Ultrasound-GuidedvsNon-GuidedPharmacopunctureforCervicalMyofascialPainSyndrome:AMulti-CenterProspectiveComparativeStudyProtocol

Cervical Myofascial Pain Syndrome (CMPS) is a widespread musculoskeletal condition that causes significant pain and restricts movement, substantially affecting daily life and productivity. In South Korea alone, approximately 7.8 million individuals received treatment for Visual Display Terminal (VDT) Syndrome in 2019, with total medical expenses reaching 824.8 billion KRW. Myofascial Pain Syndrome (MPS) has an estimated lifetime prevalence of up to 85% in the general population and represents a major cause of chronic pain, accounting for 54.6% of chronic head and neck pain cases. When CMPS becomes chronic, it can severely diminish quality of life and lead to considerable disability and economic costs.

The Levator Scapulae muscle shortening is identified as one of the primary causes of this syndrome, potentially leading to movement disorders and muscle deformities. Given these substantial impacts on individuals, families, communities, healthcare systems, and businesses, prompt and effective management of CMPS is essential for reducing the global healthcare burden.

While Ultrasound-Guided Acupuncture (UGA) has gained increasing attention worldwide for its effectiveness and safety, research on Ultrasound-Guided Pharmacopuncture (UGP) specifically remains limited globally. Most existing studies are single-center trials or retrospective analyses lacking large-scale comparative data. Pharmacopuncture combines acupuncture with herbal medicine injection, and this study focuses on Hominis Placenta (HP) solution, which contains bioactive substances including polydeoxyribonucleotides, RNA, DNA, peptides, amino acids, enzymes, trace elements, cell growth factors, interferons, and colony-forming stimulating factors. These components contribute to anti-inflammatory, antiviral, antioxidant, and analgesic effects.

The study targets a specific anatomical region called the "SLS Triangle" — the interfascial space where the Splenius Capitis, Levator Scapulae, and Serratus Posterior Superior muscles intersect — where the Dorsal Scapular Nerve passes and can become compressed.

This study protocol describes a multi-center prospective observational comparative study designed to evaluate the efficacy and safety of Ultrasound-Guided Pharmacopuncture (UGP) compared to Non-Guided Pharmacopuncture (NGP) in patients with acute CMPS. The study will recruit a minimum of 100 patients with acute CMPS (defined as symptom onset within 7 days) from two hospitals and five Korean medicine clinics across South Korea. Participants will be assigned to either the UGP group or the NGP group based on site-based allocation, with each institution recruiting for a different group.

In the UGP group, practitioners use the AcuViz Pocket Ultrasound Device with a magnetic needle tracking system to visualize the SLS Triangle interfascial space in real-time and inject 2 cc of HP solution under direct ultrasound guidance. The needle guidance system can achieve precision of up to ±2 mm. In the NGP group, practitioners locate the SLS Triangle through palpation, apply the ultrasound probe to verify the location without viewing the screen, and then administer the pharmacopuncture treatment without real-time guidance. Both groups receive a single treatment session.

Assessments are conducted before and immediately after the procedure, with a follow-up safety assessment via telephone 24–36 hours post-treatment. Primary outcomes include pain measured by the Numerical Rating Scale (NRS, 0–10), Pressure Pain Threshold (PPT) measured with a digital algometer at bilateral Levator Scapulae and Supraspinatus muscles, and cervical Range of Motion (ROM) including flexion, extension, lateral bending, and rotation. The study was designed as a prospective comparative observational study rather than a randomized controlled trial, intended to calculate effect size for future RCT design.

As this is a study protocol, no actual results are reported. The paper presents the planned methodology and expected outcomes. The authors based their sample size estimation on previous research reporting a minimum clinically important difference (MCID) of 2.17 points for the NRS and a standardized effect size (Cohen's d) of approximately 1.3 when comparing ultrasound-guided acupuncture to non-guided approaches. This effect size exceeds the threshold for a "large effect" (≥0.6).

The study assumes a large effect size for sample size estimation, supporting the adequacy of 100 total participants.

The planned statistical analysis includes two-way mixed ANOVA to examine differences between groups (UGP vs NGP) and across time (pre- and post-procedure), with effect sizes calculated using partial eta-squared. Student's t-tests, Chi-square tests, and Fisher's exact tests are planned as appropriate, with a significance level of p < 0.05. The authors note that outcome assessors will not be blinded to treatment groups due to the real-world clinical setting, though standardized protocols and pre-study training are implemented to minimize bias.

This protocol represents an important step toward establishing evidence for ultrasound-guided pharmacopuncture in acute cervical myofascial pain syndrome. If the study demonstrates positive results, it would provide the first registered multi-center evidence supporting UGP with Hominis Placenta for CMPS, potentially expanding clinical applications in Korean medicine clinics and beyond. The use of a portable ultrasound device with needle tracking technology is particularly noteworthy, as most previous studies have relied on fixed console-type ultrasounds that limit clinical mobility.

For clinicians, this study highlights the potential value of real-time ultrasound visualization for precise interfascial injections, particularly in anatomically complex regions like the SLS Triangle where neurovascular structures including the Dorsal Scapular Nerve and transverse cervical artery branches are at risk. The protocol emphasizes safety advantages of ultrasound guidance in preventing nerve injury and vascular complications compared to blind injection techniques.

However, several limitations in the study design should be considered when interpreting future results. The non-randomized, observational design introduces potential for selection bias. The restrictive 7-day acute phase definition may limit generalizability to patients with longer symptom duration. The single-session treatment with only immediate and 24–36 hour follow-up provides no data on longer-term efficacy.

Patients and clinicians should recognize that this protocol establishes preliminary evidence at best, and more rigorous randomized controlled trials with extended follow-up will be needed to confirm clinical utility.