Effectiveness of Ultrasound-Guided Percutaneous Electrolysis for Musculoskeletal Pain: A Systematic Review and Meta-Analysis

Effectiveness of Percutaneous Needle Electrolysis to Reduce Pain in Tendinopathies: A Systematic Review With Meta-Analysis

CONTEXT

Tendon injuries are common disorders in both workers and athletes, potentially impacting performance in both conditions. This is why the search for effective treatments is continuing.

OBJECTIVE(S)

The objective of this study was to analyze whether the ultrasound-guided percutaneous needle electrolysis technique may be considered a procedure to reduce pain caused by tendinosis.

EVIDENCE ACQUISITION

The search strategy included the PubMed, SCOPUS, CINAHL, Physiotherapy Evidence Database, SciELO, and ScienceDirect up to the date of February 25, 2024. Randomized clinical trials that assessed pain caused by tendinosis using the Visual Analog Scale and Numeric Rating Scale were included. The studies were evaluated for quality using the Cochrane Risk of Bias 2, and the evidence strength was assessed by the GRADEpro GDT.

EVIDENCE SYNTHESIS

Out of the 534 studies found, 8 were included in the review. A random-effects meta-analysis and standardized mean differences (SMD) were conducted. The ultrasound-guided percutaneous needle electrolysis proved to be effective in reducing pain caused by tendinosis in the overall outcome (SMD = -0.97; 95% CI, -1.26 to -0.68; I2 = 58%; low certainty of evidence) and in the short-term (SMD = -0.83, 95% CI, -1.29 to -0.38; I2 = 65%; low certainty of evidence), midterm (SMD = -1.28; 95% CI, -1.65 to -0.91; I2 = 0%; moderate certainty of evidence), and long-term (SMD = -0.94; 95% CI, -1.62 to -0.26; I2 = 71%; low certainty of evidence) subgroups.

CONCLUSION(S)

The application of the ultrasound-guided percutaneous needle electrolysis technique for reducing pain caused by tendinosis appears to be effective. However, due to the heterogeneity found (partially explained), more studies are needed to define the appropriate dosimetry, specific populations that may benefit more from the technique, and possible adverse events.

Placebo and nocebo effects of percutaneous needle electrolysis and dry-needling: an intra and inter-treatment sessions analysis of a three-arm randomized double-blinded controlled trial in patients with patellar tendinopathy

Objective

This study aimed to investigate the influence of potential placebo and nocebo effects on pain perception of percutaneous needle electrolysis (PNE) in individuals with patellar tendinopathy.

Methods

In this secondary analysis of a three-arm randomized double-blinded controlled trial, intra and inter-session pain perception data from 48 sporting participants with patellar tendinopathy between 18 and 45 years were investigated. Participants were divided into 3 parallel groups: "no-sham group" [PNE intervention], "single-sham group" [sham PNE by using dry needling], and "double-sham group" [sham PNE by using sham needles]. Every group received 4 sessions of the needling therapies targeting the patellar tendon over 8 weeks and was instructed to perform a unilateral eccentric exercise program of the quadriceps muscle on the affected side. Clinical and needle-related pain was assessed before, during, and after each treatment session using a visual analog scale.

Results

No differences were found between groups intra- or inter-session in terms of pain reduction (P = 0.424) despite clinical pain decreased in all groups since the first treatment session (P < 0.001). Furthermore, although the double-sham group showed a lower percentage of participants reporting needle-related pain during needle intervention (P = 0.005), the needle-related pain intensity after needle intervention was similar between groups (P = 0.682). Moreover, there were no group differences for the duration of pain sensation after any needle intervention (P = 0.184), extending in many cases beyond 24 h.

Conclusion

Needling therapies for individuals with patellar tendinopathy are prone to elicit placebo effects regarding clinical pain and nocebo effects regarding needling-related pain. Clinicians and physical therapists treating musculoskeletal pain conditions should consider the added value and potential mechanisms of action before routinely using needle techniques.

