Writer's cramp is a task-specific dystonia impairing writing and sometimes other fine motor tasks. Neuroimaging studies using manifold designs have shown varying results regarding the nature of changes in the disease. To clarify and extend the knowledge of underlying changes by investigating functional connectivity (FC) in intrinsic connectivity networks with putative sensorimotor function at rest in an increased number of study subjects. Resting-state functional magnetic resonance imaging with independent component analysis was performed in 26/27 writer's cramp patients/healthy controls, and FC within and between resting state networks with putative sensorimotor function was compared. Additionally, voxel-based morphometry was carried out on the subjects' structural images. Patients displayed increased left- and reduced right-hemispheric primary sensorimotor FC in the premotor-parietal network. Mostly bilaterally altered dorsal/ventral premotor FC, as well as altered parietal FC were observed within multiple sensorimotor networks and showed differing network-dependent directionality. Beyond within-network FC changes and reduced right cerebellar grey matter volume in the structural analysis, the positive between-network FC of the cerebellar network and the basal ganglia network was reduced. Abnormal resting-state FC in multiple networks with putative sensorimotor function may act as basis of preexisting observations made during task-related neuroimaging. Further, altered connectivity between the cerebellar and basal ganglia network underlines the important role of these structures in the disease.
Background: For patients with acute vessel occlusions of the anterior circulation histopathology of retrieved cerebral thrombi has been reported to be associated to stroke etiology. Due to the relatively small incidence of posterior circulation stroke, exclusive histopathologic analyses are missing for this subgroup. The aim of the study was to investigate thrombus histology for patients with basilar artery occlusions and uncover differences to anterior circulation clots with respect to underlying etiology. Methods: A total of 59 basilar thrombi were collected during intracranial mechanical recanalization and quantitatively analyzed in terms of their relative fractions of the main constituents, e.g. fibrin/platelets (F/P), red (RBC) and white blood cells (WBC). Data were compared to histopathological analyses of 122 thrombi of the anterior circulation with respect to underlying pathogenesis. Results: The composition of basilar thrombi differed significantly to thrombi of the anterior circulation with an overall higher RBC amount (median fraction in % (interquartile range):0.48 (0.37–0.69) vs. 0.37 (0.28–0.50), p < 0.001) and lower F/P count (0.45 (0.21–0.58) vs. 0.57 (0.44–0.66), p < 0.001). Basilar thrombi composition did not differ between the different etiological stroke subgroups. Conclusion: The results depict a differing thrombus composition of basilar thrombi in comparison to anterior circulation clots with an overall higher amount of RBC. This may reflect different pathophysiologic processes between anterior and posterior circulation thrombogenesis, e.g. a larger proportion of appositional thrombus growth in the posterior circulation.