How Does Sacral Modulation Work Best? Placement and Programming Techniques to Maximize Efficacy

Efficacy and Safety of Sacral Neuromodulation by Converting Constant Frequency Stimulation Into Variable Frequency Stimulation in Patients With Detrusor Overactivity and Impaired Contractility: A Single-Center Prospective Study

OBJECTIVES

In patients with detrusor overactivity with impaired contractility (DOIC), it is difficult to relieve abnormal lower urinary tract symptoms during both storage and voiding using sacral neuromodulation (SNM) with constant frequency stimulation (CFS). We sought to evaluate the efficacy and safety of SNM using variable frequency stimulation (VFS) in patients with DOIC by comparing it with outcomes of SNM with CFS.

MATERIALS AND METHODS

Between September 2020 and May 2021, we prospectively enrolled 20 patients with DOIC, confirmed on urodynamic examination, and administered SNM with VFS. The patients were followed up and required to maintain voiding diaries and record scale scores of overactive bladder symptoms, psychology and quality of life, uroflowmetry, ultrasonic postvoid residual urine, and adverse events at baseline and during the CFS and VFS phases.

RESULTS

The average testing phase was 26.3 ± 4.1 days. Compared with baseline values, overactive bladder symptom, psychologic health questionnaire, and quality of life scores, in addition to voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic postvoid residual (PVR) decreased significantly during both the CFS and VFS phases (p < 0.05). The average voided volume, functional bladder capacity, and maximum urine flow rate significantly increased during the CFS and VFS phases (p < 0.05). In the VFS phase, voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic PVR further decreased (p < 0.05), whereas functional bladder capacity, maximum urine flow rate, quality of life score, overactive bladder symptom score, and psychologic health questionnaire score further improved compared with results obtained in the CFS phase (p < 0.05). In the VFS phase, the success rate of further improvement of symptoms was 85.0%, and no new complications were noted.

CONCLUSIONS

SNM that converts CFS into VFS may be an effective treatment option for patients with DOIC, exhibiting no increase in adverse events.

Effectiveness and safety of sacral neuromodulation for neurogenic bladder

BACKGROUND

The treatment of neurogenic bladder (NB) is a challenge because conventional therapy often fails. Sacral neuromodulation (SNM) is a minimally invasive technique and an unconventional treatment for neurogenic bladder. Its research is still in the exploratory stage. The research on its effectiveness and safety is not clear.

OBJECTIVE

To assess the effectiveness and safety of sacral neuromodulation (SNM) for neurogenic bladder (NB).

METHODS

By searching the PubMed databases and Cochrane Library databases, combined with the method of literature tracing, the clinical researches and works on neurogenic bladder and sacral neuromodulation therapy were collected. Two reviewers independently selected and extracted data, (1) determine whether the study meets the inclusion criteria and exclude the literature that meets the exclusion criteria. (2) Researchers' screening results and data, if there are differences in the results, will be discussed to eliminate the differences. (3) Read the full text of the literature carefully to determine the final literature to be included. (4) The relevant data of 11 independent studies, a total of 291 patients, were systematically reviewed using review manager 5.3 software.

RESULTS

This research included 11 independent studies with a total of 291 patients. The improvements of main outcomes before and after SNM therapy were significant: incontinence episodes /24 h (WMD -2.52; 95%CI-3.14-1.90; p <0.001), frequency/24 h (WMD-5.96; 95%CI -6.27，-5.66; p <0.001), voiding volume (WMD 116.09 mL; 95%CI 86.68，145.51; p <0.001), cystometric capacity (WMD 129.84 mL; 95%CI 100.53, 159.15; p <0.001), post-void residual volume (WMD-198.00 mL; 95%CI-264.60, -131.40; p <0.001), clean intermittent self-catheterization/24 h (WMD-2.48; 95%CI -2.96, -2.00; p <0.001).

CONCLUSION

This systematic review indicated that the sacral neuromodulation treatment for neurogenic bladder was effective and safe.

