Piper Steven L, Howarth Samuel J, Triano John, Herzog Walter
Canadian Memorial Chiropractic College, Toronto, Ontario M2H 3J1, Canada.
University of Calgary, Calgary, Alberta T2N 1N4, Canada,.
Clin Biomech (Bristol). 2014 Dec;29(10):1099-107. doi: 10.1016/j.clinbiomech.2014.10.004. Epub 2014 Oct 23.
Spontaneous vertebral artery dissection has significant mortality and morbidity among young adults. Unfortunately, causal mechanisms remain unclear. The purpose of this study was to quantify mechanical strain in the vertebral artery while simultaneously capturing motion analysis data during passive movements of the head and neck relative to the trunk during spinal manipulation and cardinal planes of motion.
Eight piezoelectric crystals (four per vertebral artery) were sutured into the lumen of the left and right vertebral arteries of 3 cadaveric specimens. Strain was then calculated as changes in length between neighboring crystals from a neutral head/neck reference position using ultrasound pulses. Simultaneously, passive motion of the head and neck on the trunk was captured using eight infrared cameras. The instantaneous strain arising in the vertebral artery was correlated with the relative changes in head position.
Strain in the contralateral vertebral artery during passive flexion-rotation compared to that of extension-rotation is variable ([df=32]: -0.61<r<0.55). Peak strain does not coincide with peak angular displacement during spinal manipulation and cardinal planes of motion. Axial rotation displayed the greatest amount of strain. The greatest amount of strain achieved during spinal manipulation was comparably lower than strains achieved during passive end range motions and previously reported failure limits.
The results of this study suggest that vertebral artery strains during head movements including spinal manipulation, do not exceed published failure strains. This study provides new evidence that peak strain in the vertebral artery may not occur at the end range of motion, but rather at some intermediate point during the head and neck motion.
自发性椎动脉夹层在年轻成年人中具有显著的死亡率和发病率。不幸的是，其致病机制仍不清楚。本研究的目的是在脊柱手法操作和基本运动平面过程中，在头部和颈部相对于躯干进行被动运动时，量化椎动脉中的机械应变，同时获取运动分析数据。
将八个压电晶体（每条椎动脉四个）缝合到3个尸体标本的左右椎动脉腔内。然后使用超声脉冲根据中立头/颈参考位置计算相邻晶体之间长度的变化来计算应变。同时，使用八个红外摄像机捕捉头部和颈部在躯干上的被动运动。椎动脉中产生的瞬时应变与头部位置的相对变化相关。
与伸展-旋转相比，被动屈曲-旋转过程中对侧椎动脉的应变是可变的（[自由度=32]：-0.61<r<0.55）。在脊柱手法操作和基本运动平面过程中，峰值应变与峰值角位移不一致。轴向旋转显示出最大量的应变。脊柱手法操作过程中达到的最大应变低于被动终末范围运动过程中达到的应变以及先前报道的失效极限。
本研究结果表明，在包括脊柱手法操作在内的头部运动过程中，椎动脉应变未超过已发表的失效应变。本研究提供了新的证据，表明椎动脉的峰值应变可能并非出现在运动的终末范围，而是出现在头颈部运动的某个中间点。
