Wuest Sarah, Symons Bruce, Leonard Timothy, Herzog Walter
Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada.
J Manipulative Physiol Ther. 2010 May;33(4):273-8. doi: 10.1016/j.jmpt.2010.03.007.
The purpose of this study was to measure strains in the human vertebral artery (VA) within the cervical transverse foramina and report the first results on the mechanical loading of segments of the VA during spinal manipulation of the cervical spine.
Eight piezoelectric ultrasound crystals of 0.5-mm diameter were sutured into the lumen of the left and right VA of one cadaver. Four hundred-nanosecond ultrasound pulses were sent between the crystals to measure the instantaneous lengths of the VA segments (total segments n = 14) at a frequency of 200 Hz. Vertebral artery engineering strains were then calculated from the instantaneous lengths during cervical spinal range of motion testing, chiropractic cervical spinal manipulation adjustments, and vertebrobasilar insufficiency testing.
The results of this study suggest complex and nonintuitive strain patterns of the VA within the cervical transverse foramina. Consistent (for 2 chiropractors) and repeatable (for 3 repeat measurements for each chiropractor) elongation and shortening of adjacent VA segments were observed simultaneously and could not be explained with a simple model of neck movement. We hypothesized that they were caused by variations in the location and stiffness of the VA fascial attachments to the vertebral foramina and by coupled movements of the cervical vertebrae. However, in agreement with previous work on VA strains proximal and distal to the cervical transverse foramina, strains for cervical spinal manipulations were consistently lower than those obtained for cervical rotation.
Although general conclusions should not be drawn from these preliminary results, the findings of this study suggest that textbook mechanics of the VA may not hold, that VA strains may not be predictable from neck movements alone, and that fascial connections within the transverse foramina and coupled vertebra movements may play a crucial role in VA mechanics during neck manipulation. Furthermore, the engineering strains during cervical spinal manipulations were lower than those obtained during range of motion testing, suggesting that neck manipulations impart stretches on the VA that are well within the normal physiologic range of neck motion.
本研究旨在测量颈椎横突孔内人体椎动脉（VA）的应变，并报告颈椎手法整复过程中椎动脉节段机械负荷的首批结果。
将八颗直径0.5毫米的压电超声晶体缝合到一具尸体左右椎动脉的管腔内。在晶体之间发送400纳秒的超声脉冲，以200赫兹的频率测量椎动脉节段（共14个节段）的瞬时长度。然后在颈椎活动范围测试、整脊颈椎手法调整和椎基底动脉供血不足测试期间，根据瞬时长度计算椎动脉工程应变。
本研究结果表明，颈椎横突孔内椎动脉的应变模式复杂且不符合直觉。同时观察到相邻椎动脉节段一致（针对两名整脊师）且可重复（每位整脊师进行3次重复测量）的伸长和缩短，且无法用简单的颈部运动模型来解释。我们推测，它们是由椎动脉筋膜附着于椎间孔的位置和刚度变化以及颈椎的耦合运动引起的。然而，与先前关于颈椎横突孔近端和远端椎动脉应变的研究一致，颈椎手法整复的应变始终低于颈椎旋转时的应变。
尽管不应从这些初步结果得出一般性结论，但本研究结果表明，教科书中关于椎动脉的力学原理可能不成立，仅根据颈部运动无法预测椎动脉应变，并且横突孔内的筋膜连接和颈椎的耦合运动可能在颈部手法操作过程中椎动脉力学中起关键作用。此外，颈椎手法整复期间的工程应变低于活动范围测试期间的应变，这表明颈部手法操作对椎动脉施加的拉伸完全在颈部运动的正常生理范围内。
