Data from: Thalamic volume is reduced in cervical and laryngeal dystonias

Background: Dystonia, a debilitating movement disorder characterized by abnormal fixed positions and/or twisting postures, is associated with dysfunction of motor control networks. While gross brain lesions can produce secondary dystonias, advanced neuroimaging techniques have been required to identify network abnormalities in primary dystonias. Prior neuroimaging studies have provided valuable insights into the pathophysiology of dystonia, but few directly assessed the gross volume of motor control regions, and to our knowledge, none identified abnormalities common to multiple types of idiopathic focal dystonia. Methods: We used two gross volumetric segmentation techniques and one voxelwise volumetric technique (voxel based morphometry, VBM) to compare regional volume between matched healthy controls and patients with idiopathic primary focal dystonia (cervical, n = 17, laryngeal, n = 7). We used (1) automated gross volume measures of eight motor control regions using the FreeSurfer analysis package; (2) blinded, anatomist-supervised manual segmentation of the whole thalamus (also gross volume); and (3) voxel based morphometry, which measures local T1-weighted signal intensity and estimates gray matter density or volume at the level of single voxels, for both whole-brain and thalamus. Results: Using both automated and manual gross volumetry, we found a significant volume decrease only in the thalamus in two focal dystonias. Decreases in whole-thalamic volume were independent of head and brain size, laterality of symptoms, and duration. VBM measures did not differ between dystonia and control groups in any motor control region. Conclusions: Reduced thalamic gross volume, detected in two independent analyses, suggests a common anatomical abnormality in cervical dystonia and spasmodic dysphonia. Defining the structural underpinnings of dystonia may require such complementary approaches.背景：肌张力障碍（Dystonia）是一种使人衰弱的运动障碍，以异常固定姿势及/或扭转姿势为特征，与运动控制网络功能异常相关。尽管大体颅脑损伤可引发继发性肌张力障碍，但原发性肌张力障碍的网络异常需借助先进神经影像技术方可识别。既往神经影像学研究为肌张力障碍的病理生理学提供了宝贵见解，但极少有研究直接评估运动控制脑区的大体体积，且据我们所知，尚无研究明确多种特发性局灶性肌张力障碍共有的异常特征。 方法：我们采用两种大体体积分割技术与一种体素级体积分析技术（基于体素的形态测量学，voxel based morphometry, VBM），对比特发性原发性局灶性肌张力障碍患者（颈段肌张力障碍，cervical dystonia，n=17；喉段肌张力障碍，laryngeal dystonia，n=7）与匹配健康对照者的区域体积差异。本研究使用三类分析方法：(1) 借助FreeSurfer分析软件包对8个运动控制脑区开展自动化大体体积测量；(2) 采用盲法设计、经解剖学家监督的全丘脑手动分割（同样属于大体体积测量范畴）；(3) 基于体素的形态测量学，该方法可测量局部T1加权信号强度，并在单体素水平估算灰质密度或体积，分析覆盖全脑与丘脑两个维度。 结果：通过自动化与手动大体体积测量两种方法，我们仅在两类局灶性肌张力障碍患者的丘脑中发现了显著的体积缩减。全丘脑体积缩减与头部及颅脑体积、症状偏侧性以及病程均无关联。VBM测量结果显示，肌张力障碍组与对照组在所有运动控制脑区均无显著差异。 结论：两项独立分析均检测到丘脑大体体积缩减，提示颈段肌张力障碍与痉挛性发声障碍（spasmodic dysphonia）存在共通的解剖学异常。明确肌张力障碍的结构基础或许需要这类互补的研究策略。