Conventionally, peripheral nerve stimulation (PNS) for treatment of chronic pain has involved a two-stage process: a short-term (e.g., 7 days) trial and, if significant pain relief is achieved, a permanent PNS system is implanted. A percutaneous PNS treatment is now available where a coiled lead may be implanted for up to 60 days with the goal of producing sustained relief. In the present review, published prospective trials using percutaneous PNS treatment were identified and synthesized. The collected evidence indicates that percutaneous PNS treatment for up to 60 days provides durable clinically significant improvements in pain and pain interference. Similar efficacy across diverse targets and etiologies supports the broad applicability for use within the chronic pain population using this nonopioid technology.
What is this review about? This review looks at a drug-free way to treat chronic pain called percutaneous peripheral nerve stimulation (PNS). Percutaneous means it is placed through the skin. PNS applies small amounts of electricity to the nerves to reduce chronic pain. Most PNS systems involve a two-step process. A short trial is first performed to see if a patient has pain relief. A permanent system is then placed if the person had pain relief. Percutaneous PNS treatments are different. They use a thin wire called a lead placed in the body for up to 60 days. The lead is taken out at the end of the treatment period. Studies have shown that this type of PNS treatment can reduce chronic pain even after the treatment is over. No previous article has collected all these studies of percutaneous PNS in one place.What evidence was gathered? This review found evidence from studies on treatment of chronic pain. Pain types included shoulder pain, neuropathic pain and low back pain. It found that percutaneous PNS treatment for up to 60 days can reduce pain and how pain interferes with daily life.How can these data lead to better care for patients? These findings mean that percutaneous PNS treatments could be a useful, non-drug option for many types of chronic pain.

UNASSIGNED: This multicenter, randomized, double-blinded, active sham-controlled pivotal study was designed to assess the efficacy and safety of high-frequency nerve block treatment for chronic post-amputation and phantom limb pain.
UNASSIGNED: QUEST enrolled 180 unilateral lower-limb amputees with severe post-amputation pain, 170 of whom were implanted with the Altius device, were randomized 1:1 to active-sham or treatment groups and reached the primary endpoint. Responders were those subjects who received ≥50% pain relief 30 min after treatment in ≥50% of their self-initiated treatment sessions within the 3-month randomized period. Differences between the active treatment and sham control groups as well as numerous secondary outcomes were determined.
UNASSIGNED: At 30-min, (primary outcome), 24.7% of the treatment group were responders compared to 7.1% of the control group (p=0.002). At 120-minutes following treatment, responder rates were 46.8% in the Treatment group and 22.2% in the Control group (p=0.001). Improvement in Brief Pain Inventory interference score of 2.3 ± 0.29 was significantly greater in treatment group than the 1.3 ± 0.26-point change in the Control group (p = 0.01). Opioid usage, although not significantly different, trended towards a greater reduction in the treatment group than in the control group. The incidence of adverse events did not differ significantly between the treatment and control groups.
UNASSIGNED: The primary outcomes of the study were met, and the majority of Treatment patients experienced a substantial improvement in PAP (regardless of meeting the study definition of a responder). The significant in PAP was associated with significantly improved QOL metrics, and a trend towards reduced opioid utilization compared to Control. These data indicate that Altius treatment represents a significant therapeutic advancement for lower-limb amputees suffering from chronic PAP.

Objective.Rapid switching of magnetic resonance imaging (MRI) gradient fields induces electric fields that can cause peripheral nerve stimulation (PNS) and so accurate characterization of PNS is required to maintain patient safety and comfort while maximizing MRI performance. The minimum magnetic gradient amplitude that causes stimulation, the PNS threshold, depends on intrinsic axon properties and the spatial and temporal properties of the induced electric field. The PNS strength-duration curve is widely used to characterize simulation thresholds for periodic waveforms and is parameterized by the chronaxie and rheobase. Safety limits to avoid unwanted PNS in MRI rely on a single chronaxie value to characterize the response of all nerves. However, experimental magnetostimulation peripheral nerve chronaxie values vary by an order of magnitude. Given the diverse range of chronaxies observed and the importance of this number in MRI safety models, we seek a deeper understanding of the mechanisms contributing to chronaxie variability.Approach.We use a coupled electromagnetic-neurodynamic PNS model to assess geometric sources of chronaxie variability. We study the impact of the position of the stimulating magnetic field coil relative to the body, along with the effect of local anatomical features and nerve trajectories on the driving function and the resulting chronaxie.Main results.We find realistic variation of local axon and tissue geometry can modulate a given axon\'s chronaxie by up to two-fold. Our results identify the temporal rate of charge redistribution as the underlying determinant of the chronaxie.Significance.This charge distribution is a function of both intrinsic axon properties and the spatial stimulus along the nerve; thus, examination of the local tissue topology, which shapes the electric fields, as well as the nerve trajectory, are critical for better understanding chronaxie variations and defining more biologically informed MRI safety guidelines.

