The myofascial trigger point region: correlation between the degree of irritability and the prevalence of endplate noise.
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.


METHODS
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.
Kuan
Ta-Shen
TS
Department of Physical Medicine and Rehabilitation, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Hsieh
Yueh-Ling
YL
Chen
Shu-Min
SM
Chen
Jo-Tong
JT
Yen
Wei-Chang
WC
Hong
Chang-Zern
CZ
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009045:Motor Endplate / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009209:Myofascial Pain Syndromes / Q000503:physiopathology*; D017288:Pain Threshold