Reprogramming Sacral Neuromodulation for Sub-Optimal Outcomes: Evidence and Recommendations for Clinical Practice

Objectives

In some patients treated for urinary or fecal incontinence with sacral neuromodulation (SNM) persistence of symptoms, a reduction in efficacy or adverse effects of stimulation can occur. In such situations, further programming of the SNM device can help resolve problems. Infrequently hardware failure is detected. This article aims to provide practical guidance to solve sub‐optimal outcomes (troubleshooting) occurring in the course of SNM therapy.

Materials and Methods

A systematic literature review was performed. Collective clinical experience from an expert multidisciplinary group was used to form opinion where evidence was lacking.

Results

Circumstances in which reprogramming is required are described. Actions to undertake include changes of electrode configuration, stimulation amplitude, pulse frequency, and pulse width. Guidance in case of loss of efficacy and adverse effects of stimulation, developed by a group of European experts, is presented. In addition, various hardware failure scenarios and their management are described.

Conclusions

Reprogramming aims to further improve patient symptoms or ensure a comfortable delivery of the therapy. Initial changes of electrode configuration and adjustment of stimulation parameters can be performed at home to avoid unnecessary hospital visits. A logical and stepwise approach to reprogramming can improve the outcome of therapy and restore patient satisfaction.

The science behind programming algorithms for sacral neuromodulation

AIM

Sacral neuromodulation (SNM) is a widely adopted treatment for overactive bladder, non-obstructive urinary retention and faecal incontinence. In the majority, it provides sustained clinical benefit. However, it is recognized that, even for these patients, stimulation parameters (such as amplitude, electrode configuration, frequency and pulse width) may vary at both initial device programming and at reprogramming, the latter often being required to optimize effectiveness. Although some recommendations exist for SNM programming, the scientific data to support them are understood by few clinicians.

METHODS

This is a narrative review of the literature covering some of the science behind stimulating a mixed peripheral nerve and available preclinical data in the field of SNM. It covers electrode configuration, amplitude, frequency, pulse width and cycling considerations. The review is targeted at clinicians with an interest in the field and does not seek to provide exhaustive detail on basic neuroscience.

RESULTS AND CONCLUSIONS

Knowledge of the science of neuromodulation provides some guiding principles for programming but these are broad. These principles are not refuted by preclinical data but specific parameters in clinical use are not strongly supported by animal data, even after the limitations of small and large animal models are considered. The review presents a shortlist of programming principles on a theoretical basis but acknowledges that current practice is as much derived from evolved experience as science.

The effect of the number of active electrode poles during tined lead placement on long-term efficacy of sacral neuromodulation in patients with faecal incontinence

AIM

There is an ongoing debate as to whether or not the efficacy of sacral neuromodulation (SNM) is optimized by maximizing the total number of active electrode poles (AEPs) during lead placement because there are more programming options. However, this is at the cost of increased operating time. The aims of this study were to establish if a higher number of AEPs improves SNM efficacy during the trial period and after permanent implantable pulse generator (IPG) placement and if there is there a correlation between number of AEPs and battery life of the first placed IPG.

METHOD

This was a single centre retrospective cohort study of new patients with faecal incontinence who underwent SNM between 2000 and 2018. Exclusion criteria were sphincter defect > 30%, rectocele/enterocele Grade 3 or higher and incomplete records.

RESULTS

In all, 288/456 (63%) patients (women 91%; mean age 58.5 ± 11.7 years) were eligible for analysis. The number of AEPs during lead placement was two (n = 42, 14.5%), three (n = 82, 28.5%) and four (n = 164, 57%). There was no association between the number of AEPs during tined lead placement and long-term efficacy. Neither the success rate of the trial phase nor the battery life after first placed IPG was influenced by the number of AEPs.

CONCLUSION

In this study, the number of AEPs does not seem to influence long-term efficacy of SNM success rate during the trial phase or the battery life of the first placed IPG. However, we also suggest that at the very least there should be two AEPs at lead placement.

