Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
Department of Neurology, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
J Neurophysiol. 2019 Jun 1;121(6):2013-2019. doi: 10.1152/jn.00873.2018. Epub 2019 Apr 10.
For many years, people working near strong static magnetic fields of magnetic resonance imaging (MRI) machines have reported dizziness and sensations of vertigo. The discovery a decade ago that a sustained nystagmus can be observed in all humans with an intact labyrinth inside MRI machines led to a possible mechanism: a Lorentz force occurring in the labyrinth from the interactions of normal inner ear ionic currents and the strong static magnetic fields of the MRI machine. Inside an MRI, the Lorentz force acts to induce a constant deflection of the semicircular canal cupula of the superior and lateral semicircular canals. This inner ear stimulation creates a sensation of rotation, and a constant horizontal/torsional nystagmus that can only be observed when visual fixation is removed. Over time, the brain adapts to both the perception of rotation and the nystagmus, with the perception usually diminishing over a few minutes, and the nystagmus persisting at a reduced level for hours. This observation has led to discoveries about how the central vestibular mechanisms adapt to a constant vestibular asymmetry and is a useful model of set-point adaptation or how homeostasis is maintained in response to changes in the internal milieu or the external environment. We review what is known about the effects of stimulation of the vestibular system with high-strength magnetic fields and how the understanding of the mechanism has been refined since it was first proposed. We suggest future ways that magnetic vestibular stimulation might be used to understand vestibular disease and how it might be treated.
多年来，在磁共振成像（MRI）机器强静磁场附近工作的人报告说会出现头晕和眩晕感。十年前的一项发现表明，在 MRI 机器内部完整的迷路中，所有人都可以观察到持续的眼球震颤，这可能是一种机制：洛伦兹力在迷路中产生，是由于内耳离子电流与 MRI 机器的强静磁场相互作用。在 MRI 内部，洛伦兹力作用于诱导上半规管和外半规管的半规管杯状突的恒定偏斜。这种内耳刺激会产生旋转的感觉，以及一种只能在去除视觉固定时才能观察到的恒定水平/扭转眼球震颤。随着时间的推移，大脑会适应旋转感和眼球震颤，通常在几分钟内感知会减弱，而眼球震颤会在较低水平持续数小时。这一观察结果导致了对中枢前庭机制如何适应恒定前庭不对称的发现，这是一种关于设定点适应的有用模型，或者是在内部环境或外部环境发生变化时如何维持体内平衡的模型。我们回顾了关于高强度磁场刺激前庭系统的已知效应，以及自首次提出以来，对该机制的理解是如何得到完善的。我们提出了未来可能使用磁前庭刺激来了解前庭疾病以及如何治疗它的方法。
