Analyses of mechanism of pain through use of blood flow status evaluated by a color Doppler sonography in masticatory muscles

对38例健康志愿者的咬肌四条主要动脉的血管形态进行了观察。并结合血流内径、血流速度、动脉阻力等指标对这些动脉的形态特征进行了研究。计算对称性指数，评价其病理变化。健康志愿者面横动脉分支、咬肌动脉分支和上颌或颈外动脉分支的检出率分别为98.7%、21.1%和84.2%。下部供血的面动脉按解剖变异分为咬肌支(22.4%)和主干本身(77.6%)两种类型。正常人的平均血流内径为1.8 mm，最大流速为24.6 cm/s，最小流速为5.1 cm/s，阻力指数(RI)为0.80，搏动指数(PI)为2.51。虽然水肿与血液流入和流出的平衡有关，但没有关于厚度变化和血流量之间的关系的数据。用彩色多普勒超声测定了30名健康志愿者面部动脉在10%最大压力收缩20min时的血流速度，并分析了其厚度的变化。厚度和流速变化均在收缩初期达到峰值。最初的厚度变化与面动脉的血流速度没有相关性，而运动后即刻的厚度变化与面动脉的速度有很高的相关性。面动脉的血流速度变化可能既取决于对收缩的一般反应，也取决于收缩的咬肌局部代谢或机械因素。

The vascular appearances were examined for the four main arteries feeding the masseter muscle in healthy volunteers (n=38). The features of these arteries were investigated together with the flow diameter, flow velocities and arterial resistances. The symmetry indices were also calculated to assess their pathological changes. The detection rates of the branch from the transverse facial artery, the masseter artery and the branch from the maxillary or external carotid artery were 98.7 %, 21.1 % and 84.2 % in healthy volunteers, respectively. The facial artery feeding the muscle from the inferior part represented two patterns according to anatomical variant, that is, the masseteric branch (22.4 %) and the main trunk itself (77.6 %). The means of the flow diameter, maximum and minimum velocities, resistive index (RI) and pulsatility index (PI) in healthy subjects were 1.8 mm, 24.6 cm/sec, 5.1 cm/sec, 0.80 and 2.51, respectively.Muscle edema, which can be evaluated as a thickness increment by ultrasonography, plays an important role in provoking pain and fatigue in low-level contraction. Although edema is related to the balance of in- and out-flows of blood, there are no data regarding the relationship between thickness change and blood flow. The blood flow velocities of the facial artery were measured by color Doppler ultrasonography in 30 healthy volunteers during 20 minutes contraction with 10 % of maximum force together with thickness change. Both the thickness and flow velocity changes reached a peak in the initial phase of contraction. The initial change of thickness did not correlate to the velocities of the facial artery, while those immediately after exercise showed a high correlation. The velocity changes of the facial artery might depend on both the general response to the contraction and the local metabolic or mechanical factors in the contracted masseter muscles.