The myofascial pain syndrome is a chronic pain disorder that is characterized by its physical findings such as trigger points, palpable muscle band, etc.

The local twitch response of palpable muscle band is one of the characteristic physical findings in myofascial pain syndrome but no definite objective method to evaluate the local twitch response is present.

Authors think that the electromyographic evaluation in myofascial pain syndrome is essential because its suggested pathophysiology focuses on the muscle system. Thus we performed electromyographic recordings of local twitch response in myofascial pain syndrome and discussed standardization of the method.

The summary are:

1) The motor unit activity of local twitch response is greater than that of the control subjects, responded to snapping palpation.

2) The difference between patients and control subjects is greater in the superficially located electrode and in the snapping the most tender site of trigger point.

3) We suggest the electromyographic evaluation of local twitch response as a diagnostic tool in myofascial pain syndrome.