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Abstract
Introduction Myofascial pain syndrome (MPS), especially in the neck and shoulder region, is one of the most common chronic pain disorders worldwide. Dry needling (DN) and pulsed radiofrequency (PRF) are the two effective methods for treating MPS. We aimed to compare the effects of DN and PRF in chronic neck and shoulder MPS patients.
Methods and analysis This is a prospective, single-centre, randomised, controlled trial in a tertiary hospital. We plan to recruit 108 patients aged 18–70 years who are diagnosed with chronic MPS in the neck, shoulder and upper back regions and randomly allocate them to either the DN or PRF group at a 1:1 ratio. The DN group will receive ultrasound-guided intramuscular and interfascial DN 8–10 times per pain point or until local twitch responses are no longer elicited and 30 min of indwelling. The PRF group will receive ultrasound-guided intramuscular (0.9% saline 2 mL, 42℃, 2 Hz, 2 min) and interfascial (0.9% saline 5 mL, 42℃, 2 Hz, 2 min) PRF. Follow-up will be performed by the research assistant at 0, 1, 3 and 6 months postoperatively. The primary outcome is the postoperative 6-month pain visual analogue score (0–100 mm). Secondary outcomes include pressure pain threshold measured by an algometer, Neck Disability Index, depression (Patient Health Questionnaire-9), anxiety (Generalised Anxiety Disorder-7), sleep status (Likert scale) and overall quality of life (36-Item Short Form Survey). Between-group comparisons will be analysed using either a non-parametric test or a mixed effects linear model.
Ethics and dissemination This study was approved by the medical ethics committee of Peking Union Medical College Hospital (JS-3399). All participants will give written informed consent before participation. The results from this study will be shared at conferences and disseminated in international journals.
Trial registration number NCT 05637047, Pre-results.
- PAIN MANAGEMENT
- Musculoskeletal disorders
- REHABILITATION MEDICINE
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STRENGTHS AND LIMITATIONS OF THIS STUDY
This is a prospective, randomised controlled clinical trial.
This study will compare the treatment effects of ultrasound-guided pulsed radiofrequency and dry needling (DN) in myofascial pain syndrome (MPS) patients. To the best of our knowledge, we have not identified any similar study.
This study has a 6-month follow-up period. In addition to pain, patients’ neck function, depression, anxiety, sleep and overall quality of life will also be evaluated and reported.
Findings from the study may provide more evidence to guide clinical practice in MPS patients.
The study results may not be applicable to radiofrequency ablation or DN treatment using other parameters.
Introduction
Background and rationale
Myofascial pain syndrome (MPS) is the leading cause of chronic and persistent regional pain, affecting as many as 85% of the general population.1 2 The neck and shoulder are some of the most commonly involved pain regions and are the leading causes of disability worldwide.3 4 The exact mechanism of MPS has not been fully illustrated. However, existing studies have suggested that muscle overuse or trauma, ergonomic and structural factors and psychological stress might be potential causes or triggers of this disorder.1
A variety of treatment methods for MPS have been investigated, including injection of saline, local anaesthetics and/or steroids, dry needling (DN), mini-scalpel, rich platelet plasma injection, and pulsed radiofrequency (PRF). Among these methods, ultrasound-guided DN and PRF of the pain region have been considered two effective and promising treatments for MPS.5 6
DN is the insertion of a thin needle into a muscle pain region to alleviate pain. The exact analgesic mechanisms have not been unravelled, but it is hypothesised that DN may increase endplate discharge and local blood flow, reduce spontaneous electrical activities and acetylcholine stores, and change the release of descending inhibitory neurotransmitters as well as the central and peripheral sensitisation process.7–9 Cerezo-Téllez et al’s study on 130 non-specific neck pain patients showed that DN can effectively reduce pain intensity, mechanical hyperalgesia, neck active angle of motion and muscle strength at 1, 3 and 6 months postoperatively.6 Several meta-analysis results also supported the use of DN, especially deep DN, in the management of chronic MPS.10–12 Cagnie et al reviewed 15 randomised controlled trials including approximately 800 patients and concluded that there was a strong evidence for DN to have a positive effect on pain intensity.10 In addition, the use of ultrasonography further improves procedural safety and accuracy.5 13 However, DN is not an all-around treatment method. There were still some patients who did not respond well to it14 15 and were in request of new therapies.
