Electroacupuncture on Neck Muscle Stiffness in Chronic Neck Pain

The Hong Kong Polytechnic University66 enrolled

Overview

This randomized, single-blind, placebo-controlled clinical trial aims to investigate the immediate physiological effects of a single session of electroacupuncture (EA) on neck muscle stiffness in individuals with chronic neck pain. While acupuncture is a widely used complementary therapy for musculoskeletal pain, high-quality, objective evidence demonstrating its immediate effects on muscle biomechanics remains limited. This study will utilize Shear Wave Elastography (SWE)-a non-invasive, objective ultrasound-based technology-to measure these changes. Adult participants aged 18 to 65 with non-specific chronic neck pain (lasting ≥ 3 months) will be randomly allocated into one of two groups: 1. True Electroacupuncture (EA) Group: Participants will receive a 20-minute session of active electroacupuncture with comfortable electrical stimulation at specific neck and tender points. 2. Sham Acupuncture (Placebo) Group: Participants will receive a 20-minute session of non-penetrating sham acupuncture with a deactivated electroacupuncture device to ensure participant blinding. The primary objective is to evaluate immediate changes in the stiffness of the upper trapezius muscle, measured objectively via SWE (as Young's Modulus in kPa) before and immediately after the intervention. Secondary objectives include assessing immediate post-treatment changes in subjective pain and stiffness (Visual Analogue Scale), Pressure Pain Threshold (PPT), and active Cervical Range of Motion (CROM), alongside a 7-day post-intervention follow-up questionnaire on neck function.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Interventions

ElectroacupuncturePROCEDURE

A single 20-minute session of electroacupuncture administered by a registered Chinese Medicine Practitioner (\>10 years experience). Sterile single-use needles (0.25 mm × 25 mm or 0.30 mm × 40 mm) inserted at GB21, GB20, BL10, and local Ashi points on the affected upper trapezius to elicit de-qi. Needle pairs connected to a HANS-200A pulse generator delivering continuous asymmetric biphasic square wave at 2 Hz, pulse duration 200 μs, intensity titrated to maximum comfortable tolerance (checked every 5 min). Applied to the more painful/stiffer side; if bilateral and symmetrical, the dominant side is treated.

Sham ElectroacupuncturePROCEDURE

A single 20-minute session using validated Streitberger non-penetrating placebo needles at the same acupoints (GB21, GB20, BL10, Ashi). The blunt-tip needle retracts into the handle upon skin contact without penetrating the skin, secured with adhesive rings. The same HANS-200A device is connected but set to a deactivated mode (blinking lights and sounds active, no electrical current delivered). The practitioner follows an identical protocol and communication script as the EA group, including adjusting the intensity dial on the sham device.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Aged 18-65 years 2. Chronic non-specific neck pain persisting for ≥3 months 3. Average pain intensity ≥3 on a 0-10 Numeric Rating Scale over the past week 4. Pain primarily located in the posterior cervical region, which may radiate to the upper trapezius muscles 5. Able to provide informed consent and sufficient language proficiency to complete questionnaires Exclusion Criteria: 1. Specific pathological causes for neck pain (cervical radiculopathy or myelopathy, fracture, infection, tumour, systemic rheumatic disease) 2. History of neck or shoulder surgery 3. Contraindications to acupuncture (severe needle phobia, bleeding disorders, pregnancy) 4. Received acupuncture or other physical therapy for neck pain within the past 6 months

Outcomes

Primary Outcomes

Upper trapezius shear modulus

Shear modulus (kPa) of the upper trapezius muscle measured by shear-wave elastography (SWE) at the midpoint between C7 spinous process and acromion on the treated side. Mean of 3 consecutive measurements. Young's modulus values divided by 3 to obtain shear modulus.

Time frame: Baseline (pre-intervention) and immediately post-intervention (within 15 minutes after needle removal, following a 5-minute rest period)

Secondary Outcomes

Pain intensity (VAS)

Current neck pain intensity measured using a 100-mm Visual Analogue Scale, anchored "no pain" to "worst pain imaginable."