A Cadaveric Study on the Efficacy of Surface Marking and Bony Landmarks Used in Sacral Neuromodulation

Background Anatomical landmarks and surface markings have long been used in out-patient contexts for conducting percutaneous nerve evaluation procedures, but studies testing the reliability of these anatomical landmarks are scant. There have been reports where the procedure has failed. Could it be possible that the anatomical landmarks that are used are not reliable enough? To answer this question, we used this study to understand the reliability of these anatomical landmarks. Methods Twenty cadavers, 10 males and 10 females, were dissected in the sacral region; the landmarks were tested, and the angulation and curve made by the sacral 3 (S3) nerve were also studied. Results Sacral 3 was identified mainly at the four o'clock position on the right and at the eight o'clock position on the left side. The Sacral 3 foramen was found at a mean distance of 9.17 ± 0.23 cm from the tip of the coccyx. The mean distance of the lateral margin of S3 from the median sacral ridge was found to be 2.16 ± 0.07 cm. Conclusion  The landmark of 9 cm from the coccyx tip is a valid landmark for sacral neuromodulation (SNM) procedures. The tip of the lead should follow the curve of the nerve as close as possible at the four and eight o'clock positions on the right and left side, respectively. However, the length of the coccyx differs from person to person. The proximity of the adjacent foramina to each other and the variations in the emerging of the nerve are a few factors to be considered while performing SNM procedures. Further study with a larger sample is required in order to investigate the course of the nerve, and its relationship to response to SNM.

Programming Algorithms for Sacral Neuromodulation: Clinical Practice and Evidence-Recommendations for Day-to-Day Practice

Background

In sacral neuromodulation (SNM), stimulation programming plays a key role to achieve success of the therapy. However to date, little attention has been given to the best ways to set and optimize SNM programming during the test and chronic stimulation phases of the procedure.

Objective

Standardize and make SNM programming easier and more efficient for the several conditions for which SNM is proposed.

Methods

Systematic literature review and collective clinical experience report.

Results

The basic principles of SNM programming are described. It covers choice of electrode configuration, stimulation amplitude, pulse frequency and pulse widths, while use of cycling is also briefly discussed. Step‐by‐step practical flow charts developed by a group of 13 European experts are presented.

Conclusions

Programming of SNM therapy is not complex. There are few programming settings that seem beneficial or significantly impact patient outcomes. Only four basic electrode configurations could be identified according to four different options to define the cathode. In a majority of patients, the proposed stimulation parameters will allow a satisfactory improvement for long periods of time. A regular follow‐up is, however, necessary to assess and eventually optimize results, as well as to reassure patients.

What uro-gynecologists should know about sacral neuromodulation (SNM) for the treatment of refractory overactive bladder

PURPOSE

To inform uro-gynecologists about the current standards and latest developments of sacral neuromodulation (SNM) in women with overactive bladder (OAB).

METHODS

Literature search in the PubMed database for articles published between 1988 and 2019 on SNM for OAB in women.

RESULTS

In total, 361 articles were identified and 51 articles retrieved for the review. SNM shows an objective success rate of 70-80%, OAB cure rate of 17-47% and a subjective satisfaction rate of 80-90%. These benefits have to be weighed against an adverse event rate of approx. 40%. SNM is significantly more successful than switching to another antimuscarinic after failed antimuscarinic drug therapy. Efficacy of SNM is slightly lower compared to bladder wall injections with 200 U botulinum toxin in the first months but efficacy of both treatments appears to be similar after 24 months. MRI examinations of patients with a sacral neurostimulator should only be performed after radiologist consultation. Sacral neurostimulators in patients with another pacemaker system should only be implanted after interdisciplinary consultation. The sacral neuromodulator should be turned off during pregnancy and delivery. SNM for OAB in patients with concomitant female sexual dysfunction or fecal incontinence seems to be beneficial.

CONCLUSIONS

SNM is a successful and recommended second-line treatment of OAB. Sacral neurostimulators should preferably be implanted in SNM-centers because complications and the frequency of revisions are significantly reduced with increasing experience of the surgeon.

