Neurostimulation for Postsurgical Analgesia: A Novel System Enabling Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation

Peripheral Nerve Stimulation for Neuropathic Pain Management: A Narrative Review

This narrative review examines the therapeutic efficacy of peripheral nerve stimulation (PNS) in the treatment of neuropathic pain (NP), a type of pain arising from lesions or diseases of the somatosensory system with a global prevalence ranging from 6.90% to 10.00%. Traditional pharmacological interventions often fall short for many persons, highlighting the need for alternative treatments such as PNS, which has demonstrated significant promise with minimal side effects. The review summarizes the effectiveness of PNS in various NP conditions, including trigeminal neuralgia and postherpetic neuralgia, and underscores the need for further research to refine treatment approaches. The mechanism of PNS is discussed, involving the activation of non-nociceptive Aβ fibers and modulation of neurotransmitters, and offering pain relief through both peripheral and central pathways. Despite the proven efficacy of PNS, challenges remain, including the need for randomized controlled trials and the optimization of stimulation parameters. The review concludes that PNS is a promising treatment modality for NP, warranting additional high-quality trials to solidify its role in clinical practice.

A single-center retrospective chart review of percutaneous PNS for treatment of chronic shoulder pain

Objective

The present IRB-approved retrospective chart review describes the use of a 60-day PNS treatment for shoulder pain at a single center in 60 total consecutive patients.

Background

Chronic shoulder pain affects an increasing number of patients per year and is especially prevalent in elderly populations. Percutaneous peripheral nerve stimulation (PNS) treatment targeting the nerves of the shoulder has been shown to reduce pain in prospective clinical studies and in analysis of real-world data.

Methods

Data were extracted from the electronic medical records of patients who had previously undergone percutaneous PNS treatment for chronic shoulder pain. Demographic data and treatment characteristics were summarized alongside treatment outcomes.

Results

Overall, 84 % (49/58) of patients reported substantial (≥50 %) pain relief at the end-of-treatment. The records for 2 patients did not include patient-reported percent pain relief. The average indwelling period for leads (i.e., treatment period) was 57 days. Findings on treatment effectiveness were consistent when the patient population was stratified by cause of pain, duration living with pain, and presence of pain-modifying comorbidities. Stimulation paradigms were identified and categorized by the nerve target and stimulation frequency (e.g., motor stimulation, sensory stimulation, or bimodal stimulation).

Conclusions

These results indicate percutaneous PNS is an effective treatment for patients with various shoulder pain histories, and while all stimulation paradigms were effective at reducing pain, patients who received bimodal PNS reported the greatest pain relief. Key limitations of the study included heterogeneous shoulder pain etiologies among patients and sparse availability of long-term follow-up data. These data support existing real-world and prospective clinical evidence on the efficacy of 60-day PNS treatment at treating chronic pain and provide valuable insights into its use in clinical practice.

Peripheral Nerve Stimulation in Postoperative Analgesia: A Narrative Review

PURPOSE OF REVIEW

Recent research has shown the effectiveness of peripheral nerve stimulators (PNS) in managing chronic pain conditions. Ongoing studies aim to explore its potential application in treating acute postoperative pain states. The purpose of this systematic review is to assess the role of PNS in providing relief for postoperative pain.

RECENT FINDINGS

Clinical studies investigating the use of peripheral nerve stimulators (PNS) for analgesia following various surgeries, such as total knee arthroplasty, anterior cruciate ligament repair, ankle arthroplasty, rotator cuff repair, hallux valgus correction, and extremity amputation, have shown promising results. Lead placement locations include the brachial plexus, sciatic, femoral, tibial, genicular, perineal, sural, radial, median, and ulnar nerves. These studies consistently report clinically significant reductions in pain scores, and some even indicate a decrease in opioid consumption following PNS for postoperative pain. PNS involves the subcutaneous placement of electrode leads to target peripheral nerve(s) followed by delivery of an electric current via an external pulse generator. While the precise mechanism is not fully understood, the theory posits that PNS modulates electrical stimulation, hindering the signaling of nociceptive pain. PNS presents itself as an alternative to opioid therapy, holding promise to address the opioid epidemic by offering a nonpharmacologic approach for both acute and chronic pain states.

The Relevance of Implanted Percutaneous Electrical Nerve Stimulation in Orthopedics Surgery: A Systematic Review

Background: Percutaneous peripheral nerve stimulation (PNS) is a form of neuromodulation that involves the transmission of electrical energy via metal contacts known as leads or electrodes. PNS has gained popularity in orthopedic surgery as several studies have supported its use as a pain control device for patients suffering from pain due to orthopedic pathologies involving the knee, shoulder, and foot. The purpose of this systematic review is to summarize the literature involving peripheral nerve stimulation in orthopedic surgery. The existing body of literature provides support for further research regarding the use of PNS in the management of knee pain, hip pain, shoulder pain, foot pain, and orthopedic trauma. Notably, the evidence for its efficacy in addressing knee and shoulder pain is present. Methods: This study was conducted following PRISMA guidelines. Seven hundred and forty-five unique entries were identified. Two blinded reviewers assessed each article by title and abstract to determine its relevance and categorized them as "include", "exclude", and "maybe". After a preliminary review was completed, reviewers were unblinded and a third reviewer retrieved articles labeled as "maybe" and those with conflicting labels to determine their relevance. Twenty-eight articles were included, and seven hundred and seventeen articles were excluded. Articles discussing the use of PNS in the field of orthopedic surgery in patients > 18 years of age after 2010 were included. Exclusion criteria included neuropathic pain, phantom limb pain, amputation, non-musculoskeletal related pathology, non-orthopedic surgery related pathology, spinal cord stimulator, no reported outcomes, review articles, abstracts only, non-human subjects. Results: A total of 16 studies analyzing 69 patients were included. All studies were either case series or case reports. Most articles involved the application of PNS in the knee (8) and shoulder (6) joint. Few articles discussed its application in the foot and orthopedic trauma. All studies demonstrated that PNS was effective in reducing pain. Discussion: Peripheral nerve stimulation can be effective in managing postoperative or chronic pain in patients suffering from orthopedic pathology. This systematic review is limited by the scarcity of robust studies with substantial sample sizes and extended follow up periods in the existing literature.

Peripheral nerve stimulation for saphenous neuralgia

BACKGROUND

Injury to saphenous nerve branches is frequent during knee surgery and can result in chronic pain. This saphenous neuralgia remains challenging to treat. Peripheral nerve stimulation (PNS) is a new potential non-pharmacologic treatment option. We present our outcomes experience using this technology in 12 patients.

METHODS

We retrospectively reviewed PNS placement for saphenous neuralgia between 2000 and 2022 at a single institution. Demographic information was collected as well as response to the device. Four-question short-form Patient-Reported Outcome Measurement Information System (PROMIS) Scores were collected before and 2 weeks, 6 weeks, and 6 months postprocedure. Specific scores included pain interference and behavior, functional mobility, depression, anxiety, and sleep impairment. Change in pain interference measured by the short-form PROMIS tool at 6 months was chosen as the primary outcome.

