (SNM) on pregnancy and the impact of delivery on SNM function.

Methods

A systematic search was conducted through January 2016. We selected studies including women who had SNM and a subsequent pregnancy.

Results

Out of 2,316, eight studies were included, comprising 22 patients (26 pregnancies). SNM indications were Fowler’s syndrome in 11, urinary retention in 6, fecal incontinence in 1, fecal and urinary urgency in 1, overactive bladder in 1, intractable interstitial cystitis in 1, and myelodysplasia in 1. SNM stayed on in 8 pregnancies. In the remaining 18 pregnancies in which the device was deactivated, 7 had recurrent urinary tract infections, including 1 with pyelonephritis and 2 who requested reactivation owing to recurrent symptoms. Outcomes were reported in 25 pregnancies, 16 had Cesarean section (CS) and 9 had vaginal delivery, including 2 operative deliveries. Out of 25, two infants had pilonidal sinus and motor tic disorder (exhibited at the age of 2 years), both from the same mother. After delivery, SNM was functioning in 15 (60%), 4 required reprogramming, and 3 required replacement (1 had recurrence of fecal incontinence after her operative delivery with evidence of displaced leads and 1 patient reported decreased SNM effects after her two CS), and 3 decided to remove the device (2 out of 3 patients were free of symptoms after SNM deactivation and requested removal).

Conclusion

Within the current limited evidence, the decision regarding SNM activation or deactivation should be individualized. A registry for those patients is recommended.

     

Surgical principles of sacral foramen electrode implantation

Summary Neuromodulation of sacral roots provides an alternative mode of treatment for patients presenting with voiding dysfunctions and chronic pelvic pain. To date, the implantation of permanent electrodes into the sacral foramen and long-term chronic stimulation have not resulted in peripheral nerve damage. In this paper, we describe the surgical technique used for sacral foramen electrode implantation. The nuances of this therapy are illustrated by case reports.     

The Role of Neuromodulation in Patients with Neurogenic Overactive Bladder

To review the treatment options for patients with neurogenic overactive bladder (OAB), specifically the use of sacral neuromodulation (SNM). A search was performed on the available literature on SNM and lower urinary tract dysfunction. Based on published studies available and also on personal experience, the treatment options for neurogenic OAB are reviewed, and specifically, the role for SNM in these patients is discussed. SNM is FDA-approved for patients with urge incontinence, urgency/frequency, and non-obstructive urinary retention. It involves stimulation of the third sacral nerve with an electrode implanted in the sacral foramen and connected to a pulse generator. The procedure is minimally invasive and is effective in about 70?% of patients who have a permanent system. The original trials leading to the approval of SNM excluded patients with neurogenic disease, as it was felt that intact spinal pathways were necessary for neuromodulation to occur. However, similar success rates have been observed in patients with neurogenic OAB. Special considerations for SNM use in patients with neurogenic OAB include recognizing that it is incompatible for patients who will need MRI's due to their progressive neurologic disease. Many treatment options are available for patients with neurogenic OAB. First-line approaches remain conservative with lifestyle changes and anticholinergic medications. SNM has been used successfully in this patient population with good results, though larger randomized trials are lacking.     

Acute effect of sacral neuromodulation for treatment of detrusor overactivity on urodynamic parameters

Aim

The aim of this study is to evaluate the acute effects of sacral neuromodulation (SNM) on various urodynamic parameters.

Methods

Patients with overactive bladder and detrusor overactivity (DO) who were planned for percutaneous nerve evaluation (PNE) were included. Directly after the PNE, a urodynamic study (UDS) was performed. The stimulation was turned off during the first UDS (UDS 1), and during the second filling cycle, stimulation was turned on (UDS 2). The UDS was followed by a test phase of 1 week and the bladder diaries were evaluated during an outpatient clinic visit. Primary outcome measures were the differences in UDS parameter values with SNM off and on.

Results

Ten female patients were included in the study and completed the study protocol. Eight patients showed ≥50% improvement of symptoms following a test phase. There were no differences between UDS 1 and UDS 2 in the UDS parameters; bladder volume at first sensation, bladder volume at first DO, highest DO pressure, bladder capacity, maximum flow rate, and pressure at maximum flow rate.

Discussion

None of the aforementioned urodynamic parameters was influenced by acute SNM in patients who responded to SNM. To the best of our knowledge, this is the first study investigating the acute effects of SNM on bladder function.

     

Restoration of voiding in chronic urinary retention using the neuroprosthesis

Summary Six women and one man presenting with chronic urinary retention for >1 year were restored to normal voiding after implantation of a neuroprosthetic device. Detrusor contractions could not be elicited in a preoperative urodynamic investigation, and failure of urethral sphincter relaxation was noted in all cases. Test stimulation of the pudendal and sacral nerve roots resulted in normal motor responses. A temporary wire electrode was inserted in either the S3 or the S2 foramen and the patient was connected to a self-controlled pulse generator for 3–5 days. Voiding returned within the first 24 h and continued for the duration of the test. Retention recurred after removal of the temporary wire electrode. Permanent electrodes were then inserted. Five patients continue to void normally at 2–48 months (mean, 16 months) postimplantation. These subjects demonstrate that chronic retention can be the result of impaired reflex triggering of the voiding reflex in the presence of completely normal motor pathways. Sacral nerve root stimulation can identify this subset of patients and restore their normal voiding function.     

Neuromodulation of voiding dysfunction and pelvic pain

Summary Neuromodulation of sacral roots provides an alternative mode of therapy for patients presenting with voiding dysfunctions and chronic pelvic pain. Physiologically, this is accomplished by intervention in the neuronal pathways of micturition via sacral nerve-root electrical stimulation. Preoperative evaluation using temporary percutaneous sacral root stimulation selects the patients who are most likely to benefit from permanent electrode implantation. To date, no evidence of peripheral nerve damage has been recorded. Our experience with >1500 percutaneous tests and 150 permanent foramen implant procedures documents the safety and efficacy of this technique.     

