Toshihito Katsumura

The Effect of Acupuncture on Muscle Blood Volume and Oxygenation

A considerable number of patients (61.5/1000) who complain of shoulder stiffness visit oriental therapeutic clinics (Journal of Health and Welfare Statistics, 2007). Several studies have shown that acupuncture can be a useful modality for treating pain due to muscle spasms (Lundeberg et al., 1988: Sandberg et al., 2005: Inoue et al., 2006). It is believed that shoulder stiffness is caused primarily by restriction of blood flow to the working muscles where accumulated metabolites appear to activate sympathetic vasoconstrictors. Acupuncture stimulation (AS) is reported to increase local tissue blood flow in animals (Noguchi et al., 1999; Sato et al., 2000; Uchida et al., 2007) and humans (Sakai 2005; Sandberg et al., 2003; Sandberg et al., 2005) and are applicable in therapeutic interventions of shoulder stiffness. The effects of acupuncture include neural, endocrinological, cardiovascular, and immunological functions. Among cardiovascular effects, in particular, acupuncture stimulation elicits enhanced muscle blood flow via peripheral vasodilatation. The enhanced blood flow response induced by acupuncture may be attributable to C-fibre mediated axon reflex (Nishijo et al., 1997) resulting from noxious mechanical stimulation. Conventional invasive techniques for evaluating muscle blood flow have limitations such as a relatively great burden on subjects and tissue destruction that may influence blood flow itself. On the other hands, noninvasive methodologies such as laser Doppler flowmetry and thermography could primarily measure and evaluate superficial skin blood flow response. In vivo near-infrared spectroscopy (NIRS) is a noninvasive technology for measuring muscle blood volume and oxygenation response with a depth of ~2cm from the skin surface (Hamaoka et al., 2007), which is suitable for assessing the effect of acupuncture on deep tissue blood flow and metabolic response. First, we documented in the section 2.1 whether AS would provoke vasodilatation in the trapezius muscle and whether the influence of AS would propagate to a region distant from the stimulation point (spatial distribution of the stimulation). Further, the temporal response at the stimulation onset was also examined. In the section 2.2, we reported the trapezius muscle blood volume and oxygenation in the stimulation region during four different acupuncture techniques, which are popular intervention techniques in Japan.