Sacral nerve stimulation results may be improved by electrodiagnostic techniques

Sensing in Sacral Neuromodulation: A Feasibility Study in Subjects With Urinary Incontinence and Retention

OBJECTIVES

Sacral neuromodulation (SNM) therapy standard of care relies on visual-motor responses and patient-reported sensory responses in deciding optimized lead placement and programming. Automatic detection of stimulation responses could offer a simple, consistent indicator for optimizing SNM. The purpose of this study was to measure and characterize sacral evoked responses (SERs) resulting from sacral nerve stimulation using a commercial, tined SNM lead.

MATERIALS AND METHODS

A custom external research system with stimulation and sensing hardware was connected to the percutaneous extension of an implanted lead during a staged (tined lead) evaluation for SNM. The system collected SER recordings across a range of prespecified stimulation settings (electrode configuration combinations for bipolar stimulation and bipolar sensing) during intraoperative and postoperative sessions in 21 subjects with overactive bladder (OAB) and nonobstructive urinary retention (NOUR). Motor and sensory thresholds were collected during the same sessions.

RESULTS

SERs were detected in all 21 subjects. SER morphology (number of peaks, magnitude, and timing) varied across electrode configurations within and across subjects. Among subjects and electrode configurations tested, recordings contained SERs at motor threshold and/or sensory threshold in 75% to 80% of subjects.

CONCLUSIONS

This study confirmed that implanted SNM leads can be used to directly record SERs elicited by stimulation in subjects with OAB and NOUR. SERs were readily detectable at typical SNM stimulation settings and procedural time points. Using these SERs as possible objective measures of SNM response has the capability to automate patient-specific SNM therapy, potentially providing consistent lead placement, programming, and/or closed-loop therapy.

The Influence of Electrode Configuration Changes on the Sensory and Motor Response During (Re)Programming in Sacral Neuromodulation

OBJECTIVES

This study aimed to assess the neurophysiological basis behind troubleshooting in sacral neuromodulation (SNM). Close follow-up of SNM patients with program parameter optimization has proven to be paramount by restoring clinical efficacy and avoiding surgical revision.

MATERIALS AND METHODS

A total of 34 successful SNM patients (28 overactive bladder wet, six nonobstructive urinary retention) with an implantable pulse generator were included. All possible bipolar and monopolar electrode settings were tested at sensory threshold (ST) to evaluate sensory (mapped on a perineal grid with 1 cm² coordinates) and motor (peak-to-peak amplitude and latency of muscle action potential) responses of the pelvic floor. Pelvic floor muscle electromyography was recorded using a multiple array probe, placed intravaginally. Parametric tests were used for paired data: repeated-measures ANOVA or t-test. A nonparametric test was used for paired data: Friedman ANOVA or Wilcoxon signed rank (WSR) test; p < 0.05 was considered statistically significant. If significant, ANOVA was followed by Dunn-Bonferroni post hoc analysis.

RESULTS

Monopolar configurations showed significantly lower STs-1.38 ± 0.73 V vs 1.76 ± 0.89 V (paired t-test: p < 0.0001)-and presented with significantly higher peak-to-peak amplitudes-115.67 ± 79.03 μV vs 90.77 ± 80.55 μV (WSR: p = 0.005)-than bipolar configurations. When polarity was swapped, configurations with the cathode distal to the anode showed significantly lower STs, 1.73 ± 0.91 V vs 1.85 ± 0.87 V (paired t-test: p = 0.003), and mean peak-to-peak amplitudes, 81.32 ± 72.82 μV vs 100.21 ± 90.22 μV (WSR: p = 0.0001). Cathodal changes resulted in more changes in sensory responses than anodal changes (χ² test: p = 0.044). In cathodal changes only, peak-to-peak amplitudes were significantly higher when the distance between electrodes was maximally spread (WSR: p = 0.046).