BACKGROUND: Lower extremity pain is one of the most common types of chronic pain and can be very challenging to treat using conservative management modalities.
OBJECTIVE: Our study intends to present the effective management of chronic neuralgias in the lower extremities through peripheral nerve stimulation (PNS).
METHODS: This retrospective study included 21 patients who received a permanent Curonix Freedom® PNS System for treating chronic pain in the lower extremities. A retrospective chart review was conducted to assess the baseline and follow-up parameters.
METHODS: Fourteen of the patients (67%) received one neurostimulator at either the superficial peroneal or posterior tibial nerve. Seven patients (33%) received 2 neurostimulators at either the sural and superficial peroneal, posterior tibial and superficial peroneal, or common and superficial peroneal nerves. The data were collected from electronic medical records, followed by case report forms. Pain scores and complications were reported up to 6 months after permanent implantation. Adverse events (AEs) were reported descriptively and classified as serious or nonserious AEs and related or nonrelated AEs.
RESULTS: At the end of the trial visit, 21 of the 21 patients (100%) reported more than 50% pain relief, with mean pain scores reducing from 7.29 ± 0.9 to 2.81 ± 0.7 (61%; P < 0.001). Nineteen patients completed the long-term follow-up. Fourteen of those 19 patients (74%) experienced at least a 50% improvement in pain. The average NRS score decreased significantly to 3.66 ± 1.8 (50%; P < 0.001). No complications were reported.
CONCLUSIONS: PNS done with the Curonix Freedom® PNS System is an effective and safe therapy for lower-extremity neuralgias.

UNASSIGNED: Spinal cord injuries (SCI) often result in motor impairment and lifelong disability.
UNASSIGNED: This systematic review, conducted in agreement with PRISMA guidelines, aimed to evaluate the effects of cortico-spinal paired associative stimulation (PAS) on motor outcomes in individuals with SCI. PubMed, Scopus/EMBASE, Pedro, and Cochrane databases were consulted from inception to 2023/01/12.
UNASSIGNED: In 1021 articles, 10 studies involving 84 patients meet the inclusion criteria, 7 case series/study, and 3 clinical trials. Despite light differences, the included studies performed a cortico-peripheral PAS using a single transcranial magnetic stimulation and high frequency electrical peripheral nerve stimulation for a consistent number of sessions (>20). All included studies reported improvement in motor outcomes recorded via clinical and/or neurophysiological assessment.
UNASSIGNED: Available evidence showed an increase in motor outcomes after PAS stimulation. Indeed, both clinical and neurophysiological outcomes suggest the effectiveness of a high number of PAS sessions in chronic individuals with SCI. Due to a limited number of studies and an unsatisfactory study design, well-designed RCTs are needed to confirm the potentiality of these approaches and clarify the adequate dose-response of PAS in the SCI population.
UNASSIGNED: The protocol was registered on the PROSPERO database (CRD42023485703).

OBJECTIVE: Peripheral nerve stimulation (PNS) limits the usability of state-of-the-art whole-body and head-only MRI gradient coils. We used detailed electromagnetic and neurodynamic modeling to set an explicit PNS constraint during the design of a whole-body gradient coil and constructed it to compare the predicted and experimentally measured PNS thresholds to those of a matched design without PNS constraints.
METHODS: We designed, constructed, and tested two actively shielded whole-body Y-axis gradient coil winding patterns: YG1 is a conventional symmetric design without PNS-optimization, whereas YG2\'s design used an additional constraint on the allowable PNS threshold in the head-imaging landmark, yielding an asymmetric winding pattern. We measured PNS thresholds in 18 healthy subjects at five landmark positions (head, cardiac, abdominal, pelvic, and knee).
RESULTS: The PNS-optimized design YG2 achieved 46% higher average experimental thresholds for a head-imaging landmark than YG1 while incurring a 15% inductance penalty. For cardiac, pelvic, and knee imaging landmarks, the PNS thresholds increased between +22% and +35%. For abdominal imaging, PNS thresholds did not change significantly between YG1 and YG2 (-3.6%). The agreement between predicted and experimental PNS thresholds was within 11.4% normalized root mean square error for both coils and all landmarks. The PNS model also produced plausible predictions of the stimulation sites when compared to the sites of perception reported by the subjects.
CONCLUSIONS: The PNS-optimization improved the PNS thresholds for the target scan landmark as well as most other studied landmarks, potentially yielding a significant improvement in image encoding performance that can be safely used in humans.