The Precision and Safety of Ultrasound-Guided versus Palpation-Guided Needle Placement on the Plantar Fascia and Flexor Digitorum Brevis Interface: An Anatomical Study

BACKGROUND

Evidence suggests the plantar fascia and its interphase with the flexor digitorum brevis muscle can play a relevant role in plantar heel pain. Needling interventions could offer an appropriate treatment strategy to addressing this interface.

OBJECTIVE

We compared the accuracy and safety of ultrasound-guided versus palpation-guided procedures for the proper targeting of the interface between the plantar fascia and the flexor digitorum brevis with a solid needle.

METHODS

A crossover cadaveric study was conducted. Five experienced therapists performed a series of 20 needle insertions each (n = 100 in total, 10 landmark-guided and 10 ultrasound-guided) on 10 anatomical samples. The therapists were instructed to accurately place the needle on the interface between the plantar fascia and the flexor digitorum brevis muscle. The distance of the tip of the needle to the identified target (accuracy), the surrounding sensitive structures targeted (safety), the time needed for the procedure, the number of needle passes, and the needle length outside the skin were assessed.

RESULTS

The ultrasound-guided technique was associated with a significantly higher accuracy (p < 0.001) but without differences in safety (p = 0.249) as compared to the palpation-guided procedure.

CONCLUSION

Our results suggest that ultrasound-guided insertion exhibits greater accuracy but not greater safety than palpation-guided insertion when targeting the interface between the plantar fascia and the flexor digitorum brevis.

Effectiveness of different percutaneous electrolysis protocols in the endogenous modulation of pain: A Double-Blinded Randomized Clinical Trial

OBJECTIVE

This randomized clinical trial investigated if the application of percutaneous electrolysis (PE) enhances endogenous pain mechanisms (EPM) when compared with a simple needle application (acting as sham).

METHODS

Forty-six asymptomatic subjects, aged 18-40 years, were randomized into three groups receiving a single ultrasound-guided PE intervention consisting of a needle insertion on the lateral epicondyle: sham (without electrical current), low-intensity (0.3 mA, 90s), or high-intensity (three pulses of 3 mA, 3s) PE. Widespread pressure pain thresholds (PPT), conditioned pain modulation (CPM), and temporal summation (TS) were bilaterally assessed in the lateral epicondyle, bicipital groove, transverse process of C5 and tibialis anterior muscle. Outcomes were obtained by an assessor blinded to the treatment allocation of the subjects.

RESULTS

No significant changes in CPM were observed in either group (omnibus ANOVA all, P > .05). A significant bilateral increase in PPT in the lateral epicondyle in the high intensity group as compared with the sham group was observed (P < .01). A significant decrease of TS in both low (P = .002) and high (P = .049) intensity groups on the right, but not on the left, tibialis anterior was also observed when compared with the sham group.

CONCLUSIONS

One session of PE is able to slightly stimulate modulatory pathways related to nociceptive gain, particularly pressure pain sensitivity and temporal summation but not conditioning pain modulation, when compared with a sham needle intervention, with changes even contralaterally. No significant differences were found between low- and high-intensity doses of percutaneous electrolysis.

Precision and Safety of Ultrasound-Guided versus Palpation-Guided Needle Placement on the Patellar Tendon: A Cadaveric Study

