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

对健康志愿者（n=38）的4条主要咬肌动脉的血管外观进行了检查。研究了这些动脉的特征以及血流直径、流速和动脉阻力。同时计算对称性指数，评价其病理变化。面横动脉支、咬肌动脉支、上颌动脉支和颈外动脉支的检出率分别为98.7%、21.1%和84.2%。面动脉从下段供给肌肉，根据解剖变异呈现两种形态，即咬肌支（22.4%）和主干本身（77.6%）。健康受试者的血流直径、最大和最小流速、阻力指数（RI）和脉搏指数（PI）均值分别为1.8 mm、24.6 cm/sec、5.1 cm/sec、0.80和2.51。肌肉水肿在低水平收缩时引起疼痛和疲劳起着重要的作用，可以通过超声检查来评估其厚度的增加。虽然水肿与血液的进出平衡有关，但没有关于厚度变化与血流之间关系的数据。用彩色多普勒超声测量30例健康志愿者面部动脉在10%最大收缩力下20分钟的血流速度及厚度变化。厚度和流速变化均在收缩初始阶段达到峰值。最初的厚度变化与面部动脉的速度无关，而运动后立即的厚度变化与面部动脉的速度有很高的相关性。面动脉的速度变化可能取决于对收缩的一般反应和收缩的咬肌的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.