PRF is an important and effective interventional treatment for chronic neuropathic pain disorders. It generates an electromagnetic field in the pain region that acts on several biological pathways, including ion channels, neurotransmitters, postsynaptic receptors and immune activities,16 thus eliciting a neuromodulation effect.17 Recent studies have reported that ultrasound-guided PRF might also be a promising treatment for chronic MPS.18–21 Niraj administered PRF and steroid injections to 12 patients with abdominal rectus muscle pain. At the 6-month postoperative follow-up, 8 patients had 50% pain relief.18 Cho et al compared the analgesic effects of interfascial PRF (42°C, 5 Hz, 55 V) and local anaesthetic (0.6% lidocaine 10 mL) injection in trapezius and rhomboid muscle pain patients, and the results showed that the pain visual analogue score (VAS) of the PRF group was lower than that of the local anaesthetic injection group at 4 and 8 weeks postoperatively.21 Park et al compared the analgesic effects of interfascial PRF and local anaesthetic injection on gastrocnemius and soleus muscle pain patients, and the results showed that the pain intensity and physical and mental component summary scores were better in the PRF group than in the injection group.22 However, both studies performed treatment only once and followed the patients for only 2 months. MPS always requires multiple sessions of continuous treatment and long-term management.23 To date, there are currently a lack of high-quality studies on the treatment effects of PRF in MPS patients, and it is also unknown whether PRF can exhibit a superior analgesic effect to DN. Since placebo/sham comparison of each individual intervention provides only limited information, we decided to design a parallel study comparing the two interventions together.
Objectives
This study aims to compare the treatment effects of ultrasound-guided PRF and DN in chronic MPS patients. We hypothesised that at the 6-month postoperative follow-up, the pain VAS of patients undergoing PRF would be lower than that of patients undergoing DN, and the differences in pain VAS between the PRF and DN groups would be statistically significant.
Methods and analysis
Trial design and study setting
This is a parallel, randomised, equivalence trial that will be conducted at the Peking Union Medical College Hospital in Beijing, China. The proposed trial was designed by following the SPIRIT guidelines (online supplemental file 2) and approved by the institutional review board (JS-3399). We will report it in accordance with the guidelines of the Consolidated Standards of Reporting Trials. The planned start and end dates of the study are 1 September 2023 and 1 June 2025, respectively.
Supplemental material
Eligible criteria
Participants must meet all the following criteria for inclusion:
Aged between 18 and 70 years old.
Chronic (>3 months) MPS in the neck, shoulder and upper back region.
MPS will be diagnosed based on Simons and Travell’s criteria: taut band palpable, exquisite spot tenderness of a nodule in a taut band, patient’s recognition of current pain complaint by pressure on the tender nodule and painful limit to full stretch range of motion.6 24
Have at least a pain VAS Score of 40 mm; thus, a minimal clinically significant change is detectable.25
Participants must meet at least one of the following criteria for exclusion:
History of receiving DN or PRF treatment or currently undergoing other pain-related treatments (acupuncture, laser, infrared therapy, etc).
Presence or history of trauma, surgery or infection in the pain region.
Current or history of taking moderate-to-strong analgesics, such as tramadol and morphine.
Severe systemic disease (eg, severe hepatic or renal dysfunction), coagulopathy or medications affecting the coagulation system.
Allergy to medications used.
Pregnancy, psychiatric disease, medical background, inability to cooperate or refusal to participate.
Participants who meet the following criteria will be withdrawn from the study.
Unwilling to continue participation or unable to follow the treatment plan.
Unable to obtain the primary outcome data due to any reason.
