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The Myofascial Trigger Point Region: Correlation Between the Degree of Irritability and the Prevalence of Endplate Noise

Kuan, Ta-Shen MD, MS; Hsieh, Yueh-Ling PhD, RPT; Chen, Shu-Min MD; Chen, Jo-Tong MD, PhD; Yen, Wei-Chang MD; Hong, Chang-Zern MD

American Journal of Physical Medicine & Rehabilitation: March 2007 - Volume 86 - Issue 3 - pp 183-189
doi: 10.1097/PHM.0b013e3180320ea7
Research Article: Myofascial Pain

Kuan T-S, Hsieh Y-L, Chen S-M, Chen J-T, Yen W-C, Hong C-Z: The myofascial trigger point region: correlation between the degree of irritability and the prevalence of endplate noise. Am J Phys Med Rehabil 2007;86:183–189.

Objective: This study was designed to investigate the correlation between the irritability of the myofascial trigger point (MTrP) and the prevalence of endplate noise (EPN) in the MTrP region of human skeletal muscle.

Design: Twenty normal subjects with latent MTrPs and 12 patients with active MTrPs in the upper trapezius muscles were recruited for this study. The patients reported the subjective pain intensity of the active MTrP (0–10). The MTrP and an adjacent non-MTrP site were confirmed and marked for the measurement of pressure pain threshold (with a pressure algometer) and the prevalence of EPN (with electromyographic recordings).

Results: The prevalence of EPN in the MTrP regions was significantly higher (P < 0.01) in the active MTrPs than in the latent ones. However, no EPN could be found in the non-MTrP region near either the active or the latent MTrPs. The pain intensity and the pressure pain threshold were highly correlated with the prevalence of EPN in the MTrP region (r = 0.742 and −0.716, respectively).

Conclusions: The irritability of an MTrP is highly correlated with the prevalence of EPN in the MTrP region of the upper trapezius muscle. The assessment of EPN prevalence in an MTrP region may be applied to evaluate the irritability of that MTrP.

From the Department of Physical Medicine and Rehabilitation, College of Medicine, National Cheng Kung University, Tainan, Taiwan (T-SK, S-MC, J-TC, W-CY, C-ZH); Department of Physical Therapy, Hungkuang University, Sha-Lu, Taichung, Taiwan (Y-LH, C-ZH); and Department of Rehabilitation Medicine, Han-Ming Hospital, Chang-Hua, Taiwan (C-ZH).

All correspondence and requests for reprints should be addressed to Chang-Zern Hong, MD, Department of Physical Therapy, Hungkuang University, 34 Chung-Chie Road, Sha-Lu, Taichung 433, Taiwan.

No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.

© 2007 Lippincott Williams & Wilkins, Inc.