Comparative pilot study of implantation techniques for pudendal neuromodulation: technical and clinical outcome in first 20 patients with chronic pelvic pain

Peripheral Nerve Stimulation for Pain Management: A Review

PURPOSE OF REVIEW

Peripheral nerve stimulation has seen a recent upsurge in utilization for various chronic pain conditions, specifically from a neuropathic etiology, where a single peripheral nerve can be pinpointed as a culprit for pain.

RECENT FINDINGS

There is conflicting evidence about the efficacy and long-term outcomes of peripheral nerve stimulation for chronic pain, with most studies being small sized. The focus of this article is to review available evidence for the utilization of peripheral nerve stimulation for chronic pain syndromes as well as upcoming evidence in the immediate postoperative realm. The indications for the use of PNS have expanded from neuropathic pain such as occipital neuralgia and post-amputation pain, to more widespread disease processes such as chronic low back pain. Percutaneous PNS delivered over a 60-day period may provide significant carry-over effects including pain relief, potentially avoiding the need for a permanently implanted system while enabling improved function in patients with chronic pain.

[Therapeutic value of neuromodulation in women]

BACKGROUND

Neuromodulative treatment for the treatment of overactive bladder has been used in clinical practice since its introduction in the early 1980s.

OBJECTIVES

Description and update of the various neuromodulative techniques (tibial nerve stimulation, sacral and pudendal neuromodulation), presentation of their effectiveness and safety, and evaluation of their evidence for clinical practice.

MATERIALS AND METHODS

Literature search in PubMed and Embase, inclusion of studies according to the following criteria: evidence level, timeliness, length of follow-up and number of female patients according to the author's preference.

RESULTS

The efficacy and safety of both percutaneous tibial nerve stimulation (PTNS) and sacral neuromodulation (SNM) has been proven by studies with an evidence level of 1. Long-term data of up to 20 years are available for SNM, while long-term data for PTNS are limited. Permanent implants for tibial nerve stimulation are promising new developments. Pudendal neuromodulation (PNM) is suitable for more complex indications but is surgically more challenging.

CONCLUSIONS

Both PTNS and SNM are suitable for broad application in clinical practice. PTNS can be offered as an alternative to pharmacotherapy, while SNM provides the most convincing clinical data of all neuromodulative therapies.

Pain specialist management of sexual pain: III-neuromodulation

INTRODUCTION

Some women with sexual pain do not respond to conservative multi-modal care modalities. Neuromodulation is a group of methods which alter nerve activity by delivering electrical energy or pharmaceutical agents directly to target neural structures. Multiple forms of neuromodulation may provide durable treatment options to fill the unmet therapeutic need of a certain population of women with chronic sexual pain.

OBJECTIVES

To provide a current review of neuromodulation treatments used for female sexual pain and introduce neuromodulation techniques which may be applied in novel ways to specific sexual pain phenotypes.

METHODS

Internet, PubMed and Cochrane Library were searched for relevant articles on female sexual pain within the clinical purview and scope of practice of pain management.

RESULTS

A thorough review of the literature was conducted to include basic science studies, clinical trials, systematic reviews, consensus statements, and case-reports. A sampling of information on real-world patient outcomes was included. The amount and quality of evidence for neuromodulation to treat female sexual pain is low-moderate. Descriptions of neuromodulation procedures for sexual pain were made and clinical studies reviewed. The effects of autonomic nervous system (ANS) dysregulation on the experience of pain were discussed with consideration of interventional procedures to facilitate restoration of ANS equilibrium.

CONCLUSION

Treating female sexual pain is complex. There are considerable numbers of women who have unsatisfactory sexual pain relief despite evidence-based interdisciplinary care. These women may benefit from referral to consider neuromodulation treatment options. Neuromodulation is a relatively new capability in the arsenal of pain management and other specialists that can be considered for women with treatment refractory sexual pain.