Interventions
The workflow of this trial is described in figure 1. Patients from the pain clinics of the study hospital will be screened for eligibility. After obtaining informed consent, all participants will complete the baseline assessment form and be randomised to either the DN or PRF group before treatment.
Flowchart of the study protocol. LTR: local twitch response. NS, normal saline.
Pretreatment assessment
Baseline assessments, including participants’ demographics, clinical data and questionnaire answers, will be collected using a digital healthcare system. Demographic data included age, sex, body mass index, occupation and educational level. Clinical data included sites, duration and characteristics of pain, pain degree measured by VAS, Neck Disability Index (NDI), depression measured by the Patient Health Questionnaire-9 (PHQ-9) Scale, anxiety measured by the Generalised Anxiety Disorder-7 (GAD-7) Scale, sleep status measured by the Likert scale and overall quality of life measured by the health-related quality-of-life questionnaire (36-Item Short Form Survey (SF-36)).
Prepare
The whole procedure will be performed in a standard operating room with qualified disinfection and surgical kits, an ultrasound machine (Sonosite X-port, USA) and a PRF machine (R-2000B A1 Beiqi Corp, China). A certified pain clinician with 3 years of fellowship training and 5 years of independent clinical practice experience will provide treatment for all participants with assistance from a pain nurse with more than 10 years of nursing experience.
After putting the patient in the prone position on the operating table with vital signs monitored, the pain clinician will palpate the patient and mark the pain regions with ‘×------×’. The pressure pain threshold will be measured at the centre of the marked pain region using an algometer with a probe area of 1 cm2. The algometer will be applied perpendicular to the tissue at a constant rate of approximately 30 kPa/s. A 30 s resting period will be allowed between each measure to avoid temporal summation, and the average of three trials will be calculated and recorded as the final results. Then, patients will be sterilised and draped using a standard fashion; thus, the whole procedure can only be felt but not seen by the patient.
Both interventions will be performed under real-time ultrasound guidance (Sonosite X-port, USA) with the transducer covered by sterilised protective bags. A linear transducer will be placed on the marked pain region to identify the musculoskeletal structures, including the superficial and deep muscle layers, as well as the fascia. The ultrasound parameters will be set as follows: linear transducer 4–13 Hz, musculoskeletal general mode, target depth 3–5 cm, medium brightness.
Pulsed radiofrequency
After using ultrasound to identify the muscle and fascia of the pain region, a radiofrequency cannula (20G, Inomed Corp, German) will be inserted into the previously marked pain region under real-time ultrasound guidance. PRF will be performed both in the superficial (trapezius muscle, supraspinatus muscle) and deep (splenius capitis, rhomboid muscle, levator scapulae) muscle layers, as well as in the fascia between the two layers. Intramuscular PRF will be performed after injecting 2 mL of 0.9% saline into the muscle using the following parameters: 42°C, 2 Hz, 2 min. Interfascial PRF will be performed after injecting 5 mL of 0.9% saline into the fascia layers using the following parameters: 42°C, 2 Hz, 6 min. After PRF, the cannula will be extracted, and the wound will be covered with sterilised cotton.
Dry needling
After using ultrasound to identify the muscle and fascia of the pain region, a thin acupuncture needle (0.03 mm, 60–100 mm, Chengzhen Corp, China) will be inserted into the previously marked pain region under real-time ultrasound guidance. Then, rapid insertion of the needle in and out of the pain point will be performed in a way similar to Hong’s fast-in and fast-out technique.26 Based on previous study experiences, DN will be performed either until local twitch responses are no longer elicited or 8–10 times per pain point and indwelled for 30 min.23 27 28 Then, the needle will be extracted, and haemostatic compression will be applied on the needled muscle.
Follow-up
Both PRF and DN will be repeated every week for a total of four times. Follow-up will be completed during an outpatient visit by an experienced clinician blinded to group allocation at 0, 1, 3 and 6 months after cessation of the treatment programme.
