Myofascial Trigger Points Show Spontaneous Needle EMG Activity

摘要

Monopolar needle electromyogram (EMG) was recorded simultaneously from trapezius myofesial trigger points (TrPs) and adjacent nontender fibers (non-TrPs) of the same muscle in normal subjects and in two patient groups, tension headache and flbromyalgia, Sustained spontaneous EMG activity was found in the 1ndash;2 mm nidus of all TrPs, and was absent in non-TrPs. Mean EMG amplitude in the patient groups was significantly greater than in normals. The authors hypothesize that TrPs are caused by sympathetically activated intrafusal contractions.