Longitudinal Deformation-Based Morphometry Reveals Spatio-Temporal Dynamics of Brain Volume Changes in Patients with Corticobasal Syndrome

Background/Objective: Corticobasal syndrome (CBS) is a rare neurodegenerative disorder characterized by a progressive and asymmetric manifestation of cortical and basal-ganglia symptoms of different origin. The spatio-temporal dynamics of cerebral atrophy in CBS is barely known. This study aimed to longitudinally quantify the individual dynamics of brain volume changes in patients with CBS as compared to healthy controls. Methods: We used deformation-field-based morphometry (DFM) to study volumetric changes of each individual brain in short intervals of a few months. DFM enabled the quantitative analysis of local volume changes without predefining regions of interest in MR images of 6 patients with CBS and 11 matched healthy controls. A total of 64 whole brain 3D-MR-scans were acquired two to eight times over periods of 14 to 26 months. Based on repeated registrations of MR observations to the initial scan, maps of local volume ratio changes were computed. Results: Compared to controls patients showed significant and increasing volume loss over time in premotor and primary-motor-cortices, somatosensory area 3a, superior parietal areas BA 5/7, and corticospinal tract. Furthermore, significant and asymmetric atrophy was identified in the caudate nucleus head, putamen, pallidum, motor-thalamus and substantia nigra. Temporal lobe was affected in those patients who presented progressive cognitive impairment. Conclusions: The analysis revealed localized, pathological changes in brains of patients with CBS, which differed significantly from those occurring during aging in healthy controls. As compared to age- and sex-matched controls, brains of CBS patients showed a common degenerating neural network comprising the motor circuit with basal ganglia and motor thalamic nuclei as well as the premotor and primary-motor-cortex.