CANVAS患者的 vestibular 功能：定性与定量 vHIT 分析

文献信息

中文摘要

背景/目的： 前庭功能障碍是伴有双等位基因 RFC1 扩增的小脑性共济失调、神经病和前庭反射消失综合征（CANVAS）的重要特征。本研究旨在描述经基因确诊的 CANVAS 患者 vHIT 的定量和定性表现。方法：15 例经基因确诊的 CANVAS 患者接受了临床神经耳科评估，包括水平视频头脉冲试验（vHIT）。定量分析包括前庭眼反射（VOR）增益测量，而定性分析侧重于纠正性扫视的特征，包括数量、峰速度、潜伏期间隔、时间组织和主要代偿模式。探讨了前庭参数、疾病病程与使用共济失调评估与分级量表（SARA）评估的临床严重程度之间的相关性。研究特别关注定量和定性特征。结果：所有患者均表现出双侧前庭功能障碍，VOR 增益显著降低且耳间不对称性普遍较低，证实存在严重且基本对称的前庭功能减退。疾病病程与 VOR 增益呈负相关，与纠正性扫视数量呈正相关。较低的 VOR 增益与较大的纠正性扫视和较宽的潜伏期间隔显著相关，而扫视幅度与潜伏期呈正相关。定性分析显示出一致的主要为显性、时间上分散（非等时）的纠正性扫视模式，没有证据表明存在主要隐性反应或等时聚集。前庭损害与临床严重程度之间的关系存在差异，提示前庭和小脑功能障碍的进展部分独立。结论：在这组经基因确诊的 CANVAS 患者中，观察到严重、双侧且基本对称的前庭功能减退，并伴有主要为显性和时间分散的纠正性扫视模式。水平 vHIT 反应的定性分析可能为传统 VOR 增益测量提供补充信息，并可能有助于更详细地描述 RFC1 相关疾病中的前庭和眼动表现。

英文摘要

Background/Objectives: Vestibular dysfunction is an important feature of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) associated with biallelic RFC1 expansions. This study aimed to characterize both quantitative and qualitative vHIT findings in genetically confirmed CANVAS patients. Methods: Fifteen patients with genetically confirmed CANVAS underwent a clinical neuro-otological assessment including horizontal video Head Impulse Test (vHIT). Quantitative analysis included vestibulo-ocular reflex (VOR) gain measurements, while qualitative analysis focused on corrective saccade characteristics, including number, peak velocity, latency interval, temporal organization, and predominant compensatory pattern. Correlations between vestibular parameters, disease duration, and clinical severity assessed using the Scale for the Assessment and Rating of Ataxia (SARA) were explored. The study specifically focused on the quantitative and qualitative characteristics. Results: All patients exhibited bilateral vestibular dysfunction, with markedly reduced VOR gains and generally low interaural asymmetry, confirming severe and largely symmetric vestibular hypofunction. Disease duration negatively correlated with VOR gain and positively correlated with the number of corrective saccades. Lower VOR gains were significantly associated with larger corrective saccades and wider latency intervals, while saccadic amplitude and latency were positively correlated. Qualitative analysis revealed a consistent pattern of predominantly overt, temporally dispersed (anisochronous) corrective saccades, with no evidence of predominant covert responses or isochronous clustering. The relationship between vestibular impairment and clinical severity was variable, suggesting partially independent progression of vestibular and cerebellar dysfunction. Conclusions: In this cohort of genetically confirmed CANVAS patients, severe, bilateral, and largely symmetric vestibular hypofunction was observed, together with a predominantly overt and temporally dispersed corrective saccade pattern. Qualitative analysis of horizontal vHIT responses may provide complementary information to conventional VOR gain measurements and may contribute to a more detailed characterization of vestibular and oculomotor findings in RFC1-related disease.