RESULTS

Twelve patients met inclusion criteria, with 10 patients having the full 6-month follow-up. In these 10 patients, the mean change from baseline in the short-form adjusted pain interference score (greater difference means improved pain) at 6 months was 5.8 (SD 6.5). Among all patients, average follow-up was 11.5 months (range 3-35 months). Most patients' symptoms developed after knee surgery (84%). Prior to PNS, patients underwent other treatments including cryoablation (8%), radiofrequency ablation (16%), saphenous neurectomy (16%), or surgical release of adjacent nerves (25%). Ten patients (83%) reported any improvement in symptoms while two reported no benefit. Complications occurred in four patients (33%). Two patients had the device removed and a third discontinued use. PROMIS Scores for pain, functional mobility, mood, and sleep impairment all improved.

DISCUSSION

Limited effective treatments exist for saphenous neuralgia. Our case series demonstrates the potential of PNS as a treatment for saphenous neuralgia. Comparative effectiveness studies are warranted to assess whether our effect size is clinically relevant.

Literature Review: Mechanism, Indications, and Clinical Efficacy of Peripheral Nerve Stimulators in Lower Extremity Pain

PURPOSE OF REVIEW

Lower extremity pain is deemed by Center for Disease Control and Prevention (CDC) to be a significant source of chronic pain in adults. If not appropriately managed, patients are subjected to risks of prolonged musculoskeletal dysfunction, disruption to quality of life, and elevated healthcare expenditures. Peripheral nerve stimulation (PNS) has shown great potential in recent years demonstrating efficacy in multiple diagnoses ranging from acute post-surgical pain to complex regional pain syndrome (CRPS). This study seeks to delineate efficacy of peripheral neuromodulation in the context of chronic lower extremity pain.

RECENT FINDINGS

Prevailing clinical studies demonstrate evidence levels ranging from II to V (Oxford Centre of Level of Evidence) in lower limb PNS, attaining positive outcomes in pain scores, opioid use, and quality of life measures. Nerves most frequently targeted are the sciatic and femoral nerves with post-amputation pain and CRPS most commonly investigated for efficacy. PNS is a promising therapeutic modality demonstrated to be effective for a variety of nociceptive and neuropathic pain conditions in the lower extremity. PNS offers chronic pain physicians a powerful tool in the multi-modal management of lower limb chronic pain.

Advanced Interventional Procedures for Knee Osteoarthritis: What Is the Current Evidence?

The prevalence of knee osteoarthritis (OA) is the highest among all joints and likely to increase over the coming decades. Advances in the repertoire of diagnostic capabilities of imaging and an expansion in the availability and range of image-guided interventions has led to development of more advanced interventional procedures targeting pain related to OA pain while improving the function of patients presenting with this debilitating condition. We review the spectrum of established advanced interventional procedures for knee OA, describe the techniques used to perform these procedures safely, and discuss the clinical evidence supporting each of them.

Peripheral Nerve Stimulation After Total Knee Arthroplasty and Non-Operable Patella Fracture

Chronic knee pain, affecting over 25% of adults in the United States, has surged by 65% over the past two decades leading to rising functional deficits, mobility problems, and a diminished quality of life. While conservative management with pharmacologic and minimally invasive injections are pursued early in the disease process, total knee arthroplasty for refractory osteoarthritis of the knee is often considered. This procedure usually improves pain and functionality within the first three months. However, a significant portion of patients often suffer from postoperative pain that can become chronic and debilitating. We detail the case of a patient with a previous TKA as well as a non-operable patella fracture who obtained significant relief with PNS despite prior conservative and minimally invasive management.

Peripheral Nervous System Pain Modulation

The percutaneous technique of electrode insertion in the vicinity of the greater occipital nerves to treat occipital neuralgia was first described in the 1990s by Weiner and Reed. This subsequently stimulated awareness of peripheral nerve stimulation (PNS). The more recent advent emergence of a minimally invasive percutaneous approach by way of using ultrasound has further increased the interest in PNS as a viable alternative to more invasive techniques. PNS has become more popular recently and is increasingly used to treat various pain conditions. Its foundation is fundamentally based on the gate control theory, although the precise mechanism underlying its analgesic effect is still indefinite. Studies have demonstrated the peripheral and central analgesic mechanisms of PNS by modulating the inflammatory pathways, the autonomic nervous system, the endogenous pain inhibition pathways, and the involvement of the cortical and subcortical areas. Peripheral nerve stimulation exhibits its neuromodulatory effect both peripherally and centrally. Further understanding of the modulation of PNS mechanisms can help guide stimulation approaches and parameters to optimize the use of PNS. his chapter aims to review the background and mechanisms of PNS modulation. PNS is becoming one of the most diverse therapies in neuromodulation due to rapid evolution and expansion. It is an attractive option for clinicians due to the simplicity and versatility of procedures that can be combined with other neuromodulation treatments or used alone. It has a distinct role in the modulation of functional conditions.

Peripheral Nerve Stimulation in Chronic Knee Pain: A Case Series

Introduction Chronic knee pain is increasing in prevalence and is associated with substantial limitations in functional mobility. Peripheral nerve stimulation (PNS) has been increasingly used to treat various chronic pain conditions. However, there is a paucity of research exploring the potential therapeutic benefit of PNS for chronic knee pain. Methods This research is a retrospective case series of all patients who received PNS for the treatment of chronic knee pain performed at a single-center academic medical institution between March 2021 and June 2022. The primary outcome was percent pain reduction six months after implantation. Outcome data was obtained via chart review and phone calls to patients. Secondary outcomes included percent pain reduction two weeks and two months after implantation and adverse medical events related to the procedure and nerve stimulation. Results Fourteen individual patients received PNS for chronic knee pain during the study period. Three of these patients received bilateral PNS for a total of 17 cases. The mean percent pain reduction six months after implantation was 52% (SD=28.2) (N=12). A total of 75.0% of participants (9/12) reported ≥50% reductions in pain six months after implantation. No adverse events were reported relating to the implantation procedure and/or nerve stimulation. Conclusion PNS is a safe and efficacious treatment modality for chronic knee pain with demonstrated long-term benefit. Further research should clarify patient factors associated with improved treatment response.

Peripheral nerve stimulation for chronic knee pain following total knee arthroplasty: a systematic review

Chronic knee pain following total knee arthroplasty (TKA) affects a subset of patients that is refractory to pharmacological and non-pharmacological modalities. Peripheral nerve stimulation (PNS) has been used in patients with chronic knee pain following TKA and has shown some efficacy. Methods: Comprehensive search of Ovid Medline, Elsevier Embase, Cochrane Central Register of Controlled Trials, CINAHL Plus with Full Text, Scopus, SPORTDiscus with Full Text and the Web of Science platform. From inception to August 2022, for studies using PNS to treat chronic knee pain following TKA. Primary outcomes included pain scores, functional status and medication usage. Results: Nine studies were extrapolated with all demonstrating effectiveness of PNS for patients with chronic knee pain following TKA. Discussion: PNS for chronic knee pain following TKA has been shown to be an efficacious treatment modality. The level of evidence is low and more research is needed to assess its safety and effectiveness.

The Emerging Role of Peripheral Nerve Stimulation in Postoperative Analgesia

PURPOSE OF REVIEW

Though peripheral nerve stimulation has long been utilized in the field of chronic pain management, its use in acute pain management in the postoperative period is relatively novel and warrants further consideration.

