Govender Sendhil, Colebatch James G
Prince of Wales Clinical School and Neuroscience Research Australia, University of New South Wales, Randwick, Sydney, New South Wales , Australia.
J Neurophysiol. 2018 Mar 1;119(3):1045-1056. doi: 10.1152/jn.00695.2017. Epub 2017 Dec 13.
Our object was to investigate the effect of location and phase on the properties of oVEMPs and cVEMPs evoked by two bone conducted (BC) stimuli, 500 Hz and an impulsive stimulus for midline skull sites from Nz to Iz, in normal volunteers. Compressive and rarefactive onset phases were used and the induced linear and rotational accelerations measured. We confirmed our previous finding of marked changes in the polarity of oVEMPs with location. For cVEMPs using the 500Hz stimulus there were few changes with location or phase, but the impulsive stimulus showed clear phase-related changes at several locations, with the shortest latencies occurring with compressive stimuli at AFz and Fz and the largest amplitudes at Iz. For oVEMPs, both stimuli showed clear effects of phase, with the shortest latencies with compressive stimuli at AFz and Fz and with the largest negativity at Oz or Iz. Whereas the effectiveness at Iz is consistent with a role in the linear VOR, the inversion of polarity and shorter latency around AFz and Fz is not and could not be explained by changes in acceleration of the head. The latency for BC 500Hz oVEMPs for AFz was the same as that for air-conducted (AC) stimuli. We suggest that whereas BC stimuli at most sites work through displacement of the otolith membrane, BC oVEMPs evoked at AFz and Fz may work through a direct action on utricular hair cells. Our findings have implications for clinical testing of VEMPs using midline BC stimuli. NEW & NOTEWORTHY We investigated VEMPs evoked from multiple midline skull sites. Large oVEMP responses were obtained with compressive stimuli at Iz, consistent with a role in the linear VOR, but we also showed inversion of polarity and the shortest latency for stimuli given at AFz and Fz. We propose that BC stimuli given at AFz and Fz may have a direct effect on otolith hair cells, whereas at other sites they work through displacement of the otolith membrane.
我们的目的是研究在正常志愿者中，位置和相位对由两种骨传导（BC）刺激（500Hz以及针对从Nz至Iz的中线颅骨部位的脉冲刺激）诱发的眼前庭诱发肌源性电位（oVEMPs）和颈前庭诱发肌源性电位（cVEMPs）特性的影响。使用了压缩起始相位和稀疏起始相位，并测量了诱发的线性和旋转加速度。我们证实了之前关于oVEMPs极性随位置显著变化的发现。对于使用500Hz刺激的cVEMPs，其随位置或相位变化不大，但脉冲刺激在几个位置显示出明显的相位相关变化，在AFz和Fz处压缩刺激的潜伏期最短，在Iz处振幅最大。对于oVEMPs，两种刺激都显示出明显的相位效应，在AFz和Fz处压缩刺激的潜伏期最短，在Oz或Iz处负向最大。虽然在Iz处的有效性与在线性前庭眼反射（VOR）中的作用一致，但AFz和Fz周围极性的反转和较短潜伏期并非如此，也无法用头部加速度的变化来解释。AFz处BC 500Hz oVEMPs的潜伏期与气导（AC）刺激的潜伏期相同。我们认为，虽然大多数部位的BC刺激通过耳石膜的位移起作用，但在AFz和Fz处诱发的BC oVEMPs可能通过对椭圆囊毛细胞的直接作用起作用。我们的发现对使用中线BC刺激进行VEMPs的临床测试具有启示意义。新发现与值得注意之处我们研究了从多个中线颅骨部位诱发的VEMPs。在Iz处压缩刺激获得了较大的oVEMP反应，与在线性VOR中的作用一致，但我们还显示了AFz和Fz处刺激的极性反转和最短潜伏期。我们提出，在AFz和Fz处给予的BC刺激可能对耳石毛细胞有直接作用，而在其他部位它们通过耳石膜的位移起作用。
