Exploratory structural assessment in craniocervical dystonia: Global and differential analyses

Abstract

IntroductionOur goal was to investigate the cortical thickness and subcortical volume in subjects with craniocervical dystonia and its subgroups.MethodsWe studied 49 subjects, 17 with cervical dystonia, 18 with blepharospasm or oromandibular dystonia, and 79 healthy controls. We performed a whole group analysis, followed by a subgroup analysis. We used Freesurfer software to measure cortical thickness, subcortical volume and to perform a primary exploratory analysis in the craniocervical dystonia group, complemented by a region of interest analysis. We also performed a secondary analysis, with data generated from Freesurfer for subgroups, corrected by false discovery rate. We then performed an exploratory generalized linear model with significant areas for the previous steps using clinical features as independent variables.ResultsThe primary exploratory analysis demonstrated atrophy in visual processing regions in craniocervical dystonia. The secondary analysis demonstrated atrophy in motor, sensory, and visual regions in blepharospasm or oromandibular dystonia, as well as in limbic regions in cervical dystonia. Cervical dystonia patients also had greater cortical thickness than blepharospasm or oromandibular dystonia patients in frontal pole and medial orbitofrontal regions. Finally, we observed an association between precuneus, age of onset of dystonia and age at the MRI exam, in craniocervical dystonia; between motor and limbic regions and age at the exam, clinical score and time on botulinum toxin in cervical dystonia and sensory regions and age of onset and time on botulinum toxin in blepharospasm or oromandibular dystonia.ConclusionsWe detected involvement of visual processing regions in craniocervical dystonia, and a pattern of involvement in cervical dystonia and blepharospasm or oromandibular dystonia, including motor, sensory and limbic areas. We also showed an association of cortical thickness atrophy and younger onset age, older age at the MRI exam, higher clinical score and an uncertain association with longer time on botulinum toxin.

Multimodal Quantitative MRI Reveals No Evidence for Tissue Pathology in Idiopathic Cervical Dystonia

“…Previous conventional MRI studies have demonstrated subtle differences in the volume in multiple brain structures in patients with idiopathic dystonia. However, there is little agreement among these studies (10): Increased (12, 13) and decreased GM volume in various brain regions (14–16) or even a combination of both (46–48) have been observed. The discrepancies between these imaging studies seem to suggest that volume changes in idiopathic dystonia are—if present at all—rather small and, thus, difficult to detect in small cohorts.…”

“…However, previous imaging studies in idiopathic dystonia have failed so far to provide a definitive answer as to the presence and localization of morphological abnormalities (10, 11). For instance, an increased gray matter (GM) volume has been observed in the striatum and cerebral cortex in some patient cohorts (12, 13), whereas other studies have reported widespread decreases of GM volume (14–16). Importantly, most previous studies are based on conventional MRI techniques showing mixed signal contrasts, which cannot be easily linked to the underlying microstructural tissue changes.…”

Morphological Abnormalities in the Basal Ganglia of Dystonia Patients

“…Pantano et al [3] describe a volume reduction in the putamen and caudate similar to our data, and Obermann et al [12] also describe a volume reduction in the putamen. However, there are several more recent studies reporting no volumetric difference in the BG at all [7, 13, 14]. Some studies even account of a putaminal volume increase [21, 22].…”

“…They have produced diverging, sometimes even contradicting, results. More recent reports using voxel-based morphometry (VBM) have focused on craniocervical dystonias (CCD) [7-9] and other forms of focal dystonias [10-13]. A majority of these data suggest a volume reduction in the motor, sensory, and visual cortices of the brain’s convexity [3, 10, 13, 14], while also some reports of gray matter increases in these areas exist [15].…”

“…More recent reports using voxel-based morphometry (VBM) have focused on craniocervical dystonias (CCD) [7-9] and other forms of focal dystonias [10-13]. A majority of these data suggest a volume reduction in the motor, sensory, and visual cortices of the brain’s convexity [3, 10, 13, 14], while also some reports of gray matter increases in these areas exist [15]. As concerns the BG, several authors have reported a reduction of putaminal volumes [3, 12], while others could not detect any volumetric changes in the BG [7, 13, 14].…”