Reduced blood flow in fibromyotic muscles during ultrasound therapy

The muscle blood flow (MBF) in m. trapezius was studied in 7 subjects with fibromyotic pain syndrome before and during treatment with ultrasound (1 Watt/cm2) and during placebo treatment, using the local 133Xe-washout technique. MBF in the fibromyotic muscles was significantly reduced during ultrasound treatment (p less than 0.05) compared to the blood flow before the treatment and during placebo treatment 1.57 +/- SEM 0.52 and 2.51 +/- SEM 0.43 ml/100 g/min, respectively. In 6 normal trapezius muscles the mean MBF was 2.30 +/- SEM 0.44 ml/100 g/min before ultrasound treatment and 2.31 +/- SEM 0.41 ml/100 g/min during ultrasound therapy. MBF decreased in a lidocaine blocked fibromyotic muscle during ultrasound treatment while no effect on MBF was detectable during ultrasonic treatment a normal lidocaine pretreated muscle. It is concluded that ultrasound treatment decreases MBF in fibromyotic muscles and that this is paradoxical effect of ultrasound might be due to a direct effect on the vessels or a local release of vasoactive substances in the fibromyotic muscles.