Sacral Neuromodulation: Does It Affect the Rectoanal Angle in Patients with Fecal Incontinence?

Background  

In the past decade numerous studies have been published on the successful treatment of fecal incontinence with sacral neuromodulation (SNM). The underlying mechanism of action for lower bowel motility disorders has been unclear. In the present study, the effect of SNM on the rectoanal angle in patients with fecal incontinence was investigated.     

Urodynamic evaluation of sacral neuromodulation for urge urinary incontinence

OBJECTIVE

To evaluate the urodynamic data before and 6 months after implantation of sacral neuromodulation (SNM, an established treatment for voiding dysfunction, including refractory urge urinary incontinence, UI) and to assess the correlation between the urodynamic data and clinical efficacy in patients with UI.

PATIENTS AND METHODS

In all, 111 patients with a >50% reduction in UI symptoms during a percutaneous nerve evaluation test qualified for surgical implantation of SNM. Patients were categorized in two subgroups, i.e. those with UI with or without confirmed detrusor overactivity (DO) at baseline. At the 6‐month follow‐up all patients had a second urodynamic investigation, with the stimulator switched on.

RESULTS

At baseline, there was urodynamically confirmed DO in 67 patients, while 44 showed no DO. A review of filling cystometry variables showed a statistically significant improvement in bladder volumes at first sensation of filling (FSF) and at maximum fill volume (MFV) before voiding for both UI subgroups, compared with baseline. In 51% of the patients with UI and DO at baseline, the DO resolved during the follow‐up. However, those patients were no more clinically successful than those who still had DO (P = 0.73). At the 6‐month follow‐up, 55 of 84 implanted patients showed clinical benefit, having a ≥50% improvement in primary voiding diary variables. Patients with UI but no DO had a higher rate of clinical success (73%) than patients with UI and DO (61%), but the difference was not statistically significant.

CONCLUSION

These urodynamic results show a statistically significant improvement in FSF and MFV in patients with UI with or with no DO after SNM. Although there was a urodynamic and clinical improvement in both groups, patients with UI but no DO are at least as successful as patients with UI and DO. Therefore in patients with UI, DO should not be a prerequisite selection criterion for using SNM.     

Sacral nerve stimulation for constipation

Background:

For over 10 years sacral nerve stimulation (SNS) has been used for patients with constipation resistant to conservative treatment. A review of the literature is presented.

Methods:

PubMed, MEDLINE and Embase databases were searched for studies demonstrating the use of SNS for the treatment of constipation.

Results:

Thirteen studies have been published describing the results of SNS for chronic constipation. Of these, three were in children and ten in adults. Test stimulation was successful in 42–100 per cent of patients. In those who proceeded to permanent SNS, up to 87 per cent showed an improvement in symptoms at a median follow‐up of 28 months. The success of stimulation varied depending on the outcome measure being used. Symptom improvement correlated with improvement in quality of life and patient satisfaction scores.

Conclusion:

SNS appears to be an effective treatment for constipation, but this needs to be confirmed in larger prospective studies with longer follow‐up. Improved outcome measures need to be adopted given the multiple symptoms that constipation may be associated with. Comparison with other established surgical therapies also needs consideration. Copyright © 2012 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.     

The long-term efficacy of sacral neuromodulation in the management of intractable cases of bladder pain syndrome: 14 years of experience in one centre

Study Type – Therapy (case series)
Level of Evidence 4 What’s known on the subject? and What does the study add? Bladder pain syndrome (BPS) is a chronic debilitating disease. A recently done survey estimates the prevalence of the BPS symptoms among adult females in the U.S. to be 7%. Conservative management is the first line of therapy but at least 10% of the patients show poor response. Sacral neuromodulation is a minimal invasive technique with good long‐term outcomes in these patients. It should be considered before any invasive surgical intervention is planned. However, the revision rate is high and patients need lifelong follow‐up.

OBJECTIVE

? To evaluate the long‐term success and tolerability of sacral neuromodulation (SNM) in the control of the symptoms of bladder pain syndrome (BPS).

METHODS

? This was a retrospective study of all patients with BPS who underwent peripheral nerve evaluation and then SNM in our department of urology by a single surgeon from 1994 till 2008. The global response assessment scale was used to evaluate the outcome of the SNM.

RESULTS

? A total of 78 patients fulfilled the International Consultation on Incontinence clinical criteria for BPS and showed cystoscopic evidence of glomerulation or ulcer as recommended by the European Society for the Study of Interstitial Cystitis/Painful Bladder Syndrome. All patients failed conservative management before considering SNM. ? Permanent SNM implant was performed in patients who showed at least 50% improvement in their symptoms with a temporary peripheral nerve evaluation test. Median follow up was 61.5 months (sd ± 27.7). Good long‐term success of the SNM was seen in 72% of the patients. ? Presence of urgency was a positive predictor of the long‐term success of the implant. The explantation rate was 28%. The commonest reason for explantation was poor outcome (54% of the failed patients). The revision rate was 50%. ? The most common indication for revision was lack of stimulation sensation and worsening of symptoms. The average durability of the pulse generator battery was 93 months.

CONCLUSION

? SNM is an effective treatment to control the symptoms of BPS. It should be considered before any major invasive surgical intervention if conservative measures have failed. It is a minimally invasive, safe procedure with good long‐term outcome. However, the revision rate is high and patients require lifelong follow‐up.     

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).