For decades, needling interventions have been performed based on manual palpation and anatomic knowledge. The increasing use of real-time ultrasonography in clinical practice has improved the accuracy and safety of needling techniques. Although currently ultrasound-guided procedures are routinely used for patellar tendon pathology, e.g., during percutaneous electrolysis, the accuracy of these procedures is still unknown. This study used a cadaveric model to compare and evaluate both the accuracy and safety of ultrasound-guided and palpation-guided needling techniques for the patellar tendon. A total of five physical therapists performed a series of 20 needle insertion task each (n = 100), 10 insertions based on manual palpation (n = 50) and 10 insertions guided with ultrasound (n = 50) to place a needle along the interface between the patellar tendon and Hoffa's fat pad. All procedures were performed on cryopreserved knee specimens. Distance to the targeted tissue, time of the procedure, accurate rate of insertions, number of passes, and unintentional punctured structures between both applications (with and without ultrasound guiding) were compared. The results revealed higher accuracy (100% vs. 80%), a lower distance from needle to the targeted tissue (0.25 ± 0.65 vs. 2.5 ± 1.9 mm), longer surface of contact with the needle (15.5 ± 6.65 vs. 4.7 ± 7.5 mm), and a lower frequency of patellar tendon puncture (16% vs. 52%, p < 0.001) with the ultrasound-guided procedure as opposed to palpation-guided one. Nevertheless, the ultrasound-guided procedure took longer (54.8 ± 26.8 vs. 23.75 ± 15.4 s) and required more passes (2.55 ± 1.9 vs. 1.5 ± 0.95) to be conducted than the palpation-guided procedure (all, p < 0.001). According to these findings, the accuracy of invasive procedures applied on the patellar tendon is higher when conducted with ultrasound guidance than when conducted just on manual palpation or anatomical landmark. These results suggest that ultrasound could improve the clinical application of invasive procedures at the fat-patellar tendon interface. Due to the anatomical features of the targeted tissue, some procedures require this precision, so the use of ultrasound is recommended.

Inclusion of cross-sectional and radiological images for better understanding of musculoskeletal anatomy and decreasing the risk of adverse events during dry needling in undergraduate physiotherapy students

Since there is an increasing rate of physiotherapists using invasive procedures during the clinical practice, understanding the cross-sectional anatomy and radiological images is essential for ensuring patients' safety during these interventions. Therefore, the aim of this study was to analyze the students' opinion of including cross-sectional and radiological images to traditional methodologies, to evaluate whether these additional resources improve their ability to identify musculoskeletal structures in radiological images and their understanding of neurovascular and visceral structures related with specific muscles to be avoided during invasive procedures. First-year undergraduate physiotherapy students were enrolled in the study. A brief online survey asking about their opinion about the use of cross-sectional and radiological images as complementary resources was built. In addition, two open-answer tests (before and after the inclusion of these resources) were conducted to evaluate their ability to identify correctly musculoskeletal structures in magnetic resonance and ultrasound images and to evaluate their awareness of high-risk structures related with specific muscles. One-hundred-thirty-two students returned the online survey and one-hundred-forty-eight completed all the tests. In general, students opined cross-sectional images to be of utility for learning anatomy (81.8%) and radiological images (93.9%) and felt they benefited from cross-sectional and ultrasound images (78.0%). All tests showed significant improvements after the inclusion of these complementary resources (all, p < 0.001) except for trunk structures in MRI (p = 0.777). The implementation of anatomical cross-sectional and radiological images resulted in better understanding of radiological images and better cognition of possible risk during invasive procedures.

Efficacy of different intensities of percutaneous electrolysis for musculoskeletal pain: A systematic review and meta-analysis

Objective

A meta-analysis of randomized controlled trials (RCTs) was conducted to determine the effect of ultrasound-guided percutaneous electrolysis (PE) alone or as an adjunct to other interventions on pain intensity generated by musculoskeletal disorders, depending on the intensity of the technique.

Data sources

PUBMED, EMBASE, Cochrane Library, Web of Science, SCOPUS, Health Medical Collection, and CINALH from inception to September 2022 were searched to identify documents.

Study selection

Publications investigating the effect of ultrasound-guided PE in musculoskeletal pain.

Data extraction

Data were extracted into predesigned data extraction and tables. Risk of bias was evaluated with the Cochrane Risk of Bias Tool (Rob 2.0). Thirteen articles met inclusion criteria.

