前庭耳蜗植入（VCI）调制改善中频和高频前庭眼反射（VOR）

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中文摘要

引言： 前庭眼反射（VOR）通过产生补偿性眼动，在头部运动期间稳定凝视。在双侧前庭病（BV）中，前庭功能丧失导致VOR丧失，进而引起视振荡。目前尚无治愈性治疗方法。前庭耳蜗植入（VCI）旨在通过根据头部运动调节对壶腹神经的电刺激来恢复前庭功能。尽管既往研究已证明可部分恢复VOR，但针对不同刺激条件的全面评估仍有限。本研究评估了多种刺激条件对植入最新VCI原型的BV患者VOR增益的影响。
方法： 9例BV患者单侧植入迷路内VCI。使用旋转椅试验（中频域）和视频头脉冲试验（vHIT；高频域）评估VOR反应。评估了五种刺激条件：参考（VI关闭）、仅基线（恒定刺激）、默认（围绕基线的运动调制）、降低基线（围绕阈值水平的运动调制）和增强刺激（最大化调制）。受试者在侧壶腹神经阻滞刺激期间被分为亚组A（峰值眼速，PEV，≥ 30°/s）和亚组B（PEV < 30°/s）。
结果： 6例受试者被归入亚组A。在旋转椅试验中，兴奋性VOR增益在所有测试频率下于调制刺激下均显著增加（p < 0.05），中位增益从0.09-0.20（参考）升至0.82（降低基线）。未观察到抑制性改善。在vHIT中，亚组A在所有半规管平面均显示兴奋性中位增益显著改善（p < 0.005）。水平半规管增益从0.12（参考）改善至0.69（增强），前半规管中位增益高达0.74。后半规管增益改善但仍< 0.60。抑制性增益无变化。亚组B在任何条件下均未显示有意义的增益改善。
讨论： 运动调制刺激增强了在阻滞刺激期间表现出较高PEV的患者的中频和高频兴奋性VOR功能。然而，仅基线刺激无效。降低基线和增强条件显示出最大改善，部分受试者的增益接近功能水平。然而，抑制性反应仍然有限，反映了生理和技术限制。这些发现支持个体化、频率依赖的调制策略，以优化凝视稳定并可能减少日常生活中的视振荡。

英文摘要

INTRODUCTION: The vestibulo-ocular reflex (VOR) stabilizes gaze during head movements by generating compensatory eye movements. In bilateral vestibulopathy (BV), loss of vestibular function leads to loss of VOR and consequently, oscillopsia. Currently, no curative treatment exists. Vestibulocochlear implants (VCI) aim to restore vestibular function by modulating electrical stimulation of the ampullary nerves in response to head motion. Although prior studies have demonstrated partial VOR restoration, a comprehensive evaluation across different stimulation conditions remains limited. This study assessed the effects of multiple stimulation conditions on VOR gain in BV patients implanted with the latest VCI prototype.
METHODS: Nine BV patients were unilaterally implanted with an intralabyrinthine VCI. VOR responses were assessed using rotatory chair testing (mid-frequency domain) and video head impulse testing (vHIT; high-frequency domain). Five stimulation conditions were evaluated: Reference (VI off), Baseline only (constant stimulation), Default (motion modulation around baseline), Lowered baseline (motion modulation around threshold level), and Boosted stimulation (maximized modulation). Subjects were classified into subgroup A (peak eye velocity, PEV, ≥ 30°/s) during lateral ampullary nerve block stimulation and subgroup B (PEV < 30°/s).
RESULTS: Six subjects were classified in subgroup A. In rotatory chair testing, excitatory VOR gain increased significantly under modulated stimulation at all tested frequencies (p < 0.05), with median gains rising from 0.09-0.20 (Reference) to 0.82 (Lowered baseline). No significant inhibitory improvements were observed. In vHIT, subgroup A demonstrated significant excitatory median gain improvements across all canal planes (p < 0.005). Lateral canal gains improved from 0.12 (Reference) to 0.69 (Boosted), and anterior canal median gains up to 0.74. Posterior gains improved but remained < 0.60. Inhibitory gains showed no changes. Subgroup B showed no meaningful gain improvements in any condition.
DISCUSSION: Motion-modulated stimulation enhanced excitatory VOR function at mid- and high frequencies in patients who demonstrated higher PEV during block stimulations. However, baseline stimulation alone was ineffective. Lowered baseline and Boosted conditions showed the largest improvements, with gains approaching functional levels in several subjects. However, inhibitory responses remained limited, reflecting physiological and technical constraints. These findings support individualized, frequency-dependent modulation strategies to optimize gaze stabilization and potentially reduce oscillopsia in daily life.