PMC3259139_01
Insertion of radiofrequency (RF) needle at the trapezius muscle under ultrasound guided.
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F1
Following sensory stimulation performed at 50 Hz with a potential less than 1V, pulsed RF (PMG230, Baylis medical company Inc, Montreal, Quebec, Canada) treatment was performed two times for each muscle (120 s, 20 ms, 2 Hz, 42C, impedance below 400 ohms) (Fig. 1).