Data analysis

Random-effects meta-analysis models were used to quantify the difference in pain between the PE and control groups.

Data synthesis

A significant reduction in pain was found in favor of low- (-1.89; 95% CI: -2.69; -1.10; p < 0.001) and high-intensity PE (-0.74; 95% CI: -1.36; -0.11; p: 0.02) compared to control group. Low-intensity PE showed significant reduction in pain in the short (-1.73; 95% CI: -3.13; -0.34; p < 0.02) and long term (-2.10; 95% CI: -2.93; -1.28; p = 0.005), with large effect sizes compared to control group. High-intensity PE only showed significant lower pain than control group in the long term (-0.92; 95% CI: -1.78; -0.07; p < 0.03), with a small effect size, but not in the short term.

Conclusion

We found small evidence suggesting that low-intensity PE could be more effective for musculoskeletal pain reduction than high-intensity PE. Nevertheless, scientific evidence on this subject is still scarce and studies comparing the two modalities are warranted.

Systematic review registration

www.crd.york.ac.uk/prospero, identifier CRD42022366935.

Efficacy of percutaneous needle electrolysis versus dry needling in musculoskeletal pain: A systematic review and meta-analysis

BACKGROUND

Physical therapists use dry needling (DN) and percutaneous needle electrolysis (PNE) to treat musculoskeletal pain.

OBJECTIVE

To investigate the efficacy of PNE vs. DN in the treatment of musculoskeletal pain.

METHODS

This systematic review and meta-analysis was based on the PICOS and PRISMA protocols. The PubMed, PEDro, Cochrane Library, SCOPUS, and Google Scholar databases were searched for randomized clinical trials measuring pain intensity in various musculoskeletal syndromes using PNE and DN. Pain outcome measures were the visual analog scale or the numerical pain rating scale. Risk of bias was assessed according to Cochrane guidelines and quality of evidence was reported using the Grading of Recommendations Assessment, Development, and Evaluation approach (GRADE). Standardized mean differences were calculated using random effects models.

RESULTS

The meta-analysis of the six included studies showed that the overall effect of PNE vs. DN for pain reduction was statistically significant at -0.74 (95% confidence interval [CI], -1.34 to -0.14) with a large effect size (SMD =-0.41; 95% CI, -0.75 to -0.08), albeit clinically insignificant in the short, medium, and long term. Risk of bias was generally low with moderate-level evidence due to the overall effect heterogeneity and the small sample.

CONCLUSIONS

Moderate-quality evidence showed that PNE is slightly more effective than DN in reducing pain. However, because the results were not clinically significant, we cannot recommend the application of PNE over DN. More high-quality studies comparing the two interventions are needed to draw firm conclusions.

Efficacy of percutaneous electrolysis for the treatment of tendinopathies: A systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy of percutaneous electrolysis for the treatment of patients with tendinopathies.

DATA SOURCES

A systematic search of publications was conducted in Pubmed, Cinahl, Medline, Scopus and Web of Science.

METHODS

The Oxford 2011 Levels of Evidence and the Jadad scale were used to assess the quality of studies. The mean and standard deviation were obtained for each study group and used to calculate the effect size. The DerSimonian and Laird method was used to develop a random-effects model.

RESULTS

Of the 14 articles, four applied percutaneous electrolysis to the knee, three to the shoulder, three to the elbow, two to the hip and two to the ankle and foot. A meta-analysis on intensity of pain (evaluated with algometer and the Visual Analogue Scale) was performed on studies comparing percutaneous electrolysis with a control group, indicating that the groups treated with percutaneous electrolysis had better results (p = 0.01). Although percutaneous electrolysis did not overcome the analgesic effect achieved by corticosteroid injections.

CONCLUSIONS

The percutaneous electrolysis is effective for the treatment of tendinopathies. The combination of this technique with eccentric training has proven to be one of the most effective treatments to date for improving pain. PROSPERO Registration: CRD42021230005.