Sacral neuromodulation treating chronic pelvic pain: a meta-analysis and systematic review of the literature

INTRODUCTION AND HYPOTHESIS

Sacral neuromodulation (SNM) is gaining popularity as a treatment option for chronic pelvic pain (CPP). Our hypothesis is that SNM is effective in improving CPP.

METHODS

A systematic search was conducted through September 2018. Peer-reviewed studies using pre- and postpain intensity scores were selected. The primary outcome was pain improvement on a 10-point visual analog scale (VAS) (adjusted or de novo) in patients with CPP. Secondary outcomes included comparing SNM approaches and etiologies and evaluating lower urinary tract symptoms (LUTS).

RESULTS

Fourteen of 2175 studies, evaluating 210 patients, were eligible for further analysis. The overall VAS pain score improvement was significant [weighted mean difference (WMD) -4.34, 95% confidence interval (CI) = -5.22, to-3.64, p < 0.0001)]. Regarding SNM approach, both standard and caudal approaches had significant reduction in pain scores: WMD -4.32, CI 95% = -5.32, to -3.31 (p < 0.001) for the standard approach, compared with WMD -4.63, 95% CI = -6.57 to -2.69 (P < 0.001), for the caudal approach (p = 0.75). While significant improvement in pain was observed both in patients with and without interstitial cystitis/bladder pain syndrome (IC/BPS), the observed improvement was lower in patients with (WMD -4.13, CI 95% -5.36 to -2.90 versus without (WMD -5.72, CI 95% = -6.18, to-5.27) IC/BPS (p = 0.02). SNM was effective in treating voiding symptoms (frequency, urgency, nocturia) associated with IC/BPS (all p < 0.01).

CONCLUSIONS

SNM is an effective therapy for CPP in both IC/BSP and non-IC/BSP patients, with better results in non-IC/BSP patients. Outcomes of the antegrade caudal approach were comparable with the standard retrograde approach.

Electroceutical Targeting of the Autonomic Nervous System

Autonomic nerves are attractive targets for medical therapies using electroceutical devices because of the potential for selective control and few side effects. These devices use novel materials, electrode configurations, stimulation patterns, and closed-loop control to treat heart failure, hypertension, gastrointestinal and bladder diseases, obesity/diabetes, and inflammatory disorders. Critical to progress is a mechanistic understanding of multi-level controls of target organs, disease adaptation, and impact of neuromodulation to restore organ function.

The functional outcome of sacral nerve stimulation for faecal incontinence can be improved by using lead model 3889 and a standardized implantation technique

AIM

Sacral nerve stimulation has been recognized as an effective treatment option for faecal incontinence when conservative therapy has failed. Refinement of the procedural technique and the use of a curved stylet may improve the functional outcome. Our aim was to explore the relationship between lead model, functional outcome, stimulation amplitude and the need for extra visits during the first year of follow-up.

METHOD

Patient data from May 2009 to February 2017, which were prospectively collected in a local database, were extracted and analysed for differences between lead model and improvement in incontinence scores, stimulation amplitude and the need for additional visits during the first year of follow-up.

RESULTS

A foramen lead model 3093(straight stylet) was used in 134 patients and lead model 3889(curved stylet) was used in 40 patients. There were no differences in baseline characteristics or incontinence scores. Comparing results between the two lead models we found that the improvement (delta value) in the Wexner score at 6 months' follow-up (P = 0.05) and the St Mark's score at 12 months' follow-up (P = 0.02) was greater in patients implanted with lead model 3889(curved stylet) compared with patients implanted with lead model 3093(straight stylet). Patients implanted with lead model 3889 (curved stylet) were less likely to have to alter the stimulation amplitude or pole configuration during the first year of follow-up (P = 0.04). No difference was found for stimulation amplitude (P = 0.170) or the need for additional visits (P = 0.663).

CONCLUSION

Lead model 3889 (curved stylet) improves functional results compared with lead model 3093 (straight stylet) during the first year of follow-up. Lead model 3889 (curved stylet) reduces the need for reprogramming but has no influence on stimulation amplitude or the number of additional visits required.

