Abstract
BackgroundDystonia, 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.MethodsWe 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.ResultsUsing 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.ConclusionsReduced 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.
Highlights
Dystonia is a neurologic disorder characterized by involuntary, abnormal twisting or deforming movements that lead to painful and debilitating positions and/or postures
Using both automated and manual gross volumetry, we found a significant volume decrease only in the thalamus in two focal dystonias
A prerequisite for the diagnosis of primary dystonia is an absence of pathology on clinical imaging, neuroimaging research has demonstrated numerous subtle structural and/or connectivity abnormalities in dystonia, using measures such as voxel based morphometry (VBM) and diffusion tensor imaging (DTI).[1, 2]
Summary
Dystonia is a neurologic disorder characterized by involuntary, abnormal twisting or deforming movements that lead to painful and debilitating positions and/or postures. Prior morphometry studies that evaluated multiple types of dystonia identified type-specific grey matter abnormalities, but many of these abnormalities were not consistent between and within types. 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
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