Diagnosis and treatment of pudendal and inferior cluneal nerve entrapment syndrome: a narrative review

AIM

Pudendal and inferior cluneal nerve entrapment can cause a neuropathic pain syndrome in the sensitive areas innervated by these nerves. Diagnosis is challenging and patients often suffer several years before diagnosis is made. The purpose of the review was to inform healthcare workers about this disease and to provide a basis of anatomy and physiopathology, to inform about diagnostic tools and invasive or non-invasive treatment modalities and outcome.

METHODS

A description of pudendal and inferior cluneal nerve anatomy is given. Physiopathology for entrapment is explained. Diagnostic criteria are described, and all non-invasive and invasive treatment options are discussed.

RESULTS

The Nantes criteria offer a solid basis for diagnosing this rare condition. Treatment should be offered in a pluri-disciplinary setting and consists of avoidance of painful stimuli, physiotherapy, psychotherapy, pharmacological treatment led by tricyclic antidepressants and anticonvulsants. Nerve blocks are efficient at short term and serve mainly as a diagnostic tool. Pulsed radiofrequency (PRF) is described as a successful treatment option for pudendal neuralgia in patients non-responding to non-invasive treatment. If all other treatments fail, surgery can be offered. Different surgical procedures exist but only the open transgluteal approach has proven its efficacy compared to medical treatment. The minimal-invasive ENTRAMI technique offers the possibility to combine nerve release with pudendal neuromodulation.

CONCLUSIONS

Pudendal and inferior cluneal nerve entrapment syndrome are a challenge not only for diagnosis but also for treatment. Different non-invasive and invasive treatment options exist and should be offered in a pluri-disciplinary setting.

Neuromodulation in Chronic Pelvic Pain: A Narrative Review

Chronic primary pelvic pain syndrome (CPPPS) is a heterogeneous disease with unknown pathogenesis and a lack of distinct pathological features, which complicates diagnosis and therapy and has a significant impact on patients' daily life. Because pharmacological management is ineffective and long-term use may result in additional system damage, developing a more effective treatment is critical. Neuromodulation has advanced rapidly over the last few decades, and various types of neuromodulations have demonstrated efficacy in the treatment of CPPPS. In this article we discuss the evolution of neuromodulation technology in the treatment of chronic pelvic pain, its application to various subtypes of chronic pelvic pain, and the comparison of relevant efficacy and parameter differences, as well as assess the relative advantages and disadvantages of sacral neuromodulation, percutaneous tibial nerve stimulation , transcutaneous electrical nerve stimulation, electroacupuncture, and pudendal neuromodulation. Furthermore, it was noted that chronic pelvic pain should be evaluated in terms of pain, associated symptoms, psychological problems, and quality of life. Although neuromodulation approaches have been shown to be effective in treating chronic pelvic pain, more extensive multicenter trials are required to confirm this.

Current role of neuromodulation in bladder pain syndrome/interstitial cystitis

Neuromodulation is recommended by major international guidelines as a fourth-line treatment in bladder pain syndrome/interstitial cystitis (BPS/IC) patients after failure of behavioural, oral and intravesical pharmacological treatments, including hydrodistension. A non-systematic review of studies identified by electronic search of MEDLINE was performed with no time limitation. A narrative synthesis of the existing evidence regarding the results of sacral, tibial and pudendal nerve stimulation in the management of BPS/IC was developed. Neuromodulation in pelvic chronic pain disorders, including BPS/IC, is a useful tool for refractory patients to conventional treatments. Sacral neuromodulation may be effective in patients with BPS without Hunner's lesions, and the effect seems to be maintained in the mid- and long-term. Posterior tibial nerve stimulation can be offered to patients with BPS/IC in the context of a multidisciplinary approach. When pudendal neuralgia is suspected, selective pudendal nerve stimulation has a high response rate. The aetiology of the pain can influence the outcomes in the mid- and long-term of the different neuromodulation approaches, thus careful diagnosis is recommended.