Optimal Lead Positioning in Sacral Neuromodulation: Which Factors Are Related to Treatment Outcome?

OBJECTIVES

Sacral neuromodulation (SNM) is a well-established treatment for overactive bladder (OAB) and non-obstructive urinary retention (NOR). During test stimulation, the lead is positioned along the third sacral nerve, which ideally results in a response in all four contact points (active electrodes). However, it is unclear whether the position of the lead (depth, angle, deflection) and the number of active electrodes is related to the outcome of SNM.

METHODS

All patients who underwent test stimulation using the tined lead between January 2011 and September 2016 were included in this retrospective study. Success was defined as >50% improvement in voiding diary parameters compared to baseline. The correlation between lead position and outcome of test stimulation was evaluated. The lead position was determined by evaluating the depth, angle and deflection with respect to the sacral foramen. Binary logistic regression was used in order to determine the predictive value of these factors.

RESULTS

We included 189 patients of whom 105 were diagnosed with OAB and 84 with NOR. After a SNM test period of 4 weeks, 111 patients (59%) were successful and received a permanent implant. The position of the lead and the number of active electrodes did not predict success of test stimulation in neither the OAB group nor the NOR. However, lateral deflection of the lead was associated with finding more active electrodes (p = 0.01).

CONCLUSION

In our study, the position of the lead or the number of active electrodes did not predict the outcome of SNM test stimulation. However, the impact of lead positioning and number of active electrodes on long-term outcome remains to be proven.

Evaluation of the axonics modulation technologies sacral neuromodulation system for the treatment of urinary and fecal dysfunction

INTRODUCTION

Sacral neuromodulation (SNM) remains one of the few effective treatments for refractory bladder and bowel dysfunction. However, SNM is associated with frequent need for surgical intervention, in many cases because of a failed battery. A rechargeable SNM system, with a manufacturer-reported battery life of 15 years or more, has entered post-market clinical testing in Europe but has not yet been approved for clinical testing in the United States. Areas covered: We review existing neuromodulation technologies for the treatment of lower urinary tract and bowel dysfunction and explore the limitations of available technology. In addition, we discuss implantation technique and device specifications and programming of the rechargeable SNM system in detail. Lastly, we present existing evidence for the use of SNM in bladder and bowel dysfunction and evaluate the anticipated trajectory of neuromodulation technologies over the next five years. Expert commentary: A rechargeable system for SNM is a welcome technological advance. However surgical revision not related to battery changes is not uncommon. Therefore, while a rechargeable system would be expected to reduce costs, it will not eliminate the ongoing maintenance associated with neuromodulation. No matter the apparent benefits, all new technologies require extensive post-market monitoring to ensure safety and efficacy.

Is the efficacy of sacral nerve stimulation for faecal incontinence dependent on the number of active electrode poles achieved during permanent lead insertion?

AIM

Sacral nerve stimulation (SNS) is effective for faecal incontinence (FI). Little is known about the relationship between the implantation technique and the functional outcome. This study aimed to explore the relationship between the numbers of active electrode poles (AEP) achieved during permanent lead placement and subsequent function, therapeutic amplitude and the need for extra appointments between scheduled follow-up visits.

METHOD

One hundred and eighty-six patients with FI who underwent permanent implantation between May 2009 and March 2015 with a tined (barbed) lead (3093/3080, Medtronic) using the straight stylet were registered on the European two-centre SNS prospective database (SNSPD). Correlation between the number of AEP, function, stimulation amplitude and the need for extra visits was analysed.

RESULTS

The numbers of patients having an intra-operative motor response on stimulation of one, two, three and four poles were 18 (9.7%), 75 (40.3%), 61 (32.8%) and 32 (17.2%). The Wexner incontinence score was significantly reduced from 15 (±2.8) at baseline to 9.2 (±4.8) at the latest follow-up after a mean 878 ± 561 days (SD; P < 0.001). No correlation was found between the number of AEP and the functional outcome (P > 0.05). Patients with four-AEP had a reduced therapeutic amplitude up to 289 (±146) days of follow-up (P < 0.03). The number of AEP did not influence the need for extra follow-up visits (P < 0.223).