RECENT FINDINGS

In the postsurgical period, peripheral nerve stimulation may offer an additional low-risk, opioid-sparing analgesic option, which is particularly pertinent in the setting of the ongoing opioid epidemic, as inadequate postsurgical analgesia has been shown to increase the risk of developing persistent or chronic postsurgical pain. In this review, we discuss the current literature that illustrate the emerging role of peripheral nerve stimulation as an effective treatment modality in the postoperative period for the management of acute pain, as various studies have recently been conducted evaluating the feasibility of utilizing percutaneous peripheral nerve stimulation as an adjunct in postsurgical analgesia. Nonetheless, future studies are necessary to continue to elucidate the short- and long-term impacts of peripheral nerve stimulation use in acute postsurgical analgesia.

Role of neuromodulation in acute pain settings

Peripheral nerve stimulation (PNS), a type of neuromodulatory technique, is increasingly used to treat chronic pain syndromes. PNS has also recently gained popularity as a viable adjunct analgesic modality in acute pain settings, where the practice primarily relies on using boluses or infusion of local anesthetics for nerve blockade, followed by stimulation to extend the analgesia. There is some early promise in PNS for perioperative analgesic control, but considerable obstacles must be addressed before it can be implemented into standard practice. In this daring discourse, we explore the possibilities and constraints of using the PNS paradigm in acute pain.

A Case Report of Three Patients Who Underwent Temporary Peripheral Nerve Stimulation for Treatment of Knee Pain Secondary to Osteoarthritis

Knee osteoarthritis affects millions of people worldwide. There remains a role for novel therapies to manage pain for patients who are unable or unwilling to undergo knee arthroplasty. A peripheral nerve stimulator (PNS) may be beneficial in this population. We present a case report of three patients who received temporary femoral or saphenous PNS and were either unwilling or unable to undergo knee arthroplasty. Two of the three patients reported significantly reduced pain and improved functioning. Our case report demonstrates that temporary PNS may offer a safe and effective treatment for chronic knee pain secondary to knee osteoarthritis.

Mechanism of Action of Peripheral Nerve Stimulation for Chronic Pain: A Narrative Review

The use of stimulation of peripheral nerves to test or treat various medical disorders has been prevalent for a long time. Over the last few years, there has been growing evidence for the use of peripheral nerve stimulation (PNS) for treating a myriad of chronic pain conditions such as limb mononeuropathies, nerve entrapments, peripheral nerve injuries, phantom limb pain, complex regional pain syndrome, back pain, and even fibromyalgia. The ease of placement of a minimally invasive electrode via percutaneous approach in the close vicinity of the nerve and the ability to target various nerves have led to its widespread use and compliance. While most of the mechanism behind its role in neuromodulation is largely unknown, the gate control theory proposed by Melzack and Wall in the 1960s has been the mainstay for understanding its mechanism of action. In this review article, the authors performed a literature review to discuss the mechanism of action of PNS and discuss its safety and usefulness in treating chronic pain. The authors also discuss current PNS devices available in the market today.

Educational Curriculum for Peripheral Nerve Stimulation Developed by the North American Neuromodulation Society

BACKGROUND

Peripheral nerve stimulation (PNS) is an effective neuromodulation therapy for chronic neuropathic and nociceptive pain. Although the total number of PNS implantations has increased over the last decade, no curriculum exists to guide training and learning of this therapy. The goal of the North American Neuromodulation Society (NANS) education committee is to develop a series of competency-based curriculums for neuromodulation therapies. The PNS curriculum is the latest part of such series, following the curriculums for spinal cord stimulation and intrathecal drug delivery system.

MATERIALS AND METHODS

A multidisciplinary task force (anesthesiology, physical medicine and rehabilitation, neurosurgery, preventive medicine and public health, and neurology) was created by the educational committee of NANS to develop a PNS curriculum in accordance with the Accreditation Council for Graduate Medical Education (ACGME) milestones. The curriculum was created based on the best available evidence and expert knowledge (from our task force members) of available PNS systems. The final PNS curriculum was approved by the NANS board.

RESULTS

A PNS curriculum was developed by the task force. Milestones included professionalism, practice-based learning, interpersonal communication, medical knowledge, systems-based practice, procedural skills, and patient care. Each milestone was defined into three categories: early learner, advanced learner, and practitioner.

CONCLUSIONS

This manuscript provides a PNS training curriculum developed by a multidisciplinary task force of the NANS educational committee in accordance with the milestones described by ACGME for basic learners, advanced learners, and practitioners. This curriculum will help provide a structured training and evaluation process for obtaining proficiency in PNS treatment(s).

Infection of a Retained Peripheral Nerve Stimulation Lead: A Case Report

Percutaneous peripheral nerve stimulation is used to provide analgesia for weeks or even months. While infection of any percutaneously implanted object is a concern, it is exceedingly rare for helically coiled leads, with a reported incidence of less than 1 infection for every 32,000 indwelling days. We now report an infected helically coiled lead requiring sedation for extraction and complicated by lead fracture during removal, leaving a remnant in situ. The infection was successfully treated with oral antibiotics. We speculate on the cause of this infection and propose steps to prevent this complication, including the avoidance of sling-to-lead insertion site overlap.

Extending Perioperative Analgesia with Ultrasound-Guided, Percutaneous Cryoneurolysis, and Peripheral Nerve Stimulation (Neuromodulation)

The use of regional anesthesia is key to a successful approach to improving postoperative analgesia, which involves local anesthetic deposition either around peripheral nerves or within a fascial plane. Unfortunately, the realistic duration even with continuous peripheral nerve blocks usually does not match the duration of surgical pain, comprising a major limitation. Here, the use of 2 interventional modalities-ultrasound-guided percutaneous cryoneurolysis and peripheral nerve stimulation-is discussed, both of which may be used to treat acute and subacute pain and may therefore have a positive impact on the incidence and severity of chronic pain development.

Sciatic nerve stimulation alleviates acute neuropathic pain via modulation of neuroinflammation and descending pain inhibition in a rodent model

Background

Neuropathic pain (NP) is characterized by abnormal activation of pain conducting pathways and manifests as mechanical allodynia and thermal hypersensitivity. Peripheral nerve stimulation is used for treatment of medically refractory chronic NP and has been shown to reduce neuroinflammation. However, whether sciatic nerve stimulation (SNS) is of therapeutic benefit to NP remains unclear. Moreover, the optimal frequency for SNS is unknown. To address this research gap, we investigated the effect of SNS in an acute NP rodent model.

Methods

Rats with right L5 nerve root ligation (NRL) or Sham surgery were used. Ipsilateral SNS was performed at 2 Hz, 20 Hz, and 60 Hz frequencies. Behavioral tests were performed to assess pain and thermal hypersensitivity before and after NRL and SNS. Expression of inflammatory proteins in the L5 spinal cord and the immunohistochemical alterations of spinal cord astrocytes and microglia were examined on post-injury day 7 (PID7) following NRL and SNS. The involvement of the descending pain modulatory pathway was also investigated.

Results

Following NRL, the rats showed a decreased pain threshold and latency on the von Frey and Hargreaves tests. The immunofluorescence results indicated hyperactivation of superficial spinal cord dorsal horn (SCDH) neurons. Both 2-Hz and 20-Hz SNS alleviated pain behavior and hyperactivation of SCDH neurons. On PID7, NRL resulted in elevated expression of spinal cord inflammatory proteins including NF-κB, TNF-α, IL-1β, and IL-6, which was mitigated by 2-Hz and 20-Hz SNS. Furthermore, 2-Hz and 20-Hz SNS suppressed the activation of spinal cord astrocytes and microglia following NRL on PID7. Activity of the descending serotoninergic pain modulation pathway showed an increase early on PID1 following 2-Hz and 20-Hz SNS.

