Dayan Michael, Olivito G, Molinari M, Cercignani Mara, Bozzali Marco, Leggio M
Funct Neurol. 2016 Oct/Dec;31(4):239-248. doi: 10.11138/fneur/2016.31.4.239.
In recent years the cerebellum has been attributed amore important role in higher-level functions than previously believed. We examined a cohort of patients suffering from cerebellar atrophy resulting in ataxia, with two main objectives: first to investigate which regions of the cerebrum were affected by the cerebellar degeneration, and second to assess whether diffusion magnetic resonance imaging (dMRI) metrics within the medial (MCP) and superior cerebellar peduncle (SCP) - namely fractional anisotropy (FA) and radial diffusivity (RD) - could be used as a biomarker in patients with this condition. Structural and dMRI data of seven patients with cerebellar atrophy (2 with spinocerebellar atrophy type 2, 1 with Friedreich's ataxia, 4 with idiopathic cerebellar ataxia) and no visible cortical lesions or cortical atrophy were investigated with Freesurfer and voxel-based morphometry (VBM) of gray matter (GM) as well as MCP and SCP FA maps. Correlations of MCP and SCP mean FA with ataxia scores and subscores were also evaluated. Freesurfer showed that patients had significantly reduced volume of the thalamus, ventral diencephalon and pallidum. VBM also demonstrated significantly lower local GM volumes in patients, notably in the head of the caudate nucleus, posterior cingulate gyrus and orbitofrontal cortex bilaterally, as well as in Broca's area in the left hemisphere, and a significant increase in RD in the MCP and SCP of both hemispheres. A significant correlation was found between MCP mean FA and total ataxia score (R=-0.7, p=0.03), and subscores for kinetic functions (R=-0.74, p=0.03) and oculomotor disorders (R=-0.70, p=0.04). The regions of the cerebrum found to have significantly lower local GM volumes have been described to be involved in higher-level cerebellar functions such as initiation of voluntary movements, emotional control, memory retrieval and general cognition. Our findings corroborate recent research pointing to a more extensive corticocerebellar system than previously thought. The significant difference in the MCP and SCP dMRI metrics between patients and controls as well as the significant correlation with ataxia total score and subscores support the use of dMRI metrics as an imaging biomarker for cerebellar degeneration and ataxia.
近年来，小脑在高级功能中所起的作用比之前认为的更为重要。我们对一组因小脑萎缩导致共济失调的患者进行了研究，主要有两个目的：一是调查大脑的哪些区域受到小脑退变的影响，二是评估在内侧小脑脚（MCP）和上小脑脚（SCP）内的扩散磁共振成像（dMRI）指标——即分数各向异性（FA）和径向扩散率（RD）——是否可作为这种疾病患者的生物标志物。我们使用Freesurfer和基于体素的灰质形态测量法（VBM）以及MCP和SCP的FA图，对7例小脑萎缩患者（2例2型脊髓小脑萎缩、1例弗里德赖希共济失调、4例特发性小脑共济失调）的结构和dMRI数据进行了研究，这些患者无可见的皮质病变或皮质萎缩。还评估了MCP和SCP平均FA与共济失调评分及子评分的相关性。Freesurfer显示，患者丘脑、腹侧间脑和苍白球的体积显著减小。VBM也显示患者局部灰质体积显著降低，特别是双侧尾状核头部、后扣带回和眶额皮质，以及左半球的布洛卡区，并且双侧MCP和SCP的RD显著增加。发现MCP平均FA与共济失调总分（R = -0.7，p = 0.03）、运动功能子评分（R = -0.74，p = 0.03）和动眼神经障碍子评分（R = -0.70，p = 0.04）之间存在显著相关性。已发现局部灰质体积显著降低的大脑区域参与了诸如自主运动启动、情绪控制、记忆检索和一般认知等高级小脑功能。我们的研究结果证实了最近的研究，即皮质小脑系统比之前认为的更为广泛。患者与对照组之间MCP和SCP的dMRI指标存在显著差异，以及与共济失调总分和子评分的显著相关性，支持将dMRI指标用作小脑退变和共济失调的成像生物标志物。