CONCLUSIONS

From a neurophysiological point of view, monopolar configurations stimulated more motor nerve fibers at lower STs, therefore providing more therapeutic efficiency. Swapping polarity or changing the position of the cathode led to different sensory and motor responses, serving as potential reprogramming options.

Sacral Neuromodulation Changes Pelvic Floor Activity in Overactive Bladder Patients-Possible New Insights in Mechanism of Action: A Pilot Study

OBJECTIVES

To evaluate if electrodiagnostic tools can advance the understanding in the effect of sacral neuromodulation (SNM) on pelvic floor activity, more specifically if SNM induces changes in pelvic floor muscle (PFM) contraction.

MATERIALS AND METHODS

Single tertiary center, prospective study (October 2017-May 2018) including patients with overactive bladder syndrome undergoing SNM. Electromyography of the PFM was recorded using the Multiple Array Probe Leiden. The procedure consisted of consecutive stimulations of the lead electrodes with increasing intensity (1-3, 5, 7, 10 V). Recordings were made after electrode placement (T0) and three weeks of SNM (T1). Patients with >50% improvement were defined as responders, others as nonresponders. For the analyses, the highest electrical PFM response (EPFMR), defined as the peak-to-peak amplitude of the muscle response, was identified for each intensity. The sensitivity (intensity where the first EPFMR was registered and the normalized EPFMR as percentage of maximum EPFMR) and the evolution (EMFPR changes over time) were analyzed using linear mixed models.

RESULTS

Fourteen patients were analyzed (nine responders, five nonresponders). For nonresponders, the PFM was significantly less sensitive to stimulation after three weeks (T0: 1.7 V, T1: 2.6 V). The normalized EPFMR was (significantly) lower after three weeks for the ipsilateral side of the PFM for the clinically relevant voltages (1 V: 36%-23%; p = 0.024, 2 V: 56%-29%; p = 0.00001; 3 V: 63%-37%; p = 0.0002). For the nonresponders, the mean EPFMR was significantly lower at 8/12 locations at T1 (T0: 109 μV, T1: 58 μV; mean p = 0.013, range <0.0001-0.0867). For responders, the sensitivity and evolution did not change significantly.

CONCLUSIONS

This is the first study to describe in detail the neurophysiological characteristics of the PFM, and the changes over time upon sacral spinal root stimulation, in responders and nonresponders to SNM. More research is needed to investigate the full potential of EPFMR as a response indicator.

Neuromodulation

Sacral neuromodulation (SNM) has been available in the United States for more than 20 years and is a guideline-recommended therapy by both the American Urological Association and the American Society of Colon and Rectal Surgeons, with proven long-term success for urinary urgency incontinence, urinary urgency frequency, nonobstructive urinary retention, and fecal incontinence. Initially the therapy involved a more invasive surgical approach that included a large cut down over the sacrum. This article reviews recent advancements in SNM therapy including updates in best practices for implant technique, technological innovations, and the new clinical literature relevant to contemporary practice.

Pelvic Floor Muscle Electromyography as a Guiding Tool During Lead Placement and (Re)Programming in Sacral Neuromodulation Patients: Validity, Reliability, and Feasibility of the Technique

PURPOSE

To assess the validity, reliability, and feasibility of electromyography (EMG) as a tool to measure pelvic floor muscle (PFM) contractions during placement and (re)programming of the tined lead electrodes in sacral neuromodulation (SNM) patients.

MATERIALS AND METHODS

Single tertiary center, prospective study conducted between 2017 and 2019 consisting of three protocols including a total of 75 patients with overactive bladder (wet/dry) or nonobstructive urinary retention. PFM EMG was recorded using the multiple array probe (MAPLe), placed intravaginally. All stimulations (monophasic pulsed square wave, 210 μsec, 14 Hz) were performed using Medtronic's standard SNM stimulation equipment. During lead implantation, all four lead electrodes were stimulated with fixed increasing stimulation intensities (1-2-3-5-7-10 V). During lead electrode (re)programming, five bipolar lead electrode configurations were stimulated twice up to when an electrical PFM motor response (EPFMR), sensory response, and pain response were noted (i.e., the threshold), respectively. Additionally, amplitude and latency of the EPFMRs were determined. Validity, reliability, and feasibility were statistically analyzed using the intraclass correlation coefficient, weighted Cohen's kappa and linear regression, respectively.