Cadaveric and Ultrasound Validation of Percutaneous Electrolysis Approach at the Distal Biceps Tendon: A Potential Treatment for Biceps Tendinopathy

Distal biceps brachii tendinopathy is a musculoskeletal pain condition-comprising chronic intrasubstance degeneration with alterations of the tendon structure-that is difficult to treat. Preliminary evidence suggests a positive effect for pain and related disability of percutaneous electrolysis treatment in patients with tendinopathy. Ultrasound is an excellent diagnostic tool to identify tendon injuries, such as tendinopathy, and to guide treatment approaches. Different approaches using ultrasound evaluation of the biceps tendon have been described. Our aim was to determine the validity and safety of a percutaneous electrolysis approach, targeting insertion of the distal tendon of biceps brachii, in both human (ultrasound-guided) and Thiel-embalmed cadaver (not ultrasound-guided) models. There were two approaches evaluated: an anterior approach with the elbow in extension and the forearm in supination and a posterior approach with the elbow in flexion and the forearm in pronation. A needle was inserted following the tendon up to its insertion into the radial tuberosity. The anterior approach, both in cadaveric study and US-guided intervention, revealed a close relationship between the distal biceps tendon and the brachial artery. The mean distance of the depth of the biceps tendon distal to the brachial artery was 0.21 ± 0.021 cm in the cadavers and 0.51 ± 0.024 cm in subjects. It was also found that the anterior approach has a potential technical difficulty due to the anatomical location of the brachial artery. With the posterior approach, it was possible to safely identify the tendon insertion and the needle approach, since no important vascular and nervous structures were visualized in the window of insertion of the needle. The clinician rated the posterior approach as low difficulty in all subjects. Current results would support a posterior approach with US guidance as a safe approach for applying the percutaneous electrolysis technique for insertional tendinopathies of the distal biceps brachii tendon. The current study did not assess the effectiveness of the proposed intervention; accordingly, future studies investigating the clinical effectiveness of the proposed intervention are needed.

Application of Percutaneous Needle Electrolysis Does Not Elicit Temperature Changes: An In Vitro Cadaveric Study

Percutaneous needle electrolysis (PNE) consists of the ultrasound-guided application of a galvanic electrical current through a solid filament needle. One proposed therapeutic mechanism for this intervention is a potential thermal effect. The aim of this study was to investigate if the application of PNE induces changes in temperature in different cadaveric musculoskeletal tissues. A repeated measure experimental cadaveric study was designed with 10 cryopreserved knees (5 men, 5 women). Sterile stainless-steel needles of 40 mm length and 0.30 mm caliber were used in this study. An ultrasound-guided needling puncture was performed in the targeted tissue (patellar tendon, infra-patellar fat, and vastus medialis muscle). Additionally, the tip of the needle was placed next to the thermometer sensor at the minimum possible distance without direct contact with it. The temperature differences before and after different applications were measured. The applications were: three applications for 3 s of 3 mA of intensity (3:3:3) when the tendon was the targeted tissue, three applications for 3 s of 1.5 mA of intensity (1.5:3:3) when the fat or muscle was the targeted tissue, and 24 s of 1 mA of intensity (1:24:1) in all tissues. No statistically significant Group*Time interactions were found in any tissue (tendon: F = 0.571, p = 0.459, ŋ2 = 0.03; fat pad: F = 0.093; p = 0.764, ŋ2 = 0.01; muscle: F = 0.681; p = 0.420, ŋ2 = 0.04). Overall, no changes in temperature were observed between both applications in the tendon (3:3:3 vs. 1:24:1) and fat/muscle (1.5:3:3 vs. 1:24:1) tissues. The application of two different percutaneous needle electrolysis protocols did not produce appreciable thermal changes in the tendon, fat, and muscle tissues of human cadavers. The results from the current cadaver study support that a thermal effect should not be considered as a mechanism of clinical action regardless of the targeted human tissue when applying percutaneous needle electrolysis since no changes in temperature after its application were observed.