Initial experience using a novel nerve stimulator for the management of pudendal neuralgia

AIMS

In patients with pudendal neuralgia, prior studies have shown efficacy in chronic stimulation with Interstim® (Medtronic, Inc.). This feasibility study reports on the initial experience of using a wireless system to power an implanted lead at the pudendal nerve, StimWave®, to treat pudendal neuralgia.

METHODS

Retrospective chart review identified patients with a lead placed at the pudendal nerve for neuralgia and powered wirelessly. Clinical outcomes were assessed at Postoperative visits and phone calls. Administered non-validated follow-up questionnaire evaluated the Global Response Assessment, percentage of pain improvement, satisfaction with device, and initial and current settings of the device (h/day of stimulation).

RESULTS

Thirteen patients had the StimWave® lead placed at the pudendal nerve, 12 (92%) female and 1 (7.6%) male. Mean age was 50 years (range: 20-58). Failed prior therapies include medical therapy (100%), pelvic floor physical therapy (92%), pudendal nerve blocks (85%), pelvic floor muscle trigger point injections (69%), neuromodulation (30.7%), or surgeries for urogenital pain (23.1%). After the trial period, 10/13 (76.9%) had >50% improvement in pain with 6/13 (46.1%) reporting 100% pain improvement. Nine underwent permanent lead placement. At last postoperative visit (range, 6-83 days), 5/9 patients reported >50% pain improvement. Seven patients reached for phone calls (22-759 days) reported symptoms to be "markedly improved" (n = 2), "moderately improved" (n = 4), or "slightly improved" (n = 1). At follow up, complications included lead migration (n = 2), broken wire (n = 1), or nonfunctioning antenna (n = 2).

CONCLUSION

Complex patients with pudendal neuralgia may benefit from pudendal nerve stimulation via StimWave®.

Neuromodulation in Treating Pelvic Pain

PURPOSE OF REVIEW

Chronic pelvic pain (CPP) is a complex condition that can be multifactorial, disabling, and difficult to treat. It is important to understand the various diagnoses and pathways that can be involved and have an understanding of the available treatment options.

RECENT FINDINGS

There is a complex innervation of the pelvic region which makes its treatment very challenging. There are pathophysiological similarities of CPP to disease states like complex regional pain syndrome and sympathetically driven pain. CPP is poorly understood and includes psychological, psychosocial, cultural, and economic influences. Treatment options vary, but neuromodulation does remain a centerpiece and can include sacral stimulation, SCS, DRG stimulation, and PNS.

Pilot study: pudendal neuromodulation combined with pudendal nerve release in case of chronic perineal pain syndrome. The ENTRAMI technique: early results

INTRODUCTION AND HYPOTHESIS

Chronic perineal pain syndrome due to pudendal nerve impingement is difficult to diagnose and to treat. All the known treatment options leave room for improvement considering the outcome. Early neuromodulation of the pudendal nerve after its surgical release could improve outcomes.

OBJECTIVES

The aim of the study was to evaluate the potential beneficial effect of pudendal neuromodulation combined with release surgery using the ENTRAMI technique (endoscopic transgluteal minimally invasive technique).

STUDY DESIGN

This is a single-center prospective descriptive study. Between March 2019 and March 2020, 16 patients (2 males, 14 females) were included. Data were collected at baseline and 1 month after surgery.

METHODS

Patients eligible for inclusion had chronic perineal pain for at least 3 months in the area served by the pudendal nerve. We combined pudendal nerve release with neuromodulation.

RESULTS

At 1 month, the numeric pain rating scale (NPRS) dropped from 9.5 at baseline to 3.5 (p = 0.003). Seventy-six percent of patients showed a global impression of change (PGIC) of > 50% at 1 month, and optimal treatment response (PGIC ≥ 90%) was found in 41% of patients.

LIMITATIONS

The drawback of our study was that it was not randomized or blinded. The peripheral nerve evaluation lead (PNE) used could only be implanted for 1 month because of infection risk and is also prone to dislocations and technical failures.