Conclusions

Our results support that both 2-Hz and 20-Hz SNS can alleviate NP behaviors and hyperactivation of pain conducting pathways. We showed that SNS regulates neuroinflammation and reduces inflammatory protein expression, astrocytic gliosis, and microglia activation. During the early post-injury period, SNS also facilitates the descending pain modulatory pathway. Taken together, these findings support the therapeutic potential of SNS for acute NP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02513-y.

60-Day PNS Treatment May Improve Identification of Delayed Responders and Delayed Non-Responders to Neurostimulation for Pain Relief

Objective

Conventional neurostimulation typically involves a brief (eg, ≤10-day) trial to assess presumed effectiveness prior to permanent implantation. Low trial conversion rates and high explant rates due to inadequate pain relief highlight the need for improved patient identification strategies. The development of a 60-day percutaneous peripheral nerve stimulation (PNS) system enables evaluation of outcomes following an extended temporary treatment period of up to 60 days, that may obviate or validate the need for permanent implant. The present study provides the first real-world evidence regarding patient response throughout a 60-day PNS treatment period.

Methods

Anonymized data listings were compiled from patients who underwent implantation of temporary percutaneous leads and opted-in to provide real-world data to the device manufacturer during routine interactions with device representatives throughout the 60-day treatment.

Results

Overall, 30% (222/747) of patients were early responders (≥50% pain relief throughout treatment). Another 31% (231/747) of patients initially presented as non-responders but surpassed 50% pain relief by the end of treatment. Conversely, 32% (239/747) of patients were non-responders throughout treatment. An additional 7% (55/747) of patients initially presented as responders but fell below 50% relief by the end of the treatment period.

Conclusion

An extended, 60-day PNS treatment may help identify delayed responders, providing the opportunity for sustained relief and improving access to effective PNS treatment. Compared to a conventionally short trial of ≤10 days, a longer 60-day PNS treatment may also help reduce explant rates by identifying delayed non-responders unlikely to benefit long-term. These scenarios support the importance of an extended 60-day temporary PNS stimulation period to help inform stepwise treatment strategies that may optimize outcomes and cost-effectiveness.

Peripheral Nerve Stimulation: A Review of Techniques and Clinical Efficacy

Chronic pain is a common source of morbidity in many patient populations worldwide. There are growing concerns about the potential side effects of currently prescribed medications and a continued need for effective treatment. Related to these concerns, peripheral nerve stimulation has been regaining popularity as a potential treatment modality. Peripheral nerve stimulation components include helically coiled electrical leads, which direct an applied current to afferent neurons providing sensory innervation to the painful area. In theory, the applied current to the peripheral nerve will alter the large-diameter myelinated afferent nerve fibers, which interfere with the central processing of pain signals through small-diameter afferent fibers at the level of the spinal cord. Multiple studies have shown success in the use of peripheral nerve stimulation for acute post-surgical pain for orthopedic surgery, including post total knee arthroplasty and anterior cruciate ligament surgery, and chronic knee pain. Many studies have investigated the utility of peripheral nerve stimulation for the management of chronic shoulder pain. Peripheral nerve stimulation also serves as one of the potential non-pharmacologic therapies to treat back pain along with physical therapy, application of transcutaneous electrical neurostimulation unit, radiofrequency ablation, epidural steroid injections, permanently implanted neurostimulators, and surgery. Studies regarding back pain treatment have shown that peripheral nerve stimulation led to significant improvement in all pain and quality-of-life measures and a reduction in the use of opioids. Further studies are needed as the long-term risks and benefits of peripheral nerve stimulation have not been well studied as most information available on the effectiveness of peripheral nerve stimulation is based on shorter-term improvements in chronic pain.

Percutaneous Neuromodulation of the Brachial Plexus and Sciatic Nerve for the Treatment of Acute Pain Following Surgery: Secondary Outcomes From a Multicenter, Randomized, Controlled Pilot Study

OBJECTIVES

We recently reported that percutaneous peripheral nerve stimulation (PNS or "neuromodulation") decreased pain and opioid consumption within the first two weeks following ambulatory surgery. However, the anatomic lead locations were combined for the analysis, and benefits for each location remain unknown. We therefore now report the effects of percutaneous PNS for brachial plexus and sciatic nerve leads separately.

MATERIALS AND METHODS

Before surgery, leads were implanted percutaneously to target the brachial plexus (N = 21) for rotator cuff repair or sciatic nerve (N = 40) for foot/ankle surgery, followed by a single injection of local anesthetic. Postoperatively, subjects were randomized in a double masked fashion to 14 days of electrical stimulation (N = 30) or sham/placebo (N = 31) using an external pulse generator. The primary outcome of interest was opioid consumption and pain scores evaluated jointly. Thus, stimulation was deemed effective if superior on either outcome and at least noninferior on the other.

RESULTS

For brachial plexus leads, during the first seven postoperative days pain measured with the numeric rating scale in participants given active stimulation was a median [interquartile range ] of 0.8 [0.5, 1.6] versus 3.2 [2.7, 3.5] in patients given sham (p < 0.001). For this same group, opioid consumption in participants given active stimulation was 10 mg [5, 20] versus 71 mg [35, 125] in patients given sham (p = 0.043). For sciatic nerve leads, pain scores for the active treatment group were 0.7 [0, 1.4] versus 2.8 [1.6, 4.6] in patients given sham (p < 0.001). During this same period, participants given active stimulation consumed 5 mg [0, 30] of opioids versus 40 mg [20, 105] in patients given sham (p = 0.004). Treatment effects did not differ statistically between the two locations.

CONCLUSIONS

Ambulatory percutaneous PNS of both the brachial plexus and sciatic nerve is an effective treatment for acute pain free of systemic side-effects following painful orthopedic surgery.

Percutaneous Peripheral Nerve Stimulation (Neuromodulation) for Postoperative Pain: A Randomized, Sham-controlled Pilot Study

BACKGROUND

Percutaneous peripheral nerve stimulation is an analgesic technique involving the percutaneous implantation of a lead followed by the delivery of electric current using an external pulse generator. Percutaneous peripheral nerve stimulation has been used extensively for chronic pain, but only uncontrolled series have been published for acute postoperative pain. The current multicenter study was undertaken to (1) determine the feasibility and optimize the protocol for a subsequent clinical trial and (2) estimate the treatment effect of percutaneous peripheral nerve stimulation on postoperative pain and opioid consumption.

METHODS

Preoperatively, an electrical lead was percutaneously implanted to target the sciatic nerve for major foot/ankle surgery (e.g., hallux valgus correction), the femoral nerve for anterior cruciate ligament reconstruction, or the brachial plexus for rotator cuff repair, followed by a single injection of long-acting local anesthetic along the same nerve/plexus. Postoperatively, participants were randomized to 14 days of either electrical stimulation (n = 32) or sham stimulation (n = 34) using an external pulse generator in a double-masked fashion. The dual primary treatment effect outcome measures were (1) cumulative opioid consumption (in oral morphine equivalents) and (2) mean values of the "average" daily pain scores measured on the 0 to 10 Numeric Rating Scale within the first 7 postoperative days.