Outcomes
The primary outcome is patients’ pain VAS at the 6-month postoperative follow-up. The pain VAS measures pain intensity on a line of 100 mm, with 0 mm indicating no pain and 100 mm indicating the worst imaginable pain.25
Secondary outcomes include pressure pain threshold measured by an algometer, depression measured by the PHQ-9, anxiety measured by the GAD-7 Scale, NDI Scale, sleep quality measured by the Likert scale and overall quality of life measured by the health-related quality-of-life (SF-36) scale. All scales provided to participants will be corresponding validated Chinese versions.29–31
Participant timeline
The participant timeline is listed in table 1. The recruitment and baseline assessment will last for 1 week. The intervention period will last for 4 weeks, starting after the baseline assessment. The follow-up period will last 6 months, starting at the end of the intervention period. Patients will be asked to measure the pressure pain threshold and complete questionnaires during follow-up visits at 0, 1, 3 and 6 months after the intervention period.
Schedule of enrolment, interventions and assessments
Sample size
The sample size was calculated based on a null hypothesis of the primary outcome, pain VAS at 6 months postoperatively. According to prior study and our pilot study experiences, the pain VAS after DN and PRF treatment was 38±15 mm and 26±18 mm, respectively.5 Assuming an α of 0.05 and β of 0.9, 42 patients will be needed in each group to detect significant differences. Accounting for a 20% dropout rate, a total of 108 patients will be recruited.
Recruitment
All patients visiting the pain clinics of the study hospital can be invited by clinicians to participate in this trial. These patients will be informed of the trial by the clinicians. If a patient intends to participate, the research team will be contacted to provide further information on the trial. If a patient confirms participation, eligibility will be checked, and informed consent will be signed. After completion of the baseline assessment, randomisation will be performed by a research member, and the clinician responsible for the patient’s treatment will be informed of the randomisation result.
Allocation
Participants will be randomly allocated to either PRF or DN groups at a 1:1 ratio by a research member based on a computer-generated randomisation result. According to a pregenerated random sequence, each enrolled patient will be given a sealed opaque envelope based on the order of enrolment. After the patient has been sterilised, a pain nurse will open the sealed envelope and assign the patient to the corresponding group according to the random number in the envelope, and an experienced clinician will perform the corresponding treatment on the patient.
Blinding
The clinician responsible for participants’ treatment will not be blinded to group allocation. The researchers responsible for postoperative follow-up and statistical analysis will be blinded to group allocation. The pain clinician will try his or her best to blind the patients as much as possible during treatment. For instance, a patient will be asked to lie in the prone position and covered with sterilised drapes so that the whole treatment procedure can only be felt but not seen by the patient. A research assistant will broadcast the sound of PRF during DN treatment to simulate similar scenarios. The adequacy of blinding will be tested after completion of the treatment by asking the participants to guess whether they received DN or PRF. The questionnaire will have seven choices: certainly DN, certainly PRF, probably DN, probably PRF, possibly DN, possibly PRF and do not know. Unblinding will be carried out after completion of the statistical analysis. Participants who select ‘certainly’, ‘probably’, ‘possibly’ and are correct about the answer are considered correct.
Data collection
After signing informed consent, a dedicated research member will guide the participants in completing the baseline assessment. Subsequently, the participants will be randomised to one of the two intervention groups. Participants will be asked to complete follow-up assessments during outpatient clinic revisits at 0, 1, 3 and 6 months after completion of the entire treatment programme. If a participant does not show up during the revisit, a telephone call will be made to remind the participant. All questionnaires can also be sent as online links to participants via short messages.
Data management
Data will be managed using a digital healthcare system. A unique code will be allocated to each participant and recorded on trial documents, except for informed consent and contact details. The identifiable data of each participant will be stored separately and securely from other study data.