Job-Related Performance and Quality of Life Benefits in First Responders Given Access to H-Wave® Device Stimulation: A Retrospective Cohort Study

Current chronic pain treatments primarily target symptoms and are often associated with harmful side-effects and complications, while safer non-invasive electrotherapies like H-Wave® device stimulation (HWDS) have been less explored. The goal of this study is to evaluate first responder-reported effects of HWDS on job-related and quality-of-life measures. This is a retrospective cohort study where first responders were surveyed following voluntary use of HWDS regarding participant experience, frequency of use, job-related performance, and quality-of-life. Responses were analyzed using means comparison tests, while bivariate analysis assessed responses associated with HWDS usage. Overall, 92.9% of first responder HWDS users (26/28) reported a positive experience (p < 0.0001), with 82.1% citing pain reduction (p = 0.0013), while 78.6% indicated it would be beneficial to have future device access (p = 0.0046). Participants using H-Wave® were at least six times more likely to report higher rates of benefit (100% vs. 0%, p = 0.022), including pain reduction (91.3% vs. 8.7%, p = 0.021) and improved range-of-motion (93.3% vs. 69.2%, p = 0.044). Spending more time with family was associated with better job performance following frequent HWDS use (50% vs. 8.3%, p = 0.032). Repetitive first responder H-Wave® use, with minimal side effects and easy utilization, resulted in significant pain reduction, improvements in job performance and range-of-motion, and increased time spent with family, resulting in overall positive experiences and health benefits. Level of Evidence: III.

Cadaveric and Ultrasound Validation of Percutaneous Electrolysis Approach at the Achilles Tendon as a Potential Treatment for Achilles Tendinopathy: A Pilot Study

Achilles tendon tendinopathy (AT) is a musculoskeletal condition characterized by pain in the Achilles tendon and impaired physical performance or sport activities. AT is difficult to treat, and the results are variable. Preliminary evidence suggests a positive effect for pain of percutaneous electrolysis in patients with tendinopathy. Our aim was to determine the validity and safety of a percutaneous electrolysis approach targeting the interphase between the Achilles tendon and the Kager's fat with ultrasound imaging in both healthy individuals and on a fresh cadaver model (not ultrasound guiding). A needle was inserted from the medial to the lateral side under the body of the Achilles tendon, just between the tendon and the Kager's triangle, about 5 cm from the insertion of tendon in the calcaneus in 10 healthy volunteers (ultrasound study) and 10 fresh cadaver legs. An accurate needle penetration of the interphase was observed in 100% of the approaches, in both human and cadaveric models. No neurovascular bundle of the sural nerve was pierced in any insertion. The distance from the tip of the needle to the sural nerve was 5.28 ± 0.7 mms in the cadavers and 4.95 ± 0.68 mms in the volunteer subjects, measured in both cases at a distance of 5 cm from the insertion of the Achilles tendon. The results of the current study support that percutaneous electrolysis can be safely performed at the Kager's fat-Achilles tendon interphase if it is US guided. In fact, penetration of the sural nerve was not observed in any needle approach when percutaneous needling electrolysis was performed by an experienced clinician. Future studies investigating the clinical effectiveness of the proposed intervention are needed.

Endogenous Pain Modulation in Response to a Single Session of Percutaneous Electrolysis in Healthy Population: A Double-Blinded Randomized Clinical Trial

