Two-Dimensional Ultrasound and Ultrasound Elastography Imaging of Trigger Points in Women with Myofascial Pain Syndrome Treated by Acupuncture and Electroacupuncture

Abstract

Chronic pain has been often associated with myofascial pain syndrome (MPS), which is determined by myofascial trigger points (MTrP). New features have been tested for MTrP diagnosis. The aim of this study was to evaluate two-dimensional ultrasonography (2D US) and ultrasound elastography (UE) images and elastograms of upper trapezius MTrP during electroacupuncture (EA) and acupuncture (AC) treatment. 24 women participated, aged between 20 and 40 years (M ± SD = 27.33 ± 5.05) with a body mass index ranging from 18.03 to 27.59 kg/m2 (22.59 ± 3.11), a regular menstrual cycle, at least one active MTrP at both right (RTPz) and left trapezius (LTPz) and local or referred pain for up to six months. Subjects were randomized into EA and AC treatment groups and the control sham AC (SHAM) group. Intensity of pain was assessed by visual analogue scale; MTrP mean area and strain ratio (SR) by 2D US and UE. A significant decrease of intensity in general, RTPz, and LTPz pain was observed in the EA group (p = 0.027; p < 0.001; p = 0.005, respectively) and in general pain in the AC group (p < 0.001). Decreased MTrP area in RTPz and LTPz were observed in AC (p < 0.001) and EA groups (RTPz, p = 0.003; LTPz, p = 0.005). Post-treatment SR in RTPz and LTPz was lower than pre-treatment in both treatment groups. 2D US and UE effectively characterized MTrP and surrounding tissue, pointing to the possibility of objective confirmation of subjective EA and AC treatment effects.

Monitoring symptom improvements after the treatment of active myofascial trigger points with ultrasound elastography

“…They found a positive correlation between SR and the existing parameters for muscle hardness. Muller et al 27 selected a reference point in an unaffected and normal region of muscle for the SR measurement in their study, which evaluated MTrPs in the trapezius muscle. They suggested that the use of UE may provide objective confirmation of treatment effects.…”

“…The second step was to perform the UE (longitudinal) exam. The examiner used methods described previously in other studies 27 . According to the standardization of the technique by tissue compression and decompression sinusoid visualization, after placing the transducer over marked MTrPs, the practitioners made 6 to 10 rhythmic motion of the transducer on the affected muscles.…”

“…They reported good to excellent intra-examiner and inter-examiner reliability for tendon assessment. Additionally, several studies have assessed muscular tissue using UE 11,27,38,39 .…”

Non-pharmacologic Treatment of Peripheral Nerve Entrapment

“…Comparison of needling cycles and amplitude of bidirectional robotic needle rotation in mouse subcutaneous tissue explants has showed signifi cant effects on fi broblast size [ 11 ]. Subjective and objective improvements in myofascial pain and MTrP characteristics after acupuncture treatment have been shown using 2-D ultrasound and ultrasound elastography [ 8 ]. Further development of objective protocols and outcome measures should improve the ability of studies to show clear results.…”

“…The controllability of the current applied is another strategy to improve objective quantifi cation of acupuncture "dose" [ 92 ]. Electroacupuncture has been shown to be more effective than simple acupuncture for treatment of injury to the superior cluneal nerves [ 93 ] and pain in the head, neck, and/ or upper back [ 8 ].…”