CONCLUSION

The functional outcome and number of extra visits after SNS for FI did not depend on the number of AEP achieved. The therapeutic amplitude was reduced during the first postoperative year if four AEP were achieved during lead placement.

Prospective Randomized Crossover Trial Comparing Continuous and Cyclic Stimulation in InterStim Therapy

OBJECTIVES

The aim of this study was to assess a difference in efficacy and patient preference in cyclic versus continuous stimulation with InterStim therapy for urge incontinence or urinary frequency.

METHODS

Patients with refractory urge incontinence/urinary frequency and with recent implantation of the InterStim system were randomized to continuous or cyclic InterStim stimulation after institutional review board-approved consent. They completed a 3-day voiding diary after 1 month of stimulation. They were then switched to the alternative setting for 1 month and completed another voiding diary. Subjective responses were evaluated with the Urinary Incontinence Impact Questionnaire and the Urinary Distress Inventory. Patient preference of stimulation setting was assessed. Statistical analysis was performed with paired t tests and repeated-measures analysis of variance.

RESULTS

Data were available for 32 patients. Indication for InterStim: urge incontinence = 24, frequency = 8. No differences were noted in the number of urgency or urge incontinence episodes (mild, moderate, severe, or total) with cyclic or continuous stimulation. No differences were noted in the number of number of pads per day or the number of daytime or nighttime voids. The Urinary Incontinence Impact Questionnaire and Urinary Distress Inventory symptoms scores showed no significant differences between cyclic and continuous stimulation. No significant difference was noted in measured parameters based on the order of stimulation. Continuous stimulation was preferred by 17 patients, 9 preferred cyclic stimulation, and 6 had no preference.

CONCLUSIONS

No significant differences were noted in voiding diaries and subjective responses between cyclic and continuous stimulation in InterStim therapy for patients with urge incontinence or frequency.

Intermittent sacral neuromodulation for idiopathic urgency urinary incontinence in women

AIMS

SNM has been proven to be effective in the treatment of refractory UUI. Total costs and patient burden due to regular battery changes may prevent broad implementation of this treatment. The aim was to achieve a minimal improvement of 50% in incontinence episodes compared to pre-SNM by using iSNM.

METHODS

This prospective cohort study was performed in women with UUI receiving treatment with SNM for a minimum of 6 months. The neurostimulator was programmed to 8 hr "on" and 16 hr "off" per day for 12 weeks. Prior to iSNM, data were collected during no SNM and cSNM. Bladder diaries and various patient reported outcome measures were collected at predetermined time points: 1-5 weeks, and 8, 12, and 16 weeks. Nonparametric tests were used for the statistical analysis.

RESULTS

Of the 19 patients 63% showed an improvement of >50% of incontinence episodes during iSNM compared to pre-SNM. Bladder diary parameters showed a difference between pre-SNM and iSNM median (P-value); incontinence episodes/24 hr, 4.1-1.0 (P = 0.04), incontinence severity, 2.0-1.0 (P = 0.001), voiding episodes/24 hr, 13.0-8.0 (P = 0.001), and voided volume, 149-219 ml (P = 0.04). The UDI-6, 50.0-27.8 (P = 0.03), and the IIQ-7 scores, 50.0-9.5 (P = 0.04) also showed a significant improvement. No difference was demonstrated between iSNM and cSNM.

CONCLUSIONS

Compared to pre-SNM parameters, iSNM shows an improvement in both objective and subjective outcomes. Specifically no difference was found between iSNM and cSNM, indicating that iSNM could be a feasible and cost-effective alternative. Neurourol. Urodynam. 36:385-389, 2017. © 2015 Wiley Periodicals, Inc.