RESULTS

During the first 7 postoperative days, opioid consumption in participants given active stimulation was a median (interquartile range) of 5 mg (0 to 30) versus 48 mg (25 to 90) in patients given sham treatment (ratio of geometric means, 0.20 [97.5% CI, 0.07 to 0.57]; P < 0.001). During this same period, the average pain intensity in patients given active stimulation was a mean ± SD of 1.1 ± 1.1 versus 3.1 ± 1.7 in those given sham (difference, -1.8 [97.5% CI, -2.6 to -0.9]; P < 0.001).

CONCLUSIONS

Percutaneous peripheral nerve stimulation reduced pain scores and opioid requirements free of systemic side effects during at least the initial week after ambulatory orthopedic surgery.

EDITOR’S PERSPECTIVE

The expanding role of chronic pain interventions in multimodal perioperative pain management: a narrative review

Surgery is a risk factor for chronic pain and long-term opioid use. As perioperative pain management continues to evolve, treatment modalities traditionally used for chronic pain therapy may provide additional benefit to patients undergoing surgery. Interventions such as radiofrequency ablation, cryoneurolysis, and neuromodulation may potentially be used in conjunction with acute pain procedures such as nerve blocks and multimodal analgesia. Pharmacological agents associated with chronic pain medicine, including gabapentinoids, ketamine, and selective serotonin reuptake inhibitors, may be useful adjuncts in perioperative pain management when indicated. There may also be a role for acupuncture, music therapy, and other integrative medicine therapies. A transitional pain service can help coordinate outpatient care with inpatient perioperative pain management and promote a more personalized and comprehensive approach that can improve postoperative outcomes.

Peripherally Induced Reconditioning of the Central Nervous System: A Proposed Mechanistic Theory for Sustained Relief of Chronic Pain with Percutaneous Peripheral Nerve Stimulation

Peripheral nerve stimulation (PNS) is an effective tool for the treatment of chronic pain, although its efficacy and utilization have previously been significantly limited by technology. In recent years, purpose-built percutaneous PNS devices have been developed to overcome the limitations of conventional permanently implanted neurostimulation devices. Recent clinical evidence suggests clinically significant and sustained reductions in pain can persist well beyond the PNS treatment period, outcomes that have not previously been observed with conventional permanently implanted neurostimulation devices. This narrative review summarizes mechanistic processes that contribute to chronic pain, and the potential mechanisms by which selective large diameter afferent fiber activation may reverse these changes to induce a prolonged reduction in pain. The interplay of these mechanisms, supported by data in chronic pain states that have been effectively treated with percutaneous PNS, will also be discussed in support of a new theory of pain management in neuromodulation: Peripherally Induced Reconditioning of the Central Nervous System (CNS).

Peripheral Nerve Stimulation in Pain Management: A Systematic Review

BACKGROUND

Peripheral nerve stimulation (PNS) has been increasingly used to manage acute and chronic pain. However, the level of clinical evidence to support its use is not clear.

OBJECTIVES

To assess the clinical evidence of PNS in the treatment of acute or chronic pain.

STUDY DESIGN

A systematic review of the efficacy and safety of PNS in managing acute or chronic pain.

METHODS

Data sources were PubMed, Cochrane Library, Scopus, CINAHL Plus, Google Scholar, and reference lists. The literature search was performed up to December 2019. Study selection included randomized trials, observational studies, and case reports of PNS in acute or chronic pain. Data extraction and methodological quality assessment were performed utilizing Cochrane review methodologic quality assessment and Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB) and Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment for Nonrandomized Studies (IPM-QRBNR). The evidence was summarized utilizing principles of best evidence synthesis on a scale of 1 to 5. Data syntheses: 227 studies met inclusion criteria and were included in qualitative synthesis.

RESULTS

Evidence synthesis based on randomized controlled trials (RCTs) and observational studies showed Level I and II evidence of PNS in chronic migraine headache; Level II evidence in cluster headache, postamputation pain, chronic pelvic pain, chronic low back and lower extremity pain; and Level IV evidence in peripheral neuropathic pain, and postsurgical pain. Peripheral field stimulation has Level II evidence in chronic low back pain, and Level IV evidence in cranial pain.

LIMITATIONS

Lack of high-quality RCTs. Meta-analysis was not possible due to wide variations in experimental design, research protocol, and heterogeneity of study population.

CONCLUSIONS

The findings of this systematic review suggest that PNS may be effective in managing chronic headaches, postamputation pain, chronic pelvic pain, and chronic low back and lower extremity pain, with variable levels of evidence in favor of this technique.

Acute postoperative pain management with percutaneous peripheral nerve stimulation: the SPRINT neuromodulation system

INTRODUCTION

Ultrasound-guided percutaneous peripheral nerve stimulation (PNS) may be used to treat acute postoperative pain for various types of surgeries. This modality avoids several limitations of traditional local anesthetic-based peripheral nerve blocks including avoidance of motor blockade and sensory deficits.

AREAS COVERED

In this review, we discuss the use of SPRINT (SPR Therapeutics, Cleveland, OH) neuromodulation system in the setting of acute postoperative pain management.

EXPERT OPINION

PNS is a novel modality in regional anesthesia that has much promise in reducing overall opioid use after surgery. Placement of PNS is very similar to that of catheter-based regional anesthesia techniques. Ultrasound is used to guide the percutaneously placed introducer needle in proximity to the target nerve. There are several benefits of PNS over catheter-based approaches, including: 1) avoidance of motor or sensory blockade; 2) no medication bag required to be carried; and 3) electric leads may be kept in situ safely for up to 60 days. While several proof-of-concept studies have been published highlighting its use in various types of surgeries, large high-quality randomized controlled trials are still needed.

Cryoneurolysis and Percutaneous Peripheral Nerve Stimulation to Treat Acute Pain

Two regional analgesic modalities currently cleared by the U.S. Food and Drug Administration hold promise to provide postoperative analgesia free of many of the limitations of both opioids and local anesthetic-based techniques. Cryoneurolysis uses exceptionally low temperature to reversibly ablate a peripheral nerve, resulting in temporary analgesia. Where applicable, it offers a unique option given its extended duration of action measured in weeks to months after a single application. Percutaneous peripheral nerve stimulation involves inserting an insulated lead through a needle to lie adjacent to a peripheral nerve. Analgesia is produced by introducing electrical current with an external pulse generator. It is a unique regional analgesic in that it does not induce sensory, motor, or proprioception deficits and is cleared for up to 60 days of use. However, both modalities have limited validation when applied to acute pain, and randomized, controlled trials are required to define both benefits and risks.