RESULTS

Validity: EPFMRs were strongly associated with visually detected PFM motor responses (κ = 0.90). Reliability: EPFMR amplitude (ICC = 0.99) and latency (ICC = 0.93) showed excellent repeatability. Feasibility: linear regression (EPFMR threshold = 0.18 mA + 0.76 * sensory response threshold) showed an increase in the sensory response threshold is associated with a smaller increase in EPFMR threshold, with the EPFMR occurring before or on the sensory response threshold in 83.8% of all stimulations.

CONCLUSIONS

Measuring PFM contractions with EMG during placement and (re)programming of lead electrodes in SNM patients is valid, reliable, and feasible. Therefore, the use of PFM EMG motor responses could be considered as a tool to assist in these procedures.

Sacral neuromodulation for female pelvic floor disorders

Objective: To systematically review available studies on the effectiveness and safety of sacral neuromodulation (SNM) in women with various pelvic floor disorders not responding to more conservative treatment, as SNM is indicated in such women.

Methods: Data source: We did a systematic review through the PubMed and the Cochrane Library according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement from 1998 to 2018 in English using the keywords ‘Sacral Neuromodulation’ and ‘Sacral Nerve Stimulation’.

Study selection: Randomised controlled trials and prospective studies were selected, with a minimum sample size of 20 patients and ≥6 months of follow-up.

Results: We identified 19 articles. A ≥50% reduction in symptoms qualifies the patient for a permanent implant. Several advances have been introduced into SNM to decrease the invasiveness of the procedure, including a smaller implantable pulse generator battery (improved comfort) and better localisation of the lead wire (improved outcome). The literature reports success for overactive bladder (OAB) to range between 56% and 68% (up to 80%). We report a 5-year therapeutic success rate of 67%. In our previous studies, 38% of our patients with urge urinary incontinence achieved complete continence at 60-months follow-up, with a therapeutic response rate of 57%. Effectiveness in patients with urinary retention and faecal incontinence are about 70% and 85%, respectively. Effectiveness in interstitial cystitis/bladder pain syndrome appears to be lower compared with OAB.

Conclusion: SNM is a safe and effective therapy for women with various pelvic floor disorders.

Abbreviations: BONT: botulinum toxin; FDA: USA Food and Drug Administration; FS: Fowler’s syndrome; FI: faecal incontinence; IC/BPS: interstitial cystitis/bladder pain syndrome; ICIQ-OABqol: International Consultation on Incontinence Modular Questionnaire-Overactive Bladder Symptoms Quality of Life; INS: implantable neurostimulator; OAB: overactive bladder; PET: positron emission tomography; PNE: peripheral nerve evaluation; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; PTNM: posterior tibial nerve modulation; PVR: post-void residual urine; QoL: quality of life; RCT: randomised controlled trial; SNM: sacral neuromodulation; (U)UI: (urgency) urinary incontinence

Sacral nerve stimulation--hidden costs (uncovered)

AIM

The aim of this study is to determine the occurrence of surgical revision in a cohort of patients treated with sacral nerve stimulation (SNS) for faecal incontinence and constipation and to establish the types of procedures performed and indications for surgery.

METHOD

From the years 2002 to 2014, 125 patients were identified who had undergone permanent SNS therapy with 36 (28.8 %) patients requiring surgical intervention postimplantation. These cases were retrospectively reviewed (range of follow-up 1-99 months).

