Effect of head pitch and roll orientations on magnetically induced vertigo.
Effect of head pitch and roll orientations on magnetically induced vertigo.
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DOI：
10.1113/jp271513
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发表时间：
2016-02-15
期刊：
影响因子：
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通讯作者：
Day BL
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文献类型：
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作者：
Mian OS;Li Y;Antunes A;Glover PM;Day BL
仰卧在强磁场中，例如在磁共振成像扫描仪中，可能会引起全身旋转的感觉。解释这一现象的主要假设是洛伦兹力机制作用于前庭内淋巴，从而刺激半规管。该假设预测，全身旋转的感知将取决于现场的头部方向。结果表明，在7 T磁场中静止时，表观全身旋转的方向和幅度受头部方向的影响。这些数据与磁前庭刺激的洛伦兹力假设相一致，并且进一步证明了从头部参考前庭信号到地球参考身体运动的空间转换过程的操作。已知高强度静磁场会诱发眩晕，据信是通过刺激前庭系统。主导假设（洛伦兹力）预测，诱导的眩晕应该取决于磁场相对于头部的方向。在这项研究中，我们研究了静态头部俯仰（-80至+40度; 12名参与者）和滚动（-40至+40度; 11名参与者）对健康人在黑暗中暴露于7 T MRI扫描仪内的静态均匀磁场时所经历的眩晕的定性和定量方面的影响。三名参与者在180度俯仰和滚动方向进行了额外检查。还测量了滚动方向对水平和垂直眼球震颤的影响，发现仅影响垂直分量。当头部俯仰在60度左右伸展时，眩晕最令人不适，当头部俯仰在20度左右屈曲时，眩晕最轻微。眩晕的定量分析集中在在线报告的借助于手持开关的水平面旋转的诱导感知上。头部朝向对这种感知旋转的幅度和方向都有影响。这些数据表明，头部方向和感知之间的正弦关系与空间周期为180度的俯仰和360度的滚动，我们解释是一致的洛伦兹力假设。头部俯仰对眩晕和先前报道的眼球震颤的影响与由共同的前庭信号驱动的两种影响一致。为了解释所有观察到的效应，这个共同信号需要多个半规管的贡献。仰卧在强磁场中，例如在磁共振成像扫描仪中，可能会引起全身旋转的感觉。解释这一现象的主要假设是洛伦兹力机制作用于前庭内淋巴，从而刺激半规管。该假设预测，全身旋转的感知将取决于现场的头部方向。结果表明，在7 T磁场中静止时，表观全身旋转的方向和幅度受头部方向的影响。这些数据与磁前庭刺激的洛伦兹力假设相一致，并且进一步证明了从头部参考前庭信号到地球参考身体运动的空间转换过程的操作。
Lying supine in a strong magnetic field, such as in magnetic resonance imaging scanners, can induce a perception of whole‐body rotation. The leading hypothesis to explain this invokes a Lorentz force mechanism acting on vestibular endolymph that acts to stimulate semicircular canals. The hypothesis predicts that the perception of whole‐body rotation will depend on head orientation in the field. Results showed that the direction and magnitude of apparent whole‐body rotation while stationary in a 7 T magnetic field is influenced by head orientation. The data are compatible with the Lorentz force hypothesis of magnetic vestibular stimulation and furthermore demonstrate the operation of a spatial transformation process from head‐referenced vestibular signals to Earth‐referenced body motion. High strength static magnetic fields are known to induce vertigo, believed to be via stimulation of the vestibular system. The leading hypothesis (Lorentz forces) predicts that the induced vertigo should depend on the orientation of the magnetic field relative to the head. In this study we examined the effect of static head pitch (−80 to +40 deg; 12 participants) and roll (−40 to +40 deg; 11 participants) on qualitative and quantitative aspects of vertigo experienced in the dark by healthy humans when exposed to the static uniform magnetic field inside a 7 T MRI scanner. Three participants were additionally examined at 180 deg pitch and roll orientations. The effect of roll orientation on horizontal and vertical nystagmus was also measured and was found to affect only the vertical component. Vertigo was most discomforting when head pitch was around 60 deg extension and was mildest when it was around 20 deg flexion. Quantitative analysis of vertigo focused on the induced perception of horizontal‐plane rotation reported online with the aid of hand‐held switches. Head orientation had effects on both the magnitude and the direction of this perceived rotation. The data suggest sinusoidal relationships between head orientation and perception with spatial periods of 180 deg for pitch and 360 deg for roll, which we explain is consistent with the Lorentz force hypothesis. The effects of head pitch on vertigo and previously reported nystagmus are consistent with both effects being driven by a common vestibular signal. To explain all the observed effects, this common signal requires contributions from multiple semicircular canals. Lying supine in a strong magnetic field, such as in magnetic resonance imaging scanners, can induce a perception of whole‐body rotation. The leading hypothesis to explain this invokes a Lorentz force mechanism acting on vestibular endolymph that acts to stimulate semicircular canals. The hypothesis predicts that the perception of whole‐body rotation will depend on head orientation in the field. Results showed that the direction and magnitude of apparent whole‐body rotation while stationary in a 7 T magnetic field is influenced by head orientation. The data are compatible with the Lorentz force hypothesis of magnetic vestibular stimulation and furthermore demonstrate the operation of a spatial transformation process from head‐referenced vestibular signals to Earth‐referenced body motion.