Ultrasound-guided percutaneous electrical stimulation for a patient with cubital tunnel syndrome: a case report with a one-year follow-up

Objective: Patients with ulnar neuropathy usually experience sensory disturbances, weakness, and decreased function; however, optimal treatment approaches for this condition are not conclusive.Case Description: A 48-year-old male with cubital tunnel syndrome was previously managed with a multimodal approach including splinting, neural mobilizations, and exercises with no change in symptoms. Approximately 1 year after the initial onset, he received three sessions of ultrasound-guided percutaneous electrical stimulation (PENS) and self-neural glides as a home program.Outcomes: After PENS intervention, the patient experienced a dramatic improvement in function and symptoms as measured by the Disabilities of the Arm, Shoulder and Hand Outcome Measure (DASH) and self-reported version of the Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) pain scale as outcomes. These improvements were maintained after 1, 3, 6, and 12 months. The patient also experienced self-perceived improvement in his condition as measured by the Global Rating of Change (GROC) at each follow-up.Conclusion: A patient with ulnar nerve entrapment at the elbow did not respond to a multimodal conservative care for the previous year. Once the patient was treated with ultrasound-guided PENS targeting the ulnar nerve, full functional recovery and resolution of symptoms were documented. Future clinical studies should examine the effects of PENS in managing neural entrapment syndromes on a statistically powered sample of patients.

Ultrasound-Guided Peripheral Nerve Stimulation for Knee Pain: A Mini-Review of the Neuroanatomy and the Evidence from Clinical Studies

Objectives

Peri- and postoperative pain frequently develops after joint replacement for severe knee osteoarthritis. A continuous nerve block is commonly used for pain relief, but the risks of infection and catheter dislodgement should be considered. The present mini-review aimed to brief the innervation and neural sonoanatomy of the knee joint and summarize the newest evidence of peripheral nerve stimulation (PNS) use in the management of knee pain.

Methods

We used a systematic approach to search for relevant articles. We used the combination of “peripheral nerve stimulation” and “knee pain” as the key words for the literature search using the electronic database without language or article type restriction. The search period was from the earliest record to August 2019.

Results

The present review identified six studies, four of which were related to PNS for management of postoperative knee pain and two of which probed neuropathic pain. Most of the studies were either case series or case reports. Based on our search result, PNS is likely to be a feasible and safe treatment for knee pain, but its effectiveness remains uncertain.

Conclusions

The present review reveals that PNS is feasible for the management of knee pain, especially in the postoperative period. The procedure is safe under ultrasound guidance used for proper placement of the electrodes near the target nerves. In the future, more prospective randomized controlled trials are needed to validate the effectiveness of PNS in acute and chronic knee pain.

Percutaneous Peripheral Nerve Stimulation for the Treatment of Chronic Pain Following Amputation

Introduction

Chronic pain and reduced function are significant problems for Military Service members and Veterans following amputation. Peripheral nerve stimulation (PNS) is a promising therapy, but PNS systems have traditionally been limited by invasiveness and complications. Recently, a novel percutaneous PNS system was developed to reduce the risk of complications and enable delivery of stimulation without surgery.

Materials and Methods

Percutaneous PNS was evaluated to determine if stimulation provides relief from residual and phantom limb pain following lower-extremity amputation. PNS leads were implanted percutaneously to deliver stimulation to the femoral and/or sciatic nerves. Patients received stimulation for up to 60 days followed by withdrawal of the leads.

Results

A review of recent studies and clinical reports found that a majority of patients (18/24, 75%) reported substantial (≥50%) clinically relevant relief of chronic post-amputation pain following up to 60 days of percutaneous PNS. Reductions in pain were frequently associated with reductions in disability and pain interference.

Conclusions

Percutaneous PNS can durably reduce pain, thereby enabling improvements in quality of life, function, and rehabilitation in individuals with residual or phantom limb pain following amputation. Percutaneous PNS may have additional benefit for Military Service members and Veterans with post-surgical or post-traumatic pain.

Advancement in Neuromodulation Technology with the Innovation of Design-Specific Peripheral Nerve Stimulators: Sural Nerve Stimulation for Radiculopathy

BACKGROUND

Peripheral nerve stimulation (PNS) is a form of neuromodulation that is used to treat chronic and refractory neuropathic pain. Peripheral nerve stimulation was first described in the early 1960s when Shelden implanted a PNS device for trigeminal neuralgia. Despite PNS being known since the 1960s, technology designed specifically for PNS was lacking. Within the past few years, design-specific PNS devices have become widely available, with favorable efficacy and safety profiles. Here we report a case of design-specific PNS that provided two years of pain relief in a patient with lower extremity neuropathic pain.

CASE PRESENTATION

A 53-year-old female with a history of congenital lumbar meningocele status post-L4-L5 laminectomy presented to the Mayo Clinic for treatment of foot pain that began three days after her laminectomy. She experienced a 6/10 burning, tingling sensation in the lateral dorsal portion of her right foot and posterolateral calf in addition to allodynia that prevented her from wearing shoes. She failed gabapentin, amitriptyline, cannabis, transforaminal epidural steroid injections, and two spinal cord stimulator trials. The patient ultimately underwent implantation of a right sural nerve stimulator, resulting in a 50% improvement in pain and functionality at two-year follow-up.

CONCLUSIONS

This report emphasizes the recent development of design-specific PNS devices and their successful use in this patient. Peripheral nerve stimulation technology and applications have diminished the role of spinal cord stimulation devices used for the periphery. Peripheral nerve stimulation should be considered for patients with isolated extremity pain, especially in those with spinal abnormalities (e.g., arachnoid cyst).

A review of the bioelectronic implications of stimulation of the peripheral nervous system for chronic pain conditions

Background

Peripheral Nerve Stimulation has been used to treat human disease including pain for several decades. Innovation has made it a more viable option for treatment of common chronic pain processes, and interest in the therapy is increasing.

Main body

While clinical data is forthcoming, understanding factors that influence successful outcomes in the use of PNS still needs to be delineated. This article reviews the evolution and bioelectronic principles of peripheral nerve stimulation including patient selection, nerve targets, techniques and guidance of target delivery. We collate the current evidence for outcomes and provide recommendations for salient topics in PNS.

Conclusion

Peripheral nerve stimulation has evolved from a surgically invasive procedure to a minimally invasive technique that can be used early in the treatment of peripheral nerve pain. This review identifies and addresses many of the variables which influence the success of PNS in the clinical setting.

Percutaneous Peripheral Nerve Stimulation for Chronic Low Back Pain: Prospective Case Series With 1 Year of Sustained Relief Following Short-Term Implant

INTRODUCTION

Percutaneous peripheral nerve stimulation (PNS) provides an opportunity to relieve chronic low back pain and reduce opioid analgesic consumption as an alternative to radiofrequency ablation and permanently implanted neurostimulation systems. Traditionally, the use of neurostimulation earlier in the treatment continuum has been limited by its associated risk, invasiveness, and cost.

METHODS

Percutaneous PNS leads (SPRINT MicroLead) were placed bilaterally to target the medial branches of the dorsal rami nerves under image guidance. The percutaneous leads were connected to miniature wearable stimulators (SPRINT PNS System) for the 1-month therapy period, after which the leads were removed. Pain and disability were assessed long-term up to 12 months after lead removal.

RESULTS

Substantial, clinically significant reductions in average pain intensity (≥50% reduction as measured by the Brief Pain Inventory Short Form) were experienced by a majority of subjects (67%) at end of treatment compared to baseline (average 80% reduction among responders; P < 0.05, analysis of variance; n = 9). Twelve months after the end of PNS treatment, a majority of subjects who completed the long-term follow-up visits experienced sustained, clinically significant reductions in pain and/or disability (67%, n = 6; average 63% reduction in pain intensity and 32-point reduction in disability among responders). No serious or unanticipated adverse events were reported.