RESULTS

Over a total of 1512 months of SNS treatment, 51 unplanned surgical procedures were required in 36 patients. At present, 48 procedures have been performed at an average of 2.6 years following implantation and three patients are awaiting surgery. Lead-related problems accounted for 30 (58.8 %) procedures at an average of 1.7 years affecting 22 patients. Battery and implantable pulse generator-related problems attributed to 13 procedures (25.5 %) in 12 patients at an average of 5.0 years. Battery depletion occurred in seven patients at an average of 5.4 years. Surgical revision was required to replace, remove, or resite various components of the SNS system. Indications for surgery included lead damage, pain and loss or lack of SNS efficacy. Explantation was warranted in six patients due to poor SNS efficacy, pain, infection and facilitation of a magnetic resonance imaging scan. This was performed at an average of 1.6 years.

CONCLUSION

A considerable proportion of patients treated with SNS therapy require surgical revision. These unplanned procedures are associated with substantial unexpected costs that financially burden SNS services.

The technique of sacral nerve modulation

AIM

The aim of this review was to summarize current knowledge and recommendations regarding the technique of implantation of the electrode in performing sacroneuromodulation (SNM) and the available information on programming parameters and implantation algorithms.

METHOD

All English-language articles published from January 1985 to December 2013 that reported the SNM surgical technique and results were considered for inclusion. Data were considered useful for the present review only if related to: (i) peripheral nerve evaluation; (ii) temporary nerve stimulation; (iii) definitive impulse generator placement; and (iv) parameters programming.

RESULTS

The literature search revealed 193 potentially relevant studies from initial electronic search terms and eligibility criteria, and these studies were evaluated in detail. In total, 41 studies were included in the final analysis. Of the studies reviewed, the majority (n = 37) were prospective or retrospective case series. Only three randomized clinical trials were eligible for inclusion.

CONCLUSION

Although the technique seems to be standardized, several steps still need to be clarified in order to define the best way to perform the procedure and then to maximize the outcome.

Sacral nerve stimulation for faecal incontinence: optimizing outcome and managing complications

AIM

A knowledge of the principles of neurostimulation is essential to achieve optimal efficacy and minimize adverse effects. The aim of this article was to review the current evidence regarding device programming in the management of patients having sacral nerve stimulation (SNS) for faecal incontinence.

METHOD

A Medline search was performed including the keywords and/or MeSH headings of sacral nerve stimulation, neuromodulation, artificial pacemaker, faecal incontinence, programming, adverse effects and complications. Further studies were identified by cross-referencing from relevant articles and by appraisal of recent peer-reviewed conference abstracts and proceedings.

RESULTS

Neurostimulator programming is an important component of SNS. Efficacy can be improved or restored with reprogramming. Adverse stimulation is often reversible, and nonstimulation-related complications are correctable. A total loss of efficacy can be explained in over one-half of patients.

CONCLUSION

An improved outcome of SNS can be achieved by selecting the best possible stimulation parameters individualized to each patient. Further research into the optimal settings is needed.

Predictive factors for successful sacral nerve stimulation in the treatment of faecal incontinence: results of trial stimulation in 200 patients

AIM

Sacral nerve stimulation (SNS) has a place in the treatment algorithm for faecal incontinence (FI). However, after implantation, 15-30% of patients with FI fail to respond for unknown reasons. We investigated the effect of SNS on continence and quality of life (QOL) and tried to identify specific predictive factors of the success of permanent SNS in the treatment of FI.

METHOD

Two hundred consecutive patients (six men; median age = 60; range 16-81) underwent permanent implantation for FI. The severity of FI was evaluated by the Cleveland Clinic Score. Quality of life was evaluated by the French version of the American Society of Colon and Rectal Surgeons (ASCRS) quality of life questionnaire (FIQL). All patients underwent a preoperative evaluation. After permanent implantation, severity and QOL scores were reevaluated after six and 12 months and then once a year.

