School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.
J Appl Physiol (1985). 2012 Aug 15;113(4):532-40. doi: 10.1152/japplphysiol.00100.2012. Epub 2012 Jun 14.
Whiplash injuries are common following rear-end collisions. During such collisions, initially relaxed occupants exhibit brisk, stereotypical muscle responses consisting of postural and startle responses that may contribute to the injury. Using prestimulus inhibition, we sought to determine if the startle response elicited during a rear-end collision contributes to head stabilization or represents a potentially harmful overreaction of the body. Three experiments were performed. In the first two experiments, two groups of 14 subjects were exposed to loud tones (124 dB) preceded by prestimulus tones at either four interstimulus intervals (100-1,000 ms) or five prestimulus intensities (80-124 dB). On the basis of the results of the first two experiments, 20 subjects were exposed to a simulated rear-end collision (peak sled acceleration = 2 g; speed change = 0.75 m/s) preceded by one of the following: no prestimulus tone, a weak tone (85 dB), or a loud tone (105 dB). The prestimulus tones were presented 250 ms before sled acceleration onset. The loud prestimulus tone decreased the amplitude of the sternocleidomastoid (16%) and cervical paraspinal (29%) muscles, and key peak kinematics: head retraction (17%), horizontal head acceleration (23%), and head angular acceleration in extension (23%). No changes in muscle amplitude or kinematics occurred for the weak prestimulus. The reduced muscle and kinematic responses observed with loud tones suggest that the startle response represents an overreaction that increases the kinematics in a way that potentially increases the forces and strains in the neck tissues. We propose that minimizing this overreaction during a car collision may decrease the risk of whiplash injuries.
追尾碰撞后常见挥鞭样损伤。在这类碰撞中，最初松弛的乘员表现出快速、刻板的肌肉反应，包括姿势和惊吓反应，这些反应可能导致损伤。我们采用刺激前抑制，旨在确定追尾碰撞中诱发的惊吓反应是否有助于头部稳定，还是代表身体的潜在有害过度反应。进行了三项实验。在前两项实验中，两组共 14 名受试者分别暴露于响亮的声音（124dB）之前，给予四个刺激间隔（100-1000ms）或五个刺激强度（80-124dB）的前置刺激声。在前两项实验的结果基础上，20 名受试者暴露于模拟追尾碰撞（峰值雪橇加速度=2g；速度变化=0.75m/s）之前，给予以下一种刺激：无前置刺激声、弱刺激声（85dB）或强刺激声（105dB）。前置刺激声在雪橇加速度开始前 250ms 呈现。强前置刺激声降低了胸锁乳突肌（16%）和颈脊柱旁肌（29%）的振幅，以及关键峰值运动学：头部回缩（17%）、头部水平加速度（23%）和头部伸展时的角加速度（23%）。弱前置刺激声未引起肌肉振幅或运动学的变化。强刺激声引起的肌肉和运动学反应减少表明，惊吓反应是一种过度反应，以增加运动学的方式增加颈部组织的力和应变，我们提出在汽车碰撞期间最小化这种过度反应可能降低挥鞭样损伤的风险。