CONCLUSIONS

This study challenges the long-held notion that a positive trial of PNS should be followed by a permanent implant in responders. Percutaneous PNS may serve as an effective neurostimulation therapy for patients with chronic low back pain and should be considered earlier in the treatment continuum as a motor-sparing means of avoiding opioids, denervation, and permanently implanted neurostimulation systems.

Percutaneous Peripheral Nerve Stimulation to Control Postoperative Pain, Decrease Opioid Use, and Accelerate Functional Recovery Following Orthopedic Trauma

Orthopedic trauma is a significant military problem, causing several of the most disabling conditions with high rates of separation from duty and erosion of military readiness. The objective of this report is to summarize the findings of case series of a non-opioid therapy-percutaneous peripheral nerve stimulation (PNS) - and describe its potential for postoperative analgesia, early opioid cessation, and improved function following orthopedic trauma. Percutaneous PNS has been evaluated for the treatment of multiple types of pain, including two case series on postoperative pain following total knee replacement (n = 10 and 8, respectively) and a case series on postamputation pain (n = 9). The orthopedic trauma induced during TKR is highly representative of multiple types of orthopedic trauma sustained by Service members and frequently produces intense, prolonged postoperative pain and extended opioid use following surgery. Collectively, the results of these three clinical studies demonstrated that percutaneous PNS can provide substantial pain relief, reduce opioid use, and improve function. These outcomes suggest that there is substantial potential for the use of percutaneous PNS following orthopedic trauma.

Peripheral nerve blocks for postoperative analgesia: From traditional unencapsulated local anesthetic to liposomes, cryoneurolysis and peripheral nerve stimulation

Peripheral nerve blocks (PNBs) using local anesthetics either via single injection or continuous perineural catheter have been the mainstay for regional anesthesia and are a vital component of postoperative multimodal opioid-sparing pain management. There are some limitations to PNBs, however, mainly its limited duration of action, but also risk of catheter-associated infection and dislodgements. Furthermore, local anesthetic-based blocks can induce sensory deficits and motor weakness, possibly increasing the risk of falling and/or decreasing the ability to participate in postoperative rehabilitation. In this review, we first discuss various local anesthetic-based PNB techniques for major surgery and then review newer modalities, including liposome bupivacaine, cryoanalgesia, and peripheral nerve stimulation; all of which may offer advantages over single and continuous local anesthetic-based PNBs.

Percutaneous peripheral nerve stimulation for acute postoperative pain

Peripheral nerve stimulation or peripheral neuromodulation is a modality utilized for decades to manage chronic pain. There have been recent studies published describing its use in managing acute surgical pain for orthopedic surgery. The postoperative acute pain associated with several types of surgeries often outlasts the analgesia duration provided by single and continuous peripheral nerve blocks. Ultrasound-guided percutaneous peripheral nerve stimulation has the potential to provide much longer analgesia for acute pain while avoiding some limitations associated with local anesthetic-based peripheral nerve blocks. We summarize the current devices used in published studies to demonstrate feasibility with a focus on acute pain control.

Ultrasound-Guided Percutaneous Electrical Nerve Stimulation of the Radial Nerve for a Patient With Lateral Elbow Pain: A Case Report With a 2-Year Follow-up

BACKGROUND

Patients with lateral elbow pain are often diagnosed with lateral epicondylalgia. Lateral elbow pain is often associated with dysfunction of the wrist extensor muscles; however, in some cases, it can also mimic signs and symptoms of radial nerve dysfunction.

CASE DESCRIPTION

In this case report, a 43-year-old man, who was originally referred with a diagnosis of lateral epicondylalgia as a result of playing table tennis and who previously responded favorably to manual therapy and exercise, presented to the clinic for treatment. An exacerbation while participating in a table tennis match resulted in a return of his lateral epicondylalgia symptoms, which did not respond favorably to the same interventions used in his prior course of therapy. Further examination revealed sensitization of the radial nerve, which was treated with 2 sessions of ultrasound-guided percutaneous electrical nerve stimulation and 4 weeks of a low-load, concentric/eccentric exercise program for the wrist extensors.

OUTCOMES

Following this intervention, the patient experienced clinically meaningful improvement in pain intensity (numeric pain-rating scale), function (Patient-Rated Tennis Elbow Evaluation), and related disability (Disabilities of the Arm, Shoulder and Hand questionnaire). The patient progressively exhibited complete resolution of pain and function, which was maintained at 2 years.

DISCUSSION

This case report demonstrates the outcomes of a patient with lateral elbow pain who did not respond to manual therapy and exercise. Once radial nerve trunk sensitivity was identified and the intervention, consisting of ultrasound-guided percutaneous electrical nerve stimulation targeting the radial nerve combined with a low-load exercise program, was applied, a full resolution of pain and function occurred rapidly. Future clinical trials should examine the effect of percutaneous electrical nerve stimulation in the management of nerve-related symptoms associated with musculoskeletal pain conditions.

LEVEL OF EVIDENCE

Therapy, level 5. J Orthop Sports Phys Ther 2019;49(5):347-354. Epub 18 Jan 2019. doi:10.2519/jospt.2019.8570.

Regional Anesthesia in the Combat Setting: Are ACGME Requirements Enough?

Introduction

Updated Joint Trauma System Clinical Practice Guidelines (CPG) indicate regional anesthesia and pain management (RAAPM) are important for combat casualty care. However, it is unclear whether military anesthesiology residents are receiving adequate RAAPM training to meet the CPGs. The goal of this study was to conduct a preliminary evaluation of resident-completed combat-relevant regional anesthesia procedures. It was hypothesized that most residents would perform an adequate number of each procedure to presume proficiency.

Materials and Methods

Resident-performed, combat-relevant regional anesthesia procedure frequency was extracted from a database maintained at a military anesthesiology residency program. Data collection was limited to a 1-year period. Univariate statistics described procedure distributions, frequencies, and proportion of residents achieving pre-defined, empirically-supported experience criteria for each technique. Analyses examined proportional differences in meeting experience criteria by training-year.

Results

Residents (N = 41) performed a variety of procedures. Simple procedures, such as saphenous peripheral nerve blocks, were performed at a greater frequency than more complicated procedures such as thoracic epidurals, continuous peripheral nerve blocks, and transverse abdominus plane blocks. The majority of residents met experience criteria for four out of the eight measured combat-relevant blocks. There were no proportional differences in meeting procedural experience criteria across the different training levels.

Conclusions

These results suggest a possible gap between the needs of the Military Health System during conflict and current residency training experiences. Reasons for this gap, as well as solutions, are explored.

Ultrasound-guided percutaneous peripheral nerve stimulation: neuromodulation of the suprascapular nerve and brachial plexus for postoperative analgesia following ambulatory rotator cuff repair. A proof-of-concept study

BACKGROUND AND OBJECTIVES

Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducing needle followed by the delivery of electric current. This modality has been reported to treat chronic pain as well as postoperative pain following knee and foot surgery. However, it remains unknown if this analgesic technique may be used in ambulatory patients following upper extremity surgery. The purpose of this proof-of-concept study was to investigate various lead implantation locations and evaluate the feasibility of using percutaneous brachial plexus PNS to treat surgical pain following ambulatory rotator cuff repair in the immediate postoperative period.