RESULTS

The severity scores were significantly reduced during SNS (P = 0.001). QOL improved in all domains. At the 6-month follow-up, the clinical outcome of the permanent implant was not affected by age, gender, duration of symptoms, QOL, main causes of FI, anorectal manometry or endoanal ultrasound results. Only loose stool consistency (P = 0.01), persistent FI even though diarrhoea was controlled by medical treatment (P = 0.004), and low stimulation intensity (P = 0.02) were associated with improved short-term outcomes. Multivariate analysis confirmed that loose stool consistency and low stimulation intensity were related to a favourable outcome.

CONCLUSION

Stool consistency and low stimulation intensity have been identified as predictive factors for the short-term outcome of SNS.

Neuromodulation and the role of electrodiagnostic techniques

Electrodiagnostic techniques have been utilized in surgery since the early 1960s. These techniques have been primarily used in neurosurgery; however, with the introduction of neuromodulation for voiding dysfunction, these techniques have now found their way into the field of female pelvic medicine. This article will review techniques applicable to evaluate pelvic floor function as it relates to neuromodulation. It will also review the literature describing how these techniques are used to help determine appropriate candidates as well as improve surgical outcomes. A PubMed search was conducted using the terms neuromodulation, Interstim, electrodiagnosis, electrodiagnostic techniques, electromyography with limits to the pelvic floor, and voiding dysfunction. Eight articles and three abstracts were found that directly related to the use of electrodiagnostic techniques as they apply to neuromodulation. Electrodiagnostic techniques may play a role in helping predict appropriate candidates for neuromodulation as well as improve surgical outcomes.

Comparison of clinical outcome between open and percutaneous lead insertion for permanent sacral nerve neurostimulation for the treatment of fecal incontinence

PURPOSE

Results from early studies on sacral nerve stimulation are based on a stimulation electrode lead that was placed under direct vision during an open surgical procedure. A percutaneous inserted lead, introduced in 2002, is now widely used. This study was designed to investigate differences in clinical efficacy and adverse complications between the two methods of lead placement.

METHODS

Prospectively collected data were analyzed for 48 patients who had undergone permanent sacral nerve stimulation for fecal incontinence at a single institution between 1997 and 2006. Eighteen patients had undergone open lead placement (Group 1) and 30 patients percutaneous lead placement (Group 2).

RESULTS

Median follow-up was 51 (range, 22-106) months for Group 1 and 8 (range, 1-40) months for Group 2 patients. There was no difference in patient demographics, severity of incontinence, or physiologic parameters between the two groups. Lead type did not affect the outcome of chronic stimulation with reductions in total episodes of incontinence being similar between the two groups (P = 0.448). No difference in infection or lead dislocation rate between the two groups was identified.

CONCLUSIONS

The percutaneously inserted lead seems to be equal to the open inserted lead in terms of clinical efficacy and complication rate in the short-term.

Neurophysiology in neurourology

The bladder has only two essential functions. It stores and periodically empties liquid waste. Yet it is unique as a visceral organ, allowing integrated volitional and autonomous control of continence and voiding. Normal function tests the integrity of the nervous system at all levels, extending from the neuroepithelium of the bladder wall to the frontal cortex of the brain. Thus, dysfunction is common with impairment of either the central or peripheral nervous system. This monograph presents an overview of the neural control of the bladder as it is currently understood. A description of pertinent peripheral anatomy and neuroanatomy is provided, followed by an explanation of common neurophysiological tests of the lower urinary tract and associated structures, including both urodynamic and electrodiagnostic approaches. Clinical applications are included to illustrate the impact of nervous system dysfunction on the bladder and to provide indications for testing.

Predictive factors for successful sacral nerve stimulation in the treatment of faecal incontinence: a 10-year cohort analysis

OBJECTIVE

Sacral nerve stimulation (SNS) is an established treatment for faecal incontinence. We aimed to identify specific factors that could predict the outcome of temporary and permanent stimulation.