Statistical methods
Statistical analysis will follow the intention-to-treat principle. Based on previous studies and our clinical experiences, the postoperative 6-month pain VAS will have a highly skewed distribution; hence, the primary outcome, the postoperative 6-month pain VAS, will be analysed using the Mann-Whitney U test. Median difference with 95% CI will be reported as effect size using Hodges-Lehmann’s method. Secondary outcomes, including pain, psychological, sleep and life quality scale scores at different postoperative time points, will be analysed using the mixed effects linear model, in which the outcome measure will be regressed against the fixed-effect group allocation, categorial time points and interaction between group allocation and time. A random effects intercept will be included in the model without any random effects slope, and autoaggressive 1 will be used as the covariance structure. The marginal group difference with a 95% CI estimated by the mixed effects model will be used as the effect size for secondary outcomes.
If missing data occurred in the primary outcome, the last observation carried forward method was used for data imputation. A complete case dataset without any imputation will be used in the secondary outcomes. No adjustment for multiplicity will be conducted among different secondary outcomes; hence, relevant findings will be interpreted only as exploratory results. Data analysis will be conducted in Statistical Package for the Social Sciences V.23.0. A two-sided p value less than 0.05 was regarded as statistically significant.
Data monitoring and auditing
Data monitoring will be performed once per year by independent monitors. No data monitoring committee will be assigned to this study, since the risks of interventions are relatively low and the study period is short. Trial conduct and data integrity will also be audited once a year by independent auditors. We plan to perform an interim analysis after half of the patients are included. The sponsors and researchers will have access to these interim results and make the final decision of whether to continue or terminate the trial.
Harms
Adverse events will be reported by participant self-report questionnaires. The pain clinicians responsible for patient treatment will be asked to report serious adverse events to the research team. The research team will report these adverse events to the ethics committee.
Patient and public involvement
Before study design, MPS patients who recently visited the hospital pain clinics were contacted to participate in the research patient panel and provide opinions on the research question, outcome measures, burden of intervention, as well as their experiences and preferences. These patients can comment on the study design and help disseminate the final results, but they will not be involved in the recruitment or conduct of the study.
Ethics and dissemination
This study was approved by the ethics committee of Peking Union Medical College Hospital (JS-3399), was registered at Clinicaltrials.gov (NCT 05637047) and will adhere to the Declaration of Helsinki. Protocol modifications will require a formal amendment to the protocol with agreement from the project management committee (JW, YZ, XC, LS) and updates in the trial registry (Clinicaltrials.gov). Then, a research member will inform the participants. Participants have the right to withdraw from the study at any time. The researchers can also discontinue treatment for a participant’s best interest (eg, severe adverse events). All changes in the participant’s intervention will be recorded in detail in the case report form. All participants will be given detailed information about the trial by a research member, and reflection time will be given before signing informed consent (online supplemental file 1), which will be requested before participation. Participant confidentiality will be ensured according to laws and regulations. Participants’ data will be maintained in secure storage at the coordinating centre for 5 years after completion of the study.
Supplemental material
The primary data can be accessed by a dedicated research member during data collection. After the final dataset is formed from the primary data, dataset access will be limited to statisticians and all authors of the final publication. Patients will be treated during the trial with the best intention. There will be no ancillary or post-trial care. Participants will not receive any compensation from the harm of the treatment beyond the compensation from the National Medicare System if malpractice has taken place. Study results will be disseminated at medical conferences, and we also intend to publish our findings in an international journal. Substantial contributions to the conception or design of the study; acquisition, analysis or interpretation of data; draft or revision of the manuscript will be warranted as author. No professional writers will be invited.
Ethics statements
Patient consent for publication
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
XC and LS contributed equally.
JW and YZ contributed equally.
Contributors JW and XC designed the study. YZ revised the statistical design. JW and YZ drafted the manuscript, and XC and LS revised the manuscript.
Funding The research design is funded by the Beien Funding from the Bethune Charitable Foundation (Grant number: bnmr2021-009) and the National High Level Hospital Clinical Research Funding from the Peking Union Medical College Hospital (Grant number: 2022-PUMCH-B-007). Bethune Charitable Foundation and Peking Union Medical College Hospital are sponsors. They will only be involved in providing financial support for study conduction and will not affect the results of the trial.
Competing interests None declared.
Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods and analysis section for further details.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.