Surface and boney landmarks for sacral neuromodulation: a cadaveric study

INTRODUCTION AND HYPOTHESIS

Standard external landmarks have been suggested as a guide for in-office percutaneous nerve evaluation (PNE), but validity of these landmarks has not been assessed. Our objective was to determine whether the standard 9 cm from the tip of the coccyx indicates the position of the S3 sacral foramen and whether other boney landmarks and measurements improved positioning.

METHODS

Measurements and distances between external boney landmarks were obtained in 22 embalmed cadavers. Spinal needles were placed 9 cm superior to the coccyx and 2 cm lateral to midline bilaterally. After dissection, internal measurements relating to sacral length, position of S3, and location of the needle in relation to S3 were recorded. Correlations among measured variables were assessed using descriptive statistics.

RESULTS

Mean distance from the tip of coccyx to S3 was 9.26 cm (±0.84), from S3 to midline 2.30 cm (±0.2); from needle to S3 1.25 cm, and needle placement was as likely to be placed above or below S3; and S2-S3 and S3-S4 interforamenal distance 1.48 cm (±0.30) and 1.48 cm (±0.24), respectively. Mean distance from S3 to sacroiliac joint (SIJ) was shorter than S2 to SIJ. All associations between external measurements and length from tip of coccyx to S3 were not significant.

CONCLUSION

A distance 9 cm from the tip of the coccyx is a reasonable starting landmark for in-office blind PNE. However, given the variability in coccyx length, caution should be taken; also, sensory-motor response is necessary to confirm proper placement.

Sacral neuromodulation for bowel dysfunction: a consensus statement from the Italian group

BACKGROUND

Representatives from the Italian centers experienced in sacral neuromodulation (SNM) for the treatment of bowel dysfunction met in order to define the current clinical practice in Italy and to produce a consensus statement regarding indications for this therapy and patient management.

METHODS

Fifty Italian colonproctologists were asked to complete a questionnaire concerning their clinical practice in SNM (290 questions, grouped within 4 broad areas). Physicians expressed their opinion by completing the questionnaire, assigning to each statement their level of agreement according to the 5-point Likert scale; the data were analyzed by attributing to each expert's answers a weight proportional to the degree of experience. During a meeting held 2 months later, the critical aspects of the therapy were re-examined and discussions held with the goal of reaching an agreement on controversial topics. The available literature was reviewed.

RESULTS

Patient selection criteria, etiology, diagnostic investigations, test procedures and implantation, follow-up and evaluation of results have been reviewed. The aim was to achieve an algorithm for patient management, showing the place of SNM in the treatment of bowel dysfunction. The approach in case of treatment failure was also discussed.

CONCLUSIONS

Analysis of the data collected reveals substantial consensus at the national level concerning all the main points with regard to the therapy. The recommendations expressed in this article can be considered as national guidelines and taken into account by the principal international implantation centers.

Third sacral foramina morphometry for sacral neuromodulation

OBJECTIVE

This study is aimed to define the geometry and location of the human S3 foramen, with respect to bony landmarks visible on ultrasound.

METHODS

Computed tomographic (CT) image data from an institutional review board-approved database of de-identified pelvic CT images were analyzed. Points along the S3 foramina and bony sacrum were tagged, and their locations saved. The saved points were mathematically analyzed to determine the geometry and relative location of the S3 foramina with respect to other bony landmarks, specifically the sacral hiatus, and the sacral spinous processes, and the caudad aspect of the bilateral SI joints ("SI line"). Descriptive statistics were used to describe the geometry and aggregate location of the S3 foramina bilaterally. CT data sets were excluded if they had evidence of pelvic bone injury, prior bony fixation, severe osteoporosis, or other deformity.

RESULTS

One hundred thirty-three data sets met the inclusion criteria. The SI line was superior to the sacral hiatus for reliable S3 localization. The entire circumference of approximately 14% of the S3 foramina is located cephalad to the SI line. The sagittal angle of trajectory for S3 was approximately 70 degrees relative to the dorsal surface of the sacrum.