CONCLUSION

Pudendal nerve liberation by the ENTRAMI technique combined with short-term pudendal neuromodulation seems feasible and promising in treating patients with chronic perineal pain. Clinical trial number: NCT03880786.

Benefits and Harms of Electrical Neuromodulation for Chronic Pelvic Pain: A Systematic Review

CONTEXT

Patients with chronic pelvic pain (CPP) may have pain refractory to conventional pain management strategies. Neuromodulation could provide relief of pain.

OBJECTIVE

To evaluate the benefits and harms of neuromodulation for CPP.

EVIDENCE ACQUISITION

A comprehensive search of EMBASE, PUBMED, and SCOPUS was performed for the entire database to January 2018. Studies were selected, data were extracted, and quality was assessed by two independent reviewers. A meta-analysis was used to combine randomized controlled trials (RCTs); otherwise, a narrative analysis was used.

EVIDENCE SYNTHESIS

After screening 1311 abstracts, 36 studies including eight RCTs were identified, enrolling 1099 patients. Studies covered a broad range in terms of phenotypes of CPP and methods of neuromodulation. A meta-analysis was possible for percutaneous tibial nerve stimulation and transcutaneous electrical nerve stimulation, which showed improvement in pain. Only narrative synthesis was possible for other modalities (sacral nerve stimulation, spinal cord stimulation, intravaginal electrical stimulation, and pudendal nerve stimulation) which appeared to reduce pain in patients with CPP. Treatments generally improved quality of life but with variable reporting of adverse events. Many studies showed high risks of bias and confounding.

CONCLUSIONS

While electrical neuromodulation may improve symptoms in CPP, further work is needed with high-quality studies to confirm it.

PATIENT SUMMARY

Neuromodulation may be useful in reducing pain and improving quality of life in patients with chronic pelvic pain, but more research is needed.

[The use of surgical neuromodulation to treat chronic pelvic pain]

Chronic pelvic pain (CPP) is a pain syndrome that is very difficult to treat. The effectiveness of CPP treatment remains low despite the use of integrated approaches. That is why it is necessary to search for new treatment approaches and methods. Surgical neuromodulation has recently been used increasingly often to treat CPP.

OBJECTIVE

To evaluate the effectiveness of different types of neurostimulation in patients with chronic pelvic pain.

MATERIAL AND METHODS

Thirty-two patients were treated at the N.N. Burdenko National Scientific and Practical Center for Neurosurgery. All the patients were diagnosed with CPP and transferred to the Center because of unsatisfactory results of earlier treatment. The mean duration of pain was 8.6 years (range: 1-31 years). Pain intensity and the neuropathic component of the pain syndrome were assessed using the conventional scales and questionnaires (VAS, LANSS, Pain Detect, and DN4). The levels of anxiety, depression, and catastrophic pain were also assessed. The effect of pain on quality of life was evaluated using the modified Brief Pain Inventory (BPI). All the selected patients underwent trial lead implantation at the first stage. Sacral root stimulation was used in 15 patients (unilateral one in 8 patients and bilateral one in 7 patients); three patients underwent spinal cord stimulation; 14 patients were treated with combined neurostimulation.

RESULTS

In 27 (84.37%) patients, the trial period was regarded as positive and the systems were implanted for chronic neurostimulation. After one year of stimulation, the mean VAS score for pain intensity was 3.53 (compared to 8.61 before the surgery). Regarding quality of life, the most significant effects of treatment were as follows: the number of pain paroxysms was reduced; physical self-maintenance, social life, sleep, and sexual activity were improved; and daily physical activity was increased.

CONCLUSION

. Neurostimulation ensures a stable pain relief and improves quality of life in patients with chronic pelvic pain refractory to conservative treatment.

The ENTRAMI technique: Endoscopic transgluteal minimal invasive technique for implantation of a pudendal electrode under full visual control: A cadaver study

AIM

The aim of this article is to describe a minimal invasive trans gluteal endoscopic approach to implant a pudendal electrode for neuromodulation under full visual control.