METHOD

A cohort analysis was performed to identify potential predictive factors in 81 patients who underwent temporary SNS at a single institution over a 10-year period (June 1996 to June 2006). Data were obtained from prospectively collected patient symptom diaries and quality of life questionnaires, operation reports, anorectal physiological studies, endoanal ultrasound images and radiology of lead placement.

RESULTS

Clinical outcome of temporary screening was not affected by patient gender, age, body mass index, severity or length of symptoms. The need for a repeated temporary procedure was associated with subsequent failure during screening (P = 0.008). A low threshold to obtain a motor response during temporary lead insertion was associated with improved outcome (P = 0.048). Evidence of anal sphincter trauma was associated with a greater risk of failure (P = 0.040). However, there was no difference in medium-term outcome between patients with external anal sphincter (EAS) defects and patients with intact anal sphincter muscles.

CONCLUSION

Variables have been identified that help to predict the outcome of SNS. The presence of an EAS defect should not preclude treatment.

Sacral nerve neuromodulation in patients with underlying neurologic disease

OBJECTIVE

Sacral nerve neuromodulation (SNS) is an effective treatment for lower urinary tract dysfunction. Many underlying neurologic processes affect lower urinary tract function. We present results of SNS in patients with underlying neurologic dysfunction.

STUDY DESIGN

This is a retrospective case series of 33 patients with neurologic disease and lower urinary tract dysfunction who underwent an InterStim stimulation procedure. Results were evaluated by pre- and postoperative voiding diaries. Success was defined as greater than 50% improvement.

RESULTS

Twenty-eight of 33 patients (85%) underwent implantation: 13 of 16 (81%) multiple sclerosis, 4 of 6 (67%) Parkinson disease, and 11 of 11 (100%) other neurologic disorders. Incontinence episodes per 24 hours decreased 68%, number of voids per 24 hours decreased 43%, nocturia decreased 70%, and there was a 58% reduction in intermittent self-catheterization per 24 hours. Ninety-three percent reported overall satisfaction.

CONCLUSION

Sacral nerve neuromodulation is an effective treatment for lower urinary tract dysfunction in patients with underlying neurologic disease.

Neurophysiology of the neurogenic lower urinary tract disorders

The nervous system structures involved in the control of the lower urinary tract (LUT) are usually divided using a neuroanatomical classification system into suprapontine, pontine, spinal and sacral. In all patients with LUT symptoms, after exclusion of local causes, a nervous system disorder needs to be considered. For the diagnosis of neurogenic LUT disorders, in addition to clinical assessment, neurophysiologic testing might be useful. Imaging and other laboratory studies (e.g., cystometry) often provide relevant additional information. Neurophysiologic tests are more useful in patients with sacral compared with suprasacral disorders. Although in patients with LUT disorders external urethral sphincter (EUS) electromyography (EMG) would seem the most appropriate, anal sphincter EMG is the single most useful diagnostic test, particularly for focal sacral lesions, and atypical parkinsonism. Another clinically useful method that tests the sacral segments, and complements EMG, is the sacral (penilo/clitoro-cavernosus) reflex. Kinesiologic EMG is useful to demonstrate detrusor sphincter dyssynergia (i.e., increased EUS activity during bladder contraction), which is particularly common in spinal cord disease. Somatosensory evoked potential (SEP) and motor evoked potential (MEP) studies (cortical and lumbar) may be useful to diagnose clinically silent central lesions. MEP, in addition, seems to be very promising in research into cortical excitability. Theoretically, cortical SEP on bladder/urethra stimulation would be much more useful than pudendal SEP because it tests thin nerve afferents from the pelvic viscera. However, the utility of this technique is limited by technical difficulties, which can be partially overcome by the concomitant recording of a palmar sympathetic skin response (SSR). SSR recorded from the saddle region is also useful for testing the lumbosacral sympathetic system. Although the technique of detrusor EMG has been recently described in humans, a clinically useful test for evaluating the sacral parasympathetic system, which is crucial for LUT functioning, is still lacking.