Scapulalgia or shoulder pain accounts for 16% of all musculoskeletal complaints in the healthy adult population and becomes more common as we age. When this pain exceeds 3 months in duration, it is deemed to be chronic, and typically treated in an escalating manner. Spanning a continuum of conservative and non-conservative measures, chronic shoulder pain treatments range from rest and physical therapy to surgery. Since each patient presents with a unique spectrum of symptoms a customized treatment plan is often required. Over the lifetime of many of these patients, a variety of treatment options are required. One of these treatment options, peripheral nerve stimulation (PNS), is a minimally invasive procedure in which an electrical impulse is delivered through a percutaneously implanted, small caliber electrode to a peripheral nerve proximal to the lesion which interferes with the pain signals. Over the past several years, significant growth of PNS in the treatment of chronic neuropathic pain has been observed. However, the procedural techniques have not been well described. The foundation of long-term, minimally invasive percutaneous PNS in patients with chronic shoulder pain, and procedural techniques for stimulating the suprascapular and axillary nerves using fluoroscopy or ultrasonography will be described in this report.

OBJECTIVE: Total knee arthroplasty (TKA) is an effective surgery for end-stage knee osteoarthritis, but chronic postoperative pain and reduced function affect up to 20% of patients who undergo such surgery. There are limited treatment options, but percutaneous peripheral nerve stimulation (PNS) is a promising nonopioid treatment option for chronic, persistent postoperative pain. The objective of the present study was to evaluate the effect of a 60-day percutaneous PNS treatment in a multicenter, randomized, double-blind, placebo-controlled trial for treating persistent postoperative pain after TKA.
METHODS: Patients with postoperative pain after knee replacement were screened for this postmarket, institutional review board-approved, prospectively registered (NCT04341948) trial. Subjects were randomized to receive either active PNS or placebo (sham) stimulation. Subjects and a designated evaluator were blinded to group assignments. Subjects in both groups underwent ultrasound-guided placement of percutaneous fine-wire coiled leads targeting the femoral and sciatic nerves on the leg with postoperative pain. Leads were indwelling for eight weeks, and the primary efficacy outcome compared the proportion of subjects in each group reporting ≥50% reduction in average pain relative to baseline during weeks five to eight. Functional outcomes (6-minute walk test; 6MWT and Western Ontario and McMaster Universities Osteoarthritis Index) and quality of life (Patient Global Impression of Change) also were evaluated at end of treatment (EOT).
RESULTS: A greater proportion of subjects in the PNS groups (60%; 12/20) than in the placebo (sham) group (24%; 5/21) responded with ≥50% pain relief relative to baseline (p = 0.028) during the primary endpoint (weeks 5-8). Subjects in the PNS group also walked a significantly greater distance at EOT than did those in the placebo (sham) group (6MWT; +47% vs -9% change from baseline; p = 0.048, n = 18 vs n = 20 completed the test, respectively). Prospective follow-up to 12 months is ongoing.
CONCLUSIONS: This study provides evidence that percutaneous PNS decreases persistent pain, which leads to improved functional outcomes after TKA at EOT.

Chronic pain, a complex and debilitating condition, poses a significant challenge to both patients and healthcare providers worldwide. Conventional pharmacological interventions often prove inadequate in delivering satisfactory relief while carrying the risks of addiction and adverse reactions. In recent years, electric neuromodulation emerged as a promising alternative in chronic pain management. This method entails the precise administration of electrical stimulation to specific nerves or regions within the central nervous system to regulate pain signals. Through mechanisms that include the alteration of neural activity and the release of endogenous pain-relieving substances, electric neuromodulation can effectively alleviate pain and improve patients\' quality of life. Several modalities of electric neuromodulation, with a different grade of invasiveness, provide tailored strategies to tackle various forms and origins of chronic pain. Through an exploration of the anatomical and physiological pathways of chronic pain, encompassing neurotransmitter involvement, this narrative review offers insights into electrical therapies\' mechanisms of action, clinical utility, and future perspectives in chronic pain management.

Shoulder tendinopathies produce pain and reduce functionality. The aim of this randomized clinical trial was to analyze the effects of Percutaneous electrolysis (PE), Percutaneous peripheral Nerve Stimulation (PNS) and eccentric exercise (EE) on pain (NPRS), strength, electromyographic activity, ultrasound characteristics of the tendon (echogenicity, thickness and hypervascularization) and functionality (DASH and SPADI) in individuals with supraspinatus tendinopathy. Participants (n = 50) were divided into two groups; they received 4 treatment sessions, 1 per week, of PE and PNS (n = 25) or 10 treatment sessions of TENS and US (n = 25). Both groups performed the EE program consisting of 3 sets of 10 repetitions of each of the 3 exercises, twice a day, during the 4 weeks. Follow-up was carried out at 4, 12 and 24 weeks after the start of the intervention. There are statistically significant differences in the analysis between groups (p < 0.001) in the post-treatment and follow-up measurements favorable to the PE+PNS+EE treatment on pain (NPRS), strength, supraspinatus electromyographic amplitude, ultrasound characteristics of the tendon (echogenicity, thickness and hypervascularization) and DASH and SPADI questionnaires. The combined treatment with PE, PNS and EE is an effective option in the clinical management of tendinopathies, with positive results in the short and long term on the variables studied.