CONCLUSIONS

Clinical localization of the S3 foramen for sacral neuromodulator needle placement is best obtained when the needle tip is positioned 15 to 25 mm lateral to the sacral spinous processes and 0.0 cm to 25 mm caudad to the SI line, at the level of the dorsal sacrum surface. The findings presented in this study may be applied to improve the efficacy and accuracy of neuromodulator lead placement into the S3 foramen. This study provides rationale for the effectiveness of the crosshair placement technique and demonstrates the best location for needle repositioning when this technique is not initially successful.

Neural pathways involved in sacral neuromodulation of reflex bladder activity in cats

This study examined the mechanisms underlying the effects of sacral neuromodulation on reflex bladder activity in chloralose-anesthetized cats. Bladder activity was recorded during cystometrograms (CMGs) or under isovolumetric conditions. An S1-S3 dorsal (DRT) or ventral root (VRT) was electrically stimulated at a range of frequencies (1-30 Hz) and at intensities relative to threshold (0.25-2T) for evoking anal/toe twitches. Stimulation of DRTs but not VRTs at 1T intensity and frequencies of 1-30 Hz inhibited isovolumetric rhythmic bladder contractions. A 5-Hz DRT stimulation during CMGs was optimal for increasing (P < 0.05) bladder capacity (BC), but stimulation at 15 and 30 Hz was ineffective. Stimulation of the S1 DRT was more effective (increases BC to 144% and 164% of control at 1T and 2T, respectively) than S2 DRT stimulation (increases BC to 132% and 150% of control). Bilateral transection of the hypogastric or pudendal nerves did not change the inhibitory effect induced by S1 DRT stimulation. Repeated stimulation of S1 and S2 DRTs during multiple CMGs elicited a significant (P < 0.05) increase in BC (to 155 ± 11% of control) that persisted after termination of the stimulation. These results in cats suggest that the inhibition of reflex bladder activity by sacral neuromodulation occurs primarily in the central nervous system by inhibiting the ascending or descending pathways of the spinobulbospinal micturition reflex.

Impact of staged InterStim implantation on the postoperative activities of daily living and pain

OBJECTIVES

To evaluate the short-term effects of staged InterStim implantation on activities of daily living (ADL) and pain.

METHODS

This prospective study assessed women undergoing staged InterStim implantation. The Older Americans Resources and Services Program Multidimensional Functional Assessment Questionnaire asked participants about their ability to complete activities without help or what help they needed following stage I lead placement and stage II neurostimulator implantation. Narcotic use and a visual analog scale (VAS) for pain were recorded daily.

RESULTS

Thirty-eight women underwent stage I with 33 (86.8%) progressing to stage II. On stage I postoperative day (POD) 2, more women required help shopping compared with baseline (40 vs 17%, p < 0.004). The median pain score increased on Stage I POD1 (P < 0.001) and the use of narcotics increased on POD1 and 2 compared with baseline (50% vs 14%, p = 0.001). The same trends were seen following stage II.

CONCLUSIONS

Staged InterStim implantation has minimal impact on ADL, pain or narcotic requirements.

Battery explantation after sacral neuromodulation in the Medicare population

AIMS

To determine sacral neuromodulation battery life and the patient and provider risk factors for early explantation in a population-based sample.

METHODS

A 5% sample of Medicare beneficiaries from 1997 to 2007 served as the data source. All patients who had a sacral neuromodulation device implanted in that time period were included. Variables included in a multivariate analysis of risk factors for removal included gender, age, race, diagnosis, type of test phase, provider specialty, and volume. The number of device reprogramming events was also recorded in this time period.

RESULTS

Mean follow-up was 60.5 months. Patients on average had 2.15 reprogramming episodes in their first year, with that number decreasing over subsequent years. Out of the 558 batteries implanted 63 (11.3%) were explanted. Of the 19 implanted individuals who carried the diagnosis of interstitial cystitis (IC), 11 (57.9%) had the battery removed. This was the only variable that predicted early removal, with an odds ratio of explantation of 10.5 (95% CI: 3.9-28.4).

CONCLUSION

Very few sacral neuromodulation batteries, once implanted, are removed prematurely. Patients with IC, however, are at very high risk of requiring premature battery removal.