METHODS

Eight trans gluteal approaches were performed on four cadavers. The sacral transforaminal percutaneous technique was performed to implant the electrode. The electrode was then picked up and placed under visual control next to the pudendal nerve.

RESULTS

The first trocar was placed in the upper lateral quadrant of the gluteal region. The 0° optical system was used to help with the pneumodissection to identify the sciatic nerve. At that point a second 3 mm trocar was placed to insert a dissecting grasping forceps. In some cases, a second 3 mm trocar was placed. A step by step dissection, based on anatomical findings, was necessary to be able to locate the pudendal nerve. The electrode, which was placed percutaneously and transforaminal through S3 or S4, was picked up and placed under full visual control next to the pudendal nerve, slightly entering the Alcock's canal. The electrode was placed in an ideal manner, meaning that all 4-contact points of the electrode are in parallel and in contact with the targeted nerve. The electrode was fixed in that ideal position at the level of the sacrospinous ligament. After placement of that electrode, an X-ray of the pelvic area was done.

CONCLUSIONS

The ENTRAMI technique allows optimal pudendal electrode placement under full visual control and should now be tested in a clinical setting.

The development of neural stimulators: a review of preclinical safety and efficacy studies

OBJECTIVE

Given the rapid expansion of the field of neural stimulation and the rigorous regulatory approval requirements required before these devices can be applied clinically, it is important that there is clarity around conducting preclinical safety and efficacy studies required for the development of this technology.

APPROACH

The present review examines basic design principles associated with the development of a safe neural stimulator and describes the suite of preclinical safety studies that need to be considered when taking a device to clinical trial.

MAIN RESULTS

Neural stimulators are active implantable devices that provide therapeutic intervention, sensory feedback or improved motor control via electrical stimulation of neural or neuro-muscular tissue in response to trauma or disease. Because of their complexity, regulatory bodies classify these devices in the highest risk category (Class III), and they are therefore required to go through a rigorous regulatory approval process before progressing to market. The successful development of these devices is achieved through close collaboration across disciplines including engineers, scientists and a surgical/clinical team, and the adherence to clear design principles. Preclinical studies form one of several key components in the development pathway from concept to product release of neural stimulators. Importantly, these studies provide iterative feedback in order to optimise the final design of the device. Key components of any preclinical evaluation include: in vitro studies that are focussed on device reliability and include accelerated testing under highly controlled environments; in vivo studies using animal models of the disease or injury in order to assess efficacy and, given an appropriate animal model, the safety of the technology under both passive and electrically active conditions; and human cadaver and ex vivo studies designed to ensure the device's form factor conforms to human anatomy, to optimise the surgical approach and to develop any specialist surgical tooling required.

SIGNIFICANCE

The pipeline from concept to commercialisation of these devices is long and expensive; careful attention to both device design and its preclinical evaluation will have significant impact on the duration and cost associated with taking a device through to commercialisation. Carefully controlled in vitro and in vivo studies together with ex vivo and human cadaver trials are key components of a thorough preclinical evaluation of any new neural stimulator.

Current best practice management of interstitial cystitis/bladder pain syndrome

Introduction

Over the last 100 years, the terminology and diagnosis criteria for interstitial cystitis have evolved. Many therapeutic options have changed, but others have endured. This article will review the idea of separating 'classic' Hunner lesion interstitial cystitis (HL IC) from non-Hunner lesion interstitial cystitis and bladder pain syndrome (N-HL IC/BPS) and their respective treatment algorithms.

Methods/Results

A literature search was performed to identify articles and research on HL IC and N-HL IC/BPS including definitions, etiological theories, and treatments. This article is an overview of the existing literature. We also offer insight into how HL IC and N-HL IC/BPS are approached at our tertiary referral center. Additionally, American Urological Association guidelines have been integrated and newer treatment modalities and research will be introduced at the conclusion.

