Myofascial trigger points show spontaneous needle EMG activity.

Hubbard, D R; Berkoff, G M · Spine (Phila Pa 1976) · 1993

cross_sectional · Level IV

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Abstract

Monopolar needle electromyogram (EMG) was recorded simultaneously from trapezius myofascial trigger points (TrPs) and adjacent nontender fibers (non-TrPs) of the same muscle in normal subjects and in two patient groups, tension headache and fibromyalgia. Sustained spontaneous EMG activity was found in the 1-2 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.

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