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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"In 1959, Travell reported that TrPs may have a unique electromyographic signature (Travell, 1959) and in 1966, Arroyo found continuous motor activity only in the region of TrPs (Arroyo, 1966). It is was not until 1993, however, that Hubbard and coworkers confirmed spontaneous electrical activity at TrPs (Hubbard and Berkoff, 1993). Previous efforts to identify such activity had failed mostly because of methodological issues or poor definitions of myofascial pain. "
"Gerwin (2014) provided a comprehensive review of the definition, identification, causative factors, and differential diagnosis of myofascial pain syndrome and the TrP as its central feature. Although objective diagnostic identification is becoming possible using vibration sonoelastography with ultrasound (Sikdar et al., 2009), magnetic resonance elastography (Chen et al., 2008), and electromyography (Hubbard and Berkoff, 1993), clinically the diagnosis of TrPs is made through a thorough history, accurate palpation, presence of referred pain, diminished range of motion, muscle inhibition, and autonomic changes. Additionally, the author provided clinical insights to palpation including manual compression of a TrP for a minimum of 5e10 s to induce referred pain to allow activation of interneurons for central sensitization. "
"Presumably this aspect of the parasympathetic efferent system is strengthened with HRVB training. This may be at play in inhibiting sympathetic output to myofascial trigger points (Hubbard and Berkoff, 1993; Gevirtz et al., 1996; Hubbard, 1998). The work of the Aziz group in London (Hobson et al., 2008) has also demonstrated that slow breathing almost immediately prevents esophageal pain thresholds from dropping dramatically when acid is introduced to the stomach. "
[Show abstract][Hide abstract] ABSTRACT: In recent years there has been substantial support for heart rate variability biofeedback (HRVB) as a treatment for a variety of disorders and for performance enhancement (Gevirtz, 2013). Since conditions as widely varied as asthma and depression seem to respond to this form of cardiorespiratory feedback training, the issue of possible mechanisms becomes more salient. The most supported possible mechanism is the strengthening of homeostasis in the baroreceptor (Vaschillo et al., 2002; Lehrer et al., 2003). Recently, the effect on the vagal afferent pathway to the frontal cortical areas has been proposed. In this article, we review these and other possible mechanisms that might explain the positive effects of HRVB.
Frontiers in Psychology 07/2014; 5:756. DOI:10.3389/fpsyg.2014.00756 · 2.80 Impact Factor