Conclusion

The AUA guidelines have mapped out a stepwise fashion to treat IC/BPS; at our institution we separate patients with HL IC from those with N-HL IC/BPS prior to them entering a treatment pathway. We identify the rarer patient with HL as having classic 'IC'; this cystoscopic finding is critical in guiding treatment. We believe HL IC is a distinct disease from N-HL IC/BPS and therapy should focus on the bladder. The vast majority of patients with N-HL IC/BPS need management of their pelvic floor muscles as the primary therapy, complemented by bladder-directed therapies as needed as well as a multidisciplinary team to manage a variety of other regional/systemic symptoms. Ongoing research into IC/BPS will help us better understand the pathophysiology and phenotypes of this complex disease while exciting and novel research studies are developing promising treatments.

Neuromodulation for the Treatment of Endometriosis-Related Symptoms

Sacral and pudendal neuromodulation have been advocated for the treatment of refractory pelvic pain, urinary urgency and retention, as well as fecal incontinence or constipation, all of which are commonly related to endometriosis and/or its surgical treatment.

In this review, the mechanisms of action and different routes of neuromodulation will be detailed, as well as all the studied applications of neuromodulation on ameliorating symptoms related to endometriosis and/or its treatment.

Successful bilateral pudendal neuromodulation to treat male detrusor areflexia following severe pubic symphysis fracture, a case report

Background

A Drum Dock Manager in an auto manufacturing company suffers a pelvic fracture, severing the bulbar urethra and completely fracturing the right side of his pelvis.

He is unable to void without catheterization but has a complete sensation to void. Can neuromodulation help him achieve spontaneous voiding?

Case presentation

We reviewed the electronic medical record of Mr. M.E. from Detroit Medical Center following his 2012 forklift accident and subsequent orthopedic surgeries. He successfully underwent bilateral sacral neuromodulation, with a resulting max flow of 16.8 mls/sec and post-void residual urine of 50–100 mls. Unfortunately, he later presented with bilateral pocket and sacral lead infection, and both systems had to be removed. Six weeks later, M.E. had bilateral pudendal neurostimulation placement to avoid the previously infected areas. Max flow improved to 14.5 mls/sec and 0–50 mls residual urine. However, urodynamics proved that his P_det at max flow was in excess of 120 cm of H20 pressure while he had been on finesteride and tamsulosin for the preceding five years for the management of his documented benign prostate hyperplasia symptoms. He underwent Green light laser transurethral resection of the prostate and had max flow improvement to 22.5 mls/second with zero residual urine with multiple straight catheterization confirmations.

Conclusion

Sacral neuromodulation may successfully correct traumatic urinary retention in male patients. Additionally, pudendal neuromodulation can be successfully utilized as a salvage method for an infected sacral neuromodulation impulse generator (IPG) and tined lead with a return to proper voiding.

[Neuromodulation - new techniques]

Neuromodulative procedures have become an inherent component in the therapy of functional urinary bladder and pelvic floor function disorders. Sacral neuromodulation has been used in Germany for more than 20 years and reresents the standard neuromodulative therapy. Technical improvements in the field of test stimulation and the phasing out of the large pulse generator models represent current changes with the resulting advantages and disadvantages. Pudendal neuromodulation (PNM) has been known for many years as a procedure for treatment of chronic diseases of the urinary bladder and the lesser pelvis and is predominantly used as second-line neuromodulative therapy; however, for pelvic pain syndromes and in particular for pudendal neuralgia, it represents a promising minimally invasive first-line therapy. Due to the technically demanding puncture procedure, PNM has so far only been used in Germany in specialized centers. Through the development of new operation techniques, the prerequisites for a wider multicentric use, with the future aim of approval of the procedure, have been achieved. External transdermal pudendal neuromodulation is a promising therapeutic approach and after further testing in randomized studies could find an application as a conservative step before minimally invasive pudendal neuromodulation. Although the technique of laparoscopic electrode placement on neural structures of the lesser pelvis is technically attractive, it predominantly finds a monocentric use and must in due course be critically compared with established minimally invasive procedures.