Sacral neuromodulation as an effective treatment for refractory pelvic floor dysfunction

OBJECTIVES

To determine the long-term efficacy and complications of sacral nerve stimulation as an alternative therapy for pelvic floor dysfunction. Pelvic floor dysfunction is a complex problem that can be refractory to current treatment modalities. Conservative therapy rarely results in a durable cure of patients, and various surgical procedures have significant side effects and less than optimal results.

METHODS

Sixty-four patients, 54 women and 10 men, with various forms of voiding dysfunction for whom other forms of therapy had failed underwent placement of the Medtronic Implantable Pulse Generator sacral nerve implant. The mean age was 47 years. The presenting complaint was frequency, urgency, and urge incontinence in 44 patients and chronic nonobstructive urinary retention requiring self-catheterization in 20 patients. Forty-one patients also had chronic pelvic and perineal pain associated with their voiding symptoms. The mean duration of symptoms was 69 months. All patients underwent percutaneous nerve evaluation before the permanent implant and demonstrated more than 50% improvement in their symptoms. All patients were evaluated at 1, 3, 6, 12, and 24 months, and yearly thereafter. The assessment of the voiding symptoms was done both subjectively by patient symptoms and objectively using voiding diaries recorded for 3 days. A validated verbal rating pain scale was used to evaluate pain levels.

RESULTS

Eighty percent of the patients had 50% or greater improvement in their presenting symptoms and quality of life after the procedure, with a mean follow-up of 24 months. Patients with frequency-urgency showed a reduction in the number of voids per day with a significant increase in voided volumes. Patients with urge incontinence showed a reduction in leaking episodes from 6.4 to 2.0/24 hr, with a decrease in the number of pads used from 3.5 to 1.2/day. Sixteen of 20 patients with urinary retention were able to void with a residual volume of less than 100 mL. Patients with chronic pelvic pain showed a decrease in the severity of pain from a score of 5.8 to 3.7. Complications were minimal and encountered in 18.7% of the patients.

CONCLUSIONS

Sacral nerve stimulation is an effective and durable new approach to pelvic floor dysfunction with minimal complications. Test stimulation provides a valuable tool for patient selection.

Sacral nerve stimulation in patients with chronic intractable pelvic pain

PURPOSE

Transforamenal sacral nerve stimulation with an implantable neuroprosthetic device has been shown to benefit patients with chronic voiding dysfunction. In this study we measured the effectiveness of sacral nerve stimulation in 10 patients with chronic intractable pelvic pain.

MATERIALS AND METHODS

After successful percutaneous trial stimulation, a neuroprosthetic sacral nerve stimulation device was surgically implanted in 10 patients with chronic intractable pelvic pain. Leads were placed in the S3 and S4 foramen in 8 and 2 cases, respectively. Patients were evaluated throughout the study using a patient pain assessment questionnaire on a scale of 0-absent to 5-excruciating pain. Pain was assessed at baseline, during test stimulation, and 1, 3 and 6 months after surgical lead implantation. An additional long-term assessment was done at a median followup of 19 months.

RESULTS

Of the 10 patients with the implant 9 had a decrease in the severity of the worst pain compared to baseline at a median followup of 19 months. The number of hours of pain decreased from 13.1 to 6.9 at the same followup interval. There was also an average decrease in the rate of pain from 9.7 at baseline to 4.4 on a scale of 10-always to 0-never having pain. At a median of 19 months 6 of 10 patients reported significant improvement in pelvic pain symptomology.

CONCLUSIONS

These data imply that transforamenal sacral nerve stimulation can have beneficial effects on the severity and frequency of chronic intractable pelvic pain. Future clinical studies are necessary to determine the long-term effectiveness of this therapy.