Altered Callosal Morphology and Connectivity in Asymptomatic Carotid Stenosis

Abstract

BackgroundCarotid stenosis, even in the clinically asymptomatic stage, causes cognitive impairment, silent lesions, and hemispheric changes. The corpus callosum (CC) is crucial for hemispheric cortical integration and specialization.PurposeTo examine if CC morphology and connectivity relate to cognitive decline and lesion burden in asymptomatic carotid stenosis (ACS).Study TypeRetrospective, cross‐sectional.Population33 patients with unilaterally severe (70%) ACS and 28 demographically and comorbidity‐matched controls. A publicly available healthy adult lifespan (ages between 18 and 80; n = 483) MRI dataset was also included.Field Strength/SequenceA 3.0 T; T1 MPRAGE and diffusion weighted gradient echo‐planar imaging sequences.AssessmentStructural MRI and multidomain cognitive data were obtained. Midsagittal CC area, circularity, thickness, integrity, and probabilistic tractography were calculated and correlated with cognitive tests and white matter hyperintensity. Fractional anisotropy, mean diffusivity (MD), and radial diffusivity were determined from DTI.Statistical TestsIndependent two‐sample t‐tests, χ2 tests, Mann–Whitney U, locally weighted scatterplot smoothing (LOWESS) curve fit, and Pearson correlation. A P value < 0.05 was considered statistically significant.ResultsPatients with ACS demonstrated significant reductions in callosal area, circularity, and thickness compared to controls. The callosal atrophy was significantly correlated with white matter hyperintensity size (r = −0.629, P < 0.001). Voxel‐wise analysis of diffusion measures in the volumetric CC showed that ACS patients exhibited significantly lower fractional anisotropy and higher MD and radial diffusivity in the genu and splenium of the CC than controls. Further lifespan trajectory analysis showed that although the midsagittal callosal area, circularity, and thickness exhibited age‐related decreases, the values in the ACS patients were significantly lower in all age groups.Data ConclusionMidsagittal callosal atrophy and connectivity reflect the load of silent lesions and the severity of cognitive decline, respectively, suggesting that CC degeneration has potential to serve as an early marker in ACS.Level of Evidence3Technical Efficacy Stage2

Changes of White Matter Integrity and Structural Network Topology in Carotid Stenosis Patients with Vascular Cognitive Impairment

“…Regional correspondingly, they found disruption in the functional connectivity of the default mode network and the frontoparietal network [10]. In addition, Liu et al identi ed signi cantly reduced connectivity in the transcallosal bers linking the orbitofrontal cortex, the dorsolateral prefrontal cortex, and the temporoparieto-occipital regions compared with healthy controls [35]. In this study, we observed discrepancies in the integrity of these structures among CAS patients, which can account for the differences in their cognitive function.…”