颅骨振动诱发性眼震揭示与vHIT、VEMPs及速度储存相关反应分离的隐藏前庭不对称性：临床-生理学病例系列及时间域假说

文献信息

中文摘要

背景/目的： 颅骨振动诱发性眼震（SVIN）是前庭不对称性的一个稳健体征，但其与脉冲性半规管功能测试、短潜伏期耳石反射及持续性视觉-前庭处理之间的关系仍未完全明确。描述四例临床-生理学病例，其中SVIN相对于半规管、耳石反射及持续域特征占优势或不成比例，并提出对这种生理性不一致的时间域解释。
方法： 四例持续不平衡、发作性眩晕或选择性前庭反射分离的患者接受了多域神经耳科学评估，包括床旁检查、视频头脉冲试验/头脉冲范式（vHIT/HIMP）、在可用时进行抑制头脉冲范式（SHIMP）、颈性和眼性前庭诱发肌源性电位（cVEMPs和oVEMPs）、在可用时进行旋转或冷热试验，以及视动或其他视觉-前庭范式。SVIN通过100 Hz乳突振动诱发，并在可用时描述其方向、维度、刺激部位依赖性、可重复性和慢相速度。
结果： 在半规管和耳石反射结果保留、轻微异常或选择性分离的患者中，SVIN仍具有临床信息价值。反复出现的特征并非所有常规测试均正常，而是振动诱发的眼部反应与半规管、耳石反射或持续域特征之间的生理性不一致。一例患者尽管有异常大的固定方向SVIN，但六半规管vHIT正常且VEMPs对称；另一例表现为选择性cVEMP缺失，而oVEMPs保留且vHIT正常。在青少年病例中，非典型多维SVIN与显著的视动方向不对称共存。
结论： SVIN不能替代vHIT、VEMPs、冷热试验、旋转试验或速度储存相关测试。它应被解释为对振动敏感的前庭失衡的一种独特的锁相探针。不规则传入纤维提供了受支持的生理学框架，而二形传入纤维代表一种合理的、可产生假说的桥接群体，可能促成其他无法解释的临床-生理学分离。

英文摘要

BACKGROUND/OBJECTIVES: Skull vibration-induced nystagmus (SVIN) is a robust sign of vestibular asymmetry, yet its relationship with tests of impulsive canal function, short-latency otolithic reflexes, and sustained visuo-vestibular processing remains incompletely defined. To describe four clinical-physiological cases in which SVIN was dominant or disproportionate relative to the canal, otolithic-reflex, and sustained-domain profiles, and to propose a temporal-domain interpretation of this physiological non-congruence.
METHODS: Four patients with persistent disequilibrium, episodic vertigo, or selective vestibular-reflex dissociation underwent multidomain neuro-otological assessment, including bedside examination, video head impulse test/head impulse paradigm (vHIT/HIMP), suppression head impulse paradigm (SHIMP) when available, cervical and ocular vestibular-evoked myogenic potentials (cVEMPs and oVEMPs), rotatory or caloric testing when available, and optokinetic or other visuo-vestibular paradigms. SVIN was elicited by 100-Hz mastoid vibration and characterized by direction, dimensionality, stimulation-site dependence, reproducibility, and slow-phase velocity when available.
RESULTS: SVIN remained clinically informative across patients with preserved, minimally abnormal, or selectively dissociated canal and otolithic-reflex findings. The recurring feature was not normality of all conventional tests, but physiological non-congruence between the vibration-induced ocular response and the canal, otolithic-reflex, or sustained-domain profile. One patient showed normal six-canal vHIT and symmetric VEMPs despite an exceptionally large fixed-direction SVIN; another showed selective cVEMP absence with preserved oVEMPs and normal vHIT. Atypical multidimensional SVIN coexisted with marked optokinetic directional asymmetry in the adolescent case.
CONCLUSIONS: SVIN is not a surrogate for vHIT, VEMPs, caloric, rotatory, or velocity-storage-related testing. It should be interpreted as a distinct phase-locked probe of vibration-sensitive vestibular imbalance. Irregular afferents provide the supported physiological framework, whereas dimorphic afferents represent a plausible, hypothesis-generating bridge population capable of contributing to otherwise unexplained clinicophysiological dissociations.