From the Departments of Radiology and Radiological Sciences (M.R.J., M.J.D.), Neurological Surgery (D.J.E., P.E.K.), Biostatistics (Y.-C.L., H.K.), Neurology (P.T., P.H., M.J.D.), and Psychiatry (M.J.D.), Vanderbilt University Medical Center, Nashville, TN; Department of Pathophysiology and Transplantation (G.F.) University of Milan, Italy; and Chemical and Physical Biology Program (K.J.P.) and Departments of Electrical Engineering (B.A.L., B.M.D.), Computer Engineering (B.A.L., B.M.D.), Computer Science and Biomedical Engineering (B.A.L., B.M.D.), and Neurology (D.O.C.), Vanderbilt University, Nashville, TN.
Neurology. 2019 Jan 1;92(1):e30-e39. doi: 10.1212/WNL.0000000000006694. Epub 2018 Nov 30.
To assess white matter integrity in patients with essential tremor (ET) and Parkinson disease (PD) with moderate to severe motor impairment.
Sedated participants with ET (n = 57) or PD (n = 99) underwent diffusion tensor imaging (DTI) and fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity values were computed. White matter tracts were defined using 3 well-described atlases. To determine candidate white matter regions that differ between ET and PD groups, a bootstrapping analysis was applied using the least absolute shrinkage and selection operator. Linear regression was applied to assess magnitude and direction of differences in DTI metrics between ET and PD populations in the candidate regions.
Fractional anisotropy values that differentiate ET from PD localize primarily to thalamic and visual-related pathways, while diffusivity differences localized to the cerebellar peduncles. Patients with ET exhibited lower fractional anisotropy values than patients with PD in the lateral geniculate body ( < 0.01), sagittal stratum ( = 0.01), forceps major ( = 0.02), pontine crossing tract ( = 0.03), and retrolenticular internal capsule ( = 0.04). Patients with ET exhibited greater radial diffusivity values than patients with PD in the superior cerebellar peduncle ( < 0.01), middle cerebellar peduncle ( = 0.05), and inferior cerebellar peduncle ( = 0.05).
Regionally, distinctive white matter microstructural values in patients with ET localize to the cerebellar peduncles and thalamo-cortical visual pathways. These findings complement recent functional imaging studies in ET but also extend our understanding of putative physiologic features that account for distinctions between ET and PD.
评估运动障碍程度中重度的特发性震颤（ET）和帕金森病（PD）患者的白质完整性。
镇静状态下的 ET 患者（n=57）或 PD 患者（n=99）接受弥散张量成像（DTI）检查，计算各向异性分数、平均弥散系数、轴向弥散系数和径向弥散系数值。使用 3 个描述良好的图谱定义白质束。为了确定在 ET 和 PD 组之间存在差异的候选白质区域，使用最小绝对值收缩和选择算子（least absolute shrinkage and selection operator，LASSO）进行了自举分析。在候选区域中，线性回归用于评估 ET 和 PD 人群之间 DTI 指标的差异程度和方向。
区分 ET 和 PD 的各向异性分数值主要定位于丘脑和视觉相关通路，而弥散差异定位于小脑脚。与 PD 患者相比，ET 患者的外侧膝状体（lateral geniculate body，LGN）（<0.01）、矢状层（sagittal stratum，SS）（=0.01）、内囊前肢（forceps major，FM）（=0.02）、脑桥交叉束（pontine crossing tract，PCT）（=0.03）和视辐射后内囊（retrolenticular internal capsule，RIC）（=0.04）的各向异性分数值较低。与 PD 患者相比，ET 患者的上小脑脚（superior cerebellar peduncle，SCP）（<0.01）、中小脑脚（middle cerebellar peduncle，MCP）（=0.05）和下小脑脚（inferior cerebellar peduncle，ICP）（=0.05）的径向弥散系数值较大。
在区域上，ET 患者的白质微观结构值的差异定位于小脑脚和丘脑皮质视觉通路。这些发现补充了 ET 患者的近期功能影像学研究结果，也扩展了我们对导致 ET 和 PD 之间区别的潜在生理特征的理解。