METHODS

Preoperatively, an electrical lead (SPR Therapeutics, Cleveland, Ohio) was percutaneously implanted to target the suprascapular nerve or brachial plexus roots or trunks using ultrasound guidance. Postoperatively, subjects received 5 min of either stimulation or sham in a randomized, double-masked fashion followed by a 5 min crossover period, and then continuous stimulation until lead removal postoperative days 14-28.

RESULTS

Leads (n=2) implanted at the suprascapular notch did not appear to provide analgesia, and subsequent leads (n=14) were inserted through the middle scalene muscle and placed to target the brachial plexus. Three subjects withdrew prior to data collection. Within the recovery room, stimulation did not decrease pain scores during the first 40 min of the remaining subjects with brachial plexus leads, regardless of which treatment subjects were randomized to initially. Seven of these 11 subjects required a single-injection interscalene nerve block for rescue analgesia prior to discharge. However, subsequent average resting and dynamic pain scores postoperative days 1-14 had a median of 1 or less on the Numeric Rating Scale, and opioid requirements averaged less than 1 tablet daily with active stimulation. Two leads dislodged during use and four fractured on withdrawal, but no infections, nerve injuries, or adverse sequelae were reported.

CONCLUSIONS

This proof-of-concept study demonstrates that ultrasound-guided percutaneous PNS of the brachial plexus is feasible for ambulatory shoulder surgery, and although analgesia immediately following surgery does not appear to be as potent as local anesthetic-based peripheral nerve blocks, the study suggests that this modality may provide analgesia and decrease opioid requirements in the days following rotator cuff repair. Therefore, it suggests that a subsequent, large, randomized clinical trial with an adequate control group is warranted to further investigate this therapy in the management of surgical pain in the immediate postoperative period. However, multiple technical issues remain to be resolved, such as the optimal lead location, insertion technique, and stimulating protocol, as well as preventing lead dislodgment and fracture.

TRIAL REGISTRATION NUMBER

NCT02898103.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation: Neuromodulation of the Sciatic Nerve for Postoperative Analgesia Following Ambulatory Foot Surgery, a Proof-of-Concept Study

BACKGROUND AND OBJECTIVES

Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducing needle followed by the delivery of electric current. This modality has been reported to treat chronic pain as well as postoperative pain the day following knee surgery. However, it remains unknown if this analgesic technique may be used in ambulatory subjects following foot procedures beginning within the recovery room immediately following surgery, and with only short series of patients reported to date, the only available data are derived from strictly observational studies. The purposes of this proof-of-concept study were to demonstrate the feasibility of using percutaneous sciatic nerve PNS to treat postoperative pain following ambulatory foot surgery in the immediate postoperative period and provide the first available data from a randomized controlled study design to provide evidence of analgesic effect.

METHODS

Preoperatively, an electrical lead (SPRINT; SPR Therapeutics, Inc, Cleveland, Ohio) was percutaneously inserted posterior to the sciatic nerve between the subgluteal region and bifurcation with ultrasound guidance. Following hallux valgus osteotomy, subjects received 5 minutes of either stimulation or sham in a randomized, double-masked fashion followed by a 5-minute crossover period and then continuous stimulation until lead removal on postoperative days 14 to 28.

RESULTS

During the initial 5-minute treatment period, subjects randomized to stimulation (n = 4) experienced a downward trajectory in their pain over the 5 minutes of treatment, whereas those receiving sham (n = 3) reported no such change until their subsequent 5-minute stimulation crossover. During the subsequent 30 minutes of stimulation, pain scores decreased to 52% of baseline (n = 7). Three subjects (43%) used a continuous popliteal nerve block for rescue analgesia during postoperative days 0 to 3. Overall, resting and dynamic pain scores averaged less than 1 on the numeric rating scale, and opioid use averaged less than 1 tablet daily with active stimulation. One lead dislodged, 2 fractured during use, and 1 fractured during intentional withdrawal.

CONCLUSIONS

This proof-of-concept study demonstrates that percutaneous sciatic nerve PNS is feasible for ambulatory foot surgery and suggests that this modality provides analgesia and decreases opioid requirements following hallux valgus procedures. However, lead dislodgement and fracture are concerns.

CLINICAL TRIAL REGISTRATION

This study was registered at Clinicaltrials.gov, identifier NCT02898103.

Current Innovations in Peripheral Nerve Stimulation

Peripheral nerve stimulation has been used in the treatment of several chronic pain conditions including pain due to peripheral nerve dysfunctions, complex regional pain syndrome, and cranial neuralgias. It has been shown to be effective for chronic, intractable pain that is refractory to conventional therapies such as physical therapy, medications, transcutaneous electrical stimulations, and nerve blocks. Recently, a new generation of peripheral nerve stimulation devices has been developed; these allow external pulse generators to transmit impulses wirelessly to the implanted electrode, and their implantation is significantly less invasive. In this review, we discuss the history, pathophysiology, indications, implantation process, and outcomes of employing peripheral nerve stimulation to treat chronic pain conditions.

Novel Methodologies in Regional Anesthesia for Knee Arthroplasty

Maximizing analgesia is critical following joint arthroplasty because postoperative pain is a major barrier to adequate physical therapy. Continuous peripheral nerve blocks have been the mainstay for acute pain management in this population; however, this and similar techniques are limited by their duration of action. Cryoneurolysis and peripheral nerve stimulation are two methodologies used for decades to treat chronic pain. With the advent of portable ultrasound devices and percutaneous administration equipment, both procedures may now be suitable for treatment of acute pain. This article reviews these two modalities and their application to joint arthroplasty.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation: Neuromodulation of the Femoral Nerve for Postoperative Analgesia Following Ambulatory Anterior Cruciate Ligament Reconstruction: A Proof of Concept Study

Objectives

The purpose of this prospective proof of concept study was to investigate the feasibility of using percutaneous peripheral nerve stimulation of the femoral nerve to treat pain in the immediate postoperative period following ambulatory anterior cruciate ligament reconstruction with a patellar autograft.

Materials and Methods

Preoperatively, an electrical lead (SPRINT, SPR Therapeutics, Inc., Cleveland, OH, USA) was percutaneously implanted with ultrasound guidance anterior to the femoral nerve caudad to the inguinal crease. Within the recovery room, subjects received 5 min of either stimulation or sham in a randomized, double‐masked fashion followed by a 5‐min crossover period, and then continuous active stimulation until lead removal postoperative Day 14–28. Statistics were not applied to the data due to the small sample size of this feasibility study.

Results

During the initial 5‐min treatment period, subjects randomized to stimulation (n = 5) experienced a slight downward trajectory (decrease of 7%) in their pain over the 5 min of treatment, while those receiving sham (n = 5) reported a slight upward trajectory (increase of 4%) until their subsequent 5‐min stimulation crossover, during which time they also experienced a slight downward trajectory (decrease of 11% from baseline). A majority of subjects (80%) used a continuous adductor canal nerve block for rescue analgesia (in addition to stimulation) during postoperative Days 1–3, after which the median resting and dynamic pain scores remained equal or less than 1.5 on the numeric rating scale, respectively, and the median daily opioid consumption was less than 1.0 tablet.

Conclusions

This proof of concept study demonstrates that percutaneous femoral nerve stimulation is feasible for ambulatory knee surgery; and suggests that this modality may be effective in providing analgesia and decreasing opioid requirements following anterior cruciate ligament reconstruction. clinicaltrials.gov: NCT02898103.