The purpose of this double-blinded randomized controlled trial was to investigate whether percutaneous electrolysis (PE) is able to activate endogenous pain modulation and whether its effects are dependent on the dosage of the galvanic current. A total of 54 asymptomatic subjects aged 18–40 years were randomized into three groups, receiving a single ultrasound-guided PE intervention that consisted of a needle insertion on the lateral epicondyle tendon: sham (without electrical current), low-intensity (0.3 mA, 90 s), and high-intensity (three pulses of 3 mA, 3 s). Widespread pressure pain thresholds (PPT), conditioned pain modulation (CPM), and temporal summation (TS) were assessed in the elbow, shoulder, and leg before and immediately after the intervention. Both high and low intensity PE protocols produced an increase in PPT in the shoulder compared to sham (p = 0.031 and p = 0.027). The sham group presented a significant decrease in the CPM (p = 0.006), and this finding was prevented in PE groups (p = 0.043 and p = 0.025). In addition, high-intensity PE decreased TS respect to sham in the elbow (p = 0.047) and both PE groups reduced TS in the leg (p = 0.036 and p = 0.020) without significant differences compared to sham (p = 0.512). Consequently, a single PE intervention modulated pain processing in local and widespread areas, implying an endogenous pain modulation. The pain processing effect was independent of the dosage administrated.

Cadaveric and Ultrasound Validation of Percutaneous Electrolysis Approaches at the Arcade of Frohse: A Potential Treatment for Radial Tunnel Syndrome

Entrapment of the radial nerve at the arcade of Frohse could contribute to symptoms in patients with lateral epicondylalgia or radial tunnel syndrome. Our aim was to determine the validity of applying percutaneous electrolysis, targeting the supinator muscle at the Frohse’s arcade with ultrasound imaging and in a Thiel-embalmed cadaver model (not ultrasound-guiding). Percutaneous electrolysis targeting the supinator muscle was conducted in five healthy volunteers (ultrasound study) and three Thiel-embalmed cadaver forearms. Two approaches, one with the forearm supinated and other with the forearm pronated were conducted. The needle was inserted until the tip reached the interphase of both bellies of the supinator muscle. Accurate needle penetration of the supinator muscle was observed in 100% in both US-imaging and cadaveric studies. No neurovascular bundle of the radial-nerve deep branch was pierced in any insertion. The distance from the tip of the needle to the neurovascular bundle was 15.3 ± 0.6 mm with the forearm supinated, and 11.2 ± 0.6 mm with the forearm pronated. The results of the current study support that percutaneous electrolysis can properly target the supinator muscle with either the forearm in supination or in pronation. In fact, penetration of the neurovascular bundle was not observed in any approach when percutaneous needling electrolysis was performed by an experienced clinician.

Effects of Percutaneous Electrolysis on Endogenous Pain Modulation: A Randomized Controlled Trial Study Protocol

Percutaneous electrolysis consists of the application of a galvanic electrical current throughout an acupuncture needle. It has been previously hypothesized that needling procedures' neurophysiological effects may be related to endogenous pain modulation (EPM). This protocol study describes the design of a double-blind (participant, assessor) randomized controlled trial with the aim to investigate whether percutaneous electrolysis is able to enhance EPM and whether the effect is different between two applications depending on the dosage of the galvanic electrical current. Seventy-two asymptomatic subjects not reporting the presence of pain symptoms the previous 6 months before the study, aged 18-40 years, are randomized into one of four groups: a control group who does not receive any intervention, a needling group who receives a needling intervention without electrical current, a low-intensity percutaneous electrolysis group (0.3 mA × 90 s), and a high-intensity percutaneous electrolysis group (three bouts of 3 mA × 3 s). Needling intervention consists of ultrasound-guided insertion of the needle on the common extensor tendon of the lateral epicondyle. The primary outcome is conditioned pain modulation (CPM), and secondary outcomes include widespread pressure pain sensitivity (pressure pain thresholds (PPT) over the lateral epicondyle, the cervical spine, and the tibialis anterior muscle) and temporal summation (TS). We expected that percutaneous electrolysis would have a greater influence on CPM than an isolated needling procedure and no intervention. In addition, we also postulated that there might be differences in outcome measures depending on the intensity of the electrical current during the percutaneous electrolysis application. This study makes a new contribution to the field of neurophysiological effects of percutaneous electrolysis and needling interventions.