Novel Use of Ultrasound Elastography to Quantify Muscle Tissue Changes After Dry Needling of Myofascial Trigger Points in Patients With Chronic Myofascial Pain

J Ultrasound Med. 2015 Dec;34(12):2149-61. doi: 10.7863/ultra.14.08033. Epub 2015 Oct 21.


Objectives: To compare a mechanical heterogeneity index derived from ultrasound vibration elastography with physical findings before and after dry-needling treatment of spontaneously painful active myofascial trigger points in the upper trapezius muscle.

Methods: Forty-eight patients with chronic myofascial pain enrolled in a prospective interventional trial of 3 weekly dry-needling treatments for active myofascial trigger points. Trigger points were evaluated at baseline and at treatment completion using palpation, the pressure-pain threshold, and the mechanical heterogeneity index. Thirty patients were reevaluated at 8 weeks. Trigger points that "responded" changed to tissue that was no longer spontaneously painful, with or without the presence of a palpable nodule. Trigger points that "resolved" changed to tissue without a palpable nodule. The mechanical heterogeneity index was defined as the proportion of the upper trapezius muscle that appeared mechanically stiffer on elastography. Statistical significance for comparisons was determined at P < .05.

Results: Following 3 dry needle treatments, the mechanical heterogeneity index decreased significantly for the 38 myofascial trigger points (79% of 48) that responded to treatment. Among these, the baseline mechanical heterogeneity index was significantly lower for the 13 trigger points (27% of 38) that resolved, but the decrease after 3 dry needle treatments did not reach significance. The pressure-pain threshold improved significantly for both groups. At 8 weeks, the mechanical heterogeneity index decreased significantly for the 22 trigger points (73% of 30) that responded and for the 10 (45% of 22) that resolved. The pressure-pain threshold improvement was significant for trigger points that responded but did not reach significance for resolved trigger points.

Conclusions: The mechanical heterogeneity index identifies changes in muscle tissue properties that correlate with changes in the myofascial trigger point status after dry needling.

Keywords: dry needling; musculoskeletal ultrasound; myofascial pain syndrome; myofascial trigger points; ultrasound elastography.

Publication types

  • Clinical Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Acupuncture Therapy / methods*
  • Adult
  • Chronic Pain / diagnostic imaging*
  • Chronic Pain / physiopathology
  • Chronic Pain / therapy*
  • Elastic Modulus
  • Elasticity Imaging Techniques / methods
  • Facial Pain / diagnostic imaging*
  • Facial Pain / physiopathology
  • Facial Pain / therapy*
  • Female
  • Humans
  • Image Enhancement / methods
  • Image Interpretation, Computer-Assisted / methods
  • Male
  • Muscle, Skeletal / diagnostic imaging*
  • Muscle, Skeletal / physiopathology
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Stress, Mechanical
  • Treatment Outcome