INTRODUCTION There is growing evidence that a proportion of patients with Essential Tremor (ET) may develop a memory impairment over time. However, no studies have evaluated whether hippocampal damage really occur in ET. This study investigated the macro and micro-structural integrity of the hippocampus in ET subjects using a multimodal MRI approach. METHODS Neuropsychological and MRI data were acquired from 110 participants (60 patients with ET and 50 age-, sex-, and education-matched healthy controls [HC]). Whole-brain T1-weighted and Diffusion Tensor Imaging (DTI) were performed to assess macro-and microstructural alterations. MRI parameters (volume; mean diffusivity [MD]; fractional anisotropy [FA]) of bilateral hippocampi were obtained. In order to evaluate the relationship between MRI alterations and neurocognitive impairment, hippocampal parameters were also correlated with cognitive test scores. RESULTS Compared to controls, ET patients showed a subclinical memory impairment with significantly lower memory scores, but within the normal ranges. Despite the subclinical damage, however, ET patients showed a significant increase in MD values in the bilateral hippocampi in comparison with HC. A significant correlation was also found between MD and memory scores in ET. CONCLUSION This study improves the knowledge on memory impairment in ET, as our results demonstrate for the first time the hippocampal microstructural damage related to subclinical memory impairment in ET patients. Further studies are needed before these findings can be considered predictive of a distinct ET subtype or suggestive of a co-occurent dementia.

中文翻译：

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原发性震颤患者的海马损伤。

引言越来越多的证据表明，一定比例的原发性震颤（ET）患者可能会随着时间的推移而发展为记忆障碍。但是，尚无研究评估ET是否确实发生海马损伤。这项研究使用多模式MRI方法研究了ET受试者海马的宏观和微观结构完整性。方法从110名参与者（60名ET患者和50名年龄，性别和教育程度相匹配的健康对照者[HC]）中获得神经心理学和MRI数据。进行全脑T1加权和弥散张量成像（DTI）以评估宏观和微观结构改变。获得了双侧海马的MRI参数（体积；平均扩散率[MD]；分数各向异性[FA]）。为了评估MRI改变与神经认知障碍之间的关系，海马参数也与认知测验分数相关。结果与对照组相比，ET患者表现出亚临床记忆障碍，记忆评分明显降低，但在正常范围内。尽管存在亚临床损害，但是与HC相比，ET患者的双侧海马MD值显着增加。在ET中的MD和记忆分数之间也发现了显着的相关性。结论本研究提高了对ET记忆障碍的认识，因为我们的结果首次证明了与ET患者亚临床记忆障碍相关的海马微结构损伤。在将这些发现视为可预示不同的ET亚型或提示共发性痴呆之前，需要进行进一步的研究。